Please help me estimate a self-build budget

[bpk101]

Hi — I'm trying to arrive at some rudimentary budgeting figures for a potential self-build project my OH and I are hoping to embark on so we can see what's possible in terms of size and spec. I've followed a few basic financing and budgeting formulas that have been suggested to me but i'm not sure whether my calculations are correct and whether i'm accounting for everything that needs to be considered. What i'd like to arrive at is... 

 

1. A rough idea of our potential construction budget 

2. An approximate house size in sqm based on this budget

 

Below are the figures i'm currently arriving at. Any advice on whether i'm doing this correctly or what the correct figures should be would be fantastic.

 

———————————

 

Joint household income: £295k 

Multiplied by 3 to arrive at a potential maximum mortgage: £885k

Plus current savings: £50k
Plus equity in current house: £300k

Equals a total budget of: £1.235m

 

Based on land being 1/3rd of this figure and the build being 2/3rds:

Land budget: £411k

Self-build budget: £822k

 

From the self-build budget i've deducted 20% / £164k for all the fees (architect, structural engineer, M&E, QS, building control, planning fee, party wall fee)

I've then deducted 20% / £164k for contingency

 

This leaves a final construction budget of: £644k

And a potential house size of:

Low spec (£2000 per sqm) = 322 sqm
Mid spec (£2500 per sqm) = 257 sqm
High spec (£3000 per sqm) = 214 sqm

 

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[ZacP]

We can borrow £600k with ecology.

paying £350k for the plot.

building 225sqm for £300k (might have to stretch to £350k) [£1300-1600/sqm] at a good spec but doing as much work ourselves as possible.

 

think your £/sqm are high depending on your build route. Are you planning on using a turnkey style build, main contractor or subies etc? These have a huge impact on cost independently from spec.
 

You can probably achieve anything you want with that budget depending on what you can do yourself. even just doing admin for the builder or shopping around for materials has already allowed us to spend saved money on nice things like ASHP and my wife’s ‘required’ aga!

[Mr Punter]

8 minutes ago, ZacP said:

wife’s ‘required’ aga

 

I have had one of these and I would advise DON'T!

 

Sweltering in the summer, crap to cook on, expensive to run.

[ZacP]

Had one as a kid. Loved cooking on it and coming in from the rain and basically hugging it to keep warm. 
I’m expensive to run too, and we’re getting one with a handy new invention called an off switch. Specifically designed for the 3 weeks a year the uk has a heatwave! 

1 minute ago, Mr Punter said:

 

I have had one of these and I would advise DON'T!

 

Sweltering in the summer, crap to cook on, expensive to run.

 

[Mr Punter]

1 minute ago, ZacP said:

Had one as a kid. Loved cooking on it and coming in from the rain and basically hugging it to keep warm. 
I’m expensive to run too, and we’re getting one with a handy new invention called an off switch. Specifically designed for the 3 weeks a year the uk has a heatwave! 

 

 

I now live in a new house and it would easily overheat with an Aga.  No heatwave required.  So will yours if it is built properly.

 

My Aga was in a cold Victorian detached with solid walls, so it was nice to come home to.

[Ferdinand]

Being slightly contrarian, can I recommend that as a foil you also do a "needs" analysis from the other end - a list of spaces and facilities that you need. Particularly in the London, house values are currently questionable having gone down for each of the last 3 years.

 

Suspect that you may  do this anyway, given your approach on the forum.

 

It's good to know what you can afford, but there is no reason why you need to spend to the max. Having some headroom is a good thing to do.

 

Whenever I go to Town I love window shopping all the expensive boutiques for the things I don't need to buy any more than I need to buy a polka dot hippopotamus.

 

Edited September 29, 2020 by Ferdinand

[bpk101]

6 hours ago, Ferdinand said:

can I recommend that as a foil you also do a "needs" analysis from the other end - a list of spaces and facilities that you need.

