Which Side Cement Board

[04HemiRam2500]

This might be a dumb question, but I am building my hearth. It is going to have 4 layers of 1/2 inch cement board and then a ceramic tile on top. Due to my time constraints and money budget gone I am going to do the tile next summer. So the tile is 1/2 inch thick so I am just going to put another cement board on. Then when I go to tile the flue and everything will be the same height and I will remove the fifth cement board. My r value will be 1.56 and then some for the tile which is good because the r value needed is 1.5.


My question is which way does the cement board go since I am not going to tile it right away? Does the side with the usg and going go face up or down?

 

[begreen]

If this is a sacrificial layer I don't think it matters. For the tile you want the textured side up.

 

[04HemiRam2500]

Hey begreen, does it matter though since I am going to use it a year without the tile because it is COLD!!

 

[04HemiRam2500]

Also, do I need to screw the layers of cement board together? Is it necessary?

Also, I am puting two pieces next to each other then stacking them four layters high. Do I need to fill the gap. Again I do not think this is necessary as the gap is underneath in between the stove. But since I am using it a year without tile I want to make sure.


Also, the cement boards are placed on the wood floor 3/4 plywood floor boards since the new edition is being built.

 

[BobUrban]

If you are laying tile onto cement board it is best to grout it to the floor and screw it down.

At the minimum use lots of screws - like ever 4 or 6"

 

[04HemiRam2500]

Is this needed though. After all the boards are not going to move and the gap is under the stove. Also, once I do the tiling the boards are not going to move either.

 

[BobUrban]

for tile you want to limit or eliminate flex - because any flex at all will begin to crack the tiles or grout or pop them loose. The more you can do to stop this the better but is it necessary - is anything necessary? A box of screws is pretty cheap insurance

 

[begreen]

Screw them down with a screw every 8" per mfg. instructions. Stagger the seams on each new layer. I see no need to put anything between layers. Screwed down properly it is not going anywhere. It should be fine to use a temporary top layer of cement board without tiel for protection of the layers beneath them. I would put some 2" x 2" metal plates under the feet so that they don't dent the cement board.

 

[04HemiRam2500]

I have the stove on the pedastal base not the legs. I am still wondering about screwing them into the floor boards I see no harm not doing it? and what do you mean by staggering the seams.

 

[begreen]

I like to put down a 3/4" plywood base and screw to that. If it takes multiple sheets of cement board to make up each layer there will be a seam. Don't have the seam for the next layer right over the seam of the layer below it. Stagger the seams.

 

[04HemiRam2500]

Just to clarify then I will not bug yall anymore. Is there any harm not using screws to screw the cement boards down. Also, which side facing up does not matter?