Building regulations drawings in Harrow

Garage conversions and side extensions on Harrow semis

A frequent Harrow brief is to turn an integral garage into a room, or to build over and beside it. Building control looks hard at a few specific points. The old garage floor has to be insulated and damp-proofed. The up-and-over door opening is infilled with a wall that matches the rest of the house. The new room needs a proper ventilation route, and a window large enough to escape through where it opens off a hall that serves the stairs.

A first-floor side extension adds structure above the garage, so the existing walls and foundations have to be checked by your engineer. We draw their sizes into the plans and sections, so the numbers on our sheets match theirs. If you have not yet appointed one, see our structural calculations in Harrow service.

Fire is the point most often missed. Opening a garage into the house removes a fire-resisting separation that the original design relied on. Building control will want to see that the new wall, door or ceiling restores it where it is needed, and that smoke alarms are linked and powered from the mains. We show these on the plans, and note the standard each element must reach.

Shared homes and the extra checks

Harrow has an Article 4 direction for turning houses into small shared homes, and that matters for building control as much as planning. Where a house is already in shared use, or where an owner intends to let rooms, fire detection, escape routes and sound separation between rooms all affect the technical set.

We ask early whether a project could ever be let that way. It costs little to build the right fire doors in at the start, and a great deal to cut them in later.

Timings, notices and decisions in Harrow

Building control body must decide a full plans application within 5 weeks, or longer if agreed in writing. Harrow decided 917 householder planning applications in its latest year and granted 81.7 per cent, with 93.7 per cent decided on time. If your plan needs permission, we normally wait for it before finishing the technical sheets.

After approval, you must tell building control before you start and again at commencement and completion. Approval lapses unless work commences; for an extension, commencement means foundations, any basement and ground floor structure complete; other work, 15% of the work stated in the application. For a side extension that means the foundations and ground-floor structure, so start the clock deliberately.

Cost, levy and what you receive

Building regulations drawings start at £845 with VAT included. The price is fixed up front, a second chartered technologist checks every sheet and we revise the sheets at no charge if the examiner raises points.

Harrow charges its own levy of £196.43/m² (Residential, Use Class C3, borough-wide) under the London Borough of Harrow CIL Charging Schedule, as well as the Mayor's scheme at £72.73 per square metre in band 2. A terraced house averages £536,748 and a flat £317,917, so we flag any liability in the handover pack before you commit to the build.

Next steps and neighbouring services

To take the sheets on to site, see construction drawings in Harrow. If you still need consent, start at planning drawings in Harrow, check permitted development with a lawful development certificate in Harrow, or read the overview at architectural drawings in Harrow. The same service is also described for Brent, Hillingdon and Ealing.