Single extension build ( kitchen - dining )

[Leo1975]

Thank you for letting me join here

My request for help ( which would extremely grateful ) if anyone could point me in the right direction.

We purchased our house ( around 2004 build ) and there scope to complete a single extension across the back. The previous owner spoke they were going to do the same ( had some drawings done and applied to council for approval- Approval given and currently still valid )

We were told they started the works but as it started the wife who looked at a new build for ideas fell for it so that put a stop to it

Through a neighbour when mentioning about possibly looking at this they spoke the previous owner had fun and games ( but hence we won’t know if they did or not? ) as you can imagine when viewing the house they weren’t going to rush to tell us if it wasn’t going to straight forward.

So my GF is worried if steels or piling would be needed ?? but if it was a case that would be needed? She wants to weigh up the costs before hand.

A think the easiest question to ask? Is there any test or sampling works that could be completed now before paying for drawings etc

A rear property ( 3 or 4 houses back on the rear ) has had a single extension and we popped to see them and they said they didn’t have any piling works completed etc.

Any help anyone could offer I would be extremely grateful

 

[Notch7]

Are there any trees or hedges close to the proposed extension?

-particularly oak trees, leylandii, hawthorn, willow etc

-soil, is it shrinkable clay or river silt

-or is house in made up ground?

any of these could mean deep footings and block and beam floor -although generally not impossibly expensive, may add say £2k -£3k.

If the previous owners didnt even start the foundation, then they may have not got to that stage of knowing foundation issues.

It may have been a complication picked up during building regs application -if there was one.

Are you sure the problems werent to do with planning consent or onerous conditions?

 

[JP_]

You say plans were approved - these should be on the council planning website. They might mention foundations - if you're lucky the info is there already.

Otherwise, it's a case of digging to see. But really, I'd just get some builders to quote for it and see what happens. Foundation trenches must be inspected by building control before being filled, so if there's a problem, they will say to go deeper etc.

Pilings are not normally required.

 

[^woody^]

Approval given and currently still valid ...
We were told they started the works

I would check that out first.

There are set criteria for works being "started" and validating any approvals - and these are different for planning and building regulations. A 2004 build may not have any permitted development rights, and planning permission has an expiry time. Building regulations start would be significant and you will know, else again, expiry period applies.

Ask at your building control office about ground condions at your location - speak with the person that covers your area and has been doing so for a while, not the intern on reception.

 

[Leo1975]

Are there any trees or hedges close to the proposed extension?

-particularly oak trees, leylandii, hawthorn, willow etc

-soil, is it shrinkable clay or river silt

-or is house in made up ground?

any of these could mean deep footings and block and beam floor -although generally not impossibly expensive, may add say £2k -£3k.

If the previous owners didnt even start the foundation, then they may have not got to that stage of knowing foundation issues.

It may have been a complication picked up during building regs application -if there was one.

Are you sure the problems werent to do with planning consent or onerous conditions?

We have a silver birch that’s all at the end of the garden.

The previous owner did start as its quite clear to see ( the replacement garden tiles, look extremely clean looking ) I think this when more was needed but did they explore it properly or just thought it would be costly ?

Paperwork on - ( in folder )
Planning permission
Building consultancy site inspection record ( dated 9th 5 16 ) from council.
Building notice letter ( council)

I emailed them and confirm permission was still in place at moment ( believe that must only be valid for so long? )

 

[Leo1975]

Last architect reply -

Council email -

UPDATE
since posted this morning managed to speak online to a architect and he has advised getting some soil sampling done.

Looked at my previous emails to the council person and forgot the 1 email I had in return ( I’ve emailed again to ask if they got any more information on record )
But email highlights ‘the fill ‘

 

[JP_]

1.5m is not much. Part of my foundation trench was almost 2m, just because the ground was so soft the digger kept going until it was solid. You might need deeper foundations than normal just because of the soil type, or because there was water in the ground, but until you dig, you won't know for sure.

 

[Leo1975]

1.5m is not much. Part of my foundation trench was almost 2m, just because the ground was so soft the digger kept going until it was solid. You might need deeper foundations than normal just because of the soil type, or because there was water in the ground, but until you dig, you won't know for sure.

But is there some sampling or test works that could be completed to give a indication of what to expect.

 

[JP_]

I'd probably ask a groundworker to dig a hole and take a look. When my neighbour started their extension I saw that they dug a test trench next to the house, mostly to check the depth of current foundations. Building inspector will want to see the current depth and either match it or go deeper. But, that is only an indication - 4m out from the property (for instance) could be very different.

 

[^woody^]

If you have fill, then its piles or a raft normally. This will increase the overall cost by about £5k to what a normal extension would cost.

Don't forget that you may need the permission of the water company if you are building over/near to their drains. They would be very interested in foundation design on built-up ground. If this applies you need to get this before even starting work, so would need the foundation design details.

Ground core tests will cost a few hundred pounds. You need the testing by a contractor, and then a structural engineer to interpret and report.