DPC tie in abutment wall

[EllwoodJT]

Could someone advise me on the correct procedure for overlapping the dpc on my extension. The house dpc is one brick below floor level. 1- Do I / can I, use 300mm dpc as a cavity tray from the extension floor level down to match the house dpc level (one brick) if so how many weep holes should I provide ? 2- how do I tie this in with the house dpc, do I need to chase very far in to overlap extension dpc and house dpc? 3- How should I approach the virtical dpc/starter kit, how far in should I chase the wall etc. Many thanks in advance! 

I can post pictures if necessary. 

Edited September 27, 2018 by EllwoodJT

[PeterW]

Hi and welcome

 

I think a quick picture or sketch may help here as it sounds like you have different floor levels unless I’ve misread your post ..??

 

Assuming this is a right angle extension wall off an existing wall and you are using some sort of stainless wall starter kit too..?? If you are building using a standard 100/100/100 construction of brick/cavity/block then 300mm DPC won’t work as you want to step it up on the inside one course. This can be fixed using 100mm on the inner course overlapping the 300mm, or you can just form the tray with 450mm. 

 

If  you have any drawings it may be worth posting them up too. 

 

 

[EllwoodJT]

So far thank you 

I will take photos and do a sketch tomorrow. ?

[EllwoodJT]

Finished floor level of house and therefore extension is green line and dpc on house is black line. Stainless crocodile wall starter will obviously be where blue lines are roughly. 

How do I overlap into house dpc? Do I carefully cut the mortar joint exposing some of the house dpc, do I additionally apply some sort of sealent? How do I cut vertical barrier, how deep etc and overlap it with the horizontal dpcs below it? 

Many thanks in advance. 

 

[PeterW]

Looking at that you’ve already got the extension DPC in place ..?? Looks fine - just put a DPC on top of the block where the roll is and trap the tray from outer to inner then just lap the DPM from the floor up the wall when you pour the floor - no need to overlap these. 

 

Where the starter is, if you can cut a slot between the two blue lines it will stop the cold bridge on the corner too - will help you make a continuous insulation layer. 

[EllwoodJT]

Thanks again. 

How deep a slot vertically? Do I need to go thru to the cavity or just 40mm ish? Do I need to wedge dpc in the virtical slot? 

How often should I position weep holes above the tray? 

Cheers 

[PeterW]

Hi 

 

weeps every 4 bricks seems to keep my BCO happy. 

 

I would go all the way through - no DPC required and don’t put one behind the crocodile either. If you take the half brick returns out by cutting with a Stihl saw it may be quicker too to form the cavity.