How big of a gap in hardie board can I fill with thinset?

Constant Improvement · 02-04-2009, 01:08 PM

I am putting porcelan tile down in my bathroom, and have cut the .5" hardie backer and laid it down in the room. I left a 1/8" to 1/4" space around the perimeter and between the boards like the instruction said, but in the door frame where I cut the hardwood floor up, there is a gap about 1-1.5" between the hardie board and the hardwood. can I just fill this little gap with thinset when I cement the hardie board down or do I need to cut a little sliver of hardie board to go in there?

I mean... cement thinset is pretty much the same at cement backer board right? theoretically, you could just pour a .5" thick layer of thinset on teh subfloor to put your tile on.

Thanks
-Eric

onlinehandyman · 02-04-2009, 07:01 PM

I have done thinset in very small places like that and it has worked just fine. I have even done grout like that where it's too small to cut a tile and it worked just fine. You would think that it would crack, but it doesn't. Good Luck!

onlinehandyman · 02-04-2009, 07:18 PM

I have done thinset in very small places like that and it has worked just fine. I have even done grout like that where it's too small to cut a tile and it worked just fine. You would think that it would crack, but it doesn't. Good Luck!

Constant Improvement · 02-05-2009, 07:46 AM

Thanks for the reply... thats what I was hoping

my drill battery dies last night, and I only got one sheet of hardie board down, but tonight I plan on finishing it.

After re-reading my original post I thought I would clarify one thing: the gap is around 1" to 1.5" wide but it the entire length of the door frame (28"), so about 30-40 square inched total... dont know if it makes a difference.

Thanks,
Eric

angus242 · 02-05-2009, 10:41 AM

I disagree. Just spend the time to put a piece of CBU in the gap. Thinset likes to shrink when it cures. I'm not comfortable with anything over 1/2" thick.
If you attempt this, 2 things might happen:
1. The thinset will shrink and you'll lose bond to the tile
2. The thinset will remain bonded to the tile but pull the tile with it and SNAP

For a gap that large, just add the CBU.

Constant Improvement · 02-05-2009, 10:49 AM

Quote:

Originally Posted by angus242

I disagree. Just spend the time to put a piece of CBU in the gap. Thinset likes to shrink when it cures. I'm not comfortable with anything over 1/2" thick.
If you attempt this, 2 things might happen:
1. The thinset will shrink and you'll lose bond to the tile
2. The thinset will remain bonded to the tile but pull the tile with it and SNAP

For a gap that large, just add the CBU.

OK... I'm glad I asked the question then. If there is any concern at all, I might as well just do it then (not like its that hard). I just wasent sure whether having a sliver of hardie board that thin, or an area of thinset that thick, would be worse...

Thanks

**Termite** · 02-05-2009, 10:49 AM

I'm with Angus 100% on this. You should cut a narrow strip of backerboard and set the backerboard strip in thinset as required, then screw or nail it down.

Constant Improvement · 02-05-2009, 10:52 AM

Quote:

Originally Posted by thekctermite

I'm with Angus 100% on this. You should cut a narrow strip of backerboard and set the backerboard strip in thinset as required, then screw or nail it down.

check... thanks guys.

homedude · 03-21-2011, 07:43 PM

This is why I love mud set