Subsidence and Proposed Plans

Jaguar_Skills

A couple of years ago we started to get subsidence cracks in our conservatory.   After a long fought battle with the insurance company they finally decided to pay out.  We have now had an architect draw up some proposed plans to knock down our conservatory and open the whole space up by removing a retaining wall and adding a utility next to the garage.   We are in two minds whether to implement this permission or whether to sell with it.   Given we are now at the point of submitting the plans, we just wondered if there is anyone who has an idea what the works may cost.   We were told between £1500-£2000 per sqm which would equate to £72-£90k but this seems extremely high given that it is not going to be all new.   For example the existing walls in kitchen and link room will remain it will just be knocking conservatory down and rebuilding that part, and adding the utility that will be brand new.   I have attached our existing and proposed plans if anyone can help. 

thearchitect

£2,000/m2 is a standard budget rate for small scale new build, I'm afraid.  Larger works have economies of scale but extensions are fiddly.  You can bring the cost down with a tame contractor or self-build.

AdrianC

Why did the old conservatory subside?

Was it simply inadequately built in the first place, with inadequate foundations - or was there an external cause?

If the latter, then you're going to need to rectify that cause, and possibly other damage to the main body of the house, which will further add to the cost.

Doozergirl

Usually, you'd only really count what you are actually building into your estimate.   So, you don't count the kitchen if it already exists.  You count the square meterage of the new extension for your rough calculation...

However, there are obviously major building works to be carried out inside the existing house here and that does cost money, as does your new kitchen.  What that costs depends on the budget you set for it, but the ballpark you've found yourself there is certainly a possibility. 

For small builds, it's working out in excess of £2,000 a metre for us.  Everyone wanted bifolds or sliding doors, then they wanted to take out the wall dividing the two rooms
at the back of the original house so the kitchen island then goes with that.  The new thing is roof lanterns.    Items just get added to the list of 'must haves' and none taken away and so the price of the 'average' single storey extension goes up and up.  

If you want to save money, you build less space.  The utility could be moved into a garage conversion or incorporated into the rear extension, which is plenty big enough.  

I can't help thinking that people sometimes end up sacrificing one lounge for another when they do this.   According to that plan, you've added 21 square metres of space for half a dining table and a small sofa.  It doesn't look all that comfy.   The actual interior design and layout of furniture should be better considered, so that you factor in what you need and what your actual budget is. 

If you don't feel that what you're looking at creates a home that you're genuinely excited about, the only reason for extending is to improve the value of the house over what you spend on it.   

Jaguar_Skills

AdrianC said:

Why did the old conservatory subside?

Was it simply inadequately built in the first place, with inadequate foundations - or was there an external cause?

If the latter, then you're going to need to rectify that cause, and possibly other damage to the main body of the house, which will further add to the cost.

A mix of the tree in the garden and poor tying in of the conservatory I think. 

Jaguar_Skills

Doozergirl said:

Usually, you'd only really count what you are actually building into your estimate.   So, you don't count the kitchen if it already exists.  You count the square meterage of the new extension for your rough calculation...

However, there are obviously major building works to be carried out inside the existing house here and that does cost money, as does your new kitchen.  What that costs depends on the budget you set for it, but the ballpark you've found yourself there is certainly a possibility. 

For small builds, it's working out in excess of £2,000 a metre for us.  Everyone wanted bifolds or sliding doors, then they wanted to take out the wall dividing the two rooms
at the back of the original house so the kitchen island then goes with that.  The new thing is roof lanterns.    Items just get added to the list of 'must haves' and none taken away and so the price of the 'average' single storey extension goes up and up.  

If you want to save money, you build less space.  The utility could be moved into a garage conversion or incorporated into the rear extension, which is plenty big enough.  

I can't help thinking that people sometimes end up sacrificing one lounge for another when they do this.   According to that plan, you've added 21 square metres of space for half a dining table and a small sofa.  It doesn't look all that comfy.   The actual interior design and layout of furniture should be better considered, so that you factor in what you need and what your actual budget is. 

If you don't feel that what you're looking at creates a home that you're genuinely excited about, the only reason for extending is to improve the value of the house over what you spend on it.   

Thanks for this Doozergirl.  A good in depth summary.   We liked the look of this layout as it matched something we saw in another house and felt it worked really well.  As I said once we have the build quotes back we may decide to move rather than build it out anyway and so a prospective buyer could vary the permission with a minor material amendment. 
I think the addition of a utility area in that dead space is a real selling point as well as the open area etc onto the garden.