# Furring out backerboard 1/8"



## 99miles (Aug 5, 2009)

Hello-
I'm tiling around my tub and realized that the existing drywall is 5/8", but the hardie board is 1/2". I just went to Lowes to get 1/8" furring strips but they don't have anything that thin. Do any lumber places sell it that thin? I'll call around tomorrow when they're open, but otherwise do I need to rip them myself? That would be a bummer cause I don't have a table saw. Are there any other options?
Thanks!


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## 99miles (Aug 5, 2009)

Actually, I just read somewhere that I may no need to do anything -- that the thinset will be enough to even it out when the tile overlaps the drywall a little. Can anyone confirm this?

I also read about trying to spread 1/8" of thinset across all the hardibacker before doing the thinset for the tile. that sounds like a messy pain...

And finally I saw a mention of getting paint stirrirs and liquid nailing them to the studs b/c apparently they are 1/8".

It also sounds like 1/2" hardibacker is actually 7/16", not sure if that makes any difference here...

Thanks for any thoughts!


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## NailedIt (Jun 19, 2009)

You can use poster-board strips or strips of any material that is of the proper thickness(or build up to it), practically. There's no unwritten law requiring you to use wood. I'm a carpenter, so I would rip my own shims with a rip-guide on my circular saw, or using my fingers on the left side of the saw-base as a rip-guide. Paper works well, or roofing felt, shingles, etc... If you have extra studs you could "sister" them allowing the extra depth required to hang out past the existing plane of the wall, etc...

Be careful not to get splinters in your fingers if you're going to use them as a rip-guide. Wearing gloves is a good idea, but care should always be taken. Maybe clamping the piece and ripping a line would be better if you aren't an advanced saw user.


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## Termite (Apr 13, 2008)

At any home center you can buy 1-1/2" x 48" strips of very dense cardboard that is about 1/16" thick. They're intended for use as drywall shims but would work perfectly for your purpose. They're found in the same aisle as the sheetrock, and are normally sold in bundles of about 100 or so...Pretty cheap too. I just bought a bundle at Home Depot a few weeks ago. Use two thicknesses of them and you're good. 

Whatever you use, just make sure it won't compress. 

As for recessing the backerboard...No, I wouldn't. You want it reasonably flush with the face of the surrounding sheetrock.


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## Paragon (Jun 14, 2009)

99 miles,

I am just going to ask a question here as I am wondering why the drywall on the walls is 5/8". I am not saying it is not possible I just want you to make sure it really is. Sometimes when drywall has a cut edge on it the frayed paper can make it look like it is 5/8" when it really is 1/2" drywall. Also sometimes we pull a tape that has a loose or worn end on it and it reads 5/8". 1/2" rock on the walls is the standard but there are some situations that 5/8 is used so please re verify the thickness of your rock by either using a different spot of the blade of the tape (inother words put the 1" mark on the inside edge of the rock and measure making sure the edge of the rock has a fresh cut and is not smooshed) or by placing a piece of 1/2" rock (if you have is around) against the existing drywall. 

If in fact it is 5/8" rock then you can use paint sticks, rip new furring strips ON A TABLE SAW I do not recommend anyone using a skill saw to perform this technique regardless of whether they clamp the boards or not that is a very dangerous manuever and please DO NOT attempt this at home!!! I would not recommend trying toskim the durock with thinset priior to applying the thinset you are going to use for setting the tile. 

Without seeing the job this is the best advise I can give and the rest is up to those who are in the field and on site.

Good luck and be safe!


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## Gary in WA (Mar 11, 2009)

I would not use the stud furring for drywall *paper *cardboard shims behind Hardie as it will feed mold when wet. Maybe behind the plastic vapor barrier required on the studs, I would rather see wood lath strips - 1-1/2" x 1/4" x 4' (builder's lath) sold at the box stores and lumber yards. Usually these go on the wall before the v.b. to shim the wall studs flush with the tub lip, anyway.Otherwise try to notch the Hardie for the tub lip. 
Be safe, G


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## 99miles (Aug 5, 2009)

Paragon, it wasn't even that I measured the thickness of the drywall as much as that when I went to put the first piece of hardiboard in, and butted up against the drywall, it became apparent that the thicknesses were different.

