The Stickman Store · Insulation
Right then.
Who's asking?
Mrs Jones wants comfort. The builder wants numbers. The QS wants square metres. The architect wants the clause. Stickman made five doors so nobody has to read the wrong sermon.
I'm a Homeowner
My bedroom is a slow cooker, my tiles are rude, and Eskom is becoming a dependant. Take me on the journey.
I'm an Architect
R-values, compliance routes, specs, datasheets, and the sentence that keeps council calm.
I'm a Builder
Give me thickness, area, fixing method, and nobody gets sent a 14-page brochure.
I'm a Quantity Surveyor
I came for square metres, wastage, rates, and the emotional safety of a clean spreadsheet.
Mrs Jones' Department of Things That Should Not Be Hot at 9pm
Your roof is not a braai.
Your bedroom is not the side dish.
Your house holds heat beautifully. That is the complaint.
A guided tour through Mrs Jones' house, where Stickman points at the naughty bits and nobody needs a hard hat. A few quick questions, then the right fix. No lecture, no clipboard, no "just trust me".
Three boards stocked SANS 10400-XA Friendly Closed-cell, closed case
★★★★★
"First summer in 12 years I did not sleep like a rotisserie chicken. Joburg bedroom officially rescued."
— Mrs M., Sandton
★★★★★
"Stickman told me what I needed without making me feel like I had failed physics. No overselling. No confusion."
— Dave T., Pretoria East
★★★★★
"The factory used to feel like a warehouse full of angry kettles. Now the staff have stopped melting."
— Riaan V., Boksburg
Diagnose My House
Tap whichever part of the house is making your life difficult. Stickman will explain why, then point you at the fix.
Things Your Roof Did Not Want Mentioned in Public
Your house holds heat beautifully. That is the complaint. Six small facts, one roof looking nervous.
Decades Proven
Older than many builders' favourite tape measures
None of the materials we stock is new. Extruded polystyrene has been in international use since the 1940s and polyisocyanurate has been in commercial use for over half a century. Both are long established in South African construction. Whichever of the three you pick, you are not the test case.
Mind = Blown
Your roof is the main suspect
In most South African homes the roof is the single largest route for summer heat gain, which is why SANS 10400-XA sets its highest R-value requirement there. Your roof has one job. It is doing one job. Just not that one.
Certified
More paperwork than a municipality queue
Insulation is certified per application, not per brand — a board approved for a ceiling is not automatically approved under a screed. So the question is never "is it certified", it is "is it certified for this job". Between them these boards carry more paperwork than most people trying to open a bank account. Ask us for the current certificate on the board and the application you are looking at. Actual proof, not a brochure wearing a bow tie.
Closed Cell
Water tries. The board shrugs.
Closed-cell means every cell is sealed off from the one beside it, so there is no route for water to travel through the board. All three test under 1% — Summit at under 0.5% by volume, ISOboard at 0.87% by volume, Lambdaboard at under 1% by mass. Somebody submerged the samples and then weighed them. That was the job.
Wide Working Range
From freezer room to Karoo roof, without complaint
ISOboard is rated −30°C to +60°C and Lambdaboard −30°C to +120°C. Either way that is a wider working range than most marriages, and considerably better documented. Worth knowing on the XPS boards: they soften if a heat source above 70°C sits against them, which is why downlight clearances matter. Mrs Jones, understandably, requires more convincing.
Updated 2026
The law has entered the chat
SANS 10400-XA has required thermal insulation in new builds and major renovations since 2011, with the standard now in its third edition (2026) — current zone map, current R-values, current wall rules. Not a luxury. Not a suggestion. Not something council politely ignores.
Stickman Stocks Three. Here They Are.
All three do the same job — keep the heat on the correct side of your ceiling. They just go about it slightly differently, and one of them comes in three colours named like a range of sports cars.
| ISOboard | Lambdaboard | Summit XPS | |
|---|---|---|---|
| What it is | A solid board, the same all the way through | A board with a bonded skin on both faces | A solid board, the same all the way through |
| How thick it comes | 25mm to 80mm | 25mm to 100mm | 30mm to 100mm |
| How well it insulates | 50mm gives R1.91 | 50mm gives R2.08 | 50mm gives R1.67 |
| Board size | 600mm wide, 1.8m to 8m long | 1220mm wide, cut to your length up to 12m | 600mm wide, 1.8m to 8m long |
| If it gets wet | Takes on 0.87% water by volume | Takes on under 1% by mass, and keeps its R-value | Takes on under 0.5% by volume |
| If it meets a flame | Softens and pulls away from the heat. Classified to SANS 428. | Does not melt or drip — it is a thermoset. Class A to external flame. | Shrinks away from the heat. Also classified to SANS 428. |
| Can you leave it on show? | Yes — bevelled edge, paint it or leave it white | Yes — three factory colours, no painting needed | Yes — smooth or pine-groove finishes |
| Painting it | Water-based paint only, on all three. Solvent-based paint damages the board. Two coats of matt acrylic or PVA is the standard. | ||
| Downlights | LED or energy-saver only, and nothing that runs hotter than 70°C against the board. Transformers sit off the board with a 150mm air gap. Tell your installer before they start. | ||
| Paperwork it arrives with | Five Agrément SA certificates, one per application | Fire and toxicity test results — no current Agrément SA certificate | Fire test report — no Agrément SA certificate |
Mrs Jones' short version: if you want the ceiling left visible and colour-matched, Lambdaboard offers White Mineral, Gun Metal Grey and Obsidian Black — three ceiling boards named by somebody who badly wanted to be naming sports cars. It also carries the highest R-value per millimetre of the three, so it does more in less space. ISOboard has the longest paperwork trail. Summit is the plain workhorse. Whichever you pick, phone us with the room size and we will tell you the thickness — that is the part that actually matters.
+ WHERE THESE FACTS COME FROM
Why we show this. Everything above is taken from the manufacturers' own certificates, datasheets and independent test reports. Where a figure could not be verified we have said so rather than filling the gap.
ISOboard: Agrément SA Certificates 2006/323 (nail-up ceilings), 2001/287 (over purlin), 2010/382 (over rafter and truss), 2000/277 (inverted roof) and 2000/276 (cavity wall). R-values from Omega Test House report OTH-T-2204-01B-R1, tested to SANS 8301 on 27 May 2022. Fire classification from FIRELAB report FTC 15/029 to SANS 428, with a SANS 53501-1 assessment by Ignis, October 2024. Product properties from the IsoBoard A4 Properties and Product Information sheets.
