Water table and foundation

[Dw50590]

Hi just wondering if some can give me some advice on my foundations.

I'm building a garden office at the start of next year and will need to put in some 800mm -1000mm deep footings, however I have noticed if you dig below 700mm in the area the footings need to be you hit water and the hole will fill up with about 200mm of water over night, now is this a problem?? Or normal in some areas? My plan would be to dig a hole in the corner and put a sump pump in to pump out the water just before the concrete is poured, obviously building control will inspect it first but just wanted some reassurance its normal or am I going to have an expensive problem on my hands...

Kind regards adam

 

[frutbunn]

Not unusual to make water, what you are proposing is OK, I've certainly accepted it on thousands of occasions,
Do you need to go that deep. what type of sub soil is it?

 

[Dw50590]

The sub soil is kinda good soil for the first 500mm then you see little bits of clay, but not that much to be fair... I just didn't want building control telling me I needed to make a raft type foundation costing lots of money. I think the reason I said that depth as its construction is going to be 100mm concrete block, 100mm cavity and 100mm concrete block on the inner.

Best regards adam

 

[frutbunn]

If its clay then your looking at 900mm depth assuming there are no trees nearby.

 

[Dw50590]

Well this is my next problem. There is a small oak tree, problem 400mm in diameter about 2m/2.5m away, now I have expressed my concern to my architect and he has basically said they might ask you to dig deeper on that side which I kinda did expect.. the building is single storey and measures 6m x 7m with a daul pitch roof. I have said to him if the price starts to rocket up and its going to be a huge problem then the build won't really be worth it...

Best regards adam

 

[SpecialK]

Have a look here https://info.labcwarranty.co.uk/foundation-calculator

Doesn't look good with an oak tree that close? (2.5m+)

Well this is my next problem. There is a small oak tree, problem 400mm in diameter about 2m/2.5m away, now I have expressed my concern to my architect and he has basically said they might ask you to dig deeper on that side which I kinda did expect.. the building is single storey and measures 6m x 7m with a daul pitch roof. I have said to him if the price starts to rocket up and its going to be a huge problem then the build won't really be worth it...

Best regards adam