waterproofing under the base ,?? on my idea

[merlyn]

After the 26 inches of rain in 24 hours I have to rethink my base .. The base is done and I will not be placing a roof over the finished oven .. No room . I thought I would pour a 2 inch thick slab [platform] the shape of the finished dome on top of the base . under this I would put some roofing material [[this is heavy material used for flat roofs not tar paper]] . so the concrete platform won`t allow water to soak into it from the base ..Then some aluminum sheeting over the platform before putting down the the 3 inchs of fiber board and fire brick after that ..... I would also seal the outside edges of the raised concrete platform . I was thinking about vermiculite concrete but a regular pour with gravel would be stronger for the weight of the dome , and I don`t feel I need the xtra insulation .any and all coments are appreciated .. For those you that have answered my ? before thank you . I had hoped to start this several months ago but life sometime dictates other needs ..

[RichC]

Re: waterproofing under the base ,?? on my idea

Hi Merlyn, my base consists of 4 retaining walls(in a box shape) with a concrete deck about 140mm from the top. This effectively gives me a box which I filled with vermicrete and then built my oven on. Mine, when finished will also have no roof on it and my climate is very wet. I intend drilling some holes in the deck from underneath so that any water that gets in can get out, downwards, rather than pooling in there.

Rich

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

G'day merlyn
A water proof layer under the stand slab is the first start. Then a gulf always recommends a secound water proof under the insulation layer is sensible as well.
I've had my oven stand flooded once and its a sod to empty of wet wood and wait forever for a large structure to dry. I've fitted a grated drain in front of the stand door and plan to fit another at the uphill side if the stand.
I wouldn't use aluminum at all its just going to corrode in short time.
Don't use gravel in you pearl - Crete insulation it will just ruin its insulation value. Trust the pearl-Crete to support your oven. Your oven has a large mass but a wide footprint so it will support it no worries.
You got to seal the oven really well in the subtropics as you well understand . So the insulation under on and under the oven gets sealed but the oven entrance gets forgotten. Rain blowing in on that entrance hearth gets sucked straight into your insulation layer where its hard to dry out. I've an external door basically a flat plate on the outside and a 4 in metal lip that goes into the oven entrance just in case something gets blown past the flat door.
On top of the dome I've fitted a 1 in sealable vent that gets left closed most times to keep out moisture and the local ants which like to head to high ground in the rain as well. Most times I open it up and leave it open when I flash the oven up to release any water and steam. Finally I've bricked over I entire dome. No chance of cracked render layer then. It's very popular with the UK builders an you can see why considering their climate.
I've spent a bit of effort to wheather proof my dome sometimes it would have been better just to roof it but I really like a dome oven out in the open, you can't beat a Queensland winter out in the warm sun.
Hope something here might help
Regards dave
Sorry misread your bit on the pearl-Crete layer your using CF board so your gold. Consider using only CF insulation over the dome as well and straight render over that without the pearl-Crete layer less water to dry out that way. That's the way I did mine

[RichC]

Re: waterproofing under the base ,?? on my idea

@CobblerDave, could you post a picture of or link to a vent of the type you have used please. Sounds like it might be a good idea for me.
Thanks
Rich

[merlyn]

Re: waterproofing under the base ,?? on my idea

Thanks Dave for tips . I did pour a 2inch thick vermiculite layer under bottom with a large piece of vinyl roofing material under that type used for flat roofs over a 1/8 inch thick .. Slab is raised up 3 foot over ground so the floods won`t be a problem. [[[Same as yours]] have wet cloth on vermiculite now for 3 days then will wait a week before proceeding .. I put this layer down to help raise the cf board up off the slab ..I have 3 inchs

?????? 2 questions please ,,,, I have the cf insulation and was going to put that over the brick ,then add a layer of 4 inches vermiculite concrete over that and finish with 2 layers of water proof mortar and then a silicone paint .. You said skip the vermiculite crete .. .. Ok I was only going to use 2 inches thick on the cf insulation . Good enough ??? then what chicken wire and the mortar.. My vinyl under the build will extend to all edges of the build including however thick the walls are ...

