Area Weighted U-value Check for Your Extension

Your assessment, explained

Large windows, bifold doors and rooflights can take your extension beyond the standard opening allowance. An Area Weighted U-value check looks at whether better insulation or glazing can balance that extra heat loss, helping you keep the design you want.

We compare your proposed walls, roof, floor and openings with a reference extension of the same size and shape. The report shows how the two compare. If improvements are needed, we'll explain which changes to the insulation or glazing could help.