Self build extension costs

[0Floz0]

Hey everyone

I’ve had a look round on the forums and can’t find any recent threads on this. Costs are always moving so that’s a big issue for me.

We are looking to move soon but struggling to get the size we need for our price point. So one of the options is to get a smaller house and extend it. Assuming we can get planning permission.

To keep costs low I’d be looking to do most of the work myself. The only exception to this would be getting a bricklayer in to do the shell which would be block and brick with a cavity.

I’ve posted a few times on various projects and have done plenty of different jobs round the house so hoping it’s a viable option.

Trying to figure out what a typical cost would be. I know that can be a wide spectrum but for the sake of ease. What is the likely cost of doing everything to up to it being plastered inside with the only trade being the bricklayer.

Size wise probably looking at 7m x 3.5m. One storey but interested to know what the likely increment would be for a two storey house.

I’m based in Warwickshire if that helps.

Thanks!

 

[noseall]

Hey everyone

I’ve had a look round on the forums and can’t find any recent threads on this. Costs are always moving so that’s a big issue for me.

We are looking to move soon but struggling to get the size we need for our price point. So one of the options is to get a smaller house and extend it. Assuming we can get planning permission.

To keep costs low I’d be looking to do most of the work myself. The only exception to this would be getting a bricklayer in to do the shell which would be block and brick with a cavity.

I’ve posted a few times on various projects and have done plenty of different jobs round the house so hoping it’s a viable option.

Trying to figure out what a typical cost would be. I know that can be a wide spectrum but for the sake of ease. What is the likely cost of doing everything to up to it being plastered inside with the only trade being the bricklayer.

Size wise probably looking at 7m x 3.5m. One storey but interested to know what the likely increment would be for a two storey house.

I’m based in Warwickshire if that helps.

Thanks!

You might save £20k on a £60k project, depending how practically competent you are and how well you can manage the job. You could also cost yourself as much. One example - after hitting several services (drains, pipes etc), whilst machine digging out his trenches, one unlucky DIYer then had a delay in getting the concrete on site, whereby the rains came and collapsed 50% of the trench sides back into the trench and filled the lot with water. He didn't seem to think diverting the now un-connected RWP's (and lots of rain) would cause such a headache.

We like to dig and pour in the same week if we can. Never start a trench dig on a Friday - ever. There are trillions of other examples, too numerous to mention.

 

[23vc]

I built mine myself in 2017-2018 as did several others on here. Did everything except muckaway, gas and electric. Total cost for a 2 storey side and single storey full width rear lean-to was 46k, and I know that similar jobs round here would have been about 90k plus for a decent builder as knew plenty of others having work done.

it’s not for the faint hearted. I missed a year of my young kids growing up, but I have a massive passion/interest/respect in building without ever having done it for a full time living. I did it primarily because I wanted to, as a kind of major life achievement rather than a way of saving money. Also worth mentioning I’d had about 15 years of experience doing places up and general work, rather than coming into it cold never having held a trowel.

Agree with noseall there’s always a risk of an expensive mistake, reduced by the amount of planning, common sense, research, experience you have.

And speaking of noseall and others, this forum is invaluable if you ever do it

 

[0Floz0]

You might save £20k on a £60k project, depending how practically competent you are and how well you can manage the job. You could also cost yourself as much. One example - after hitting several services (drains, pipes etc), whilst machine digging out his trenches, one unlucky DIYer then had a delay in getting the concrete on site, whereby the rains came and collapsed 50% of the trench sides back into the trench and filled the lot with water. He didn't seem to think diverting the now un-connected RWP's (and lots of rain) would cause such a headache.

We like to dig and pour in the same week if we can. Never start a trench dig on a Friday - ever. There are trillions of other examples, too numerous to mention.

Thanks Noseall, yeah wary of issues such as that. Its the sort of thing I'd be checking before buying the house. We have a huge sewer run under our current house and through the garden. One drain had been buried in our house under dirt and some decking! I rectified it when I put in a porcelain patio. I'd be checking locations of drains when we do any viewings and then reviewing the searches as part of the purchase.

I think the foundations is probably my biggest worry alongside the brickwork. I don't have the skill of bricklaying but pretty competent with electrics, plumbing, plaster boarding, fitting windows, flooring, insulating, etc.

Great advice on the dig and pour in the same week. Preferably when the forecast looks good as well, though assume you don't want the ground completely dry and rock solid.

I built mine myself in 2017-2018 as did several others on here. Did everything except muckaway, gas and electric. Total cost for a 2 storey side and single storey full width rear lean-to was 46k, and I know that similar jobs round here would have been about 90k plus for a decent builder as knew plenty of others having work done.

it’s not for the faint hearted. I missed a year of my young kids growing up, but I have a massive passion/interest/respect in building without ever having done it for a full time living. I did it primarily because I wanted to, as a kind of major life achievement rather than a way of saving money. Also worth mentioning I’d had about 15 years of experience doing places up and general work, rather than coming into it cold never having held a trowel.