2nd ?? Looks like you used a metal lental for the door as opposed to an archway . I was considering this as it would match the rest of the project . But was afraid the metal would get so hot [ [[being in the door way]] that it would start cracks at some point .. NOT TRUE /////????????????
I was going to build 2 doors for it and have a long entrance way also a vent on top ..
Thanks for getting back with me I am doing a lot of research as I only want to build this once Everything is time tools and endurance but you better research the project 1st ..
Laugh when you can life is to short to be anything but happy

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

@CobblerDave, could you post a picture of or link to a vent of the type you have used please. Sounds like it might be a good idea for me.
Thanks
Rich

G'day Rich
Sorry for the late reply been a bit on the busy side.

http://www.fornobravo.com/forum/8/mi...tml#post134013

This should give you a link to Gulfs oven and also another discussion on the merits of a dome vent.



This is mine take on a vent to suit my local conditions. Its basically an end piece for a 25mm (1in) copper pipe. I've added a bras chain to stop little fingers from taking the cap away. I can screw the cap down and seal the oven off as the local ant population head to the highest ground when rain threatens.
To fit something like this in the dome its as simple as making a tube the right size from a piece of cornflakes box and rendering it into position. once the render "goes off " the cardboards wet and sodden and can be easily removed. let dry and what ever fitting can be easily silasticed in.

Hope something hear might help
Regards Dave

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

Thanks Dave for tips . I did pour a 2inch thick vermiculite layer under bottom with a large piece of vinyl roofing material under that type used for flat roofs over a 1/8 inch thick .. Slab is raised up 3 foot over ground so the floods won`t be a problem. [[[Same as yours]] have wet cloth on vermiculite now for 3 days then will wait a week before proceeding .. I put this layer down to help raise the cf board up off the slab ..I have 3 inchs

?????? 2 questions please ,,,, I have the cf insulation and was going to put that over the brick ,then add a layer of 4 inches vermiculite concrete over that and finish with 2 layers of water proof mortar and then a silicone paint .. You said skip the vermiculite crete .. .. Ok I was only going to use 2 inches thick on the cf insulation . Good enough ??? then what chicken wire and the mortar.. My vinyl under the build will extend to all edges of the build including however thick the walls are ...

2nd ?? Looks like you used a metal lental for the door as opposed to an archway . I was considering this as it would match the rest of the project . But was afraid the metal would get so hot [ [[being in the door way]] that it would start cracks at some point .. NOT TRUE /////????????????
I was going to build 2 doors for it and have a long entrance way also a vent on top ..
Thanks for getting back with me I am doing a lot of research as I only want to build this once Everything is time tools and endurance but you better research the project 1st ..
Laugh when you can life is to short to be anything but happy

G'day Merlyn sorry for the late reply.
The standard for an insulation on the dome is 2 ins of CF blanket or 4 ins of pearlite/cement. A lot of folk use a layer of pearlite/cement to even out their CF blanket before rendering as it cheaper than CF and of course you cant have to much insulation. The down side is that for every inch layer of pearlite cement you need really to leave a week in good condition to dry before putting on the next. I used a 4 in layer of rockwood insulation over 2 in of CF blanket to complete mine because of the wheather conditions at the time. It more than handles the heat that makes it through the CF blanket, CF blankets the bomb!
http://www.fornobravo.com/forum/3/hi...tml#post115031
As for metal door surrounds I most certainly have angle iron in my oven mouth, as for major cracks I have a hairline crack in the mortar above the door. Cant get a pic of it though its closed when cold. Funny when you think about it the professional WF Italian pizza ovens have a metal door surrounds and metal door. Recon it probably goes a long way to protect the brick from damage from logs and tools and such. You hear a few members chip the brick on the oven mouth from time to time.
I recon you should go for an arch for a different reason. Trust me, marrying a square entrance into a dome is a mind blowing exercise. Much, much, easier to marry the dome to an arch as Ive found out since. Notice my front entranceway has a arch on it, there easier to make than I first thought and I like the look of them.
Hope something here will help in your research, Im sure your oven will work well
Regards Dave

[Gulf]

Re: waterproofing under the base ,?? on my idea

You are getting some great advise!. Dave, was my mentor for venting. I truly believe that venting is the key to not allowing enough time for the Igloo style domes render and insulation to dry. I think that it will also help, in times of unuse and after some of the incliment weather that many of us endure.

[merlyn]

Re: waterproofing under the base ,?? on my idea

Hi sorry I haven`t been on, friend passed away and got caught up ..

Liked the idea of Daves on the rock wool after a bit of time I found some 5.1/2 inches thick for a good price . I will use it over the ceramic batting . I ordered it today .. seems like a easy and great idea fireproof, easy to lay, and no water content .. The only down side I see is it does not add structure durability to the dome so this poses my next question ..

