Foundation for Wooden garage.

[sleptwithatradesman]

I have a wooden garage at the bottom of my garden 6m x 3m approx. resting on a bed of either soil or hardcore (or a mixture of both). Needless to say the plywood floor is rotten and the whole thing is beginning to sink into the ground.

The garage fronts onto a side road, and the rest of the garden has been properly paved and concreted as I have lifted a section to put down some grass.

I plan on bracing and jacking up the whole thing so I can put in a concrete floor.

I'd like some advice if I can do the following, or if there are any better alternatives:

Can I put a strip concrete foundation in of 150mm deep by 150mm wide? (on a 150mm bed of hardcore).

Then I plan to replace the rotten wood and sole plate, drop it down and attached to this foundation after fitting a DPM gasket.

Then put in a 100mm slab using these strip foundations as the perimeter.

I reckon I'm capable of the shuttering/bracing & lifting bit, (Although it's easier said than done) it's more the foundation and doing the concreting in 2 shots I'm guessing at.

Thanks in advance for any advice....

 

[noseall]

I plan on bracing and jacking up the whole thing so I can put in a concrete floor
.

Prey tell - how?

 

[theprinceofdarkness]

It all depends on what kit you have and if you can loose some room inside the "garage" (shed). As you have found its the ground/wood junction that causes the rot problem cos' the wood takes a loong time to dry out (if ever). So my thought is that at the major structural uprights or every 4' or so, dig a deep hole inside the garage and concrete in spur posts ( http://www.wickes.co.uk/Wickes-Fence-Concrete-Repair-Spur-75mmx100mmx1200mm/p/542503). The corner ones will be a devil. When the concrete has cured, put a big G clamp around the vertical stud and using the top of the new spur you then can lever the shed upwards, say 1/2" at a time, so you don't break it. After each lift put a large screw in (5mm+) to temporarily hold the wood up and/or bricks lumps of wood under post end. Once you have got to your final height, drill through the wood and bolt ( or use 8/10mm stainless steel studding) to a convenient hole in spur post.
Now your garage is standing on stilts, dig out your 6" X 6" foundation strip and around the sides and back put in two courses of engineering bricks* and tidy the levels around the spur posts. Sister up extensions to the other verticals and bracket the bottoms of these to the bricks. It might look eccentric but it should be a job well done and will give the garage another 20 years of life. Fill and concrete the floor with 4" of concrete.
* it would be nice if the outer edge of the bricks are inside the outside of the planking.
Frank

 

[sleptwithatradesman]

Thanks Frank.