Garage building - no foundations???

[vladzie]

I've just found out a mate I put planning through for is building his garage with no foundations...Yes quite bizarre and I've advised against.
However he is going through with it. Its the largest he could get away with (5x5.5m) twin skinned block and roughcast.

My query is apparently this happens quite often (builder [mates brother] did his own garage like this) with them just building 1 course of block filling floor base within with concrete and building rest around it.

It certainly doesnt sound 'sound' to me - but does this actually work?? Mate says theres no weight in it, just the roof (no hes not planning on using trusses for pulling out engines etc.) so it isnt a problem??

I'm dumbfounded....its just sounds wholey dangerous to me!

What do you guys think??

 

[Richard C]

Sounds a bit dumb to me but although he may have needed Planning, unless he also needed Building Regs. approval he can do more or less what he wants.

It depends on the ground & the weight of the structure it’s supporting but many old properties were built with virtually no foundations at all & have been standing for hundreds of years. Conversely, I think it’s quiet ridiculous when BI’s insist on 2m+ deep footings because there happens to be any sort of tree within 5 meters; no wonder the first thing many developers do with a new site is to rip out all the trees.

 

[geraint]

Sounds a bit dumb to me but although he may have needed Planning, unless he also needed Building Regs. approval he can do more or less what he wants.

It depends on the ground & the weight of the structure it’s supporting but many old properties were built with virtually no foundations at all & have been standing for hundreds of years. Conversely, I think it’s quiet ridiculous when BI’s insist on 2m+ deep footings because there happens to be any sort of tree within 5 meters; no wonder the first thing many developers do with a new site is to rip out all the trees.

ha ha... hellO MATE.

 

[alesypalsy]

Exactly the question i was going to ask!,
I currently have a concrete floor with wooden garage but brick built door frame/sides,
i wonder if i can knock it down and just put breeze block garage up without foundations as the floor is all concreted?
Also would i need any kind of planning? i guessing not as i am just replacing old for new along with a new door and roof.
please advise i have been wanting to get started for weeks!

 

[vladzie]

Well I suppose i'll leave him to it then, its not housing anyone as such, except him when footering about with cars . I believe he does need BW, (.5m away from boundary) but apparently BC have seen drawings and have said its ok (?) and they will write letter to confirm this.

Planning wise alesypalsy, I believe you do if you're changing the external material in anyway, height size of and position of windows. Its worth a phonecall to dept. to just check.

 

[alesypalsy]

I had some time on my hands and popped down to the council yesterday , asked the planning dept about it,
was told i can do it no problem with no need for planning or building regs, i am changing old for new and its not attached to my house so good stuff!

Could anyone tell me if i actually do need foundations or can i just lay breeze blocks on the concrete base?
It would make a small job big if it will need jack hammer to make the foundations, and its only around 2 metres high so i hoping ot could be built as is,
I dont have enough cash right now many jobs to do on my house so may try doing it myself or hiring a brikkie on a day rate,
cheers

 

[noseall]

You will need foundations.

It is possible to build upon a suitable raft foundation but these are designed specifically to carry the wall loads. You can not, for example, just build up 2m high garage walls off a 100mm concrete slab, as the slab will snap.

I agree that it is a simple job, but you must get the foundations right or else the rest will be as good as tat.

 

[alesypalsy]

Thanks for the reply noseall,
Could you eleborate on raft foundation please as i dont understand that, but i will just add that the concrete floor/base is 6 inches thick, it was put down to have a concrete garage put on but the guy went with a wooden one instead according to my neighbour.
I have measured the concrete base and it is indeed 6 inchs, so my lst bit of hope is can i build onto that?
Thanks for taking to time to read and answer this,
cheers

 

[Mattboyslim]

Hi Alesypalsy,

noseall is right, you just need to build on a raft which must be a minimum of 100mm thick.

I have done a couple of these in the past. You basically dig down a little way so that you can lay around 50mm of scalpings and whack them, then build a timber frame the size of the required garage floor which you will pour the concrete into. Then you need to get some thick steel mesh and place it inside the frame but raised around 50mm off of the ground. The concrete then gets poured and its job done as the steel stops the slab from snapping. I would also recommend getting concrete that has fibreglass inside it (ask the company who deliver it) as it is supposed to be much stonger.

Hope this helps,

Matt

 

[alesypalsy]

Hi Mattboyslim,
Thanks for your reply, its got me a little confused (which is not hard these days!) but are you referring to foundations of the garage floor or the walls as I already have 6 inch garage floor there in place.
Used to live in Bournemouth myself, lovely part of the world

 

[noseall]

You basically dig down a little way so that you can lay around 50mm of scalpings and whack them, then build a timber frame the size of the required garage floor which you will pour the concrete into. Then you need to get some thick steel mesh and place it inside the frame but raised around 50mm off of the ground.

A raft foundation and a fabric reinforced 100mm concrete slab are about as alike as a bulldozer and a navvy with a shovel.

A Raft foundation will have a deliberate deepening of the structure where the walls will sit and this deep area will have specific rebar running through it that is then linked to the slab.

Look at it like a strip foundation that is all inter-linked with the floor slab via reinforcing bar and mesh.

The o.p. is better off building a garage off simple strip footings.