Porch Cost Calculator 2025

Q: Can I reuse my existing base, walls or roof?

Yes. Choose “Use existing” for base, wall finish or roof to remove new-build costs for those parts. This assumes your existing structure is sound and compliant; if a survey finds it needs remedial work, actual costs can differ.

Q: How do I work out the brick/render wall area (m²)?

Use this quick formula: m² = (Projection × Height × 2) + (Width × Height) − openings. Example: two solid side walls at 1.0 m projection × 2.1 m height, plus a front upstand at 2.5 m × 2.1 m, minus a 0.9 m × 2.1 m door (1.89 m²). Enter the final m² in the calculator.

Postcode (for regional accuracy)

Do you already have a porch base?

Width (cm) Typical porch width: 150–300 cm

Projection from wall (cm) Most porches project 100–200 cm

Overall height (cm) Max permitted development height is typically 300 cm.

Wall finish

Brick/render wall area to build (m²) How to work it out: add the two side walls (projection × desired height each) + front wall (width × height) and subtract any door/window openings. If reusing existing walls, leave at 0.

Leave an opening for glazing/door? Any glazing/doors should be priced in our Double Glazing Cost Calculator and added separately.

Roof type

Electrics Includes supply spur for lights/sockets on the first feed.

Additional power feeds

Downlight (first one)

Additional downlights

Include installation (incl. VAT)

Your List of Items

Item	Size	Est. Cost (incl. VAT)
No items yet.
Total		£0 – £0

We’re a Home Improvement Agency — these prices are mid-market estimates only and may vary by supplier and specification. Any glazing/door openings should be priced in our Double Glazing Cost Calculator and added separately.

How to use this calculator

Pick whether you have a base. If yes, choose to reuse or overlay.
Enter width and projection (cm) and set overall height.
Select a wall finish and type the brick/render wall area (m²) you’ll build.
Choose a roof type, then add any electrics (feeds & downlights).
If you need doors/windows, price them in our Double Glazing Cost Calculator and add separately.

Assumptions & limits

Prices reflect mid-market supply & install and include VAT.
Regional factor adjusts figures by postcode.
Figures are estimates to two decimals; totals include installation.

Planning quick check (UK)

If new footprint is > 3 m², planning is usually required.
Typical approval time: 6–8 weeks. We add a modest allowance when applicable.

Wall area quick tips

Side walls: projection × desired height (each).
Front wall: width × height minus any door/window openings.

Roof & electrics

Roof types: Flat (budget), Pitched/Gable/Hipped (stronger look).
Electrics: First feed includes spur for lights/sockets; extras are per feed/downlight.

Porch Cost Calculator — FAQs

Do I need planning permission for my porch?

In most UK homes, porches are permitted development if the external area is 3 m² or less, the overall height is 3 m or less, and it’s not within 2 m of a boundary that fronts a highway. If your dimensions exceed these, we’ll flag it and include a typical planning fee and timeline (usually 6–8 weeks) in the illustration. Always confirm with your local planning authority if in doubt.

What costs are included — and what’s excluded?

We include mid-market pricing for: new base (if selected), brick/render wall area you enter (m²), chosen roof type (or “use existing”), basic electrics (first feed + downlights if added) and a postcode-based regional factor (incl. VAT). Excluded: glazing/doors (price these in our Double Glazing Cost Calculator and add separately), unforeseen ground/drain issues, structural lintels, and premium finishes unless chosen.

Can I reuse my existing base, walls or roof?

Yes. Choose Use existing for base, wall finish or roof to remove new-build costs for those parts. This assumes your existing structure is sound and compliant; if a survey finds it needs remedial work, actual costs can differ.

How do I work out the brick/render wall area (m²)?

Use this quick formula:
m² = (Projection × Height × 2) + (Width × Height) − openings.
Example: two solid side walls at 1.0 m projection × 2.1 m height, plus a front upstand at 2.5 m × 2.1 m, minus a 0.9 m × 2.1 m door (1.89 m²). Enter the final m² in the calculator.

Where do I price doors, windows and extra electrics?

Doors and windows are priced in our Double Glazing Cost Calculator then added to your list. For electrics beyond the “first feed” and downlights (e.g. sockets, external lights, fused spurs), add them in the electrics dropdowns or discuss during survey for a precise quote.