newbe....wonderboard help!

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  #1  
Old 11-30-04, 02:36 PM
sharvel
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newbe....wonderboard help!

hello folks......need some advice with tiling a bathroom floor. The exsisting floor is 3/4 plywood with a few layers of vinyl. Burning question here...can I apply 1/4 " wonderboard over the top of the vinyl to provide a good backing for the tile??? How do I cut this stuff....is it similar to drywall? I have some curves around the tub and I'll also have to cut a hole for the tiolet. Last thing I want is to waste this stuff by improper cutting methods. Also if I can get away with using this I'll have a few seams. Will I need to fill those???.If so with what product? Far as applying it....what type of screws are recommended? I read somewhere about also applying thinset underneath the wonderboard.......don't think it will adhere to well over vinyl is my only concern. I'm hoping I can get away with just tacking this down with screws and avoid pulling up the old flooring!!!

Thanx much!
 
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  #2  
Old 11-30-04, 03:26 PM
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Well, start ripping up that vinyl. Bad enough to go over one layer let alone two. and you know what else, remember the monster under the bed? well that wasn't real, but it lives under vinyl!!!! It's in the form of luan or particle baord, or whatever 1/4" underlayment you have under the vinyl providing the smooth surface for the floor. Once all that stuff is gone, and yes, it MUST go, if you truely have 3/4" exterior grade plywood as your subfloor, you can go overit with the backer board set in unmodified thinset and screwed down. That will be at the minimum for your floor to have a chance at survival. Bset wuld be to add 3/8" plywood over your subfloor, just screwed down ever 6-8" over the face of each panel with 1 1/4" screws and not into the joists, then your backer set into thinset. The thinset is only there to fill in any voids between the plywood and the cement board, it is not there to bond it. Gap each piece of backer 1/8" and fill and tape the seams with modified thinset and alkali resistant mesh tape as you tile. You can cut wonderboard by scoring it on both sides and snapping and you can cut a circle with a rotozip or angle grinder or fut a circle the slightly larger than the outer diameter of the flange, score both sides of the backer, line it up over your plywood template and hit it with a hammer. A carbide blade in a jig saw works well. It's cheap too, so rather than piece together a bunch of small pieces, use full sheets. At $8.50/sheet, it's not worth it to skimp..redoing it again because you tried to salvage a bunch of scraps will be much more costly. You can fasten it down with either cement board screws or galvanized roofing nails.
 
  #3  
Old 12-01-04, 07:19 AM
sharvel
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appreciate the tips tilebri. unfortuately this puts a big damper on tiling the floor ! looks like yet another sheet of luan and layer of vinyl. there's a mess under there I'm sure. most likely the 1st vinyl floor is asbestos.....think it's best to not disturb it! curious here and I'm sure folks have done it.....why not put wonderboard over the vinyl providing I use longer screws to sink into the exsisting plyboard? this is a very small room..8'x 3' and the floor is solid to say the least. I know folks who put tile over both luan and plyboard with good results. my firend tiled his bathroom 8 yrs ago and that was right over luan....he recommended luan and I thought geeeeeeez better yet wonderboard.now i'm being told none of the above! UGHHHHHHHH what are the odds and ends on what could happen installing the wonderboard the way I mentioned?? If I got 5 yrs out of the tile floor I'd be happy.not looking for the forever floor....besides with my wife and remodeling I'll probably end up tearing up in a few yrs anyways!
 
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Old 12-01-04, 09:43 AM
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Well, if you're planning on tearing it up in 5 yrs why do it now? Just curious. Tile is a good way to provide good looks and durability for several decades. It's also expensive and time consuming, so doing it once and doing it right is the practice of professionals, and should be for the average DIY'er as well.

The reason why tiling over vinyl is a bad idea is the inability to provide a rigid substrate for your tile to set on. Over time the squishyness vinyl has by nature will not supply the rigidity you need, and your grout will possibly crack, and maybe your tile as well. Wonderboard is not a structural material. Its purpose is to substitute for the old-school and mudded substrate of a mortar bed to set tile on. That's why it's critical for the subfloor to be prepared correctly.

