Porch Cost Calculator
A small job with the same fixed costs as a big one — foundations, a door, and someone on site for a week. That is why the price per square metre looks high.
Open the calculator →Price a porch in 30 seconds
4 steps. Covers construction type, size, the front door and region — with a permitted-development check built in.
How this calculator works
Porches are priced from a 3m² baseline because that is the permitted development threshold, and most porches are built right up to it. Above 3m² the calculator adds £420 per extra square metre and flags that you have probably left permitted development behind.
Two exemptions worth understanding. Planning: a porch is permitted development if it is 3m² or less, no more than 3m high, and no part is within 2m of a boundary facing a highway. Building regulations: a porch is exempt if it is under 30m², at ground level, glazed to Part K safety standards, and the existing front door stays in place. Remove that door and the porch becomes part of the heated envelope, and full regulations apply. In practice the cheapest, simplest porch is the one that keeps the original front door, stays under 3 square metres and sits clear of the boundary; the moment you cross any one of those lines you are into applications, certificates and a noticeably larger bill, so it is worth designing to stay inside them unless you specifically need more. One decision quietly drives the finished cost: whether you keep the existing front door or move it out to the porch’s new outer face. Keeping it preserves the building-regulations exemption but leaves two doors to pass through; moving it brings the porch into the heated envelope and means a properly rated external door and compliant glazing throughout. If you are replacing the door as part of the job, our external door fitting cost guide covers it, and the double glazing cost guide sets out what the glazed panels add.
Porch costs by type (2026)
| Type | Typical 2026 cost | Notes |
|---|---|---|
| uPVC lean-to (1.5–2.5m²) | £2,800–£4,500 | 20–30 year product life |
| Brick front porch (2–3m²) | £4,500–£8,500 | Lasts as long as the house |
| Enclosed brick with WC (3–5m²) | £7,500–£14,000 | Adds drainage |
| Glass-fronted modern | £8,500–£16,000 | Structural glazing |
| Foundations and base | £800–£2,000 | Included above |
| Front door and frame | £600–£2,500 | Often quoted separately |
Ranges match our porch cost guide. The front door is a common exclusion — confirm whether yours is in the quote.
Porch calculator FAQs
Not if it is 3m² or less in external floor area, no more than 3m high, and no part sits within 2m of a boundary facing a highway. Go beyond any of those and you need a householder application. Listed buildings and some conservation areas are excluded from the allowance entirely.
A porch is exempt if it is under 30m², at ground level, its glazing meets Part K safety requirements, and the existing front door remains in place. That last condition catches people out — take the old door out and the porch becomes heated space, and full regulations apply.
Compare over 25 years rather than up front. A uPVC porch is roughly half the price but has a 20–30 year product life; brick lasts as long as the house and is the version that reads as part of the building rather than an addition. Brick usually wins on cost per year. The exception is a house already finished in uPVC or render where a brick porch would look bolted on; there, matching the existing frontage matters more than the lifespan sum, and a well-detailed uPVC or timber porch is the better choice.
One to three weeks on site. The variable is the front door lead time, typically two to four weeks from order — order it at the start, not the end, or you will have a finished porch and a hole in the front of the house. If you are keeping the existing door to stay exempt from building regulations, that lead time disappears, which is one more quiet reason the keep-the-door porch is usually the least stressful as well as the cheapest.
Related cost guides
- Porch cost guide — full 2026 pricing by type
- Porch planning rules — the 3m² allowance explained
- Door and window calculator — price the front door separately
- House extension costs — every type compared
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