On a recent tile project I discovered that the 1/2″ Hardibacker actually measures about 13/32″. I had always used the 1/4″ product so this was a surprise. This creates a real problem when laying tile from a tub surround onto the adjacent drywall. I had to use furring strips to get the surface of the Hardibacker in the same plane as the drywall. Does anyone know why?
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Replies
You should ask Hardibacker about it, but I would bet that it's for the same reason that plywood isn't actually 3/4", 1/2", or 1/4". It's all manufactured overseas and the thicknesses are in metric units instead of english units.
Most plywoods are close to thier indicated thickness, certaintly not enough to make a difference when next to other building materials. With the backer its over an 1/8" difference which is enough to cause problems.
Wait. 3/32 diff. is not over an 1/8" but you're right, it can be a challange with some materials. The "not flush" approach is sometimes better, it is much easier to have a reveal than try like hell to have everything dead nuts flush, only to have it move or whatever later. Use it to your advantage.Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
.............not enough to make a difference.........
I beg to differ with that one. - lol
Most of my business is custom cabnets & woodwork. Several years ago when I first used the "new" plywood, all my dados were sloppy and I had to redo a bunch of stuff to cut the dados down by 1/32".
I spent quite a bit of money on new router bits and shaper cutters to work with the "new" plywood, and life was good for quite a while.
A few months ago, I started buying my cabinet grade plywood from a new supplier and discovered that their 3/4" plywood is actually 11/16". - lol
With plywood it's supposedly the thickness lost to sanding. They have to sand hardibacker?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
This has caused a problem for me, too. I intended to place an electric heating mesh in my bathroom floor. I wanted to place the mat over 1/4" Hardi and put the 1/2" Hardi everywhere else. The idea was to put the electric in first, embed it in thinset, smoothing over it with a screed, and then putting in tile on the whole floor at once.
I had to resort to doing the whole thing at once, which is much more of a pain. The difference between the Hardi panel heights was not enough to fully bury the mat.
In the past, I have used old fashioned backerboard, like Durock. The next time I do this, that is what I will use. I may still use the 1/4" Hardi under the mat because it has some advantages over the thinner Durock.
Edited 9/3/2007 3:25 pm ET by Sasquatch
My guess is it's really 10 mm and they round it up to 1/2 inch. Most companies are looking for ways to reduce production costs and one of the easiest is to cheap-out by making quantities smaller or fudging dimensions on the low side of the limits.
I bought some 2" diameter extruded aluminum tubing and it's usually about 0.02" oversize to allow for finishing. Not any more -- the diameter is dead nuts on 2.00". The same thing is happening with dimensional lumber and you can see it if you compare a 2x4 with one purchased a couple of years ago. The new studs are smaller by 1/32" to 1/16".
Edited 9/3/2007 3:28 pm ET by TJK
With all this Pizzing and moaning, soon enough maybe everything will sold by weight ,not volume..How'd y'all like that for math (G)Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
I just measured it with a metric machinists ruler and it is indeed 10mm.
I just assumed it was actually 1/2", it seems this could really cause problems in some installs.
Edited 9/3/2007 4:57 pm ET by 1000eyes
Yup, thats .1063 diff. I could see it needing attn. But like I said earlier, I try to incorporate a non-flush detail if possible, more room for wiggle and shadow lines and such.
In your case, you may well be hosed and have to deal with it as you did. Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
"With all this Pizzing and moaning, soon enough maybe everything will sold by weight ,not volume.."We buy tortilla chips that used to come in 16-oz bags. Well the bag is still the same size, but last year they started putting in only 12.5 ounces, and now it's down to 11 ounces, Same size bag, same price. Inflation? What inflation?
Yeah, but the inflation is the cost per OZ. Has nothing to do with the size of the bag.
Just like a 2x4x8' would contain ( estimated) 3 lbs of dry wood, well so would a 1x4x16'...but yer paying for 3lbs both ways.
I think it could get problematic...LOLSpheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
Many suggestions for this phenomena here already. I understand your situation of transition from tile surround to drywall - agree it is a problem in this application.
Perhaps the 13/32" thickness would allow for the thinset thickness under the backer board when used in a flooring situation? I.E., using nominal 1/2" Hardi with the recommended thinset underneath on a floor will yield an elevation gain of 1/2"?
Although this does not make much sense since the 1/2" product is probably used more on walls than floors, and the exact thickness is more critical on a wall.
Just a thought.
Jim
Never underestimate the value of a sharp pencil or good light.
We've noticed that problem too. Its usually not an issue though.
We plan our hardi to break right about where the trim tile comes in. Then the tile guy floats the difference with a skim of adhesive.
Hasnt been a problem for us.