Rough estimate on extension

NotAGolf

NotAGolf

NotAGolf

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A house has popped up in an area we're keen on moving to. It's quite run down so would need a full renovation and a hefty extension in order for it to work for us.

The existing footprint would stay as is, and we'd slap a big two-story extension across the full width at the back. The plans below show the existing footprint in black, with the proposed extension in red.

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Quick summary:
  • ~12.5m x 3.5m extension on ground floor
  • ~9.5m x 3.5m extension on first floor
  • New kitchen + utility room
  • 2 x new bathrooms, plus 1 downstairs WC
  • New windows and doors in extension
  • Plastering and new flooring throughout the house
  • Electrics, gas, and plumbing

I know this is massively lacking detail, so I'm only after a very rough ballpark to see if this a complete non-starter; so any guesses to the nearest 50k, or even 100k would be helpful. This is in the South East.

My incredibly uneducated guesses for each of the above is:
  • Extension - 150k
  • New kitchen + utility room - 35k
  • 2 x new bathrooms, plus 1 downstairs WC - 20k
  • New windows and doors in extension - 15k
  • Plastering and new flooring throughout the house - 10k
  • Electrics, gas, and plumbing - 15k
  • Unexpected stuff - 25k
  • Total: 270k

Any thoughts? Am I a million miles off?
 
Thanks for the feedback so far all :)

gazref said:
£3000 sqm plus vat
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So (12.5x3.5)+(9.5x3.5)*3000 = £231k, plus VAT = £277k. Does that estimate include kitting out the kitchens/bathrooms, or is that literally just the shell?

sigma said:
Why not add a fifth bedroom on top of garage and utility?
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It's extra cost for space that we don't really need, and likely can't afford.

Haze said:
Would it not be cheaper to move into a 4 bed property? Don't see how you are going to make your house worth an extra 300k
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Yes, I'd much rather pay 800k on somewhere finished over a shed worth 500k that needs 300k's worth of work, but our location is very limited (and we're not willing to budge on that), so a 700k finished place in the right area might never come up.

We're not interested in making money on the house. We'll be in the house for many many years, and negative equity isn't a concern, so if we spend 300k to make the house work for us, but it only adds 150k to the value, that's no problem.
 
dlockers said:
Individual breakdown seems a bit off but total seems sensible. @kai
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South East is like Surrey, Oxfordshire etc ( i think) :)

No doubt building cost is going to be a lot higher in terms of daily rates. As per the comments; If you are looking at spending (estimate) close to 300K on house renovations; let's say the house is 450K - will the house be worth 750-800K post completion?

You could find yourself in negative equality and finding a lender difficult, unless you envisage it as being a forever home and holds a lot of potential.

This is just from my experience of going through this over the last 1.5 years with our own renovation:
  • Extension - 150k - seems excessive based on plan but your location drives cost, so i am unable to really comment.
  • New kitchen + utility room - 35k - you could easily slash this to under £20K including quartz, you just need to shop around.
  • 2 x new bathrooms, plus 1 downstairs WC - 20k (does this including fitting costs?) I have just done the exact same for around 10K excluding fitting (again need to shop around)
  • New windows and doors in extension - 15k Seems light; are we talking PVC, Aluminum, energy rated etc?
  • Plastering and new flooring throughout the house - 10k vague, but flooring purchase alone could hit this cost. Are we talking LVT, Real wood etc.
  • Electrics, gas, and plumbing - 15k - No idea, your best speaking with each trade as you will likely find it could hold issues / code if it's an older house
  • Unexpected stuff - 25k - contingency, they say around 10%; so 30K but you need to factor in things like decorating. A good decorator will easily charge £1-1.5K per week without materials (based on my location)

    Sounds silly but factor in furniture, decoration, appliances (TV etc). This part needs to be a healthy budget as you do not want to have a beautiful new renovation and you can't afford to furnish it :)
 
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I would say the budget seems fairly sensible to me and i don't think you'd get much of a shock if ploughing ahead with the plans. As above, some things seem high (kitchen/utility for example), but we don't know your specs for that, and it's always better to go over vs under.

