Construction build-ups and U-values

Layer stacks for UK walls, roofs, floors and ceilings — each one specified with real manufacturer products, calculated in EN ISO 6946 form, and openable in the GridSnap editor.

Every conductivity below is the value the manufacturer declares, with the document it came from linked on the page. Where a product declares different conductivities at different thicknesses, the thickness actually used decides which one applies — so the number here is the number for the board in the drawing, not the headline on the brochure.

Build-ups

• Full-fill cavity wall, DriTherm 32
  Brick outer leaf, a 100 mm cavity fully filled with Knauf DriTherm Cavity Slab 32, aerated blockwork inside.
  U ≈ 0.25 W/m²K · 315 mm total
• Partial-fill cavity wall, Kooltherm K106
  Brick, a 90 mm phenolic board held against the inner leaf with a clear residual cavity, blockwork and plaster.
  U ≈ 0.17 W/m²K · 355 mm total
• Insulated ground floor slab, SOPRATHERM GA4000
  Concrete slab, 100 mm PIR board over it, and a 65 mm screed — insulation above the structure, under the finish.
  U ≈ 0.21 W/m²K · 315 mm total
• Cold loft ceiling, 300 mm Loft Roll 44
  Glass mineral wool laid at ceiling level to 300 mm, with the roof space above left cold and ventilated.
  U ≈ 0.14 W/m²K · 313 mm total
• Warm pitched roof, Thermapitch TP10
  PIR between and under the rafters to bring a loft inside the heated envelope — a room-in-roof build-up.
  U ≈ 0.13 W/m²K · 183 mm total

U-values are indicative: a series calculation through the layers listed, using declared conductivities and standard surface resistances. They are not a compliance calculation, and repeating thermal bridges are not modelled — each page says where that matters.