lapping new dpm into existing dpc

[penguinman]

Hope you can help.

I am planning to build a single storey extension to my house and need to lap the new damp proof membrane into the existing dpc of the external course of brick that I am connecting onto.

obvoiusly can't rake out the mortar along the full length of the wall or the wall will sag: should I do it a section at a time of say 500mm?

Should it go on top of or underneath the existing dpc and be bedded in before I start the next section?

Any tips welcome

Thanks from a newboy on DIYNOT

 

[iaink]

you dont have to bed it in.if you are referring to the membrane in the solem this does not need to be bedded into the existing wall

 

[noseall]

We don't bother. We only lap where we remove walls completely i.e. knock-through's thus totally exposing the damp course.

So long as the dpm is lapped far enough up the wall as to deal with the flooring material, then you will be ok.

 

[penguinman]

Thanks very much, it will make it much easier

Regards