Vertical dpc and wall starter kit help

[xdrive]

Hi.

I am building single story rear extension. I'm at dpc level.

I'm going to put starter plate on above dpc and tie in on block above dpc.

Do I place dpc behind the wall starter? Seen it done by a few builders.

Also I have read about vDPC. Is it a cut in new cavity and just hand a piece of dpm in it? Where exactly does it go and which way should it fold. Is it necessary on party wall side (my neighbor has conservatory which my extension is about 25cm away)

Cheers

 

[xdrive]

Going to start this today. Can anyone shed some light?

 

[^woody^]

No DPC behind the starter.

You cut the slot for the vDPC in the existing wall, behind where the new external outer skin will be, to stop damp going across to what would be the new internal skin.

 

[xdrive]

@^woody^ if I cut it 1 inch deep and place 4 inch dpm inside slot, add clear silicon to keep it in, then fold it inside new cavity would that suffice?

 

[^woody^]

Like this

 

[xdrive]

How about this @^woody^

Prefer not to cut 4 inches in wall.

 

[^woody^]

How about this @^woody^

Prefer not to cut 4 inches in wall.

View attachment 206246

Where is that drawing from? It's wrong as there is a direct path for moisture in to the new internal wall. Yes it may be less work but it's doing jack, you may as well not do it.

The alternative if you don't want to cut, is to just coat about 400mm of the external wall with a water repellent. But this is not the best thing if the part of the wall gets the weather, only good as an option for relatively sheltered walls

 

[xdrive]

Where is that drawing from? It's wrong as there is a direct path for moisture in to the new internal wall. Yes it may be less work but it's doing jack, you may as well not do it.

The alternative if you don't want to cut, is to just coat about 400mm of the external wall with a water repellent. But this is not the best thing if the part of the wall gets the weather, only good as an option for relatively sheltered walls

Yes both sides a well sheltered from driving rain.

Cheers for your help woody. Always appreciate your advice.

 

[Notch7]

Yes both sides a well sheltered from driving rain.

Cheers for your help woody. Always appreciate your advice.

These days its pretty normal to cut out a 50mm slot so the cavity continues -that creates a thermal break as well as a vertical DPC.

cutting just a 1/3rd of the way in is an option, but in porous brick it may not stop horizontal movement of damp.

your other options include damp proofing the wall, fittings battens and foil backed plasterboard, using render base coat with SBR and then multifinish....bascially anything that avoids bonding plaster which is hygroscopic.

are you doing cavity trays across the roof abutment?

 

[xdrive]

These days its pretty normal to cut out a 50mm slot so the cavity continues -that creates a thermal break as well as a vertical DPC.

cutting just a 1/3rd of the way in is an option, but in porous brick it may not stop horizontal movement of damp.

your other options include damp proofing the wall, fittings battens and foil backed plasterboard, using render base coat with SBR and then multifinish....bascially anything that avoids bonding plaster which is hygroscopic.

are you doing cavity trays across the roof abutment?

Hi.

Both the inner and outer leaf are block and will K render externally. I will use dot and dab plasterboard inside walls.

Is first time in doing extension. But yes will be doing the cavity trays at that point if necessary.