Lambdaboard: Lambdaboard Technical Data Sheet 2025 (Rigifoam), supplier data confirmation returned 16 July 2026, and the Lambdaboard safety data sheet. Fire classification to SANS 53501-1 and SANS 53823 from an accredited laboratory; external fire to ASTM E108.
Summit XPS: Summit XPS catalogue, September 2024, and Summit XPS fire test report, July 2024 (report 2023-02), covering SANS 53501-1 and the supporting test standards.
The regulations: SANS 10400-XA, Energy usage in buildings, currently in its third edition. Energy zone boundaries from the CSIR energy demand map.
Honest note: manufacturers occasionally contradict themselves between a certificate and a brochure. Where that happens we quote the certificate and say so, rather than quietly picking the more flattering number. If a figure matters to your project, ask us for the source document and we will send it.
Things to Know Before the Bakkie Reverses In
Small facts before someone says "just order extra".
It contains its own fire
All three behave, but not in the same way. The two XPS boards carry flame-retardant additives and soften and pull away from the heat — the fire rating equivalent of leaving the argument. Lambdaboard is a thermoset, so it does not melt or drip at all, and will not affect sprinklers. All three are classified combustible, which means none of them may be used where the regulations call for non-combustible materials — hotels and hospitals being the usual examples.
You can leave it visible
Bevelled and faced finishes are neat enough to leave exposed and painted, at which point you tell everyone it was always the plan. Two rules if you do: water-based paint only, because solvents damage all three boards, and paint it if it will see sun, because UV degrades an unpainted board over time.
Moisture genuinely bounces off
Closed-cell means every cell is sealed off with no connection to the one next to it. So, an estate. Water looks for a way in and gets politely ignored. The same structure is why the board is rot-proof, carries no food value for vermin, and will not grow mould.
Underfloor heating needs this
Without insulation below the screed you are warming the soil beneath your house. The soil did not ask for this. The soil is not grateful. With insulation the heat goes up, where the humans are.
Long boards mean fewer joins
ISOboard runs to 8m, Summit to 8m, and Lambdaboard is cut to your length up to 12m — longer than most bakkies, most driveways, and every explanation your builder has ever offered. Getting it home is between you and your roof racks.
You do not need to rip the old ceiling out
Board can go up underneath an existing ceiling, or straight onto a concrete soffit — battens go up first, board goes onto those. Less mess, less rubble, and the room stays a room.
A knock in the board is fixable
Dents fill with ordinary Polyfilla mixed with a bonding agent, and a badly damaged board can be swapped out on its own without pulling the whole ceiling apart. It also washes — by hand or with a pressure jet.
It can take a load
Rigid board is established below screeds in residential and light commercial work. ISOboard publishes 160–310 kPa and Summit 310–360 kPa; Lambdaboard does not publish a figure. For heavy-duty or industrial floor loading, ask us for the test data before you commit.
Questions Mrs Jones Asked Before She Let Stickman Near the Ceiling
Tap open. Learn fast. Nod wisely later.
Right. Let's Stop the House Behaving Like a Weather Experiment.
People say insulation is boring. That is the product — nothing happens, and you pay for nothing to happen. Send us the room, roof, wall, or floor drama and Stickman will turn "the ceiling thingy" into a proper quote before Mrs Jones orders another fan.
Builder Fast Lane
Skip the Story.
Get to the Numbers.
Four applications. Three boards. Direct links. Stickman knows you didn't come here for a journey.
Stickman note: a helpful guide to SANS 10400-XA, not a compliance sign-off — check the standard, the drawings and the competent person's assessment.
Find Your Zone, Get Your Numbers
Pick your city. Roof, wall, and floor requirements update below — no flipping between tables.
Three Boards on the Shelf
Two of them are 600mm wide and one is 1220mm, which is the kind of detail that changes a cutting list. Everything you need before you phone through an order.
| ISOboard | Lambdaboard | Summit XPS | |
|---|---|---|---|
| Material | XPS, 100% closed cell, unfaced | PIR thermoset, faced both sides | XPS, closed cell, unfaced |
| Thermal conductivity | k = 0.026 W/m·K | k = 0.024 W/m·K | k = 0.03 W/m·K |
| Thicknesses | 25 / 30 / 40 / 50 / 60 / 70 / 80mm 90mm and 100mm as doubled boards |
25 / 30 / 40 / 50 / 60 / 70 / 80 / 90 / 100mm 5mm steps special order, 14 working days |
30 / 40 / 50mm single 60 / 80 / 100mm as doubled boards 70mm and 90mm on special order — ask us to price no 25mm |
| Board width | 600mm (±2mm) | 1220mm | 600mm |
| Lengths | 1.8m – 8.0m 1.8 / 2.4 / 2.7 / 3.0 / 3.3 / 3.6 / 4.0 / 4.2 / 4.8 / 5.4 / 6.0 / 6.6 / 7.2 / 8.0m |
Cut to length, 2m – 12m Stock: 5.4m / 6m / 8m 10% cutting charge under 2m |
1.8m – 8.0m 1.8 / 2.1 / 2.4 / 2.7 / 3.0 / 3.3 / 3.6 / 4.0 / 4.2 / 4.8 / 5.4 / 6.0 / 6.6 / 7.2 / 8.0m |
| Cutting on site | Sharp knife, hacksaw, fine-tooth saw or hot wire | Handsaw or fine-tooth blade wear a dust mask — PIR dust irritates |
Handsaw or fine-tooth blade wipe with dishwashing liquid first to kill static |
| Ceiling batten spacing | Max 700mm centres | 900mm centres | Max 700mm centres |
| Fixing | Adhesive at 200mm + concealed clips; perimeter screws at 300mm | Drywall fasteners through the board into battens, or concealed clip | Adhesive 5ml drops at 200mm + 3 clips per m²; perimeter screws at 300mm |
| Max purlin span, unsupported | 30mm: 1400mm galv / 1200mm painted 40mm+: 1600mm / 1500mm |
25mm: 1300mm · 30mm: 1400mm · 40mm: 1800mm 50–60mm: 2000mm · 70–90mm: 2200mm |
30mm: 1400mm galv / 1200mm painted 40mm+: 1600mm / 1500mm |
| Density | 32 – 36 kg/m³ | 40 kg/m³ | 35 – 37 kg/m³ |
| Compressive strength | 160 – 310 kPa | Available on request | 310 – 360 kPa |
| Fire classification | SANS 428 B/B1/2/H&V SANS 53501-1 B-s1,d0 |
SANS 53501-1 D-s3,d0 ASTM E108 Class A external SANS 428 report lapsed — ask for current position |
SANS 428 B/B1/2/H&V SANS 53501-1 B-s1,d1 |
| Certification | Agrément SA × 5, one per application | Test reports; NES 713 confined spaces no Agrément SA certificate |
Fire test report; no Agrément SA certificate |
| Finish options | 25–50mm T&G · 60–80mm shiplap · IsoPine grooved | Coated glass facer × 3 colours · aluminium foil facer Decoboard 30mm: rounded edge, 600mm wide |
Smooth or pine T&G · bevel · straight |
| Lead time | Ex stock where available; confirm per order | 2–3 working days ex stock 14 working days if not in stock |
Ex stock where available; confirm per order |
| Our planning rule | We plan 14 working days from 60mm upward on all three where the thickness is not in stock. That is our own scheduling default rather than a supplier guarantee — ask us to confirm against current stock before you commit a date. | ||
Before you order: check the zone requirement above first, then pick the thickness that meets it. Longer boards mean fewer joins on open spans — ISOboard and Summit both reach 8m, Lambdaboard is cut to your length up to 12m and is nearly twice as wide. Two warnings. Want 55mm instead of 50mm? That is Lambdaboard only, and it is fourteen working days — five millimetres, three weeks, and somewhere a factory taking it personally. And on all three, 60mm and above carries the same fourteen days if it is not in stock.
