Tying new dpc into existing

[macadonald]

Hi guys,

Drains laid this weekend. Thought the muddy work after the foundations was done, but a mornings of rain, meant a lot more mud.

Any advice on how to tie the new dpc into the existing. This is not a solid slab extension, I'll have suspended timber floor with Oversite. My question here is simply the dpc on each skin of the walls into the existing dpc. Do I try to remove some mortar under the existing and push the new under the existing?

Out of interest, do you genrally keep the dpc at the same level, or is it acceptable to drop it by a coarse or two?

Thanks

Mac

 

[macadonald]

Just searching the Internet on the subject of joining dpc and not finding much. What I am finding is worrying me a bit, hope it isn't an area my research didnt give enough attention.

I'm reading about cavity trays and requiring 100mm overlap and dpc tape when joining dpc. I assume this is for joints on new dpc though?

I did briefly ask in another post, but is there a solution for the sides of the extension where my neighbours potio is just above dpc level and will come straight up to the wall and the alley side, which is also above dpc slightly. Where ive broken away the render on the alley side, I can see that some form of Dpm or bitumen has been lapped up the outer skin o father existing house. Can I simply put Dpm under the dpc and wrap it up the outer skin so the backfil is separated from the house?

 

[noseall]

DPC is ok butted to the existing.

DPM is lapped onto the inner course only and must not venture into the cavity unless you are fitting a specific gas membrane. This is then simply bedded in mortar.

Dpc level on the inner course finishes at internal floor level.

The outer dpc can vary in height according to ground conditions but is 'generally' at the same height as the inner leaf.

Cavity trays, weep vents, tape etc is solely for gas membrane details and the like.

 

[noseall]

Just read the whole post!

DPC UNDER the joists or floor beams. External dpc set at 150mm above external ground level.