Building a house extension


We are tentatively exploring the possibility of building a two story extension on the side of our house.

We have a fairly good idea of what we want out of it.

Having never done anything like this before, we don’t have a clue (apart from watching Grand Designs on the telly) as to how to go about it.

We have a local architect type person (recommended to us by a friend) coming to see us next Friday morning for an initial consultation about drawing plans up etc. for planning permission.

I know a few of you on here have been through this (or something similar) and we were looking for any top tips, advice, recommendations, questions to ask, pitfalls to avoid etc. that you may have?

Thank you!

  1. Threaten your neighbors, preferably with photographic evidence you have previously accrued

  2. Get some big trees for camouflage.

  3. Build what you like and hope it remains unchallenged for x10 years.

Points 2 & 3 are the ‘Cornish method’ (I have added 1 for prudence)


Round my way there’s no space for #2 and no-one does anything exciting enough to deploy #1. People just go straight for #3, construct abominations, and then get outraged when the council looks into it :+1:

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We went with a builder recommended by our neighbour. Turned to be a mistake. My advice is to select your builder more carefully than we did. :+1:

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Spec it to death - every plug, light, switch, the lot
Draw it all
Check the bastards did it right
Assume it’ll take much longer and cost more

Fuck it, just move

Seriously, pm me if you want the full horror story of ours. Grand designs should be banned like Crack


move house to what you do want with work that you can do yourself - it wont be what you want or it will have cost you twice yuor budget and 2 years of heartache

life is too short for extensions and its getting worse now cost materials and labour have gone through the roof

printed concrete extensions will be here in a couple of years - maybe wait for that

lose loads of weight - your house will seem much bigger

basically don’t do it!!


For the most part, this

We’ve been through it twice in recent years. The first was a dreadful experience just recently quite the opposite. Entirely down to the attitude and experience of the builder.

A good local electrician gave some good advice when we moved into our current house. He said there were only three or four good local builders and one standout, all of the rest are a law unto themselves. His daughter put on an extension and went for the least expensive option rather than taking his advice and using someone known to be reputable. The job was an utter disaster with substantial cost to put right.

I’ve kept an eye out for his standout recommendation over the years and compared to others the jobs seem to get on and be completed quickly.

Choose your builder carefully! Not as easy at it sounds

I’ve heard more stories of woe than delight from those we know who’ve had work done, could be partly expectation but generally building seems as rouge a trade as ever.

We’re delighted with the recent work however the previous experienced soured the enjoyment we should have had from what we’d created.

Best of luck, it can certainly be worth the effort


Go large hay bale or go home


Ever thought of moving house?

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Yes! But it costs alot more than building an extension…probably…though I’m not so sure now after reading these comments!

It really does depend how ambitious the extension is and how good your builder is. If it’s a box on the side and a doorway through it shouldn’t be too bad but if you’re going all grand designs and knocking walls out (we had 12 RSJs in our extension build!) it’ll be much better to move out. Then you really need to be on site or have a decent project mgr as there will be loads of decisions that will need sorting - hence drawing everything.


I second getting a project manager in. In contrast to some of the experiences shared above, we did a rear extension a few years ago (and extended our kitchen into it so had plumbing and electrics in it too). It all went fine and we’re very happy with it.

We did have a PM though and he definitely helped - as per what pbg said, it’s good to have one point of contact to help sort decisions out with, and someone who can make sure the builders do what you want (and who can use their initiative to make sure things get done right in advance and help prevent problems from arising).

Also make sure you’ve got a quote for everything you want at the outset. Anything extra you want done as the project progresses will cost disproportionately more (e.g. we asked for some more power sockets to be put in - electrician said sure fine and we didn’t think to ask how much it’d be, and then at the end he charged us a lot for doing it). Extra things will likely arise, so make sure you get a quote first (and then you can try and negotiate) before going ahead with it.

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My builder was good (a mate whose work I was happy with) but the “architect” somehow hadn’t noticed that he had drawn a fire escape Velux where a roof purlin was.


After renovating and extended a number of houses, mainly in Australia. I would advise moving to something that suits your needs and doing minor refurbishing rather than doing an extension. Builders are an utter nightmare.

The current house we are in we replaced the roof, renovated three bathrooms, rewired, replumbed the heating, replastered, redecorated and sanded all the floors managing the project ourselves and coming in on time and on budget.

We needed a builder to knock down a couple of internal walls, insert 5 RSJs and to open an aperture for French windows in the kitchen. It went over budget, ran way over the deadline because the builder wanted to use a particular double glazing firm and somehow never got fully finished (there is some tiling, some plastering and skirting boards still to go in). Builders are cunts.


went on holiday every week.

Well he did take two weeks off over Xmas. Meanwhile we had no windows, just chipboard to fill the apertures and rockwool to keep out the very worst of the drafts.

I’m glad you posted this. We are considering buying a property, raising the roof and putting a loft conversion on whilst also building out over the garage. The previous replies have put me right off.

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(Dated today)


Oh bugger…

It’s been in the papers for a while. It was on the radio this morning too.

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