typical: 2-4 m2
Advanced options
Porches enjoy generous permitted development: no planning permission needed if the footprint stays at or under 3 m2 (external measurement), no part exceeds 3m high, and it sits 2m+ from any boundary with a road: which is why so many porches are exactly 3 m2. Building regs are also waived at that size IF the front door between porch and house stays in place: remove the inner door and it becomes an extension in the eyes of the rules (and thermally).
What The Porch Cost Calculator Works Out
- Estimated cost: footprint x the rate per m2 for the specification. uPVC on a dwarf wall runs about GBP 1,000 to GBP 1,300 per m2, brick with a tiled roof GBP 1,400 to GBP 1,700 and high-spec brick or oak frame GBP 2,000 or more, so the typical 3 m2 porch lands at GBP 3,500 to GBP 5,500. The range shown is 85% to 120% of the estimate.
- The planning rules: porches at or under 3 m2 external footprint, no more than 3 m high and at least 2 m from a road boundary are permitted development, which is why so many British porches measure exactly 3 m2. Conservation areas, listed buildings and Article 4 directions suspend that generosity.
- Is it worth it: the porch is draught-lobby physics dressed as joinery, an airlock that works every winter door opening, plus coat and boot storage, parcel shelter and kerb appeal. It reliably improves saleability without reliably returning its full cost in price.
- Quoted rate and planning override (advanced): use your builder's figure, and force a planning application on if you are in a conservation area or force it off if the council has confirmed permitted development.
- Planning fee (advanced): a householder application in England costs GBP 528 since April 2025; Wales and Scotland set their own fees. A lawful development certificate for peace of mind on a borderline design costs half the application fee.
- Inner front door and building regulations (advanced): the building regs exemption at 3 m2 or under depends on the original front door staying in place between porch and house. Remove it and the porch becomes an extension needing full compliance, with a GBP 300 to GBP 500 application and thermal standards for the glazing and walls.
- Extras (advanced): a light and socket run GBP 150 to GBP 300, a level-access threshold about GBP 300 and is cheap now and expensive later, and built-in bench or shoe storage GBP 200 to GBP 600.
- All-in total (advanced): the build plus any fees and extras, and the resulting cost per square metre, which is the number to compare between quotes that do and do not include the paperwork.
- Heating saving (advanced): an unheated lobby on a busy front door saves perhaps 200 to 500 kWh of gas a year in a typical semi, priced here at the current unit rate. It is a few tens of pounds a year, so the payback on heating alone runs well past the porch's life: the case rests on comfort and dry doorsteps.
- Canopy instead (advanced): a fitted door canopy at GBP 300 to GBP 800 solves the weather without walls. The saving against the porch is shown, along with what the canopy cannot do.