Things That Catch People Out
Details that live in the certificates rather than the brochures — and that turn into a snag list if nobody reads them.
| Detail | What it means on site |
|---|---|
| Slipsheet under roof sheeting | Galvanised and fibre-cement sheets need no slipsheet. Chromadek cladding does — a slipsheet goes between the sheeting and the board. On pierced-fix systems: felt-fibre for residential and commercial, kraft paper for industrial. Get this wrong and the certificate detail is not met. |
| Curved roofs | ISOboard follows a curve, but for radii over 600mm the boards must be pre-grooved to half their thickness at 75mm centres. That is a factory instruction, not a site one — tell us the radius when you order. Summit states it can follow a 5m radius curve. |
| Extending an unsupported span | Where purlin spacing exceeds the span limit, T- or H-sections carry the board. The limits change with thickness — Lambdaboard publishes: 25mm — no section under 1300, T 1400–1800, H 1900–2800 30mm — no section under 1400, T 1500–1800, H 1900–2800 40mm — no section under 1800, T 1900–2100, H 2200–2800 50 and 60mm — no section under 2000, T at 2100, H 2200–2800 70, 80 and 90mm — no section under 2200, T 2300–2500, no H section Sections are 6m lengths, colour matched to White Mineral, made in 30–60mm only. There is no H-section above 60mm, so the thicker boards cannot be carried beyond 2500mm. On ISOboard and Summit, use square-edged board with the tongue removed where sections are fitted. |
| Facing materials void the certificate | ISOboard's Agrément certification excludes use with any other facing material — combustible or non-combustible — unless a satisfactory fire test report exists for that specific combination. Laminating a vinyl facing or slipsheet to the board raises the fire risk and needs the sales office consulted first. Do not assume a certificate travels with a build-up it was never tested in. |
| Coastal condensation | Condensation is unlikely on the underside of the ceiling, but warm humid air permeates the joints and condenses on cold roof sheeting above, then drips and stains. A continuous bead of sealant in the grooved edge during installation largely prevents it. In the Southern Coastal Condensation Problem Area, roof ventilation is required per the certificate supplement. High humidity also risks corrosion on untreated inner faces of sheeting. |
| Repairing damage | Dents and knocks fill with Polyfilla mixed with Alcolin Permabond diluted 1:3, or a compatible non-brittle polymer filler. A badly damaged board is individually replaceable — remove the tongue of the replacement board where needed rather than pulling the run apart. Boards can be washed by hand or high-pressure jet with a compatible detergent. |
| Retrofitting under an existing ceiling | Board can go up under an existing ceiling or a concrete soffit — battens fix below the soffit and the board fixes to those. For industrial retrofits under roof sheeting, brandering runs at 600mm intervals from ridge to eave with board running portal frame to portal frame, and short pieces up to 2400mm are used. Roughly 3 clips per m² with glue rows about 600mm apart. |
| Wind-exposed areas | Under eaves, on verandas and in high wind-load areas: either halve the brandering spacing or double the fixing points. Both suppliers of XPS state this. It is the single most common cause of a ceiling coming loose. |
| Order size changes the rate | Pricing steps at 500m², and the threshold is judged on the total order area — summed across every room, thickness and board length. How the order is split makes no difference. Reaching 500m² applies the better rate to the whole order, so it is worth telling us the full project rather than phoning it in room by room. |
+ SOURCES FOR THIS SECTION
Slipsheet and curved roofs: Agrément Certificate 2001/287 (Over Purlin Roof Insulation, amended October 2018), Detail A and Detail B; IsoBoard Over Purlin brochure A3, June 2023 rev 3-1. Summit curved-roof capability: Summit XPS catalogue, over-purlin installation section.
T- and H-sections: Rigifoam supplier confirmation returned 16 July 2026 (nail-up ceiling data confirmation V1.1.0) — sizes, 6m lengths and the no-H-section-above-60mm limit; span figures from the Lambdaboard H and T sections sheet and installation drawing LB-IG-R1. Known conflict: Rigifoam drawing CON-LB-R-03 gives higher unsupported spans (1800mm for 25 and 30mm, 2300mm for 40mm and above) than the span table quoted here. We publish the lower, more conservative table. Confirm against the supplier for a project that turns on it.
Facing material exclusion: Agrément Certificate 2001/287 certificate exclusion clause; IsoBoard Pre-Qualification document, over-purlin BOQ note.
Condensation: Agrément Certificate 2006/323 (Nail Up Insulated Ceilings, amended October 2018) and Certificate 2001/287, plus the Supplement to those certificates covering the Southern Coastal Condensation Problem Area.
