Raft foundation HELP PLEASE - CAN'T FIND INFO ANYWHERE!

[ThomasP1]

Hi

I'm just about to start work on building my extension, but I have a question that I hope somebody will be able to answer first...

I have plans for the raft foundation, but the design is for a single storey extension as that is what I had planned on initially. I've now changed my mind and decided that the extra space a double storey extension would provide would be useful.

Do I need to make any changes to the raft foundation plan (i.e. deeper, extra reinforcement, etc.) to ensure it'll support a double storey extension?

Also, there's no mention, on the plan, of how to tie the raft foundation in to the existing standard foundations of my house; do I not need to do this?

Thanks.

 

[freddiemercurystwin]

What do your Building Regs drawings say?

 

[ThomasP1]

Don't have building reg's drawings; I plan to just submit a building notice rather than a full plans.

 

[freddiemercurystwin]

Oh ...

 

[tony1851]

Why a raft? why not conventional footings? what is the house foundation?

 

[ban-all-sheds]

Don't have building reg's drawings; I plan to just submit a building notice rather than a full plans.

That's a very bad idea for someone who doesn't know exactly what he is doing and is absolutely sure that he won't get anything wrong.

A full plans submission doesn't cost any more.

 

[noseall]

Oh ...

....dear.

 

[jprother]

I am about to start a self build on a raft foundation, the sunroom has less steel in it than the rest of the house. So it does matter on the raft spec, best check with engineer.

 

[freddiemercurystwin]

best check with engineer.

I like your optimism!

 

[ThomasP1]

Thanks for all the comments.

I'm comfortable with constructing the extension (inc. raft) and only submitting a building notice; it's just the raft that I'm not that knowledgeable on.

Is there anybody out there that has the answer I'm looking for?......If there is anybody out there with experience of designing raft foundations who can confidently tell me that the existing single storey raft design will be fine for double storey, or that I simply need to double the reinforcement, etc, that'd be great???

Thanks.

 

[ThomasP1]

Thanks for all the comments.

I'm comfortable with constructing the extension (inc. raft) and only submitting a building notice; it's just the raft that I'm not that knowledgeable on.

Is there anybody out there that has the answer I'm looking for?......If there is anybody out there with experience of designing raft foundations who can confidently tell me that the existing single storey raft design will be fine for double storey, or that I simply need to double the reinforcement, etc, that'd be great???

Thanks.

 

[ban-all-sheds]

You don't seem to get it.

If you go down the BN route then YOU have to ensure that what YOU do will be found to be OK at inspection time. And you are not filling anybody here with confidence that you are knowledgeable enough to do that.

What are you so set against doing a full plans submission?

 

[ThomasP1]

You don't seem to get it.

If you go down the BN route then YOU have to ensure that what YOU do will be found to be OK at inspection time. And you are not filling anybody here with confidence that you are knowledgeable enough to do that.

What are you so set against doing a full plans submission?

No, it's you who doesn't seem to get it.

If you refer to my initial post, I have raised 2 queries regarding raft foundations. So long as I am confident the raft design is adequate for a double storey extension, then I will have nothing to worry about when it comes to building reg's.

 

[ban-all-sheds]

OK.

Your existing slab design will be fine as it is.

 

[tony1851]

You still haven't stated why you wish to build off a slab rather than conventional footings.
To do properly, slabs are more difficult than strip footings. Is the existing house on a slab?