 

Yes we're slowing putting this together. 

 

6 hours ago, Ferdinand said:

Particularly in the London, house values are currently questionable having gone down for each of the last 3 years.

 

 

Is this in reference to the house we currently own (and have equity in) being in London? We won't be selling for 3-4 years yet so can't really foresee what the market will be like then.

If you're suggesting the self-build will be in London, it won't. We're looking to build outside of London but ideally somewhere in the South East (land budget allowing).

[bpk101]

14 hours ago, ZacP said:

Think your £/sqm are high depending on your build route.

 

As this is our once in a lifetime 'forever home' (at least that's the plan) we do want to create something of a relatively high standard. I'm a designer by trade (sadly not in a field related to architecture or construction), and the aesthetic of the house is extremely important to us. We'd like to work with a very good architect who can deliver in the style we want and that could impact on our cost. Not that i'm considering using this company but i love their work but they clearly state on their website that projects they take on typically have a cost per sqm starting at £3500(!)

 

https://www.stromarchitects.com/architecture-one-off-contemporary-houses/

 

14 hours ago, ZacP said:

Are you planning on using a turnkey style build, main contractor or subies etc?

 

At the moment i think main contractor is the route for us with the architect doing a series of site visits to ensure the plans are being followed correctly, then i'll be overseeing the project management side of things (timings, researching and purchasing of not construction fixtures and fittings etc). 

 

Is this a cost effective route?

[bpk101]

15 hours ago, bpk101 said:

Based on land being 1/3rd of this figure and the build being 2/3rds:

Land budget: £411k

Self-build budget: £822k

 

From the self-build budget i've deducted 20% / £164k for all the fees (architect, structural engineer, M&E, QS, building control, planning fee, party wall fee)

I've then deducted 20% / £164k for contingency

 

This leaves a final construction budget of: £644k

 

Do these figures seem right and have i done the self-build estimate correctly?

Is 20% the right amount to factor in for all fees?

Is deducting 20% at the outset the right way to account for contingency and is it enough?

 

 

[Ferdinand]

17 minutes ago, bpk101 said:

 

Yes we're slowing putting this together. 

 

 

Is this in reference to the house we currently own (and have equity in) being in London? We won't be selling for 3-4 years yet so can't really foresee what the market will be like then.

If you're suggesting the self-build will be in London, it won't. We're looking to build outside of London but ideally somewhere in the South East (land budget allowing).

 

It is just a note that the London market is going to be very difficult to predict.

 

There was a piece in the FT this week claiming that it was booming, which I think very irresponsible.

 

F

[ZacP]

If its your forever home then I would consider that you may be wanting to make changes over time (e.g. making sure there is an area for a lift) so if it were me I'd spend a bit more on the structure, insulation, footprint, design, etc etc - things you can't easily change in the future. Then if the budget comes in tight to the end and you run out of contingency you can always fit a less expensive kitchen or bathrooms to save a number of 10s of thousands of pounds. Then revisit in 5-10 years and put in something all singing all dancing that you wanted in the first place. It's relatively easy to upgrade these things, but much harder to fit underfloor heating or more insulation or similar to some designs at a later date.

 

Hope that makes sense.

 

p.s. if they say their project start at £3500 then they're likely to be much much more then this! Any decent architect should be able to design something along the lines of what you're looking for. Create a Pinterest board and send that to a few to see how excited they get!

p.p.s. yes, main contractor is usually the more expensive route, investigate things like fixed price contracts to mitigate your budget risk further. More expensive, but likely to take the stress out of the build a bit for you.

p.p.p.s. sounds like an exciting project - good luck!

