A rear extension looks like the easiest win in the house. You have a garden you barely use, and you want a bigger kitchen or a family room. Push the back wall out, fill in the gap, done. That is how most people picture it.
The reality is that the part you see, the building, is the easy bit. The part that decides whether the job goes well happens before anyone lifts a tool. The right design and build contractors london homeowners trust do a surprising amount of work upfront, and that quiet groundwork is exactly why their projects run smoothly while others stall. Here is what actually happens before the first brick.
They Check What You Can Build Without Permission
A lot of rear extensions fall under permitted development, which means you can build them without full planning permission. But the rules are specific, and people get them wrong all the time.
How far you can extend depends on whether your house is detached, semi, or terraced. There are limits on height, on how close you can get to the boundary, and on what counts as the original house. A bit you think is fair game might already have been extended by a previous owner, which changes everything.
Good contractors check all this first. They figure out the biggest thing you can build legally before they design anything, so you are not in love with a plan the council will never allow.
They Look at the Drains and the Ground
This is the unglamorous part nobody thinks about, and it catches loads of projects out.
There is often a drain running right where you want to build. You cannot just bury it. You either build around it, move it, or get permission to build over it, and each of those costs different money and takes different time.
The ground matters too. Clay soil, nearby trees, old foundations- all of it changes how deep the new foundations have to go. A team that checks this early gives you a real price. A team that skips it gives you a low price now and a nasty bill later when the digger hits something.
They Design Around the Light, Not Just the Space
Here is the trap with rear extensions. You add space at the back, and you end up making the middle of the house darker than before.
The old back room becomes a middle room with no outside wall. Without thought, it turns into a dark, dead zone you walk through to get to the nice new bit.
Experienced contractors plan for this from the start. Rooflights over the new section. A glazed link. An open layout that lets light travel through. The Raynes Park rear extension is a good example of pulling light deep into a home that would otherwise have gone gloomy in the middle.
They Sort the Party Wall Conversation Early
If you are in a terrace or a semi, your extension touches a wall you share with a neighbour. That brings the party wall process into it, and it has legal steps you cannot skip.
You have to serve notice. Your neighbour can agree, or ask for a surveyor, and that takes time. Start this late, and it holds up the whole build while you wait on paperwork.
Contractors who have done plenty of London jobs raise this on day one. They know it takes weeks, so they get it moving early instead of letting it become the thing that delays everything else.
They Plan How the Old and New Parts Meet
The bit that makes a rear extension look right or look bolted on is the join. Where the new structure meets the original house is where good work shows.
Does the new roof line sit comfortably against the old one? Do the bricks match, or at least sit nicely next to the old ones? Does the floor level run through cleanly, or is there a clumsy step where the two parts meet?
These are design decisions made long before building starts. A team that designs and builds keeps them joined up, so the person picturing the finish is the same outfit laying the blocks.
They Give You a Realistic Timeline, Not a Hopeful One
Everyone wants to hear the job will take eight weeks. Honest contractors tell you the truth instead.
A rear extension involves foundations curing, inspections at set stages, deliveries that can slip, and weather that does what it wants. A realistic timeline builds in room for the normal bumps.
The team that promises the fastest finish is often the one that has not thought it through. The team that gives you a slightly longer but honest schedule is usually the one that actually hits it. That honesty before the job starts tells you a lot about how the whole thing will be run. For more information, visit our website.