Wood roof???

[Jaronimo]

My dome is done and i have almost completed the side and back enclosure walls. I am trying to figure out my roof. The outer layer of the roof is going to be copper mettalic colored standing seam metal roofing, so it matches the weber grill on the deck. it should look really nice!

I am planning on framing the roof with metal studs. The dome enclosure will be filled with loose vermiculite for insulation. Over the top of the dome i will have at least 8 inches of the vermiculite, maybe more, not sure yet.

My question is, can i use plywood sheathing over the metal studs as a substrate for the metal roof or should i use a concrete type backer board? With the insulation, will the roof get hot? Or hot enoughh to burn?

I plan on venting the eaves and peak of the roof. I am also putting in a cast iron cleanout door at the peak of the rear wall so i can look inside the enclosure and add more vermiculite later if it settles.

[brickie in oz]

Re: Wood roof???

Or hot enoughh to burn?

No it wont, if it does your insulation is all wrong.
Ive got a plywood roof with asphalt shingles on it and it doesnt even get warm with blanket and loose vermiculite on top of the oven.

[Cheesesteak]

Re: Wood roof???

What Brickie said . . . you'll be fine.

[Jaronimo]

Re: Wood roof???

I did not use a blanket wrap, i am planning on just using the vermiculite. Should still work fine, right?

[Jaronimo]

Re: Wood roof???

@Cheesesteak, thats a good looking oven!

[Mingy]

Re: Wood roof???

One thing to consider is that you have a fire with a short chimney. There is always the possibility embers will float up the chimney and land on the roof. If it is flammable this could be a problem.

[Neil2]

Re: Wood roof???

Keep some wiener roasting sticks handy for when your roof catches fire.

[brickie in oz]

Re: Wood roof???

I did not use a blanket wrap, i am planning on just using the vermiculite. Should still work fine, right?

The blanket is what what keeps most of the heat in.

I can get a probe into the back of my oven through the loose vermiculite, when the oven is at 300c the outer side of the blanket is 60c, its good stuff.

[Gulf]

Re: Wood roof???

I don't see a problem with wood used in the framing for the WFO. Most of us who have fireplaces live in wood framed structures and most have asphalt shingles.That is with all safety measures included. That woud be appropriate insulation and clearances between the "hot stuff" and the "flammable stuff". A proper spark arrestor should be included in a flue or chimney regardless of the type materials used in construction. That piece of paper you used as a starter can travel many yards before it is extinguished. Think about other combustables that are on your's or your neighbors properties. However, since you you have already framed the walls and are planning to use metal studs for the rafters, there are metal lath options for metal framing. I am sure there are some commercial materials for lath but, a stud layed flat with a homemade spacer would work to keep the screw from collapsing the stud. The spacers could be made from Hardie board if you wanted to keep the noncombustable theme going.
All things considerd (if the WFO is constructed properly) the main danger woud be from back draft, or exteme fireloads. I can see a possibility of flames traveling out of the entrance and up to the over hang. If there is a metal/insulation barrier IE: metal covered gypsum or an air space seperating the combustables from heat, there should be no problem. That is if the impingement is short lived which it should be unless for seem reason you keep adding fuel .
Just Sayin'

[Jaronimo]

Re: Wood roof???

The chimney will be on the taller side, the roofing materials will be metal. At least the outside layer will be metal. Maybe i will look into a fireproof blanket, too bad i need it this week.

[Gulf]

Re: Wood roof???

Search for industiral insulation in the Andover area. You will probably have to talk to them by phone. They are used to speaking with pro's who rebuild kilns boilers etc. The key words that you want to ask them for is ceramic fiber blanket. "Fire proof blanket" can be misinturpreted for "fire blanket" which is a throw that is placed under welding and grinding sparks in an industrial situation. Start searching and calling soon. Most industraial suppliers are not open on the weekends

[cgardella]

Re: Wood roof???

I just got my blanket in the mail from a store out of New Jersey. I would have ordered from FB but the cost of shipping to was 3 times the price of the product.

Anyway, this is the website

Welcome to CeramicFiberOnline.com

It got to may door withing 4 business days, but you might be close enough to pick it up from the factory.

[Greg in RI]

Re: Wood roof???

I have finished my oven!

Now the enclosure is developing in my mind so I thought I would revisit this topic, not so much for the wood but for the use of metal studs as rafters. I have searched the FB site and the web and haven't found any specific recommendations for using metal studs for rafters. I live in RI and worry about heavy wet snow buckling a metal stud (even 2 together, making a solid beam). I plan to use 4? wide block for the side walls and pitch the roof using metal rafters. I?ve thought of using some stops between the rafters and some metal plates used for wooden truss fabrication. Has anyone come across instructions on how to build rafters from metal studs?

I am going to wire reclaimed slate to hat channel attached lengthwise across the rafters (no sheathing) but again, I?m worried about the load on the metal rafters.

Any thoughts?

Thank you,

Greg in RI

[Gulf]

Re: Wood roof???

I don't think that there is a problem with using wood in the framing for the enclosure for a WFO. As long as there is some conscideration for the proper spacing and or insulation between the flu and the rafters. I think that someone could do a combination of the two. Wood, for all common rafters and joices, except the two sets either side of the flu. Insulate the flu, place the two sets of wood rafters and joices adjoining the flu with further spacing to allow for metal. Attach the metal studs to the wood rafters and joices separated with strips of a solid insulated barrier. I like 5/8" fire core sheet rock.
If you go with all metal, you can increase the bracing on each truss, go with 16" centers, and or increase the pitch to allow for the snow load. Increasing the pitch will most probably require adding to the height of your flu.
Many of us live in wood houses with fireplaces and even asphalt shingles . Most of us have no problems. Just remember, insulation, spacing,and spark arrestors .

[Tscarborough]

Re: Wood roof???

My take on it is that if you have fire outside the oven or chimney, then you have serious issues no matter what material you frame with. I felt comfortable framing my oven house and roof with wood, although I did use metal roofing for spark resistance.