Rear extension drawings in Hillingdon

Plot width, ground level and the numbers on the drawing

With limits this exact, the survey carries the project. Plot width decides which depth applies, so we measure it at the rear wall, not from the deeds. Ground level decides the height, so we record levels at the boundary, at the back wall and across the garden.

The right shape depends on the house type. A detached house has more freedom on depth, but the privacy and neighbour tests still apply to every flank wall.

Gardens cover 18.6 per cent of the borough's land in the Greater London Authority's land-use data, and trees are a real constraint: Hillingdon has 731 tree preservation orders. We plot protected trees on the survey, because a root zone can move a foundation.

Inside the envelope there is still plenty of room for design. Bi-fold doors, a roof lantern, a utility room or a breakfast area can all fit within the allowed depth if the plan is laid out well, and we test two or three layouts on the plot sheet so you can see how much usable space each gives.

Article 4, Green Belt and the permission route

Hillingdon has 150 Article 4 directions and 33 conservation areas. On an affected street the permitted rights may be removed, and we check the address before recommending any route.

About 42 per cent of the borough is covered by Green Belt polygons, so a house at the edge of the built-up area may face a proportionality test. Historic England lists 436 entries here, and a listed house needs separate consent.

Where permitted development applies, a deeper extension can use prior approval. Hillingdon granted 29 larger home extension prior approvals and refused 13 in the latest return. Otherwise a householder application costs £548, paid to the council.

Trees and the Green Belt are the two matters we check first, because either can change the size of the project. A protected tree near the rear wall can shift a foundation, and a house on the Green Belt edge can face a size test that no drawing can soften.

Hillingdon's householder record

Hillingdon decided 1,147 householder applications in its latest published year and granted 90.2 per cent, with 94.3 per cent decided in time.

These are borough-wide figures for every type of householder project. They help us plan timing, and they do not predict the outcome for any one house.

Timing helps with planning the build. We normally start the building regulations drawings once the design is settled, so the structural details are ready when the decision arrives.

What the drawings include and what they cost

A Hillingdon set shows existing and proposed floor plans, elevations and sections, plus the location and block plans. Our fee is £695 including VAT, fixed before you commit. A second chartered technologist checks every sheet, and we redraw free of charge if the council asks for changes.

The first step is a site visit, where we measure the house, the plot and the levels, and note trees, drains and the neighbours' extensions. Drawings are normally ready about a week later, and you see them before anything is submitted, so you can change the layout while it is still cheap to do so.

Once the design is agreed, our building regulations drawings take it through to building control. For the whole borough see architectural drawings in Hillingdon, and for the London overview see rear extension drawings.

Other extensions and nearby boroughs

Building out the side or going up a storey? See side return extension drawings in Hillingdon and double-storey extension drawings in Hillingdon. For every extension type side by side, try house extension drawings in Hillingdon.

Next door, compare Hounslow, Ealing and Harrow.