Repair and washing: Agrément Certificates 2006/323, 2001/287 and 2010/382.
Retrofit and wind exposure: IsoBoard Retro-fit A4 installation guide, March 2021; IsoBoard nailed-up ceiling document, May 2023; Summit XPS nail-up ceiling installation guide Rev 2.
Order tier: The Stickman Store pricing rule STK-RULE-002 (23 July 2026) — tier qualification by total order area.
Notes on known conflicts. ISOboard's own documents give brandering spacing as 600mm, 700mm and 750mm in different places (conflict ISO-C5 in our supplier reference); we quote 700mm as the working figure and 750mm as the truss-spacing threshold. ISOboard also publishes two different board-length ranges (conflict ISO-C7); we quote the range its costing and price lists actually use, from 1.8m. And Rigifoam's drawing CON-LB-R-03 gives higher unsupported spans than its own span table (conflict LB-C13); we publish the lower table. Across the three ranges our reference logs around 88 such disagreements. Where one affects a figure above, we take the more conservative position and say so. Confirm against the supplier for anything a project turns on.
How Each Board Is Measured and Sold
The three are not measured the same way. Blending them into one rate is the fastest route to a final account that does not reconcile.
| ISOboard | Lambdaboard | Summit XPS | |
|---|---|---|---|
| Sold by | Per board length | Per square metre | Per board length |
| Why | Fixed stock lengths | Cut to your length | Fixed stock lengths |
| Board width | 600mm | 1220mm | 600mm |
| Coverage per board | length × 0.6m | as ordered | length × 0.6m |
| A 6m board covers | 3.6m² | 7.32m² at 6m | 3.6m² |
| Cutting charge | None stated — cut-to-length available at distribution centres | 10% below 2m | None stated |
| Delivery in the price | Not stated — confirm per order | Included in JHB and Pretoria up to 6m lengths. Below 300m² delivery is charged, plus a 10% cutting premium. The supplier's own conditions 3 and 4 disagree on this threshold — confirm before quoting. |
Included — delivery to store |
| Waste | Excluded from all three price lists. Allow for it separately in the rate. | ||
The trap. A board count for ISOboard or Summit is not a board count for Lambdaboard, because 1220mm covers slightly more than twice what 600mm does. And because Lambdaboard is cut to length, its offcut profile is different — less waste on non-modular spans, but a 10% charge on anything under 2m. Price the three as three, then compare.
What Moves the Rate
The variables that change a per-square-metre figure, in the order they usually bite.
| Driver | Effect on the rate |
|---|---|
| Total order area | Pricing steps at 500m². Qualification is on the total order — summed across every room, thickness and board length. How the order is split makes no difference, and once the total reaches 500m² the better rate applies to the whole order. Price the project, not the room. |
| Energy zone | Zone sets the R-value, R-value sets the thickness, thickness sets the rate. A multi-site tender spanning two zones cannot carry one blended rate — Zone 5H needs materially less than the rest. |
| Application | Maximum thickness differs by application, so a variation from ceiling to roof is not a like-for-like swap. Nail-up caps at 50mm on the XPS boards and 40mm on Lambdaboard; over purlin and inverted roof reach 100mm. |
| Colour and finish | Never a separate add-on. The colour is priced into the board rate before markup, so a coloured board carries one rate — do not add a finishing line item on top. ISOboard offers painted categories; Lambdaboard's Gun Metal Grey and Obsidian Black carry a flat uplift over White Mineral. |
| Special-order thickness | Lambdaboard's 5mm intermediate sizes (35, 45, 55mm and so on) are special order at 14 working days. Summit's 70mm and 90mm are special order with no standard rate. Both need pricing on enquiry rather than interpolation. |
| Lead time from 60mm | All three carry 14 working days on 60mm and thicker if not in stock. That is a programme risk, not a rate change, but it belongs in the preliminaries discussion. |
| Concealed applications | Where the board will never be seen — cavity walls, under surface bed, inverted roof — damaged and seconds stock is available at a materially lower rate. First come, first serve and never reserved, so it suits a contingency saving rather than a tendered rate. |
| Volume and cash | ISOboard runs a separate volume bracket structure priced per cubic metre for 100% cash-upfront orders, starting at 50m³. Summit applies a volume discount above 500m². Worth asking about on anything large before the rate is fixed. |
Building the BOQ Line
What belongs in the description, what belongs in the rate, and what belongs nowhere near either.
| Item | Position |
|---|---|
| Unit | Square metres. Even where a board is bought per length, the BOQ line is almost always m² — convert at length × 0.6m for the 600mm boards. |
| Description must carry | Material (XPS or PIR), thickness in mm, the assembly R-value required, the application, and the fixing basis. Naming a brand narrows the tender; specifying performance keeps it open. |
| Careful with | "Agrément SA certified" in a description restricts the line to ISOboard alone — it is the only one of the three holding certificates. Include it only if you mean to. |
| Wastage | 5–10% is the standard allowance for cuts and offsets. Push it higher on irregular roof shapes and layouts with many penetrations. Cut-to-length ordering reduces it. |
| Not in the supplier rate | Waste, installation labour, and adhesive, clips and fixings — on all three. Delivery varies: Summit includes delivery to store in its list price; Lambdaboard includes JHB and Pretoria up to 6m lengths but charges below 300m² along with a 10% cutting premium; ISOboard delivery is confirmed per order. Price these separately or the line under-recovers. |
| Accessories to allow for | Concealed clips at roughly 3 per m², adhesive at roughly 30m² per litre, perimeter drywall screws, and T- or H-sections where purlin spacing exceeds the board's unsupported span. |
| Reconciliation | Confirm quantities actually installed rather than originally ordered. Insulation is usually one of the more stable line items, but returns of unused, undamaged stock are discussed case by case rather than credited automatically. |
+ SOURCES FOR THESE SECTIONS
Measurement basis and cutting charge: Rigifoam supplier confirmation returned 16 July 2026 (10% cutting charge below 2m, stock lengths 5.4m / 6m / 8m, cut to length 2–12m). ISOboard and Summit per-length structures from their current stockist and Tier 1 price lists.
Delivery inclusion: Summit XPS Tier 1 price list, 1 June – 31 August 2026 (excludes VAT, includes delivery to store, excludes waste). Lambdaboard delivery terms per supplier confirmation. ISOboard delivery not stated on the stockist list — confirm per order.
Order tier and colour costing: The Stickman Store pricing rules STK-RULE-002 (23 July 2026, tier qualification by total order area) and STK-RULE-003 (27 July 2026, colour priced into the board rate before markup, never as a separate add-on).
Special orders and lead times: Rule LB-RULE-001 (Lambdaboard standard thicknesses only; 5mm intermediates special order, 14 working days) and rule APP-RULE-002 (60mm and above carries a lead time if stock is unavailable, all three suppliers).
Application thickness maxima: Rule APP-RULE-001, confirmed maximum thickness per application per supplier.
Damaged and seconds stock: ISOboard damaged board rules, captured 24 July 2026 — first come first serve, subject to stock, for cavity walls, under surface bed and inverted roof only.
Volume structures: ISOboard volume and cash bracket schedule (per cubic metre from 50m³, 100% cash upfront); Summit volume discount rule SXP-RULE-001 (above 500m²).
Certification: Agrément SA Certificates 2006/323, 2001/287, 2010/382, 2000/277 and 2000/276, all held by Isofoam SA for ISOboard. No Agrément certificate is currently held for Lambdaboard or Summit XPS.
Note: rates and thresholds change with each supplier price list. Confirm current figures with us before a tender closes.
Questions From the Site
The ones that come up most for a builder
The Google Question Corner
Things typed on-site while holding a tape measure, a deadline, and one remaining nerve.
Need a Bulk Quote or Trade Pricing?
Send through your project specs and quantities — we'll come back with proper trade numbers fast.
Architectural Specification Centre
Spec It Properly.
Keep the Builder Honest.
SANS 10400-XA compliance routes, R-value tables by zone and by thickness, application limits, full material properties for all three stocked systems, and datasheets — without Stickman losing his sense of humour entirely.
Stickman note: this page is a helpful guide to SANS 10400-XA:2026, but final compliance must be checked against the official standard, the project drawings, the selected compliance route, and the competent person's project-specific assessment.
XPS & PIR k from 0.024 W/m·K Agrément SA certified options
Find Your Zone, Get Your Target
Start here. The zone sets the R-value the assembly has to reach, and everything below follows from it.
Three Routes to Compliance Deemed-to-Satisfy, or either of the two Rational Design routes under Regulation XA3. Choose deliberately. Comparison table
| Aspect | Deemed-to-Satisfy (DTS) | Rational Design — Standard Comparison | Rational Design — Reference Building |
|---|---|---|---|
| Regulation clause | XA3(a) | XA3(b) | XA3(c) |
| Approach | Follow the prescriptive R-value tables in SANS 10400-XA directly by zone and element type. | A competent person demonstrates the building's energy usage is equivalent to or better than what the standard's own requirements would achieve. | Certified thermal simulation software compares the actual design's theoretical energy performance against a notional reference building built to DTS minimums. |
| Speed of approval | Fast — building control officers recognise the tables immediately. | Slower — requires a submitted rational design report and sign-off. | Slower still — requires certified software output and competent person certification. |
| Flexibility | Conservative and fixed; no allowance for unusual envelope designs, glazing ratios, or thermal mass strategies. | Allows trade-offs against the standard's own benchmarks — e.g. thinner insulation offset by better glazing or orientation. | Most flexible — whole-building simulation can balance glazing, shading, fabric, and hot water against each other freely. |
| Typical cost outcome | Often conservative, sometimes over-specifying thickness "to be safe". | Can reduce insulation cost on larger projects by avoiding over-specification. | Often the biggest potential saving on glazing-heavy or architecturally complex designs, offset by consultant fees. |
| Who signs off | Self-certified against the published tables, building control verifies. | A competent person produces and stamps the rational design report. | A competent person certifies the building's theoretical energy usage and demand against the reference building, using certified thermal calculation software. |
| Best suited to | Standard residential and small commercial projects with conventional envelopes. | Projects with a specific trade-off in mind that the tables don't accommodate. | Large commercial, glazing-heavy, or architecturally ambitious projects where the fee is justified by potential savings. |
Stickman's two cents: for a standard house, DTS is almost always the path of least resistance — the tables exist precisely so you don't need an engineer to insulate a ceiling. The two Rational Design routes earn their fee on larger or more architecturally ambitious projects, with the reference-building simulation route generally offering the most design freedom at the highest cost and complexity.
+ SOURCES FOR THIS SECTION
Claim checked: The three compliance routes available under Part XA.
Reference: SANS 10400-XA:2026, Regulation XA3(a), (b), (c); clauses 4.2, 4.3, 4.4.
Technical basis: Normative requirement. XA3 sets out three deemed-to-satisfy compliance routes: (a) a building envelope and services compliant with this part of the standard; (b) a competent person's rational design demonstrating equivalent or better energy usage; (c) a competent person's certified thermal calculation software demonstrating performance equal to or better than a reference building.
Why this matters on site: The route chosen determines who needs to sign off the design and what supporting documentation is required for plan approval — confirm which route the project is following before specifying insulation thickness.
SANS 10400-XA:2026 R-Value Requirements
The R-value is the legal Deemed-to-Satisfy requirement and it applies to the completed assembly, not the insulation alone — the roof covering, air gap and ceiling all contribute. The mm shown is a conservative reference on ISOboard (k = 0.026) carrying the full figure on its own. See the R-value by thickness table below for all three boards.
| Element | Zone 1 | Zone 2 | Zone 3 | Zone 4 | Zone 5 | Zone 5H | Zone 6/7 |
|---|---|---|---|---|---|---|---|
| Roof (R-value) | 3.7 | 3.7 | 3.7 | 3.7 | 3.7 | 2.7 | 3.7 |
| Roof (~mm, ISOboard) | ~100mm | ~100mm | ~100mm | ~100mm | ~100mm | ~70mm | ~100mm |
| Floor, underfloor heating only | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| Wall (R-value, ≥270 kg/m²) | 0.6 | 0.6 | 0.4 | 0.6 | 0.4 | 0.4 | 0.6 |
| Wall deemed-to-satisfy | 50mm cavity wall | 50mm cavity wall | Collar jointed wall | 50mm cavity wall | Collar jointed wall | Collar jointed wall | 50mm cavity wall |
Verify before specifying. The standard names seven energy zones, numbered 1 to 7, with Zone 5 carrying a high-humidity sub-section marked 5H that covers the east coast strip including Durban — eight areas on the map, seven numbers on the list. Durban is so humid it was given a letter rather than a region. Cape Town shares, Johannesburg shares, Durban needed the H. Wall figures above are for standard masonry walls with a surface density ≥270 kg/m²; lightweight or steel-frame walls under 270 kg/m² are checked against a separate table (R2.2 for Zones 1/2/6/7, R1.9 for Zones 3/4/5/5H). Always cross-check against the current published standard and the official CSIR energy zone map before finalising specifications.
