The Brew Cabin

Posted: **Mon May 14, 2007 11:18 am**

Hi again. Ive just got a sectional wooden garage which dates from around the '50s 6.1m long 5.3m wide and 3.5m at apex of roof. Shiplap sides t&g roof and sliding doors on tracks which run across front and down sides. Very heavy.
I intend to lay a mesh reinforced concrete base 100mm thick going to 150mm thick around the outer 300mm over 150mm of hardcore (dtp1 or similar) The problem is the edge of one long side of the base lines up over the edge of a filled and piped ditch In fact the edge of the proposed slab aligns just to the inside edge of the pipes .
The pipes are clay 600mm deep 100mm by 600 socketed and have been laid without sealing the joints. As the front gable took four people to lift I'm concerned that even if I dig out the loose fill and replace with hard core the concrete may crack, especialy at the front corner where the weight of the gable is concentrated over an area of about a quarter square metre at each side.
Any and all opinions and advice would be welcome

Posted: **Wed May 16, 2007 8:04 pm**

Hope you got planning permission

Posted: **Sat May 19, 2007 7:46 am**

Either side of the trench dig down to virgin ground if its not to deep that is (shelving, or, beam) and the concrete will sit on that , or put a bit of extra thick steel spanning the trench to cantilever the slab.

Posted: **Sat May 19, 2007 2:23 pm**

Thanks Bob, just had a look on web, If I shorten garage by 0.5metre it will be within regs.

Hello again Sean you went a bit too fast for me there what's (shelving or beam). By extra thick steel do you mean something like an I beam under the slab and projecting across the ditch and resting on a concrete/stone pad.

Posted: **Sat May 19, 2007 7:45 pm**

to spread the load over a trench, either dig a channel in trench and an extra 200 each side. the 200 each side will act as a shelf and take the weight of concrete and spread the load. as you are covering the trench with a slab of concrete, then maybe a slight thickening in the trench with extra mesh. sorry for the confusion earlier.

Posted: **Sat May 19, 2007 9:18 pm**

Thanks for that Sean, I'll start digging!

The Brew Cabin

Garage base near ditch - How do i avoid subsidance