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Posted: Wed Sep 28, 2011 3:19 pm
by kiddo
Guys,

This question will make you laugh, and show why its important to do things properly so they don't come back to haunt you!!! hahah


Some time ago, while I was having concrete delivered for another job I was doing, I poured a C25 slab..... the idea being that I might need another shed/workshop at some point, so it would save me getting a delivery of concrete twice.

Now the time has come that I DO need another workshop/shed, but I have been offered a load of bricks for free, so was considering building a single skin shed from bricks rather than buying some wood etc.....

However, because I never intended to put anything more serious than a large shed on the slab, I just poured the slab any old how, without going about it properly. Obviously if the slab cracks or moves badly with a wooden workshop on it, its not going to matter too much, but a brick-built would suffer the consequences far more seriously!!! That will teach me for not doing things properly!!! hahahah Oh well.


SLAB SPEC:

The ground slopes so rather than dig out loads of earth to level the site, I dug out 100mm in which I compacted MOT1 to 80mm deep and then shuttered the slab to make the top of the base level. The slab itself thickens from 200mm to about 400mm to make up for that slope.

Its 2.9m x 2.9m. I also had a load of 6mm Mesh spare, so I just chucked it in, but it wasn't big enough to cover the whole slab area, just the middle 2.4m. So give or take, approx 350mm around the edges has no mesh in it.


So what do you think? I know its a mega bodge as far as the slab goes, but as it was only for a wooden shed it didn't matter at the time. If no-one thinks I may get huge cracks appearing, I could use the free bricks. If it sounds really dodgy, then a simple wooden shed (as per my original plans) will be the way to go.


Cheers.

Posted: Wed Sep 28, 2011 4:52 pm
by DNgroundworks
All i can say that if the ground is good, i cant see a "semi" re-inforced 200-400mm thick slab cracking, so id just wack the building up. If it was for a customer it would be a different story.

Posted: Wed Sep 28, 2011 5:09 pm
by seanandruby
wouldn't it need planning permission as it is a brick, therefore permanent structure as opposed to a wooden one.

Posted: Wed Sep 28, 2011 5:23 pm
by lutonlagerlout
I think as long as it isnt over 25m2 and is more than 2 m from the house and is less than 4 m high you are ok sean
always best to check with your local council
that slab seems bomb proof for a shed IMHO
LLL

Posted: Wed Sep 28, 2011 5:57 pm
by Carberry
More than enough for a shed. I laid a 300mm wide 150mm deep foundation, 4 gravel 2 sand 1 cement, that a 30T truck drove over 2 days after it went down. Sank a little bit where the wheels went over it but it did surprisingly well.

Posted: Wed Sep 28, 2011 7:46 pm
by local patios and driveway
Sounds ok to me, that said i built a 5x5x5m garage on a similar base and that shifted in three areas. Luckily it was my own so no come backs but annoying none the less

Posted: Wed Sep 28, 2011 9:01 pm
by Mikey_C
how long has it been down?

Posted: Wed Sep 28, 2011 9:07 pm
by local patios and driveway
Been down 13 years started to move after 2. Tile roof, block built. Pretty heavy but was on a budget at the time and greener than i am now...

Posted: Wed Sep 28, 2011 9:58 pm
by Mikey_C
i kinda meant that question for the op. but thanks for the info LPAD :;):

Posted: Wed Sep 28, 2011 10:16 pm
by local patios and driveway
Lol sorry mate not paying attention again :p

Posted: Thu Sep 29, 2011 7:10 am
by kiddo
hi guys. It's been down around 6 months I guess. No cracks or anything yet. Do you think the fact that its so thick might work in my favour? I suppose if I built a good 150mm inside the edge may help?

Posted: Thu Sep 29, 2011 4:50 pm
by lutonlagerlout
there are no guarantees kiddo,but i have seen garages built on 100mm rafts with 200 mm toes (the edges)
personally i would take the chance
LLL

Posted: Thu Sep 29, 2011 5:40 pm
by Carberry
Job i'm working on just now has a big wooden shed laid on 2x2 slabs laid on building sand. Shed is bulging at the sides because it is poorly built with so much junk in it but it is still standing :laugh: