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Vented Facade Insulation Calculator

Openings

Sill height (floor to opening bottom)

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Insulation boards required (incl. waste)24

A 10% waste allowance was applied to the board count.

Framing, board, and membrane quantities are calculated across the full wall length and height, ignoring openings — this calculator has no opening position, so it cannot tell which framing bay or membrane course an opening falls in. Net area (openings deducted) is shown for information only. This is the conservative choice: it does not risk under-ordering.

Board count assumes every framing bay is the nominal on-centre spacing wide. The last bay at the wall's far edge is only actually narrower when the wall length is not an exact multiple of the framing spacing — boards there are cut down on site, same as any bay narrower than the board's own width.

Thermal conductivity, fixing density, and fixing embedment depths are estimates you supplied above — they are not derived from a cited standard, since they depend on the specific insulation, fixing, and framing products used. Adjust them to match your chosen system.

This is the thermal resistance of the insulation layer alone: R = 2.86 m²·K/W. It does not include the substrate, membrane, air gap, cladding, surface resistances, or thermal bridging, so it is not the assembly U-value. Do not compare it directly against a national insulation requirement — compare the full assembly's U-value instead.

Standard: ISO 6946

The vertical framing (and cross-battens, where present) is itself a thermal bridge through the insulation layer — a further reason the layer R-value above is not the assembly's real thermal performance.

Cladding is out of scope for this calculator — cladding types differ too much to share one calculation. The cladding zone shown in the section diagram and included in the total build-up depth is an illustrative fixed allowance, not derived from a real cladding input.

The layer section diagram is schematic: only the framing/insulation cavity depth and the air gap depth are drawn to their real thickness. The substrate, membrane, and cladding zone layers are illustrative only.

Area
Gross wall area10.00 m²
Net area (openings deducted)10.00 m²
Insulation area (wall minus framing)9.10 m²
Framing
Vertical framing members8
Cross-battens0
Total framing linear length20.000 m
Timber volume40.50 L
Insulation
Boards excluding waste21
Waste boards3
Insulation volume910.00 L
Wind barrier membrane
Membrane area (incl. overlap)12.00 m²
Membrane rolls required1
Fixings
Fixings required64
Required fixing length85 mm
Build-up depth
Total build-up depth (framing + air gap + cladding zone)100 mm
Thermal resistance
Insulation layer R-value2.86 m²·K/W
Diagram
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