House Extensions Designed and Built

Not always. Many single storey rear extensions fall within householder permitted development, subject to limits on depth, height, eaves height near a boundary and how much of the garden is built on. Those rights are reduced in conservation areas, do not apply to flats, and can be removed by an Article 4 direction or a condition on the estate's original permission.

It is a separate procedure that allows a deeper single storey rear extension than standard permitted development, on the condition that the council notifies your adjoining neighbours first. If nobody objects within the consultation period, the work can proceed. If someone does, the council decides whether the impact on their amenity is acceptable.

Per square metre, usually yes, because one set of foundations and one roof serves two floors. The trade-off is planning risk and disruption. Officers scrutinise bulk, overlooking and whether the extension stays subordinate to the original house, and you are working above the existing bedrooms rather than beside them.

It is a rear extension carried around into the side return, which is the narrow strip alongside the rear outrigger on a typical Victorian or Edwardian house. It produces a much better ground floor plan than either part would on its own. The drainage in that side alley usually needs sorting out as part of it.

A straightforward single storey rear extension is generally a matter of weeks on site once groundworks start, and a two storey extension or a wrap-around runs into months. The design and approvals stage before that is usually the longer part, because planning determination alone is normally eight weeks from validation.

Usually not. Most of the new structure is built before the existing rear wall is opened up, so the genuinely disruptive stretch is short. Whole house remodelling, or anything that takes out your only kitchen or only bathroom for a long period, is worth planning around, and we would raise it before you commit.

If you are cutting into a shared wall, building on the boundary line, or excavating foundations within the distances set out in the Party Wall etc. Act, then notice has to be served on the affected neighbour. Many neighbours simply consent in writing. The important part is serving in time, because the statutory notice periods run into weeks.

It depends what kind of drain it is. A private drain serving only your house can often be diverted. A public sewer or a lateral drain shared with neighbours normally needs a build over or build near agreement with the water authority. A drainage survey early in the design is far cheaper than a redesign at foundation stage.

In most cases yes, but the glazing area affects Part L compliance, so it has to be balanced elsewhere in the fabric with better insulation, better glass or improved airtightness. Structurally the opening needs a beam sized by an engineer, and the threshold detail needs designing properly if you want a flush finish that stays watertight.

It can, and that is one of the more common regrets. Pushing the rear wall out several metres leaves the middle of the plan further from any window. It is solvable with roof lights, a lantern, a glazed link or a change to the internal layout, but it has to be designed in rather than noticed afterwards.

Sometimes. Foundation depth depends on the ground conditions, on any nearby trees, and on whether the soil is shrinkable clay, where seasonal movement and root influence can require a significantly deeper trench. Building control will inspect the excavation before concrete goes in, and that visit sets the depth in practice.

It usually does, though we would rather talk about whether it makes the house work for you, because the value depends on the local ceiling price and on how well the extension is done. A well planned extension that improves the whole ground floor tends to be worth considerably more than a large box tacked onto the back.

Yes. Permitted development rights are reduced on designated land, so a full application is more likely, and the officer will pay close attention to materials, window proportions, roof form and whether the extension is visible from the street. Rear extensions that keep away from public views are generally the more straightforward starting point.

Yes, that is how the practice is set up. The architect who designs your extension oversees the build, so the detail that was drawn is the detail that gets constructed, and the build cost quoted at the outset is the one we stick to.