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Flat Roof Venting

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  • Flat Roof Venting

    Hello everyone!

    I am just completing my enclosure and battling the clock, as the temperature is hovering just above zero this time of year. I am new to this and had a quick question: I am building a flat roof which will have flagstone on top as a finish. I am acquainted with enclosure venting with a gabled roof, but what would be the best way to vent the enclosure so that moisture can escape if I have a flat roof? I am planning on enclosing the duravent chimney with a stud frame and cement board and stone veneer, with a flagstone cap on top of the chimney. Can I use this as a vent as well? Or should I install other types of vents in the walls? If so, what would be best? Thanks for any suggestions! Much appreciated!


  • #2
    Dan, as I read your post, I'm assuming there will be no roof overhang on the sides of your enclosure. (I'm also assuming you will be putting some house wrap between the roof base and the flagstone to keep water from seeping/dripping through eventual cracks in either the stone or mortar.) There is a product made for providing venting on side walls, I've added a link below to a Home Depot page showing a picture of this type of vent. It would need to have some screening added (IMHO) to keep out smaller insects, but the louver design would keep direct rain/drips out. You might think about adding two of these in the back of your enclosure to provide some air flow. If you are using stone veneer on the enclosure back, you could also protrude the stone(s) make a little ledge above the vent(s) providing even more protection again drips/rain splashing through the mini-louvers into the enclosure. The other possibility is to tie into your chimney - just providing a path from the enclosure into the chimney stack system. Allowing some path out at the top that would not also create a water route in .

    Another inexpensive option (and probably much simpler installation) would be to take some short pieces of 3/4" plastic pipe. The pipe would only need to be long enough to span from the inside to connect with an outside elbow piece. Put some screening inline with the 90 degree elbow to make a set. Then install one set high and one set low in your back rock work (with the elbow pointing down...). This would allow a little air flow through the enclosure (since you really don't need much here), eliminate bug intrusions, and keep water from getting to your inside insulation.

    Those are just some options off the top of my head...I'm sure there are more out there. Keep us posted as to what you decide.
    Last edited by SableSprings; 11-29-2018, 01:36 PM.
    Mike Stansbury - The Traveling Loafer
    Roseburg, Oregon

    FB Forum: The Dragonfly Den build thread
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    • #3
      Hey mike, thanks a lot! You've given me some great suggestions for ventilation. There will be a trellis behind the oven but not very visible, so I may use the pvc pipe idea there and protrude it right through the trellis to make sure it gets air.

      I am going to get some pond liner for the roof, with ballast scratch coat and flagstone on top of that. Really appreciate your help, thanks again!