Porch Cost Calculator

In England, a porch may qualify for permitted development when its external ground area is no more than 3 m², no part is higher than 3 m, and no part is within 2 m of a highway-facing boundary. These allowances apply to qualifying houses and are subject to restrictions. Other UK nations have different rules. A calculator warning is not a permission decision: check with your local planning authority. Building regulations are a separate check.

The estimate uses preset allowances for the base, wall area, roof and electrics you select, with VAT and an indicative postcode adjustment. Installation depends on the checkbox. Doors and glazing, unforeseen ground or drainage work, structural alterations and unselected finishes are additional. Confirm the full specification and exclusions in an installer quote.

Possibly. Selecting an existing base, wall or roof removes its replacement allowance, but a survey must establish whether it can support the proposed work and meets the relevant requirements. Repairs or reinforcement can add to the price.

Measure each new wall in metres, multiply its length by its actual height, add the areas and subtract door and window openings. For two 1 m by 2.1 m side walls and a 2.5 m by 2.1 m front wall, minus a 0.9 m by 2.1 m door, the total is 7.56 m². Use each wall’s actual height if they differ.

Use our Double Glazing Cost Calculator for a separate door and window estimate. Include that estimate when comparing your overall project budget; it is not automatically included here. Select the available electrical allowances and ask an installer to quote for any additional sockets, external lights or other work.