A few questions on hearth

[Dan94550]

Now that my stand is complete, I'm ready to start the hearth and the instructions are excellent and straight forward. I've never worked with the vermiculite/portland mixture before and here is my question: Is it possible to attach the metal stud framing for my enclosure to it, and if so what is the best method/fasteners to use or will I have to go down to the cement in order to anchor the framing? Any input would be greatly appreciated.

Cheers,
Dan

[Versachi]

I have thought the same thing while building mine Dan. I haven't got to the stud stage yet but if I had to do it over I would frame my vermiculite/portland slab to allow for 3.5 inch steel studs to be placed directly on the conrete slab. That would eliminate the risk of a soft spot in the vermiculite slab. Eliminating the stud width around the dome would not affect the insulating value of the slab imo. Good luck!

Cheers, Versachi

[james]

That's something I have been thinking about -- and a couple of builders are doing that way. There is nothing wrong with pouring the vermiculite layer all the way out to the edge of the structural concrete, and it will hold the upper enclosure, but it might be easier to leave a clear ledge on the concrete for framing.

What do folks think?

Again, no problem for current builders, but a potential improvement. Also, using SuperIsol panels underneath the oven do not create this issue.

James

[maver]

My build would have been easier (on my first go round) if I had left room for studs attached directly to the concrete, and I think David's advice of embedding bolts in the cement for the purpose of attaching the studs should also be in there.

[nissanneill]

I agree,
the Vermiculite/cement layer is of a firm cork consistency and I would not hold too much faith in nailing, 'dynabolting' or using 'loxens' into it. I feel that it would crumble especially when close to the edge.
May I suggest that extra long bolts, or rather threaded bar chemically fastenned into the cement layer for maximum strength.
With your closure being built on the outside and probably directly above the cement block base walls, would rule out long 'coach bolts' running through both the cement and vermiculite layers and then through your timber base plates. This would give you maximum strength.

Neill

[Dan94550]

Originally Posted by james

That's something I have been thinking about -- and a couple of builders are doing that way. There is nothing wrong with pouring the vermiculite layer all the way out to the edge of the structural concrete, and it will hold the upper enclosure, but it might be easier to leave a clear ledge on the concrete for framing.

What do folks think?

Again, no problem for current builders, but a potential improvement. Also, using SuperIsol panels underneath the oven do not create this issue.

James

James,

I haven't been here long enough to view any posts using the SuperIsol panels being used. If you can lead me to any pictures I would apreciate it. Do they only go underneath the oven and then insulate with vermiculite around it? I may do that or just cut back the insulating layer to allow for the metal studs.

Dan

[Dan94550]

Originally Posted by Versachi

I have thought the same thing while building mine Dan. I haven't got to the stud stage yet but if I had to do it over I would frame my vermiculite/portland slab to allow for 3.5 inch steel studs to be placed directly on the conrete slab. That would eliminate the risk of a soft spot in the vermiculite slab. Eliminating the stud width around the dome would not affect the insulating value of the slab imo. Good luck!

Cheers, Versachi

V,

After asking the question, I thought about it last night and came up with your idea also. I,m going to think about it a little longer or switch to James idea of the SuperIsol panels. I guess this would eliminate the problem if they only ned to be underneath the oven

Dan

[Dan94550]

Originally Posted by nissanneill

I agree,
the Vermiculite/cement layer is of a firm cork consistency and I would not hold too much faith in nailing, 'dynabolting' or using 'loxens' into it. I feel that it would crumble especially when close to the edge.
May I suggest that extra long bolts, or rather threaded bar chemically fastenned into the cement layer for maximum strength.
With your closure being built on the outside and probably directly above the cement block base walls, would rule out long 'coach bolts' running through both the cement and vermiculite layers and then through your timber base plates. This would give you maximum strength.

Neill,

I agree with running the bolts through the insulation and cement would be the strongest. I'm still in time to do that also. Just another option.

Thanks,
Dan

[asudavew]

I did construction for over 10 years.....

Now I am not sure about the vermiculite/concrete mixture, but with regular concrete or tile we would sometimes used liquid nail to "attach" the bottom plate to the floor.

It worked great!

But like I said, not having worked with the vermiculite/concrete mixture, I don't know if it would peel up or something like that.

Just me 2 cents.

[DrakeRemoray]

I had a similar discussion on this topic here:
http://www.fornobravo.com/forum/f8/n...stion-530.html (New hearth slab design question)
Drake