So now my ? is how thick do you put the render coat on . I assume we are talking about what I would call a stucco finish or mortar coat .. I would want it plenty thick so if the occasional tree branch falls on it or in a hurricane the dome dosen`t split open .. I was thinking about putting some granite dust in it . should make it harder and maybe a bit more water proof .. Ideas ????? ..

and do any of you know of a good name brand for a water proof paint the pool paint I was going to use comes in blue . Not my color ..

Dave after your comments on the arch way verses the straight on with a metal lentil I`m going to go with the arch . Thank for the advice . Laugh when you can life is too short to be anything but happy ..

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

G'day Merlin
A cover of chicken wire and some bagged render were what I used and about 25 mm (1 inch) . I had to get the oven sealed as fast as possible as we were looking at a pretty wet summer season. As it turned out we had the one in 100 yr flood.
The oven and Brisbane survived. The dome did not have to suffer any hurricanes but it did get climbed over by many children ( king of the castle is pretty much an international child's game I'm sure). I thought of using one of those acrylic renders, but in the end I liked the look of brick ovens out of the UK and 1/2 bricked the dome!
If I was to redo the render over again ....
I would use an acrylic render over the original. More flexible and resistant to cracking.
Use poly propylene fibres in the mix like the local council now use in path construction so that don't now use steel mesh.
Lastly fibreglass over the render . This is one that I know little about, but I have seen some portable ovens at the local markets. It looks a bit plastic but seems to work?
Hope something here will help
Regards dave

[RichC]

Re: waterproofing under the base ,?? on my idea

@Merlyn, again sorry for chiming in with my side agenda(although related).
@Dave, that fibreglass idea seems genius to me? Would render adhere to it I wonder?
I have some ceramic fibre left over and I was thinking of putting a layer of it over the vermicrete dome(10-15mm maybe) and tying it down with chicken wire. This would create an airgap to allow for it to dry out after periods of non use. I could then fibreglass directly over this and then lastly render over the fibreglass and place a vent at the top protruding through both the fiberglass and the render.
Do you think the render would stick to the fibreglass?

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

G'day
Sorry... It seems to be a bit complex to me! Switching from one layer to another.I believe in trying to keep things as simple as possible.
The fiberglass is just something that I have seen used and I have no idea how it works , and I thought it worthwhile to mention as worthy of future investigation .
As for weather cement render will stick to it ?
My own opinion is that it would go over cement render to form an (ugly) but water resistant layer, but how it would work the other way around? Who knows?
Regards Dave

[RichC]

Re: waterproofing under the base ,?? on my idea

Now you have me searching the internet for fiberglass info Dave. I'm thinking, insulated vermicrete layer covered by a thin layer of my waste ceramic fibre held down by chicken wire. Then fiberglass over it leaving a vent hole at the top. This should be 100% impervious to rainfall and 'should' allow me to finsih over it with a white sand/cement render which is the look I want. I also wouldnt ahve to worry too much about water/dampness penetrating the render finish.
Making any sense? or am I overthinking? Probelm is I really want the igloo look with no dog house over it and Ive been at pains trying to figure out a way to seal it from the rain

[merlyn]

Re: waterproofing under the base ,?? on my idea

Hot and humid here . Put the floor on and set the 1st 3 rows today .. useing wedges in between the bricks both bottem and top,, fire brick morter everthing in place ,,with wedges takes it`s quick to set up and move on . . Have a good brick cutting machine .. Will go with 3 inchs of rock wool and 3 inchs of the cermic blanket . Great idea my vermic create floor wasn`t dry after 10 days still soft ,,humid here a good day is 80% .. Gulf recomends hardware wire Little stiffer .. I will look for a water proof morter .. good tip .. found a water proof tinable paint for the surface .. Moving right along .Ploy fibers in the mix yup I`ll do it .. . Fiberglass on top nope ruins the look . Maybe a plastic dinasaur or something .. thanks for the info .. the build goes on ..

[cobblerdave]

Re: waterproofing under the base ,?? on my idea

G'day Merlin
Goodonya ! I've double dipped before but 4 times
Just go back,hit the edit button, and remove the text! And submit.
Sounds like your making good progress, and yes I agree about the humidity its a s@it. Love the comment about the plastic dinosaur it says it all. Included the bit about the fiber glass just in the interest of information.
Regards dave