The numbers behind a warmer London roof.
A roof isn't just weatherproofing — it's the largest heat-loss surface in most London terraces. We measure pitched, flat, loft and junction performance, then publish what we find before and after.
Avg heat loss · roof
Target U-value
Loft retrofit
Avg bill cut
Live price list
Services & small jobs
23 fixed-price jobs · book any
W/m²K
0.0Best U-value after EWI install
Earthwool
0 mmStandard loft insulation depth
annual
−0%Avg heating bill reduction
EPC
C→ATypical post-insulation rating
What we measure
Four numbers that decide warmth.
U-value (W/m²K)
How readily heat moves through your walls, roof or floors. Building Regs allow 1.6 for walls. Our EWI system achieves 0.8. Cavity fill improves 1.6 to 1.1.
Insulation thickness
How deep we go. Loft: 300 mm Earthwool standard. Floor: 100 mm between joists. EWI: 60–100 mm EPS or mineral wool board.
Air tightness
How well we seal draughts. Hatch sealing with Draughtex. Floorboard gaps sealed. CWI bead fills cavity voids. Typical reduction: 30–40%.
Acoustic Rw
Sound reduction in decibels. Standard wall: 35dB. Our acoustic system with resilient bars and SoundBloc: 42dB — enough to mute a drum kit.