Layers of Durock considered solid.??

[knotdodger]

The insurance company says if the stove legs are 6in high it must have 2 in of solid masonary.
would the multple layer's be considered solid???? Plus a layer of 24g sheet metal in there somewhere.

 

[begreen]

You'll have to ask your insurance company. To me, that seems plain wacky. I could see concern about the weight maybe, but the height has little to do with it. Most commercial hearth pads are only about 1.25-1.5"" thick. What stove it this?

 

[LLigetfa]

If you bond the layers with thinset, it will be solid. It's not about the weight, it's about the heat. When I installed my RSF, if I didn't raise it 6 inches, I would have had to have a 4 inch solid masonry hearth or a special heat shield that consisted of layers of sheet metal and expanded steel mesh. They have since rescinded that requirement.

 

[knotdodger]

It is from the insurance compay for any stove. I quess to them all stove's are equall.
It is 4 in of hollow masonary with ends open for venting if stove legs are under 6 in.

I will have to go in and meet face to face with them I quess. The county mechanical
inspector (which will be issuing the permit) say's to go by the stove's specs. I will try
to please everyone I guess.

 

[fossil]

Sounds to me like the insurance company is quoting NFPA 211 for an unlisted stove. Your stove manufacturer's instructions take precedence over that IF the stove you're installing is a listed appliance. What's the stove? Rick

 

[webbie]

Rick is right - they are quoting generic specs - so unless you have some kind of old stove with no manual or listing plate this does not apply. Use the info from the manual.....but, in most cases (anyway) 2" of Durarock will do the job - and even more so with a sheet of metal slipped somewhere in there!

 

[knotdodger]

The stove I settled on is a Hearthstone Shelburne. It call's for an R-value of 0.8.
Thanks for the input .

Rob B.

 

[webbie]

OK, then that is what applies. Luckily for you, that also is the 4 sheets of Durarock, which is approx R=1.0 - so you will be veru fine as described.

 

[Highbeam]

Be sure that your floor is stout. I recall each 3x5 sheet of durock weighing 96 lbs. So 4 layers will require say 5 sheets at 500lbs. I whole sack of thinset and tiles at say 100 lbs. The stove at another 400+lbs, throw in a load of firewood and a man warming his bum and you're well over 1200 lbs there.

I added a pair of beams and 4 columns under my hearth to be sure. It wasn't hard and I feel better about the situation. I don't feel good about the steel studs in my elevated hearth pad, they seem too flexy so next time around I would use something solid.

 

[knotdodger]

Be sure that your floor is stout. I recall each 3x5 sheet of durock weighing 96 lbs. So 4 layers will require say 5 sheets at 500lbs. I whole sack of thinset and tiles at say 100 lbs. The stove at another 400+lbs, throw in a load of firewood and a man warming his bum and you’re well over 1200 lbs there.

I added a pair of beams and 4 columns under my hearth to be sure. It wasn’t hard and I feel better about the situation. I don’t feel good about the steel studs, they seem too flexy so next time around I would use something solid.

I never thought of that. Great Idea.
Thank you to everyone else also.

Rob B.