Scope, Exclusions and the Small Print
The clauses that decide whether a certificate actually covers your build-up — and whether Regulation XA applies to your project at all.
| Issue | Position |
|---|---|
| Occupancy classes inside Regulation XA | Minimum energy requirements apply to A1–A4, C1–C2, E1–E4, F1–F3, G1 and H1–H5. Assembly, institutional, educational, commercial-retail, health and residential occupancies, broadly. |
| Occupancy classes outside it | B1–B3, D1–D4 and J1–J4 fall outside the scope of Regulation XA — high-risk commercial, industrial and plant, and storage or parking. No minimum energy requirement applies to those uses beyond what the owner or tenant wants. Worth establishing before you spend a fee on a rational design for a warehouse. |
| Single layer or combination | The added R-value required for a roof may be achieved by a single layer of insulation or by a combination of compatible insulation systems. You are not obliged to reach the figure with one product. Note the exception below on Lambdaboard. |
| Double-layering Lambdaboard | Rigifoam states that double-layer boards compromise fire compliance and double the installation labour. Where ISOboard and Summit offer doubled boards as a route to greater thickness, Lambdaboard does not — specify a single thicker board. |
| Certification and facing materials | ISOboard's Agrément certification excludes use in combination with any other facing material, combustible or not, without a satisfactory fire test report on that combination. A laminated vinyl facing or a bonded slipsheet raises the fire risk and voids the certified position. Do not carry a certificate across into an untested build-up. |
| Roof table applicable | Added R-value for roofs is read from Table 8 for metal sheeting roof assemblies and Table 9 for clay tile roof assemblies. Confirm which applies before reading a figure off the wrong table. |
| Southern Coastal Condensation Problem Area | Roof ventilation is required in this area per the supplement to the Agrément certificates. Warm humid air permeating board joints condenses on cold roof sheeting; a continuous sealant bead in the grooved edge at installation greatly reduces it. High humidity also carries a corrosion risk to untreated inner faces of sheeting. |
| Application-specific certification | ISOboard's five certificates each cover one application — 2006/323 nail-up ceilings, 2001/287 over purlin, 2010/382 over rafter and truss, 2000/277 inverted roof, 2000/276 cavity wall. Under floor slab, under soffit, retrofit and cornice profiles are listed without certificates. Certification validity is reviewed every three years. |
| Over rafter and truss thickness limit | Agrément 2010/382 limits this application to a maximum 40mm board, excludes nails as a fixing, and permits no other facing material. The 2024 counter-purlin brochure presents a different method reaching 60mm — the two do not agree, so confirm which basis the project is using. |
| Repairs and replacement | Damaged boards are individually replaceable, with the tongue of the replacement removed where needed. Fillers: Polyfilla with Alcolin Permabond diluted 1:3, or a compatible non-brittle polymer filler. Re-decoration follows plasterboard practice. |
The practical point. Two of these regularly cost money. Specifying a rational design for a building that falls outside Regulation XA is a fee spent for nothing. And carrying a certificate into a build-up it was never tested in — a facing, a laminate, a bonded slipsheet — is the kind of thing that surfaces at sign-off rather than at design stage.
+ SOURCES FOR THIS SECTION
Claim checked: Regulation XA occupancy scope, certification exclusions and application limits for the stocked systems.
Occupancy scope: Agrément Certificate 2001/287 (Over Purlin Roof Insulation, amended October 2018) — states the main occupancies for that application, B1–B3, D1–D4 and J1–J4, fall outside Regulation XA, and lists the classes to which minimum requirements apply.
Single layer or combination, and Tables 8 and 9: Agrément Certificate 2006/323 (Nail Up Insulated Ceilings, amended October 2018), deemed-to-satisfy clause referencing SANS 10400-XA.
Double-layer warning: lambdaboard.co.za, R-value table footnote (logged as LB-C14 in our supplier reference).
Facing material exclusion: Agrément Certificate 2001/287 exclusion clause; IsoBoard Pre-Qualification document over-purlin BOQ note.
Condensation Problem Area: Supplement to Agrément Certificates 2006/323 and 2001/287.
Certificate numbers and scope: Agrément Certificates 2006/323, 2001/287, 2010/382, 2000/277 and 2000/276; IsoBoard Attention brochure, March 2023, listing applications held without certificates. Confirmation of Certification cards held for 2006/323, 2001/287 and 2000/276.
Over rafter thickness limit: Agrément Certificate 2010/382 (November 2010) against the IsoBoard Over Rafter and Truss A3 brochure, June 2024 — the discrepancy is logged as conflict ISO-C15 in our supplier reference.
Repairs: Agrément Certificates 2006/323, 2001/287 and 2010/382.
Technical basis: Certificate clauses are normative for the certified system. Brochure statements are manufacturer declarations. Where the two disagree the certificate governs, and we have flagged the disagreements rather than choosing silently.
Material Properties at a Glance
Thermal conductivity: 0.024, 0.026 and 0.03. Lower is better — the only test in South Africa where that is true. All three stocked systems, compared on the properties that affect a specification.
