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  • #16
    Originally posted by johnnybrewmeister View Post
    Thanks Dave for the PM, and others for the details. So regarding the vent tube, it seems that if I did seal the dome with something like Tyvek, then a vent tube would be a smart idea. But if I don't seal it (which is where I'm leaning), since stucco passes water (and therefore water vapor), then there would be no need for the vent tube - the whole stucco dome would vent.
    Sorry if I'm being thick-skulled here, but at least I'm learning alot.
    Yes, that's right. Probably the best situation is to leave the outer shell unsealed, but have a roof over your oven. The problem with that solution is that it takes more expense and time which maybe more than you wanted just for an outdoor cooker. My oven is in the weather and after heavy rain and humidity (we live in the tropics), the oven gets wet and needs a few fires to dry it out. In fact even if it hasn't rained but the humidity is really high for a prolonged period with no oven use, the thing is still damp and the insulation is not as effective, ie it's hot to touch on the outside rather than just cosy warm. I'd prefer to dry it out a bit rather than build a dedicated roof though, especially as you have a flue pipe penetrating a roof. Or you could build one of these.https://community.fornobravo.com/for...670#post395670

    Dave
    Last edited by david s; 03-21-2017, 04:03 PM.
    Kindled with zeal and fired with passion.

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    • #17
      Dave, now *that's* a cool roof! I can't imagine getting that much rain, especially since we only get 8-12" per year on average. Since we're on the drier side of things, I'm planning on just dedicating a good waterproof tarp to sling over the oven whenever serious (if I can call it that) rain is forecast. Gotta love this forum. A lot of folks probably don't realize how truly valuable all of the old (even really old) posts can be, especially pictures, and especially to people like me that search & troll A LOT learning tons from others. Thanks!

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      • #18
        So this is all very interesting for me (trying to finish off last years project)
        Finish: igloo and mosaic tile
        Weather: Ontario Canada, so ice/snow in winter and rain of course
        Likely will cover with tarp in winter

        So current state is covered in matrilite19
        I think the tile will be kerabond/keralisic dryset (ultraflex3 thinset)+ glass tile

        So questions would be to make it as waterproof/breathable/crack resistant as possible
        options any/all/some of
        1 just add a scratch coat, tile, (seal?)
        2 add vent(s) through to theCFB (top or sides would it really matter sure top might be better but need to figure out the right vent o no water issues?)
        3 add a real wterproof layer of something like aquaDefense/redguard/ mapei smart + vent
        4 or maybe add that waterproofing at the top 1/3 and bottom 1/3 leaving a slightly more breathable mid section where water will run off anyway
        5 some other cementitous waterproof/breathable layer before tile? type-N concrete I think I saw is what Francis used?

        any ideas and even better specific product recommendations would help
        going back and forth on what to do

        photo before CFB & matrilite layers


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        • #19
          Originally posted by millerlake View Post
          So this is all very interesting for me (trying to finish off last years project)
          Finish: igloo and mosaic tile
          Weather: Ontario Canada, so ice/snow in winter and rain of course
          Likely will cover with tarp in winter

          So current state is covered in matrilite19
          I think the tile will be kerabond/keralisic dryset (ultraflex3 thinset)+ glass tile

          So questions would be to make it as waterproof/breathable/crack resistant as possible
          options any/all/some of
          1 just add a scratch coat, tile, (seal?)
          2 add vent(s) through to theCFB (top or sides would it really matter sure top might be better but need to figure out the right vent o no water issues?)
          3 add a real wterproof layer of something like aquaDefense/redguard/ mapei smart + vent
          4 or maybe add that waterproofing at the top 1/3 and bottom 1/3 leaving a slightly more breathable mid section where water will run off anyway
          5 some other cementitous waterproof/breathable layer before tile? type-N concrete I think I saw is what Francis used?

          any ideas and even better specific product recommendations would help
          going back and forth on what to do

          photo before CFB & matrilite layers

          in hind-sight and if I had a chance to do it all over again, I'd choose option #4 - basically waterproof most of it, but leave plenty of ventable area. I think by doing this you could probably keep out 80-90% of the water, and would have no problem with it drying back out (either via time or warming fires).

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          • #20
            Just getting to the finishing stages of my igloo design. I'm wondering if using Specmix mortar (Portland,lime and sand )which is a brick mortar and supposedly waterproof would work as a waterproof final layer

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            • #21
              Most proprietary cement renders are partially waterproof. You wil probably notice some difficulty to get to water mixing into the dry product when first beginning to mix it. This means it has got waterproofing in it. You can also add some acrylic additive like Bondcrete around 1 part to 2 parts water when mixing. This makes the render stronger and more workable. A 100% acrylic render which comes wet in a bucket not dry in a bag, can be applied over the cement render after it has cured to make it completely waterproof. I find it easiest to water the stuff down 20% so it can be painted on.
              One school of thought is that the outer shell should be slightly porous so that moisture can escape through it. If completely waterproof the moisture will be locked inside. I prefer to make it completely waterproof and allow the moisture out via my vent.
              Last edited by david s; 08-08-2017, 03:12 PM.
              Kindled with zeal and fired with passion.

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              • #22
                I ended up using Flexcrete (+polymer) from Lowes here (valcon industries) waterproof/breathable/flexible
                seemed to tick all the right boxes
                now to tile (well next year now)

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                • #23
                  So last post is two years or so ago, but how did the flexcrete solution work out? Iím in Portland Oregon, looking at a tiled igloo finish on a Casa 90.

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                  • #24
                    Worked well left out in rain lots of times during summer
                    Covered in winter (at cottage so unused)

                    In the end I used the flexcrete but before tiling I decided to a full coat of Mapei AquaDefense on it
                    Then 1" tiles using Kerabond/Keralastic
                    grout with Mapei UltraColor Plus FA

                    so everything is polymer based
                    goal is nothing is getting in there

                    probably still buy a custom tarp to cover in times when not there (ice is just such a worry in winter, don't want to have to rebuild anything)

                    going to submit a build thread eventually chronicling all the fun work, decisions etc
                    just about done (ran out of black tile ... oops)

                    Last edited by millerlake; 08-25-2018, 07:34 AM.

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