DPM at corners - joint or fold?

[pilsbury]

When laying DPM what is the done thing regarding corners? Half of me thinks leave as a continuous piece and fold neatly as best as I can, the other half thinks cut and use jointing tape to make it neat and a tight fit....

Thoughts?

 

[23vc]

I folded mine, was all simple corners though. I think for external corners eg. around pillars you have to cut and join it

 

[pilsbury]

All internal corners for me too, however I do have to get through a door opening which is perplexing me somewhat.

 

[Doggit]

It should be under the door opening; almost sounds as though it could be at the wrong height - one of them at least. As to the corner, cut and ovelap is fine.

 

[pilsbury]

It should be under the door opening; almost sounds as though it could be at the wrong height - one of them at least. As to the corner, cut and ovelap is fine.

I shall explain - It's a side kitchen extension that also goes into the garage via a doorway as a utility room (I have removed door and lining). The floor level of the house is 380mm above ground. The garage floor is 350mm below the house floor. I intend to pour a continuous slab for the extension and utility floor, thus passing through the side garage doorway.... that I have removed

Even sound confusing to me when I read it back!

 

[Doggit]

I assume you'll have a dpm in the garage floor, and it's the side garage door that you are trying to put the DPM in. If it is, then run the dmp down around and under the door lining.

 

[cjard]

Pictures... ?

 

[pilsbury]

Here is the pics requested. Bit of distortion as I did a pano to get it all in.

I'm built to DPC. Current kitchen floor is FFL. Current DPC of house is 1 brick below. I'll be connecting it into my new higher DPC. Garage DPC is several bricks lower due to the lower floor level. In the garage I've built a small single block wall to new DPC level which I'll stud wall off. The whole new area will get MOT, blinding, DPM, insulation, concrete slab then a thin final finish of SLC at the end to get levels spot on and match floor level of house.

Think I've got a handle on the corners. I know to lap DPM onto my DPC..... what about where it meets the old kitchen floor? Just cut it off level with the floor? Same for the original opposite wall already in place?

Any advice is appreciated

 

[Doggit]

My gut feeling, is that you've come up to high before installing ithe DPM, but I think you need someone more qualified than me for this one. Best of luck.

 

[pilsbury]

Hmm, interesting Doggit - my thought process was that DPC should be at FFL. The house DPC is one brick below this, so I "tie in" the new DPC to the old one - kind of a step up.

I too shall be interested in others thoughts.

 

[Doggit]

I assume by FFL, you mean finished floor level, then no, it's set below that to allow the joists etc if you had them to be protected. In your case, you're having a concrete floor that'll have a DPM in it, so where is the wall DPM going to be in relationship to the slab DPM. Sometimes, you get round it by taking the slab DPM up the walls, but you've got different levels there, so that's why you need someone better than me to help you.

 

[pilsbury]

The slab DPM is lapped up the wall and onto the wall DPC. All well and good for the new wall. Not sure how this relates to the old walls.

 

[tomfe]

I think you are thinking about this far too much.
After you've back filled and then put hardcore down etc take your dpm and lay out down...

Just take it into the garage with a healthy over lap on the extension dpm, lap it up the walls in there up to dpc level.
The join between your kitchen and new floor could be tricky I think I'd remove the course of bricks and then tie into the dpc with the extension dpm.
Does your kitchen have a dpm, does it have any insulation? Would it be worth taking up the floor and redoing it?

 

[pilsbury]

tomfe - thank you very much for your explanation. Clears a lot up.

The old existing kitchen is nearing 100 years old - so I can safely assume there is no DPM or insulation. Beneath the 1980's floor tiles are quarry tiles - they are not damp and the 80's tiles are stuck hard. Am I a bad person if I say digging up the existing kitchen floor fills me with dread if there seems to be no problem?

I like your idea of removing the current top course of bricks to tie in the extension DPM with the house DPC in the kitchen area. Would you brick back up or just let the concrete slab run over it?