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gangelo · Oct 6, 2008, 09:54 AM

Hi All,

I have two corners in my bathroom where the two pieces of hardibacker are not flush to make a nice corner. I would like to "sand" or grind the edges flush but I do not know what to use to do it. The tools I have are (all Dewalt): cordless/corded drills, cordless cut-off/grinder tool and cordless Sawsall. Is there any attachment I can use in order to do this? I also have a Porter Cable belt sander, but I am afraid the dust will ruin it because it is not mine. What can you suggest?

ralphwingate · Oct 6, 2008, 09:59 AM

I would try a cut off tool with a fine cutting wheel. You might find a fine cut off weel for your grinder might work if you have the space to work.

Ralph

ballengerb1 · Oct 6, 2008, 10:31 AM

If you are tiling over the Hardiobacker they do not need to be all that flush. You will be applying modified thinset between the tile and the backer and this will give you quite a bit of wiggle room to get everything to appear perfect. Porter Cable and others make a special circular saw blade for Hardibacker just in case your bad pieces is too far out of bounds for my first suggestion. If you used 1/8" Hardi you can also file with a very courase rasp.

gangelo · Oct 6, 2008, 11:23 AM

Thank you; 1/8th inch hardi? Didn't know they made that?

Would you happen to know what the approx tolerance would be where I would not need to be concerned? I think I am about 1/16th - 1/8th out at most.

ballengerb1 · Oct 6, 2008, 01:38 PM

Usually we use 1/8" on top of sub floors and 1/4" for shower stalls and tubs. You use different length screws for the 2 thicknesses. If you are screwing to the studs you should be using 1/4", both can be filed but 1/4" is way tougher than 1/8". The tolerance is mostly set by your trowel notches, if you are using a 1/4x1/4 notch you have over an 1/8" tolerance.

massplumber2008 · Oct 6, 2008, 04:37 PM

Gangelo...

You can also use the modified thinset and alkaline resistant tape to square up the corner if you need too...

Here, you apply the modified thinset so that you build up the corner as you need too... blend it well by trowling out 6-12" at each side if needed!

This with fact that tile will hide quite abit as presented by Ballenger and I think you will be fine without grinding or anything like that!

Good luck...

MARK

gangelo · Oct 7, 2008, 04:44 AM

Thank you all very much; glad I asked as I have a tendency to try to do things "perfect" and this would have taken me forever.

P.S. The stinkin sheet rockers put metal corner bead on my corners without asking before the tile was laid; I guess I am half the fool for not realizing this should have been done after the tile was laid - oh well. Having to learn all this stuff on the fly is tough!!

massplumber2008 · Oct 7, 2008, 06:06 AM

Gangelo...

Corner bead usually goes down before the tile... then you tile up to corner bead or you install tile with a bullnose finish edge and between both finished edges (bull nose tile and finished edge of corner bead) you paint with a mildew-resistant bath primer/paint.

Good luck!

gangelo · Oct 7, 2008, 07:43 AM

Great! TY! Thanks for the mildew-resistant paint comment, we were just going to get the regular stuff!

ballengerb1 · Oct 7, 2008, 09:33 AM

I am confused, you say sheetrockers and corner bead but we started with Hardibacker. Hardibacker does not use any corner bead. Can you explain?

gangelo · Oct 7, 2008, 12:11 PM

I guess I was just ranting because, like you said, Hardi does not use corner bead; my sheet rockers put it on all my corners (2 in all) - over the green board AND the hardi board even though the areas they put bead on will be covered in tile. My tile guy says it is better to put it on AFTER the tile is laid so you can still put it on, just not under the tile.

ballengerb1 · Oct 7, 2008, 02:14 PM

Trying to picture your lay out, if the corner is between a sheet of Hardi and another wall of greenboard a corner bead is acceptable if its put in first and then mudded in. On the Hardi side of the bead it should not be mudded with joint compound but rather the modified thinset you will use for your tile.

pattyg2 · Oct 8, 2008, 11:13 AM

I used 1/2" Hardibacker in my shower and just taped and used thinset for the corners. I was unaware I could have used 1/4" for the walls. But then again I would have had to shim out the studs which I didn't have to using the 1/2".

ballengerb1 · Oct 8, 2008, 12:12 PM

Patty, you got me thinking but I can't correct my typos from earlier on. Hardibacker comes in 1/4" and 1/2" and you were right to use 1/2" in the wall. The 1/4" is best for flooring when there is already a suitable sub floor.

Choppy · Jan 27, 2011, 07:56 PM

Can I use 1/4" Hardie backer over "Veiga" slot hydronic heating panels on a new floor construction?

massplumber2008 · Jan 31, 2011, 06:24 PM

Hi Choppy

If you have joists at 16" O.C. and a minimum of 5/8" subfloor beneath the panels AND you set the hardibacker in thinset mortar as required by the manufacturer then YES, you can install the 1/4" hardibacker board! Use the correct screws/screw pattern on the board and use alkali-resistant tape for all seams for the best job!

Mark