What is the required U value for a flat roof?
New flat roofing insulation – The roof must have a U value of 0.13 W/m2K or lower. Existing flat roofing insulation – The roof must have a U value of 0.18 W/m2K or lower.
What are the building regulations for a flat roof?
Make sure your comply with flat roof building regulations
- There must be a slope of 1:80.
- Part H of the building regulations regarding drainage state that water should drain to one or two edges.
- Waterproofing should extend up the adjacent walls at least 150mm from the roof surface.
- Cold roofs must have ventilation.
What should a roof U value be?
The U-Value of Roof Insulation An uninsulated roof has a U-Value of approximately 2.5 W/m2k, however, adding insulation can achieve a value of 0.18 W/m2k.
What is the minimum thickness for flat roof insulation?
What Insulation Thickness Do I Need for Flat Roofs? An uninsulated flat roof has a U-Value of around 1.5 W/m2K. When insulating one, you’re aiming for a value of 0.25 W/m2K or less. To achieve this, you should insulate your flat roof with insulation boards totalling around 150mm thickness.
What U-value is needed?
The best insulating materials have a U-value of close to zero – the lower the better. Building regulations currently stipulate that for a new building, the elements must have maximum U-values as follows: Wall – 0.3 W/m2k. Roof – 0.15 W/m2k.
What is building regs U-value?
A U-value is a measure of heat loss in a building element such as a wall, floor or roof. It can also be referred to as an ‘overall heat transfer co-efficient’ and measures how well parts of a building transfer heat. This means that the higher the U-value the worse the thermal performance of the building envelope.
Do I need building regulations for flat roof?
Although planning permission for re-roofing is not typically required for straightforward residential projects, building regulations approval is usually necessary when re-roofing a dwelling. Other permissions may also be needed depending on factors such as project scope and location.
How many layers of roof can you add to a flat roof?
Asphalt shingles are most often allowed in up to two layers, but no more. For flat roofs, materials such as EPDM and TPO are usually approved for use up to two layers.
Can I change my roof without planning permission?
If you are simply just repairing the roof, then planning permission is not necessary. But to keep things simple and straight forward, the general rule to follow for best working practice is, if you’re changing anything about your roof, it is always best to inform your local Council beforehand.