GBAR, sounds like the lath strips are too big, at 1/4" -- that'll make the opposite problem of having the backerboard higher than the drywall.

Also, just to note, I'm going to use Redgard, and not a vapor barrier behind the hardibacker. 

Sounds like all agree that the paint sticks would work??? Or I could buy a table saw -- which sounds kinda fun, but not sure I'm ready.


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## Paragon (Jun 14, 2009)

99 Miles,

If you pulled a permit and I know you did if you are building a new bathroom right? lol 

Your inspector may or may not approve of the redguard in place of VB. In some localities vapor barrier is required behind all wet space wall coverings. If you pulled a permit make sure that the absence of the VB is acceptable if you have a drywall inspection or framing inspection as part of your permit process. I always go with a 6 mil vapor barrier behind my shower walls *especially* if on an exterior wall (not sure if yours is on an exterior wall or not) to satisfy code as well as for peace of mind and assurance but that is just me. 

I would encourange you (or a friend) to check with the local building inspector as to code requirements in your municipality regarding the vapor barrier and proper installation of your James Hardie products backer board.

I also do agree that paint sticks or shims would be the ticket if you need to fur out the wall 1/8" however I would put that on the dry side of the vapor barrier to eliminate any addditional areas of water/ moisture absorption.

Good luck, be safe


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## 99miles (Aug 5, 2009)

Thanks, that's a good tip. It's not a new bathroom, it's an existing one. I looked at the website and it doesn't sound like I need a permit.
I'll look into it further though.


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## NailedIt (Jun 19, 2009)

Ripping with a circular saw is no less safe than ripping on a table saw, especially if you're only ripping 3/16". I was going to post the government stat chart showing 10's of 1000's more table saw ER visits than circular saw ER visits, BUT 2 people died, which works against me:whistling2: You'd likely have more chance injuring yourself carrying the pieces of tile-backer than ripping a shim. 

BUT... it does require some skill to rip anything with any power tool. I rip all my own shims, the old fashioned way: tack the piece to the sawhorse, scribe with a tape and pencil, rip guiding with the base of the saw gripped by thumb and finger (when the factory rip guide isn't an option), as millions of carpenters (are there that many left?) would be familiar. If you aren't an advanced user, then ignore this option, please.


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## Gary in WA (Mar 11, 2009)

Wow, you have to feel good getting this many responses in such a short period of time. Just use some roofing scraps, cut with a knife and they will seal the Hardie fastener hole. Buy a bundle of plain, not Architectural, and double them up. Or measure before you buy. 
Be safe, G


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## Termite (Apr 13, 2008)

You're right-on in your use of RedGuard in lieu of a plastic vapor barrier, regardless of what the inspector might say. For your information, there is no code section in the I-codes that requries the plastic barrier. Refer to TCNA (tile council north america) installation guides for a good reference. The use of a plastic vapor barrier behind backerboard is a substandard practice in my opinion since the introduction of products such as RedGuard and Kerdi that keep moisture from ever entering the backerboard. The backerboard can take the moisture but it is highly advantageous to never get it wet in the first place.


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## Paragon (Jun 14, 2009)

thekctermite said:


> You're right-on in your use of RedGuard in lieu of a plastic vapor barrier, regardless of what the inspector might say. For your information, there is no code section in the I-codes that requries the plastic barrier. Refer to TCNA (tile council north america) installation guides for a good reference. The use of a plastic vapor barrier behind backerboard is a substandard practice in my opinion since the introduction of products such as RedGuard and Kerdi that keep moisture from ever entering the backerboard. The backerboard can take the moisture but it is highly advantageous to never get it wet in the first place.


Now, I am not one much to argue with a building codes guy or a moderator on this site (as it can have serious implications so please excuse me if I seem out of line...) but why would a building code individual or we here at the forum ever advocate going against what a building inspector in a specific municipality would determine to be the rules in the area in which he governs? Why would we ever say, *"...regardless of what the inspector might say."*?

I too agree with you termite the use of RedGuard is the way to go but if the inspector (if he did have a permit and it needed an inspection that would discover the use of redguard such as a drywall inspection) did not approve of the use of Red Guard versus the vapor barrier (maybe an exterior wall?) and flagged the project, wouldn't we be doing 99miles a great dis service? 