| Property | ISOboard | Lambdaboard | Summit XPS |
|---|---|---|---|
| Material | XPS, extruded, 100% closed cell, unfaced | PIR thermoset, faced both sides | XPS, extruded, closed cell, unfaced |
| Thermal conductivity (k) | 0.026 W/m·K declared tested 0.02624, SANS 8301 |
0.024 W/m·K aged, ASTM C518 at 22°C mean |
0.03 W/m·K ISO 8302 |
| R-value basis | Tested k, SANS 8301 heat flow meter | LTTR — measured aged, guaranteed for the life of the building | Calculated on declared k; aged basis not stated |
| Thickness range | 25 – 80mm 90 / 100mm as doubled boards |
25 – 100mm 5mm steps special order |
30 / 40 / 50mm single 60 / 80 / 100mm doubled; 70 / 90mm special order; no 25mm |
| Standard width | 600mm (±2mm) | 1220mm | 600mm |
| Available lengths | 1.8 – 8.0m 1.8 / 2.4 / 2.7 / 3.0 / 3.3 / 3.6 / 4.0 / 4.2 / 4.8 / 5.4 / 6.0 / 6.6 / 7.2 / 8.0m |
2 – 12m cut to length; stock 5.4 / 6 / 8m | 1.8 – 8.0m 15 stock lengths, 1.8m upward |
| Density | 32 – 36 kg/m³ declared tested 37.2 kg/m³ |
40 kg/m³ (ASTM D1622) core 34 kg/m³ |
35 – 37 kg/m³ (±4%) |
| Compressive strength | 160 – 310 kPa, rises with thickness | Available on request | 310 – 360 kPa |
| Water absorption | 0.87% by volume (ISO 2896) | < 1% by mass (SANS 1381-1) | < 0.5% by volume (ISO 2896) |
| Dimensional stability | < 0.86% all three axes | < 1% (ASTM 2126) | < 1% (EN 1604) |
| Vapour permeability | Not published | Not published | 369 g/m² (ISO 1663) |
| Performance when wet | Retains about 80% of thermal resistance after 1000 days wetting (CRREL research on XPS) | Does not lose R-value when exposed to water; LTTR guaranteed for the life of the building | Closed cell — long-term performance from inherent moisture resistance |
| Long-term field data | Boards in service up to 20 years average k = 0.028 W/m·K | LTTR basis — values already measured aged | Not published |
| Service temperature | −30°C to +60°C | −30°C to +120°C datasheet states −60°C to +120°C |
Not published — softens above 70°C |
| Fire classification | SANS 428 B/B1/2/H&V (25 – 80mm) SANS 53501-1 B-s1,d0 |
SANS 53501-1 D-s3,d0 ASTM E108 Class A external no current SANS 428 report |
SANS 428 B/B1/2/H&V SANS 53501-1 B-s1,d1 |
| Behaviour in fire | Thermoplastic — softens and retracts from the heat source, no flaming droplets | Thermoset — does not melt, drip or spread flame; will not affect sprinkler performance | Thermoplastic — shrinks away, no flaming droplets or flame spread |
| Where it may not be used | None of the three may be used where the regulations prescribe non-combustible materials — hotels and hospitals are the usual examples. All are classified combustible. | ||
| Combustion products | Not published | CO, CO2, HCN and NOx under sustained flame (per SDS) | Not published |
| Toxicity | Not published | Approved for confined spaces (NES 713) | Not published |
| Biological | Rot-proof; no food value to vermin; will not support mould or fungal growth | Mildew and bacteria resistant | Closed cell; cornices pest-resistant |
| Chemical resistance | Damaged by solvents and VOCs; degraded by UV if left unpainted | Resists alkalis, solvents, paints and adhesives | Damaged by ANY solvent or solvent-based product; UV exposure requires paint |
| Painting | Two coats water-based matt acrylic or PVA. Solvent-based paints must not be used. | One to two coats acrylic on Decoboard; factory facing elsewhere | Two coats water-based matt PVA over an acrylic filler coat. Water-based only. |
| Facings | None — unfaced, white | Coated glass facer, three colours; aluminium foil facer option for cavity walls and under roof covering | None — unfaced |
| Edge profiles | 25–50mm tongue & groove; 60–80mm shiplap IsoPine grooved finish optional; shiplap for inverted roof |
Square edge; Decoboard 30mm is rounded-edge T&G and is 600mm wide, not 1220mm | Smooth or pine T&G, bevel T&G, straight |
| Environmental | Zero ODP (R134a / R152a blowing agent) EcoStandard SA three-star label expired Dec 2023 |
Zero ODP, GWP under 1 GBCSA approved; made in Benoni; ISO 9001:2015 |
Zero ODP; no numeric GWP published |
| Storage on site | All three: store flat, in original packaging, under cover, out of direct sun. Keep away from solvents, VOCs and any naked flame or heat source. | ||
| Certification | Agrément SA × 5 — 2006/323, 2001/287, 2010/382, 2000/277, 2000/276 | Complies SANS 10400-T; NES 713 no Agrément SA certificate held |
Fire test report 2023-02, July 2024 no Agrément SA certificate held |
Specify against the assembly, not the board. Note the roof needs a total R3.7 and the wall R0.6 — not a typo, a verdict on your roof. The wall figure is met by the named construction (50mm cavity or collar jointed), not by a board thickness on its own. The compliance obligation is the total assembly R-value for the project's zone. These are manufacturer-published values for reference — confirm against the current datasheet and the project's chosen compliance route before committing them to a drawing.
+ SOURCES FOR THIS SECTION
Claim checked: Published material properties for the three stocked board systems.
Reference: Manufacturer datasheets — Isofoam SA (ISOboard), Rigifoam (Lambdaboard), Summit (Summit XPS).
Technical basis: Manufacturer-published values, not independently verified by The Stickman Store. Where a value is shown as available on request, the manufacturer's current figure will be supplied directly rather than published here.
Why this matters: These are input values for a specification, not a compliance outcome. The R-value required is set by SANS 10400-XA for the project's zone and element type.
R-Value by Thickness
The number council actually checks, per board, per millimetre. Read down to find the thickness that meets your zone.
| Thickness | ISOboard k 0.026 |
Lambdaboard k 0.024 |
Summit XPS k 0.03 |
|---|---|---|---|
| 25mm | 0.95 | 1.04 | — not made |
| 30mm | 1.14 | 1.25 | 1.00 |
| 40mm | 1.52 | 1.67 | 1.33 |
| 50mm | 1.91 | 2.08 | 1.67 |
| 60mm | 2.29 | 2.50 | 2.00 doubled |
| 70mm | 2.67 | 2.92 | 2.33 special order |
| 80mm | 3.05 | 3.33 | 2.67 doubled |
| 90mm | 3.43 doubled | 3.75 | 3.00 special order |
| 100mm | 3.81 doubled | 4.17 | 3.33 doubled |
Read this as board R-value, not assembly R-value. SANS checks the completed assembly, which includes the air gap, the ceiling, the roof covering and the surface resistances — so the board does not have to carry the full figure on its own. Lambdaboard reaches a given R-value in fewer millimetres because its k-value is lower; that matters most where build-up depth is tight. Doubled boards are two glued layers, not a single board.
