DIY hearth question

[not on the rug]

OK. I have been lurking for a while, and finally decided to join. I am in the process of planning a hearth for my woodstove. i recently purchased a hearthstone III for $300, and its in perfect condition. it was installed into a family friend's home years and years ago, and they only used it a handfull of times. so its really nice. anyway, i plan on installing it in to the existing old woodburning fireplace in our house. i have already purchased the chimney liner kit and insulation. now i have to build the hearth.

my idea was to put down a layer of durock. then build the frame out of bricks, mortared to the durock. then sandwich another sheet of durock on top. then finally cover it with 1.5 inch slate or flagstone. i plan on supporting the stove fully on brick, so the durock wouldn't have to support any of the stove's weight. the stove's manual requires only 4" of brick mortared to 28g sheet metal as a hearth. the durock, brick, mortar, stone, and dead air space exceeds the r value required. my question is this: is this a good design for a hearth?

the reason i am choosing to build the frame from brick, and not 2x4s or metal studs is that i have an abundance of brick that i need to use. however i do not want a brick hearth because it would not match the stone fireplace in my house

 

[r_d_gard]

What's going to be under the durock

 

[not on the rug]

under the first layer of durock is the subfloor. i think its 3/4" plywood. so, from bottom to top will be subfloor, durock, brick/dead air space, durock, mortar, stone. then the stove

 

[r_d_gard]

That's good, sounds like you have it set up. Check two other things.

1. The manual for your stove, if you haven't already done so. The manual will give the clearances.
2. Get a permit from your local county office. Ring them up or go see them and ask what specs that want it built to as the County code will differ from that of the manufacturer. Also, you should get a permit for the build and install if you want your insurance company to cover it.

 

[not on the rug]

thanks for your input

i have the manual, and all of the clearances are being met. and they only require 4" of brick mortared over 28g sheet metal as a hearth. so i am definitely exceeding the r value for the hearth.

i have already cleared everything with insurance company, and i just have to check with the county for the local codes

thanks again

 

[TROY COOK]

That's a new one on me. I have installed 100's of hearths over years,I'm a tile and stone installer.I can say it sounds like a lot of xtra work.I would use lumber.much easier to get plum and flat durock is a great tile backer but not good for holding weight if it's not fully supported under it with plywood of some other sub straight. also I really prefer thinset mortar to regular mortar,because mortar swells and thinset shrinks/Think about it. What makes a better glue something that pulls the two objects together or something that pushes it apart??for the same reasons thinset makes a lousy mortar between bricks.Use the bricks in your garden?....

 

[not on the rug]

ramsay,

you raise a good point. i should clarify more. i was using the bricks because i have tons of them to use, and didn't want to spend unnecessary money.

the durock wouldn't be holding any weight, as i plan on fully supporting the area under the stove with bricks, as well as supporting every 12-14 inches with a row of brick. picture a framed wall, but instead of 2x4s, use bricks.

i should have said thinset, and not mortar. thats my fault. i plan on using thinset. i already purchased it. i was going to thinset the brick to the durock, and then also thinset the stone layer to the top layer of durock.

do you think this sound slike a good plan? sorry for the confusion

 

[joel95ex]

i think he meant that the subfloor might flex a tiny bit causing a problem.. the brick and stove's combined weight.

 

[TROY COOK]

You still should have plywood under the Durock. This will minimize the deflection or "flex" and help support the weight.The only time you mount durock rite to the studs is on a wall. you can put your foot rite through durock if there is no sub floor.