Wimpey no fines, raft foundation.?

[banjodeano]

Guys, i am wanting to dig down near the foundations of my house, but i dont want to disturb the foundations, but because it is a Wimpey no fines, then i am led to believe it has been built on a raft and is not a problem, is this true.?

 

[tony1851]

The foundation is generally dictated by the ground conditions. Yours may or may not be on a raft. The only way to find out is to dig small trial hole.

 

[^woody^]

No-fines relates to the construction of the structure above floor level only.

These properties can have any type of foundation. Don't confuse a floor cast into the external walls as being a raft either

 

[banjodeano]

Thanks guys...so how doi find out.?
Tony1851 mentions digging a trial hole....how far would i have to go down, and how close to the house.?

 

[^woody^]

Its all a bit irrelevant as any significant digging could affect either foundation type in the same way.

You would need to dig down the side of the walls to expose the foundation and the side of it, and then you would need to know what you are looking at.

Rafts can be deep and can stick out just like strip foundations

 

[tony1851]

Unless your house is built on an old landfill site, or equally poor ground, you may find that the foundation issue is the least of your problems.
No-fines houses are generally difficult to work on, particularly as regards joining the new walls up to the old, and putting beams in to break through into the new extension.

 

[banjodeano]

what i am wanting to do is build a garage near the house, about one meter away, the corner of the garage one meter from the corner of the house, but because the house is about three feet higher than the drive, then i have to dig the three feet down, plus the footing for the garage, i just didnt want to interfere with the foundations of the house.

 

[tony1851]

Put the garage on a raft; minimal excavation so minimal impact on the house.
The garage won't be that heavy, so there will be little if any impact on the ground under the house foundation.

 

[banjodeano]

Put the garage on a raft; minimal excavation so minimal impact on the house.
The garage won't be that heavy, so there will be little if any impact on the ground under the house foundation.

Thanks for the advice Tony...so how many inches deep would i have to make the raft.. is 8.inch enough.?...bearing in mind it will have to take a breeze block structure and hold back the three feet of soil.? i was thinking i could put a tanking system round it to keep out the damp...

 

[tony1851]

Put the garage on a raft; minimal excavation so minimal impact on the house.
The garage won't be that heavy, so there will be little if any impact on the ground under the house foundation.

Thanks for the advice Tony...so how many inches deep would i have to make the raft.. is 8.inch enough.?...bearing in mind it will have to take a breeze block structure and hold back the three feet of soil.? i was thinking i could put a tanking system round it to keep out the damp...

I think I misunderstood your post.
If you are excavating that deep near to the house, you WOULD need to check on the depth of the footings of the house.
If your garage wall will be holding back 3ft of earth near the house, you would probably need to build some sort of retaining wall. Done properly, this would need some input from a SE.