What clever way did you keep costs down on your extension project?

[Tulipmonster]

We’re planning a side return and loft extension on our london terrace and I’ve (largely) made my peace with the eye watering sums this is going to cost. But this is the first time I’ve done this and I’d love to hear about the ways others have managed to lower their costs.

So please, hive mind, give me your tips!

I think it depends on how hands on you want to be.

If you can find a builder who will let you buy the materials (by setting up an account in your name at the various builders merchants, and they order what they need and you pay for it) you will avoid them having to charge you vat (on top of the vat the builders merchant also charges) for providing the materials. It also means you own the materials if there is ever a dispute.

Our builder did this, and I know a friend’s husband also does it, both as a result of a client not paying their bill and them having to write off a large debt. They then charge you for their labour and any agreed additional fee upon completion. I kept a very close eye on the finances as a result since I checked each invoice as it came in with my builder and he took up any discrepancies with the builders merchant.

Our builder also worked with subcontractors, our and his (joiner, plasterer, electrician, plumber, roofer, windows, garage doors) and we didn’t use our architect (who was pretty useless anyway) to oversee the build as the builder was experienced enough and had built an extension for DP in a previous house that stood for 20 years and I used to be a project manager and was on site throughout.

Also, don’t be afraid to look on eBay for stuff people are selling because they are doing a clear out. I bought a brand new Geberit flush for half price and a Kessebohmer larder unit for £37 (which was £650 brand new and hadn’t been fitted for some reason).

My parents found a builder who generally worked on his own, he just used a labourer & a plasterer when he needed them, my parents paid them instead of him paying them through his books. He sent my parents to a place that sold end of line kitchens where they chose a Magnet kitchen & paid less than half of the price Magnet had it on sale for. They had a kitchen extension, a utility room converted from the coal place & pantry, a patio & the top of the garden landscaped & saved over a third of what they had been quoted by another builder. Try & find someone who isn't registered for VAT, I know it is frowned on in Mumsnet, but if you can pay cash for things like plastering & stuff that will only need someone on site for a couple of days you can save a fortune when you add it up.

This is exactly the kind of thing I was hoping to learn - many thanks!

Don't change your mind.
Be very clear what you want the quote for and stick to it.

Our builder charged 18% on top of materials costs if he ordered it to cover taking responsibility for checking, chasing up faulty stuff and disposing of packaging. He was happy for us to order some stuff directly and he just told us the quantities to get so we did this with some things eg tiles. TBH it was a bit of a pain as you end up having to lurk for hours in an uninhabitable house waiting for a delivery to turn up and it did mean a few repeat trips to sort out some discrepancies. Whether you'd save money depends on how easy it is to get time off work and your set up eg if I'd been able to WFH in the house taking in a delivery would have been very straightforward.

Talk to builder about where stuff is sourced from. Most of our joinery was from Howdens which seemed a lot cheaper - think the builder passed on most of the discount he got.

Try plumbers merchant type places rather than upmarket bathroom showrooms. You'll get plumbing that actually works(!) and people who understand the practicalities rather than expensive stuff that doesn't work well but looks nice(!).

Extra stuff always gets discovered during a project. We had missing DPC under the floor! We allowed 15% for contingencies and it came in at 8%. Make it clear you want to know about this stuff but don't have an endless supply of money. Ours came up with alternative solutions to some problems that came up.

Go easy on the glazing. It’s expensive to buy, makes the room expensive to heat in winter, and you risk making a greenhouse in the summer.

Work out how much you can DIY between you eg decorating, building kitchen units etc

Some good points above. We saved so much by sourcing our own materials. Our builder gave us a list of materials at the start of the build and I shopped around. I sourced things from Marketplace and EBay although it’s getting harder to find bargains now. You can haggle with builders merchants too which helped reduce costs. Things like flooring and tiles, I found through Marketplace from others left overs. If I needed more I’d just buy the remaining from the retailer. Always call up and ask for a discount even from the big online retailers, I found they were willing to knock off around 5%.
I also declined my builders quote to dispose of all the rubbish. We built a retaining wall and terrace in the garden and so they managed to chuck a lot of the rubbish under that. The rest, I found a registered man and van to come and collect all the rubbish and dispose of it at the end of the build. You need a large enough plot to be able to keep the mountain of rubbish on site though. This saved a lot of money rather then getting multiple skips throughout the build.
A big factor was that I was at home to check things, await and check deliveries and manage the project. If you don’t have this capacity, then it may be worth paying for project management. Sometimes it’s even worth taking a work sabbatical to project manage the build as it may work out cheaper than hiring someone to do it !

Also if you need planting, a lot of gardeners and landscapers get discounts at local nurseries. Our gardener passes on his discount to us.

Thought of one more OP which is a bit controversial but if you live near a very wealthy area (I’m talking extremely wealthy places), then there are often huge mansions undergoing renovations. I walked by one and asked what they were disposing of. High end kitchens, bathrooms, materials were all just being disposed of as the new owner wanted all brand new. I managed to speak to the owner who was happy for me to take away some of her “rubbish” for free. I hired a man and grab lorry the next day and went over to collect things. I got surplus Mandarin Stone marble tiles, eglomise mirror, 2 marble worktops, building materials, the list goes on. There was some work involved eg my builder had to cut the worktops to fit etc but it saved me a fortune

@Tulipmonster We're thinking of embarking on a similar project... I've fallen down a hole trying to work out the potential costs before offering on a house and there's so much variance! Would you mind telling me roughly how much you're budgeting?

Speak to the builder everyday - friendly chat over a cup of tea. There will be lots of suggestions as issues come to light, some money saving and some not. Always, always ask “so what’s that going to cost then?” so that you’re both very clear about when you’re agreeing to spend more money than originally planned.

Try & find someone who isn't registered for VAT, I know it is frowned on in Mumsnet

There is nothing wrong with not being registered for VAT, if your business is too small to hit VAT thresholds.

Cash in hand doesn't necessarily mean tax evasion, either, as businesses get charged 2% (typically) for all bank transitions, so being paid in cash avoids the charge. If someone who takes cash is prepared to issue a proper invoice, they are less likely to be evading tax.

We put in the kitchen ourselves, did all the tiling and all the painting. We hunted around for cheap deals on floor tiles, radiators, taps and sinks. The little bits can really add up so worth taking time to shop around.

Painting is something most people can do themselves. Look at tutorials on YouTube.
There is a big difference in price for many kinds of tiles and bench tops. Do some research and think carefully about what kind to get.

@confusedandisolating We’re still refining the quote with the builder but it’s in the region of £160k for double loft extension and side return, plus moving various walls and a staircase and removing a chimney breast. This doesn’t include VAT, the kitchen, bathroom fittings or materials eg flooring - so these tips are exactly the kind of thing I was hoping for!

That's actually quite reassuring - eye watering still BUT sort of what I was expecting. Thank you for sharing. X