Need Help - Hearth Pad Build!

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TomRC

New Member
Mar 3, 2021
19
KY
Need some specific “what products” to buy from Home Depot advice for a raised hearth pad I’m building. Primary concerns are buying the correct adhesives for the project. I’m building a raised corner hearth pad for my Kuma freestanding stove to sit on. Base frame is made from 2x6’s. On top of the 2x6 raised frame will be ¾” plywood and on top of the ¾” plywood will be cement board topped off with porcelain tile. With heat from the stove being a concern I want to make sure I buy the right adhesives, mortar/thinset and grout.
  1. What general purpose adhesive for plywood deck to 2x6 frame? I will be screwing the ¾ plywood deck to the 2x6 raised frame but also want to use a general purpose adhesive as well. Is there a recommended general purpose adhesive (i.e loctite) rated for higher temps? Looks like a lot of the general purpose construction adhesives are rated for 120 degrees
  2. Should I just screw the hardiboard / cement board to the plywood deck or screw and use an adhesive?
  3. Mortar or thinset for porcelain tiles? Any specific brand, etc?
  4. Run of the mill grout ok or is there a specific grout I need to use due to heat?
  5. When I tiled my shower walls I used ¼” tile spacers. Someone recommended using smaller ⅛” tile spacers for this type of a project? Does this matter?
Thanks in advance. Never had to take into consideration "heat" on a project before so want to make sure I buy the right adhesives, mortar/thinset and grout!
 

begreen

Mooderator
Staff member
Nov 18, 2005
92,832
South Puget Sound, WA
This sounds like an ember protection only hearth. Which model Kuma?

There are no adhesives needed. Cement board screws hold down the cement board to the plywood, one every 8". Then use a good latex modified thinset for the tiles to be set. Grouts are non-combustible. Use the spacers that create the look you want and match them to the tile size. Unless the tiles are small, 1/4" spacers should be ok.
 

TomRC

New Member
Mar 3, 2021
19
KY
Thanks, saw a video online of a guy building a raised hearth pad built on a 2x6 frame and in addition to screwing the 3/4" plywood to the 2x6 raised frame he also used a general purpose adhesive. I've got 1/4" tile spacers left over from shower project so I'll just use those. Someone said go with a smaller 1/8" spacer for this type of project but if it doesn't matter 1/4" spacers it shall be.

Stove is a Kuma Tamarack.
 

begreen

Mooderator
Staff member
Nov 18, 2005
92,832
South Puget Sound, WA
For an ember protection hearth heat is not a big issue if adhesive is used between the joists and plywood, but it is overkill as long as the plywood is properly secured to the joists.