levelling batons for concrete slab

[redlee]

I'm hoping to lay the concrete slab for my extension this weekend and as the walls are up its been suggested that i use battons to get to the right height and level. Does the batton go against the wall and then dpm over it or will this make using the batton difficult? if the dpm goes up the wall and then fix the batton through it what should i do about the holes the fixings leave??

 

[landyandy]

You could place the battons higher than where the damp will be cut off. Then notch the tamp so the bottom of the tamp will be your finish hight.

 

[redlee]

You could place the battons higher than where the damp will be cut off. Then notch the tamp so the bottom of the tamp will be your finish hight.

Cheers but because there is 125mm insulation and 75mm screed going on top of the concrete (because of under floor heating) the tamp would have to be pretty big.

 

[landyandy]

Personally I wouldn't pierce the damp. Worst case scenario is the water table rises and you have leak points.

What works for me is a 8x2 tamp with a handle each end. Then tape a level to the top so you can always keep a check on the levels.

 

[redlee]

Okay 8x2 it is, do i fold the wall dpc down the wall and the floor dpm over the top of it? And my finished screed should be level with the wall dpc?

 

[redlee]

post duplicate

 

[r896neo]

dpc folds down first then dpm folded up over it.

 

[hotrod]

Okay 8x2 it is, do i fold the wall dpc down the wall and the floor dpm over the top of it? And my finished screed should be level with the wall dpc?

Yes. Have a look at this:-

 

[r896neo]

I know this picture is useful and gets trotted out a lot but it is a little misleading to people who already have the walls up and a nice flap of dpc sticking out.

The dpm only needs tucked in to the dpc course if you are laying the concrete when at dpc wall height and it is easy to do it.

I can sort of imagine some people trying to grind out the joint and lap it in when all they need do is fold down their protruding dpc.

 

[redlee]

Thanks the walls are already up in my case. The concrete slab is now down how long should i leave it before covering with the insulation (125mm polystyrene) and do i need to put another layer of visqueen on top of the concrete before the insulation?