SAP Made Simple
How it works:
1. Who needs a SAP Calculation?
You’ll need a SAP Calculation if you’re building a new home, carrying out a conversion (barn, loft, or office-to-flat), or doing an extension with more than 25% glazing (large windows, rooflights, or bi-folds). Building Control won’t sign off your project without it.
2. Do I need a SAP Calculation for my extension?
Sometimes - extensions with a lot of glazing almost always need SAP. We combine the SAP with U-value calculations for the walls, roof, and floor, then give you practical adjustments if anything needs changing. This avoids delays and makes Building Control sign-off straightforward.
3. What is a SAP Calculation?
A SAP (Standard Assessment Procedure) calculation is the government’s official energy assessment for homes. It looks at insulation, glazing, heating, and renewables to prove your design meets Part L of the Building Regulations. At the end of the build, the SAP produces your EPC (Energy Performance Certificate).
4. How much insulation do I need?
As a guide, Part L requires:
Roofs: around 0.15 U-value
Walls: around 0.18 U-value
Floors: around 0.18 U-value
Windows & Doors: around 1.4–1.6 U-value
In practice, that might mean a 100mm cavity wall with PIR boards and the right inner leaf, thicker insulation in a roof, or floor insulation depending on the design.
But you can't be sure every project is different - which is why part of our SAP service is calculating your U-values and advising whether your insulation is enough.
5. How long does a SAP take?
We usually turn reports around within 1–2 working days once we have your plans and details.
6. Do you just provide reports, or do you offer consultancy?
We act as consultants as well as assessors. That means we don’t just give you paperwork - we work with you to highlight risks early, suggest cost-effective fixes, and guide you through the process until you pass.
7. Are you qualified?
Yes - we’re fully accredited OCDEA (On Construction Domestic Energy Assessors). Our team is qualified to issue SAP Calculations, EPCs, and compliance reports under Building Regulation
8. What happens if my design fails the SAP first time
Don’t worry - this is common. We’ll work with your architect or builder to suggest simple, affordable changes (like tweaking insulation levels, upgrading glazing, or improving airtightness). Then we re-run the SAP until it passes. Unlimited revisions are included in our service.
9. Do SAP Calculations affect my build costs?
They can, but in a good way. By spotting issues early, SAP Calculations can save you from expensive changes later in the build. For example, we might find you only need to upgrade insulation in one area rather than everywhere - saving money while still meeting regulations.
📞 Still have questions ? Call us now 01172510042