Damp Proofing for Conservatory

[steveharr]

I have an existing conservatory foundation and floor which I can use again for a new conservatory.
My problem is the existing floor is about 50mm lower than the floor in the rest of the house and there is no effective damp proof membrane under the conservatory floor.
My question is can I use one of these paint/brush on DPM products and then screed on top of that?
I imagine if I use a sheet DPM a screed floor of only 45-50mm may crack up! Am i correct?

Can someone also recommend a product/products that I can easily get hold of to do the job.

 

[delmel]

I havnt come across paint on dpm but would use plastic membrane and if it is 50mm that is ok about the minimum for a decent screed thickness to be layed

 

[mrmark]

I would like to add an aditional question steveharr dpm question that may or may help you out?

With regards to the dpm, does that need to be tucked up against the internal leaf and into the same course of bricks as the existing dpc. i.e to provide a water proof seal???

Cheers

Mark

P.S Hope you don't mind me tagging on this question steveharr?

 

[masona]

there is no effective damp proof membrane under the conservatory floor.

I think you're cutting corners here, it's best to do it properly first time round and will be cheaper in the long run. I haven't got enough information to help you. What type of conservatory, a half wall or all window, have you got footing etc?

 

[masona]

With regards to the dpm, does that need to be tucked up against the internal leaf and into the same course of bricks as the existing dpc. i.e to provide a water proof seal???

Yes, the dpm goes under the dpc

 

[steveharr]

Yes there is massive footings from an existing conservatory and a floor which had a 3/4 inch screed ontop, I removed the screed floor in order to put some sort of damp proof in which was not done on the original base. I need to raise the floor by about 1 1/2 inches which will give me 2 1/4 inches/60mm of screed.

It is glass to floor type.

 

[masona]

I removed the screed floor in order to put some sort of damp proof in which was not done on the original base.

Any bitumen products such as Heviseal

With regards to the dpm, does that need to be tucked up against the internal leaf and into the same course of bricks as the existing dpc. i.e to provide a water proof seal???

That the whole idea of it but I do see some builders don't bother.

 

[fitz1]

Stick some underfloor heating in aswell. U will be glad later on.

 

[steveharr]

So is it ok just to use a plastic sheet membrane with 60mm of screed ontop or would (and why) the bitumen product be better?

 

[masona]

So is it ok just to use a plastic sheet membrane with 60mm of screed ontop or would (and why) the bitumen product be better?

Because of what you said here,

I imagine if I use a sheet DPM a screed floor of only 45-50mm may crack up!

The dpm will be better but you haven't got enough thickness after you put down a soft sand bedding to protect the dpm which will give you hardly any screed floor thickness and I don't know where your damp proof course level is.
Normally it's like this,
hardcore or rejects > sand bedding > dpm > 100mm concrete > 50mm floor screed.

Also have a read here , there is 5 pictures to give you some difference idea.
If you can post a picture, we maybe able to help you further