The Brew Cabin

Posted: **Fri Nov 26, 2010 1:26 pm**

Guys,

Im building a heavy duty workshop and have 3 questions.

1) I'm laying a 100mm slab with 1 layer of A142 on top of 100mm of compacted MOT1. I was gonna build the shed off a layer or two of bricks round the edge of slab. Is 100m Slab thick enough for light machines/ saws etc ?

2) I guess I have to lay down a DPM, more for stopping the concrete from drying out too quick rather than to stop damp? Is that right ?

3) Do I need a layer of sand to stop any rips from the MOT1 or wont it matter? Trying to save a few pennies and dont want to order a bulk bag of sand if not needed.

Incidently, if I do need sand, which one should I get? If I am laying bricks round the edge, I suppose I could use quarter of the bulk bag for that - so that would be soft sand right ?

thanks.

Posted: **Fri Nov 26, 2010 10:27 pm**

Hi there is various ways of building a base for a wooden shed if that is what you are intending to do ?

100mm concrete base should suffice but is you are worried about the weight take it up to 150.

The DPM is to stop the damp penetrating into the timbers so a sand blind would be recommended, soft sand will be fine minimum of 25mm.

Don't forget to have the dpm running up the inside of the bricks as this helps prevent water ingress. DPM needs to be min 1000 gauge however I tend to use 1200

Posted: **Sat Nov 27, 2010 7:59 am**

How heavy is your "heavy duty shed?" If very heavy you may need to go deeper around the edge and put in extra reinforcing. I would'nt bother with sand, i'd place visquinn on top of sub base. Bring the dpm up the side of the concrete just below ground level, not up the brickwork. Use dpm on top of brickwork.

The Brew Cabin

Dmp for shed