+ SOURCES FOR THIS SECTION
Claim checked: Published R-values per thickness for the three stocked systems.
Reference: ISOboard — Omega Test House report OTH-T-2204-01B-R1 (SANS 8301, 27 May 2022) plus the supplier R-value table; 25 – 50mm supplied directly, 60mm and above calculated on the same tested k. Lambdaboard — LAMBDABOARD TDS 2025, LTTR basis. Summit XPS — catalogue p9, calculated on declared k.
Technical basis: Manufacturer-published and test-house values. ISOboard figures reconcile on the tested k of 0.02624 rather than the rounded headline 0.026.
Why this matters: These are inputs to an assembly calculation, not a compliance result on their own.
Which Thickness for Which Application
Maximum confirmed thickness per application. Anything at or below the figure shown is applicable.
| Application | ISOboard | Lambdaboard | Summit XPS |
|---|---|---|---|
| Under surface bed | up to 50mm | up to 50mm | up to 50mm |
| Cavity wall | up to 50mm | up to 50mm | up to 50mm |
| Perimeter wall | up to 50mm | up to 50mm | up to 50mm |
| Nail-up ceiling | up to 50mm | up to 40mm | up to 50mm |
| Under soffit | up to 60mm | up to 60mm | up to 60mm |
| Over rafter / truss | up to 60mm | up to 60mm | up to 60mm |
| Over purlin | up to 100mm | up to 100mm | up to 100mm |
| Inverted roof | up to 100mm | up to 100mm | up to 100mm |
Four things worth knowing. Lambdaboard tops out at 40mm for nail-up ceilings where the others reach 50mm — but at k 0.024 its 40mm carries R1.67, which is what 50mm of Summit gives you anyway. From 60mm upward, all three carry a 14 working day lead time if the thickness is not in stock, so plan the order rather than the delivery. Summit's 70mm and 90mm are special order only, so ask us to price them rather than assuming a rate. And one warning worth repeating: Rigifoam states that double-layering Lambdaboard compromises its fire compliance, so where ISOboard and Summit offer doubled boards as a route to greater thickness, Lambdaboard does not — specify a single thicker board instead.
Datasheets & Specifications
Certificates, datasheets and test reports for all three boards.
Download documents coming soon
The library is being put together — Agrément SA certificates, technical datasheets, R-value test reports, fire classifications and installation details for ISOboard, Lambdaboard and Summit XPS. In the meantime, ask us for any document you need on a project and we will send you the current version directly.
Questions Architects Actually Ask
The technical ones, with straight answers
The Other Two Points of View
What the builder gets handed on site, and what the quantity surveyor has to price. Both are worth a look before the specification is issued — most of the arguments later start here.
What the Builder Sees Board sizes and lengths, batten spacing, fixings, purlin spans, and the certificate details that catch people out on site. Site detail
What the Quantity Surveyor Sees How each board is measured and sold, what moves the rate, and how a specification clause lands in a BOQ line. Cost detail
Why this is here. One phrase in a specification can decide a tender. "Agrément SA certified" narrows the field to a single supplier. A nail-up ceiling specified at 50mm rules out one of the three. A 60mm board adds a fortnight to the programme. None of that is visible from the compliance tables alone.
Need Project-Specific Specification Support?
Send through your drawings or schedule of areas and we'll help you spec the right board, thickness and application detail for the project.
The Full Stickman FAQ Library
Every Question.
Organised. Mostly Sensible.
Everything that didn't fit in the Top 10 lists, sorted by topic instead of by audience — because a good question is a good question, whether you're a homeowner, a builder, or wearing a hard hat with a clipboard.
Stickman note: this page is a helpful guide to SANS 10400-XA:2026, but final compliance must be checked against the official standard, the project drawings, the selected compliance route, and the competent person's project-specific assessment.
Getting It In
Will It Survive Me?
The Money Talk
The Long Game
Sorting the Logistics
Where You Live
The Showdown
Getting It In
Installation — DIY, professionals, and how it actually goes in
Will It Survive Me?
Fire, water, pets, kids, and general durability anxiety
The Money Talk
Pricing logic, compliance costs, and whether it's actually worth it
The Long Game
Lifespan, aftercare, and "is this normal" troubleshooting
Sorting the Logistics
Sheet sizes, ordering, delivery, and the practical stuff
Where You Live
Zone-specific quirks across South Africa
The Showdown
XPS vs PIR vs EPS vs fibreglass, and why people pick what they pick
+ SOURCES FOR EVERYTHING IN THIS LIBRARY
ISOboard (Isofoam SA): Agrément SA Certificates 2006/323, 2001/287, 2010/382, 2000/277 and 2000/276, all amended October 2018 except 2010/382 (November 2010) and 2000/277 (2005 edition). R-values from Omega Test House report OTH-T-2204-01B-R1, SANS 8301, 27 May 2022. Fire from FIRELAB FTC 15/029 (SANS 428) and an Ignis assessment to SANS 53501-1, report IT 24-10-00063, October 2024. Properties from IsoBoard A4 Properties and A4 Product Information, March 2021, plus the application brochures 2023–2024 and the retro-fit installation guide.
Lambdaboard (Rigifoam): Lambdaboard Technical Data Sheet 2025; supplier data confirmation returned 16 July 2026 covering lengths, cutting charges, accessory pricing and U-values per thickness; Lambdaboard safety data sheet; FIRELAB report FTC14/120, 29 October 2014 to SANS 10177-11 (validity expired); application brochures for cavity wall, ceiling, under purlin, over rafter, inverted roof and Decoboard.
Summit XPS: Summit XPS catalogue, September 2024; Summit XPS fire test report, July 2024 (report 2023-02) to SANS 53501-1; nail-up ceiling and over-purlin installation guides Rev 2; summitxps.co.za, retrieved July 2026.
The regulations: SANS 10400-XA, Energy usage in buildings, third edition. Energy zones from the CSIR energy demand map.
Where sources disagree. Manufacturers sometimes publish different figures in a certificate and a brochure. Our supplier reference logs around 88 such conflicts across the three ranges. Where one affects an answer above, we have quoted the certificate and flagged the disagreement rather than choosing the more flattering number. Ask us for the source document on anything that matters to your project.
Still Have a Question?
If it's not here, it's not a silly question — just ask us directly.