House Extensions in Luton

Single storey, double storey and wrap-around extensions across Luton and Dunstable. Designed with a structural engineer, built by a Chartered Member of the CIOB, and signed off by building control before we hand the house back.

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An extension is a structural job wearing a decorating job's clothes.

Most of what goes wrong with an extension has already gone wrong before the plasterer arrives. Foundations dug too shallow for the ground. A steel sized by eye rather than by a structural engineer. A cavity tray missed, so the new wall wicks damp into the old one two winters later. None of that is visible in a photograph of a finished kitchen, which is exactly why extensions are the easiest job in building to sell badly.

We build them the other way round. The structural design comes first, the steels are sized and set on proper padstones, the ground is dug to what the soil actually requires rather than what is quick, and building control inspect at every stage. The open plan kitchen at the top of this page is the last two weeks of a job that spent its first three months underground and behind plasterboard.

Bes Cuni, who runs BXC Developments, is a Chartered Member of the Chartered Institute of Building and an Associate of the Royal Institution of Chartered Surveyors. On an extension that matters more than on almost any other job, because the person managing it is the person deciding whether a detail is good enough to build on.

What an extension with us actually involves

Survey and structural design

We measure the house, look at the ground and the existing footings, then have the steels and foundations designed by a structural engineer. You get the calculations, not just a promise.

Planning and permitted development

Many rear extensions fall under permitted development and many do not. We tell you which yours is before you spend money on drawings, and we deal with Luton Borough Council or Central Bedfordshire Council on your behalf.

Groundworks and foundations

Dug to the depth the ground requires and inspected by building control before a single block goes in. This is the part nobody photographs and the part that decides whether the extension cracks.

Structure and shell

Blockwork and brickwork matched to the existing house, steels set on proper padstones, cavity trays, lintels, damp proof course and the roof structure. Watertight before the trades come in.

First fix and building control

Electrics, plumbing, drainage, insulation and glazing, with building control inspecting at each stage rather than turning up at the end and finding a problem that is now buried.

Second fix, finish and snagging

Plastering, flooring, decoration and the kitchen or bathroom fit where that is part of the job, then a snagging walk round with you and a written list we work through.

Extension questions we get asked in Luton

How much do house extensions cost in the UK?

There is no honest single figure, and a builder who gives you one before seeing the house is guessing. The cost is set by the footprint, single or double storey, how much structural steel the openings need, the ground conditions under the footings and the level of finish. We quote free, in writing and itemised, so you can see which of those is driving your number instead of being handed one total.

Can you do an extension for 30k?

Sometimes, and the difference is almost never the size. A modest single storey rear extension on good ground with a simple roof and a plain finish is a very different budget to the same footprint with a large structural opening, a glazed lantern and a kitchen in it. Tell us your budget at the site visit and we will tell you honestly what it does and does not buy, rather than quoting to fit and finding extras later.

What is the 50% rule for house extension?

It is the permitted development rule that extensions and outbuildings must not cover more than half the land around the original house. Original means the house as first built, or as it stood on 1 July 1948, not as you bought it, which catches people out on properties that have already been extended once. We check this against your property before any drawings are paid for.

Do I need planning permission for an extension in Luton?

Not always. A lot of single storey rear extensions fall under permitted development, but that depends on the size, the height, how close you are to the boundary, whether the property sits in a conservation area and whether permitted development rights have been removed. Luton Borough Council is the planning authority for Luton and Central Bedfordshire Council covers Dunstable. We establish which applies to you first.

Will I need a party wall agreement?

If you are building on or near the boundary with a neighbour, cutting into a shared wall or digging foundations within three metres of their structure, the Party Wall etc. Act 1996 usually applies. It is not a problem, it is paperwork with notice periods attached, and it only becomes a problem when it is left until the diggers are booked. We flag it at quote stage.

Can we stay in the house while you build?

In most single storey rear extensions yes, because the new structure goes up outside the existing wall and the house is only opened up near the end. Double storey and wrap-around work is more disruptive and there is usually a week or two that is genuinely unpleasant. We will tell you which weeks those are at the start so you can plan around them.