The inspectors in this country are our governing building officials and it is they whom we must please as they sign our cards to approve or dis approve projects. We must work in harmony with these individuals because if we do there is room for variance and leeway. If we choose to go against these individuals they will pull out their rule book and apply the rules as they interpret, sometimes to just make the individuals life miserable that they are doing an inspection for that has been fighting them on rule interpretation.

SO, in conclusion if you had a question where you think it may or may not be allowed isn't it wise to consult with your inspector and discuss the issue with them? I beleive and have found that if you can reason why you have done something and they are in agreeance with you as long as it does not violate any serious building codes they many times will allow you to proceed with it. 

So if you are using redguard in an area where a vapor barrier is required (because municipalities can be more restrictive than the I/U/R codes just never less) and there may be a question whether or not this is allowable it may be worth your time and effort to call your local building authority and see what their thoughts are on the bathroom that you are tinking about redoing. These building officials are not monsters looking to derail our projects (okay MAYBE some, lol) they are officials looking to keep our projects safe. So please use those officials to inform and educate yourself. 

Again Termite, I apologize if I offended you and I totally agree with your summations of the Red Guard and Kerdi membrane products. They are superior and the idea of preventing moisture infiltration into the materials is the best school of thought by far however 99miles needs to follow the instructions of their local building authorities and not the instructions of us here at the forum no matter what our expertise or knowledge level happens to be. 

Have a great day, be safe


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## LeviDIY (Apr 16, 2009)

You have the gist from the replies already, but here was a forum, I had the same problem... my tile ended up with no special layer of thinset (just regular notched trowel depth for my size tile) essentially meeting the 5/8" board. I used a bead of caulk to smooth the transition as well.

http://www.diychatroom.com/f19/5-8-fireboard-paint-meets-1-2-cement-board-tile-42557/


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## Termite (Apr 13, 2008)

Paragon said:


> Now, I am not one much to argue with a building codes guy or a moderator on this site (as it can have serious implications so please excuse me if I seem out of line...) but why would a building code individual or we here at the forum ever advocate going against what a building inspector in a specific municipality would determine to be the rules in the area in which he governs? Why would we ever say, *"...regardless of what the inspector might say."*?
> 
> I too agree with you termite the use of RedGuard is the way to go but if the inspector (if he did have a permit and it needed an inspection that would discover the use of redguard such as a drywall inspection) did not approve of the use of Red Guard versus the vapor barrier (maybe an exterior wall?) and flagged the project, wouldn't we be doing 99miles a great dis service?
> 
> ...


No apologies necessary. The fact that I'm a mod doesn't mean that you can't disagree with something I say or the way I say it.

I was just trying to convey that the plastic vapor barrier requirement (if there is one) is not code-based and could certainly be called into question in a professional conversation with the inspector. Sometimes there are inspectors that make you do it their way instead of the best way, and they should always be questioned and asked to cite code or ordinance that backs their requirements. There are two ways to approach doing this:

1) Have a tantrum and complain and argue. This doesn't work and usually causes this type of "do it my way" inspector to make your life harder.
2) Present documentation demonstrating that the proposed/installed system is as good or better than their requirement, as is the case in this particular situation. Cite the code or the lack therof that would substantiate your/their claim. Be professional and don't whine, complain or try to make them look stupid. 

As an inspector I truly belive that there is nothing worse than a tradesman, homeowner or building inspector that thinks that their way is the best/only way and adopts a narrow-minded stance. Those type of inspectors give the rest of us a bad name. Bad jurisdictional rules should be questioned and challenged if they have no basis in the code or in reality, and trust me...There are bad rules out there!

I expect and command professionalism with dealing with contractors or DIYers. Give me that and we get along great. _The last thing I ever want as an inspector is someone that simply complies with what I say out of fear that I'll get mad or pick on them_...I'd prefer that they know why I'm requiring what I'm requiring and that I can show it to them in the code. Nothing impresses me more than someone pulling out a code book or manufacturers' literature to question a call I've made with a legitimate and professional approach. If I'm wrong I back off. If I'm right I prove it.


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