Edited September 29, 2020 by ZacP

[bpk101]

6 hours ago, ZacP said:

If its your forever home then I would consider that you may be wanting to make changes over time (e.g. making sure there is an area for a lift) so if it were me I'd spend a bit more on the structure, insulation, footprint, design, etc etc - things you can't easily change in the future. Then if the budget comes in tight to the end and you run out of contingency you can always fit a less expensive kitchen or bathrooms to save a number of 10s of thousands of pounds. Then revisit in 5-10 years and put in something all singing all dancing that you wanted in the first place. It's relatively easy to upgrade these things, but much harder to fit underfloor heating or more insulation or similar to some designs at a later date.

 

Yes completely agree, we're more than happy to think economically with regards to fixtures and fittings. We don't necessarily desire a bank busting Gaggenau kitchen for example, we achieved a really high finish in our current home on a budget by spending time to research some choice products. For example our current kitchen is Ikea carcasses but doors and work surfaces made by a danish company called ReformCPH who specialise in fronts designed by architects and built for Ikea cabinets, 3 years later and it still looks and works great! We'd be happy to do this again and if we do win the lottery 10 years down the line, well!

 

6 hours ago, ZacP said:

p.p.p.s. sounds like an exciting project - good luck!

 

Thanks! Definitely exciting, if not slightly nerve-wrecking ?

[oldkettle]

21 hours ago, bpk101 said:

Not that i'm considering using this company but i love their work but they clearly state on their website that projects they take on typically have a cost per sqm starting at £3500(!)

 

https://www.stromarchitects.com/architecture-one-off-contemporary-houses/

 

I wonder whether architects here would care to comment. What strikes me about these homes is that they are very similar and in many cases seem to choose form over the convenience: I seem to remember cantilevered parts present a significant cold bridging problem. But again, that's for a professional to confirm. 

[Ferdinand]

1 hour ago, oldkettle said:

 

I wonder whether architects here would care to comment. What strikes me about these homes is that they are very similar and in many cases seem to choose form over the convenience: I seem to remember cantilevered parts present a significant cold bridging problem. But again, that's for a professional to confirm. 

 

I think any architect tends to have a house style, which is why it is so important to look at previous work.

[the_r_sole]

9 minutes ago, Ferdinand said:

 

I think any architect tends to have a house style, which is why it is so important to look at previous work.

 

We don't have a house style - we are more driven by what style the client wants (but my previous office did have a style which was kept to)

 

Strom are very particular, they state a minimum m2 price to deliberately cut people out of wanting to work with them, they'll only do the projects where the client wants to achieve that style/look and have enough money to deliver it. You wouldn't just phone them up and get them out for a chat... They are internationally renowned for their style and their focus is solely on their ideal clients.

[oldkettle]

4 hours ago, the_r_sole said:

Strom are very particular, they state a minimum m2 price to deliberately cut people out of wanting to work with them, they'll only do the projects where the client wants to achieve that style/look and have enough money to deliver it. You wouldn't just phone them up and get them out for a chat... They are internationally renowned for their style and their focus is solely on their ideal clients.

 

What can I say... Great to be able to work like this (not a hint of sarcasm here). 

[the_r_sole]

22 minutes ago, oldkettle said:

 

What can I say... Great to be able to work like this (not a hint of sarcasm here). 

 

To be fair to him, it's the absolute perfect setup, only do projects you want to do with clients who really want you to do them.

We all use some subtle types of qualifying in our websites/social media...

[oldkettle]

25 minutes ago, the_r_sole said:

We all use some subtle types of qualifying in our websites/social media...

3.5K+/m2 you call subtle? ? 

[the_r_sole]

20 minutes ago, oldkettle said:

3.5K+/m2 you call subtle? ? 

 

For that type of project it's light if anything, for high end clients they don't care about the costs, they care about the quality of the end result.

If you're cost driven then you're not the right client for that practice. The only reason anyone ever puts minimum build costs on their site is to discourage enquiries from dreamers who think they can achieve that quality for buttons.

 

He isn't targeting self builders looking to make savings on build methods/finishes/consultancy ...

Some are more subtle than others 

Edited September 30, 2020 by the_r_sole