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Workshop foundation Using concrete forms?

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grandutero

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Hi All,

I'm aware of the many post regarding this issue and I've read many and found them a great help but I still cant find anything referring to using tubes to form concrete foundations where the timber frame floor is supported off these by sinking long rods into the concrete forms. It seems to be done commonly abroad (especially the States).


I'm researching this possibility as appose to a raft foundation method due to its apparent logistical ease and seams a lot cheaper. Any thoughts or ideas would be much appreciated. My workshop would be around 3.5m x 4.5m.

Thanks.
 

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MikeG.

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Any suspended timber floor supported on any post arrangements leaves you with two fundamental problems, no matter how you make the posts. These are that you are creating a perfect hiding place for rodents, badgers, foxes etc under the floor, with no good way of keeping them out. Secondly, you need 6 inches to the underside of your floor timbers (to keep them dry and to allow sufficient air flow....them's the rules), which means at least one and possibly two steps up to your workshop floor, and desperate problems with headroom if you are trying to stick within permitted development rights limits.
 

grandutero

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Thanks Mike,

Yes I've seen these points on previous posts and was thinking that these issues can be overcome by meshing off the underside to stop animals and digging the base down slightly. I'm just looking at all the alternatives as like I say a raft option a pain both financially and logistically. Am I being stupid? (Be kind) :roll:
 

MikeG.

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If you dig down, you'll create a hollow which will require draining.

I have provided a solution....the second link in my signature.
 

RobinBHM

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grandutero wrote:
I'm researching this possibility as appose to a raft foundation method due to its apparent logistical ease and seams a lot cheaper. Any thoughts or ideas would be much appreciated. My workshop would be around 3.5m x 4.5m
I built my shed by concreting pads -because the shed is built with one corner within 18 inches of the edge of a small brook whose invert level is around 8'0 down!

so I bought a post hole digger and dug holes about 300 mm dia, as deep as needed (down to sub soil). I had to dig some of mine down to 1.8M due to the brook, but you will only need to go say 300-400mm deep to get to load bearig ground.

Pads also work where there are tree roots.

Then I screwed together strips of OSB to make a square about 125mm deep and 350 x 350.

I laid these over each hole, cut out the top of the hole so they sat down a bit, levelled up the squares so every one was dead level to another, then hammered in some pegs and screwed the squares to them.

I filled the holes with concrete and that left me with a set of pads all level to one another -I actually used 4 universal steel I beams then fitted joists in between them

As Mike has pointed out -it does leave the risk of vermin, foxes etc but Ive had the shed up for 4 years with no problem. did lay down a bulk bag of type 1 on top of Terram so the soil below isnt accessable easily to vermin, maybe that helped.
 

Fitzroy

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My shed is built on pads as I’m I the root zone of protected trees, according to the planning officer, although the neighbour hacked off half the canopy last year and no one gave a damn!

As mike said my floor level is about 30cm above ground so a good step up, and my shed is higher than permitted development to allow ceiling height, but I had to go for planning anyhow as I’m in a conservation area.

I’ve been on the lookout for vermin but I’ve seen none so far, 3yrs. However my garden has 4’ high granite walls all round and neighbours with cats on three sides, so perhaps a less than attractive target for inhabitation.

Fitz
 

JoeSheffer

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Same here. I used high density concrete blocks, and by the time i had the floor beams in etc there was a quite big step up into the workshop (maybe 30-40cm) which is quite unsightly. I have had problems with foxes under the building - they pulled out lots of the insulation which was a right pain in the buttocks.

I wouldn't do it like this again, unless you have a slope or some other reason for building in this fashion.
 
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