Double-storey extension drawings in Harrow

What the national rules add

Permitted development reaches: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. Harrow has 31 conservation areas, where: No rear extension of more than one storey under PD on article 2(3) land. Around 22 per cent of the borough is Green Belt, so edge-of-borough plots face a proportionality test on top of the design guide.

Historic England lists 295 entries in Harrow, and 22 places are on its Heritage at Risk Register. A listed house needs consent in addition to planning permission. We check each layer against your address before the first drawing. If the guide rules a layout out, we say so at the quote stage and show what can be built instead, whether that is a single-storey rear addition, a side extension within the set-back, or a loft conversion, so you do not pay for a scheme the council will not support. Where a scheme is close to a limit, we draw the dimension on the plan so the officer can read it at a glance.

Harrow's decision record

Harrow decided 917 householder applications in its latest published year and granted 81.7 per cent; 93.7 per cent were decided within eight weeks or an agreed extension.

The figures cover all householder work and not a particular house. We use them for timing. Domestic gardens make up 34.7 per cent of the borough's land in the Greater London Authority's land-use survey, a borough-wide measure and not a guide to one plot.

Windows, fire and neighbours

Upper-floor side windows must be: Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor. A new first-floor bedroom needs: Escape window: unobstructed openable area at least 0.33 m², at least 450 mm high and 450 mm wide, bottom of opening no more than 1100 mm above floor. The roof follows: Roof pitch of a 2+ storey enlargement to match the original house so far as practicable.

A first-floor side extension close to the boundary means party wall rules apply: Party structure notice at least 2 months before work. Our party wall notices service handles them.

Price and what you receive

Drawings start at £1,295, VAT included, fixed before you commit. You receive plans of both floors, elevations, sections and location and block plans, each checked by a second chartered technologist. The council's householder fee is £548. If officers ask for changes we redraw at no charge until approval.

Our planning drawings page explains the application.

Other drawings in Harrow and nearby

The borough overview is architectural drawings in Harrow. For a mid-terrace house, loft conversion drawings in Harrow are often the better route, and rear extension drawings in Harrow cover a single storey. The national rules are on the double-storey extension drawings hub. Next door: Brent, Hillingdon and Barnet.