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Periscope vents in cavity

Discussion in 'Building' started by acurachris, 16 Jul 2018.

  1. acurachris

    acurachris

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    Hi

    I will be using periscope vents to air under a block and beam floor and wondered about the below ground cavity fill. All the regs say to fill the cavity to 225mm below DPC although this will partly encase the vents in said concrete; is that okay?

    Also when I am at DPC the building inspector has requested two (yes two :mad:) 1200 gas membranes be lapped over the cavity. I was going to run these membranes across block and beam floor, up 150mm or so and across the inner and outer DPC (level bridge). The logic of bridging the cavity and laying bricks on the gas membrane/DPC has got me!

    Do I lay the gas DPM under the normal DPC and should i bed the gas membrane(s) on mortar like the DPC?

    That would be like insane layers of bed/dpm/bed/dpm/bed/dpc/bed/brick - I'm sure i've got that wrong :LOL:

    If i bridge the cavity with the gas membranes level, how far up does the cavity tray sit; next brick up? Second to this, where am I going to start the wall ties with all this going on!

    Any help appreciated!
     
  2. ^woody^

    ^woody^

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    If you require a gas membrane, then you should really be working to a proper design and not asking on a diy forum.

    Vents are encased. Membrane crosses the cavity and bedded, and a dpc tray goes on top.
     
  3. acurachris

    acurachris

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    Okay thanks!

    Who would do such a design, an architect, membrane company? The guy who drew up my plans is not a "full" architect; in fact he's been pretty useless!

    What do you mean the vents are encased? I know they are plastic periscopes attached to air bricks, I meant is it okay that concrete surrounds half of it.

    Can I use a methane DPC to cross the cavity and then join the membranes to its overlap on the slab.

    I appreciate this could be getting beyond the DIYer but help is appreciated!
     
  4. DIYnot Local

    DIYnot Local

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