My only comment would be that it might be better to redo all windows in the existing structure too to make sure they match, unless you don't mind as they're opposite sides of the house?


Also, whilst i understand the upstairs layout is being done to utilise existing walls, your bedroom 2/3 seem bigger than the master. I'd be trying to steal a bit from Bedroom 3, or moving the master to the back of the house so you're not disturbed by road noise. Although that's a comment completely not knowing the views or house location!
 
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A couple of people have mentioned specs/finishing standard. I'd say mid-range would be our target. We're not going cheap, but definitely no need for top-end stuff.

I'd also be willing to do some of the work myself. Obviously things like plastering and building I'd leave to the pro's, but I'm happy to chase cables/pipework. I fitted a kitchen and a bathroom at our current place, so would be willing to do that again to trim the cost if the quotes are silly money. Same goes for decorating and some of the carpentry work.

I just want to err on the side of caution and would rather overestimate than underestimate.

Martynt74 said:
My only comment would be that it might be better to redo all windows in the existing structure too to make sure they match, unless you don't mind as they're opposite sides of the house?
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Yes, I'd likely want to do the front of the house as well, but they don't need to be done, so I'm excluding that cost for now.


Martynt74 said:
Also, whilst i understand the upstairs layout is being done to utilise existing walls, your bedroom 2/3 seem bigger than the master. I'd be trying to steal a bit from Bedroom 3, or moving the master to the back of the house so you're not disturbed by road noise. Although that's a comment completely not knowing the views or house location!
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We've got two kids, so they'd be going in the back rooms. They need the space more than we do tbh, and having them in equal sized rooms means no arguments (well, at least not about room sizes)!
 
Just making sure this is a detached house? You'll be lucky to get planning permission for a 2 story across the full width if it's semi detached.
 
Would you not rather pay the +300k and have the finished product in the first instance? Depends on ceiling value of houses I suppose.

Edit: sorry I missed your other response.

Overall a 300k fund seems reasonable for this so you can go in "eyes open"
 
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Mason- said:
Just making sure this is a detached house? You'll be lucky to get planning permission for a 2 story across the full width if it's semi detached.
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Yes it's detached. We've done our best to measure the 45 degree angle from the neighbours windows either side, and we should be ok to push out the ~3.5m without breaking this rule.
 
I still reckon a 5th bedroom would add a lot of space and value to the house, for relatively little extra spend. You don't plan to move but you never know what lies ahead. Would it cost more than £10k?
 
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We're halfway through a single storey extension of the same size and shape in Surrey which will include a new kitchen, utility, flooring for most of the rest of the downstairs and it's currently looking like it'll come in at about £150k-£170k all in. Although we've got an extra £20k or so to spend on the garden as well, as once you extend that'll need to all be redone.

We are just at the point where it is a watertight shell - so we've had groundworks, bricks, roof, windows and bifolds and have paid out just shy of £60k inc VAT for around 42sqm.

Your total of £270k seems fair for the work. FWIW, 4m of bifolds and 2x standard 1mx1m windows have just cost us about £6.7k inc VAT.
 
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The house cost to buy plus 300k is presumably a large enough number that would get you a better property outright that's already bigger and....well...better. Is that not more appealing to move into rather than having the stress and time waiting for an Uber extension to be done? These things don't tend to go smoothly and can be literally life changing in terms of the stress.
 
jaybee said:
The house cost to buy plus 300k is presumably a large enough number that would get you a better property outright that's already bigger and....well...better. Is that not more appealing to move into rather than having the stress and time waiting for an Uber extension to be done? These things don't tend to go smoothly and can be literally life changing in terms of the stress.
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He's already covered that, and said it could be months/years that the suitable house comes to market as it's a small location which he's not willing to compromise on
 
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