Question 1

Does a porch need Building Regulations approval?

Accepted Answer

If the porch is at ground level, has a floor area of 30m² or less and is no higher than 3m, it is exempt from Building Regulations under Schedule 2 Class 7 (provided glazing meets Part K and no controlled fittings such as heating or sanitary fittings are added). Over 30m² or over 3m high, full Building Regulations apply including Part L insulation, Part B fire safety and structural requirements. Note: Building Regs exemption (30m²) is separate from Permitted Development (3m²) — see the planning question below.

Question 2

Does a porch need planning permission?

Accepted Answer

A porch is usually permitted development if: the floor area is 3m² or less, it is no higher than 3m above ground level, and no part is within 2m of a boundary fronting a highway. In conservation areas, Article 4 directions or on listed buildings, planning permission may be needed regardless of size.

Question 3

What foundation does a porch need?

Accepted Answer

A porch typically needs a strip foundation 450mm deep and 450mm wide around the perimeter. On clay soils or near trees, deeper foundations may be needed. For small porches under 3m², some local authorities accept a concrete pad or slab foundation without deep strip footings.

Question 4

Does a porch need insulation?

Accepted Answer

If the porch is Building Regs exempt (under 30m² Schedule 2 Class 7), no insulation is required by Building Regulations. If over 30m², Part L applies and walls need U-value 0.26, floor 0.22, roof 0.15. If you remove the original front door, making the porch part of the house, all porch elements must be insulated to Part L standards regardless of size.

Question 5

How much does a porch cost to build?

Accepted Answer

A small brick porch (under 3m²) typically costs £3,000–£6,000. A larger porch (3–6m²) requiring Building Regulations costs £5,000–£12,000 depending on specification. Full brick walls cost more than dwarf wall with glazing. Costs vary by region and finish quality.

Porch Calculator — Foundations, Structure & PD Limits

How We Calculate This

Exemption check

Material quantities

Frequently Asked Questions

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