Hi all -
I'm building a deck and and placing a ledger against two external walls of the house. Something I'm unsure about is the placement of the bolts (just planning to use knock-in throughbolts) in relation to the DPM. Now I always thought you'd want to go below the DPM as then any water penetration can't rise above the membrane, but according to the attached picture, you want to go above. So it's prob a stupid question but can someone be kind enough to explain why? The part of the house I'd be going off is a new extension, so to find the DPM i guess its a case of working out a rough height of concrete floor, then 50mm kingspan and then i'm assuming below that is roughly where the DPM will be. I'm assuming it comes out to the external skin and is then trimmed skimmed over on the outside during render.
I've just seen so many videos where people are drilling into the walls at all sorts of heights and doesn't seem to be a consideration for most.
This picture also shows a 10mm gap is required, for drainage i assume. Is it common to use something like plastic shims or plate washers?
Thanks
I'm building a deck and and placing a ledger against two external walls of the house. Something I'm unsure about is the placement of the bolts (just planning to use knock-in throughbolts) in relation to the DPM. Now I always thought you'd want to go below the DPM as then any water penetration can't rise above the membrane, but according to the attached picture, you want to go above. So it's prob a stupid question but can someone be kind enough to explain why? The part of the house I'd be going off is a new extension, so to find the DPM i guess its a case of working out a rough height of concrete floor, then 50mm kingspan and then i'm assuming below that is roughly where the DPM will be. I'm assuming it comes out to the external skin and is then trimmed skimmed over on the outside during render.
I've just seen so many videos where people are drilling into the walls at all sorts of heights and doesn't seem to be a consideration for most.
This picture also shows a 10mm gap is required, for drainage i assume. Is it common to use something like plastic shims or plate washers?
Thanks