Loft upgrade estimator

The steps

Work through these calculators in order. Each one takes the measurements from the step before.

1. Loft insulation
2. U-value of the new build-up
3. Condensation risk
4. Loft boarding on raised legs

Questions for your builder

• Is the loft ventilated at the eaves, and will the new insulation block it?
• Are there cables that will be buried in the insulation and need re-routing?
• Can the ceiling joists take the boarding and what you plan to store?
• Is there a vapour control layer, and does this ceiling need one?