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Hi I am building an extention and I have to lay methane gas barrier will it be crossibng over the DPC making a bridge in cavaty or I just keep this gas barrier to internal leaf.
Problem is if it is to cross cavity then, will I need cavity tray and weep holes? as wall is 8 meters long I never install a cavity tray please help.
Or I can use this gas barrier and insert weep holes am I right or just wasting my time.
Regards

Hi


You will need to install a cavity tray ,but its very simple
using 18" damp course bridge the cavity.Outside skin at normal
DPC level, the inside skin lift the 18" damp so that it sit on top of the first block laid 9" up.

Also lay 4" damps as normal.

Bye