Basement type C cavity drain that doesn't compromise the envelope

[Rob McG]

Hi, 

 

Just starting the journey down the Passive House route, a small section of the house is basement level and Newton are advising a Type C waterproofing system, so an internal cavity drain, that needs to then drain out of the building, they don't seem to have a system that closes, so its always open, therefore compromising the passive house envelope. Anyone had any experience with this or any ideas on how to get round it?

 

Thanks in advance.

 

Rob

[Conor]

Type a & b instead. External tanking and waterproof concrete.

[Big Jimbo]

@Conor said. External waterproofing. I didn't think that internal "Let the water in, and then take it out" complied with Building Control Regs, since they changed.

[Mike]

1 hour ago, Rob McG said:

Newton are advising a Type C waterproofing system, so an internal cavity drain, that needs to then drain out of the building, they don't seem to have a system that closes

It looks like the Titan-Pro Sump comes with 50mm pipe reducers, and 50mm dry traps are available - such as the MacAlpine MACVALVE-4.

 

39 minutes ago, Big Jimbo said:

I didn't think that internal "Let the water in, and then take it out" complied with Building Control Regs, since they changed.

BS 8102:2022 still includes it and NHBC still allow it, so there's no obvious restriction. Types A+C or B+C would still be my preference.

[Rob McG]

thanks for all the advice!

 

probably will end up being A+C

 

hoping not to use a sump pump though. just gravity drain.