Agree with noseall there’s always a risk of an expensive mistake, reduced by the amount of planning, common sense, research, experience you have.

And speaking of noseall and others, this forum is invaluable if you ever do it

That's great, I was hoping it'd be under the 50k mark although appreciate material costs have moved up a fair bit since then. Though i'm hoping some have come down since like wood prices!

Yeah I've got young kids too and have had numerous projects with this house and I hated missing time with them. Although its probably why its taken so long as I made sure to take breaks with them (although not as many as i'd have liked to).

I've had a fair bit of experience from this house, granted not 15 years, but I've done pretty much everything apart from brick laying in this one.

I'm a meticulous planner, the sort of person that will read up on loads of different methods and pitfalls of doing certain things and what to look out for.

The main reason for me is we can't quite afford the size of house we want. So looking at getting a 3 bed and then extending it into a 4 bed. The price difference for a detached house thats about 100m2 floor plan versus 150m2 is about £200k. There is a real shortage of that size of home so the upside is huge.

Which individual bit took the longest? Assuming it was the brickwork? Ignoring the wait time for the foundations to set of course. Did you use strip foundations?

Cheers!

 

[matlob]

I've just completed the shell of a 7x4m extension and total cost so far is 11k

Thats everything to get it watertight before the insulation / electrics go in

I've done everything myself though.

 

[0Floz0]

I've just completed the shell of a 7x4m extension and total cost so far is 11k

Thats everything to get it watertight before the insulation / electrics go in

I've done everything myself though.

I'm guessing at that price its a 1 storey extension?

That sounds really cheap, great effort! Any tips on keeping costs down?

 

[23vc]

Which individual bit took the longest?

Cavity brickwork took several months and I was a lot better when I finished than when I started

I did Trench fill foundations

 

[0Floz0]

Cavity brickwork took several months and I was a lot better when I finished than when I started

I did Trench fill foundations

I'm tempted to go the block route and have it rendered. It would save matching the bricks up it up but again rendering is a pricey job. Just depends how much it saves going the block route and whether there is enough there to cover that. I do love the aesthetic of a light render with some wood cladding and anthracite windows.

Noticed you're a fellow Warwickshire resident. I'm based in Kenilworth, are you far?

 

[23vc]

are you far?

Leamington

The other thing I forgot to say was, I never planned to do it all myself on day one. I thought I’d go as far as brickwork to dpc etc, then as time went on I just ended up cracking on. I’d think twice about doing it again though - not sure I’ve got the mental strength or time!

 

[kingandy2nd]

…. I do love the aesthetic of a light render with some wood cladding and anthracite windows.

If you get a few mins then it might be worth reading my build thread (link below in my footer).

A one storey extension isn’t too bad as limited working at height speeds things up.

To be honest, I don’t think you’ll make a massive saving if your not willing to do the brick/blockwork yourself as that’s where a lot of the labour time/cost is.

 

[0Floz0]

Leamington

The other thing I forgot to say was, I never planned to do it all myself on day one. I thought I’d go as far as brickwork to dpc etc, then as time went on I just ended up cracking on. I’d think twice about doing it again though - not sure I’ve got the mental strength or time!

Ah just down the road, what are the odds!

Which merchants did you tend to favour when sourcing materials? Did you do much shopping around?

If you get a few mins then it might be worth reading my build thread (link below in my footer).

A one storey extension isn’t too bad as limited working at height speeds things up.

To be honest, I don’t think you’ll make a massive saving if your not willing to do the brick/blockwork yourself as that’s where a lot of the labour time/cost is.

Will take a look now, thanks. Yeah, its one of my main concerns. Wondering if there are cheaper alternatives I'd be more comfortable doing myself that would still look good.

 

[23vc]

I’ve used BPS for about 20 years. Brilliant local merchants.

90% of materials through them unless very obviously cheaper elsewhere - PIR boards were cheaper online at the time, but I think now there’s nothing in it.

 

[0Floz0]

I’ve used BPS for about 20 years. Brilliant local merchants.

90% of materials through them unless very obviously cheaper elsewhere - PIR boards were cheaper online at the time, but I think now there’s nothing in it.

Nice, that the one just behind the shopping park?

I'm usually using MKM as my mate has a trade account with them so they usually do loads of things cheap for me when I need odds and ends. He gets on well with them which helps my case!

 

[kingandy2nd]

Ah just down the road, what are the odds!

Which merchants did you tend to favour when sourcing materials? Did you do much shopping around?


Will take a look now, thanks. Yeah, it’s one of my main concerns. Wondering if there are cheaper alternatives I'd be more comfortable doing myself that would still look good.

Brick/blockwork isn’t that hard to do if you take your time. Loads of videos on YouTube to learn from.

I was quite apprehensive about laying before I started, but you pick it up. I’d never be quick enough to earn a living doing it, but it holds my roof up.

Rendering will cover your sins too.

 

[Dereekoo]

Hats off to any of you chaps who have done a bit of selfbuild and especially king Andy who's a king