There are cases where people who didn't know better set wonderboard over a single layer of vinyl and got away with it for the short run (because the vinyl didn't originally have the foam backing to it, or it's so old it's rigid like plastic...), but generally it's a victim of sure failure. That doesn't even approach the problems you'd have going over more than one layer of vinyl. Think of it this way - it's a risk you'd have to be willing to take spending time and money putting down a floor you think looks good, and in a couple of months start discovering cracks in your grout and tile. If you're willing to accept that then by all means tile away, but I doubt you will.

The reason professionals who set tile for a living say you MUST have an adequate subfloor and to follow the manufacturers instructions for setting the CBU (concrete board underlayment) like wonderboard is they follow the practice of guaranteeing their work. They want their jobs to last, and the most proven method is:

1. Building an adequate subfloor (NO particle board, OSB is tolerable but the preferred is a good layer of 3/4" exterior grade plywood).
2. Providing the required water proofing or vapor barrier (especially if it's a wet area).
3. Selecting the appropriate material(s) for the substrate (CBU, medium bed mortar, etc.)
4. Using the right adhesive for the tile being set (99.9% of the time it's a type of modified thinset).
5. Selecting the right grout for the application (sanded or non-sanded).
6. Selecting the right sealer.

Cutting corners on building the subfloor will generall effect the quality of everything else on that list. I'd find out exactly how many layers of flooring you have over your subfloor, and assess the condition of your subfloor, and how it's built before you invest in tiling.
 
  #5  
Old 12-01-04, 05:53 PM
sharvel
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Thanks so much for the info! I guess nothing comes easy remodeling an old house! It's been a battle from day one to say the least. My plan was tile and I'd hate to toss another layer of vinyl on. That being said looks like I'm tearing up the floor. I'm 99% sure theres just 2 layers of vinyl. 1st layer was just laid over the ply..no luan . For a quick fix I laid self adhesive vinyl squares over that to get me by for a few yrs. I'd like to do what tilebri recommended laying a 3/8" sheet of ply over the exsisting ply....then wonderboard. Problem is this.I have 3/4" height to work to match my carpeted floor meeting at the threshold. I do not want a lip there.I already have that problem in the kitchen when somebody laid 3/4 osb over the exsisting 3/4 tongue and groove flloor. So I basically have a 3/4 lip entering my kitchen from the living room.a true toe stubber! Any advice with my height issue??? also you mentioned a vapor barrier.what will I need for that??? felt??? something tells me for height purpose I'll only be able to do wonderboard over the old ply.
 
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Old 12-02-04, 09:00 AM
sharvel
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definitly need some help! I tore the old vinyl up....as I suspected 2 layers and the 1st layer just laid over the 3/4 ply subfloor. The residue is dk brown next to black which makes me think asbestos possibly. It is an extremely thin layer next to nothing however I don't want to scrape or tamper with it to be on the safe side. Can I apply thinset over this and tack wonderbaord over that??? also my floor height is obviously going to increase which concerns the toilet flange . will I be ok doubling up with wax rings for sealing that or I believe there's a new rubber flange which glues to the bottom of the toilet for sealing.any sugestions??? also a big question here and nows the time....should I do a vapor barrier??? if so ....what to use and between what underlayment???

thanx!!
 
  #7  
Old 12-02-04, 09:34 AM
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If you have t-g flooring in the kitchen, you have it throughout. Once you pull the toilet, you should be able to see the plywood underlayment over the t-g. Let thet be your guide as to wht to do next. If you have plywood less that 1/2" over your t-g subfloor then you must replace it with 1/2" bc or better plywood. I usually just do this as a matter of course since that way, I know the quality of the plywood underlayment and can inspect the subfloor for any damage that needs to be repaired. After you determine what needs to be done, replace or reuse the plywood underlayment, you can go over the black ahdesive if the plywood is at least 1/2" thick with your cement board set into thinset. I believe Custom Building Products requires modified thinset under the backer board, so use Versabond. They do offer a lifetime warranty on the floor IF you use there products exclusively througout the whole process and if the subfloor is properly constructed. Since you already have an undrelayment, pulling it up and replacing it as needed would only add 1/4" of height maximum if you have 1/4" plywood over the t-g. If you have 3/4 ply down there, which may be the case if they were trying to match the height of solid hardwood floors meeting the bath floor, replacing it with 1/2" and then the wonderboard would bring you to the original floor height and your only build up after that would be the height of the tile.
For the toilet, you can get extra thick wax rings if the height is not much different or you can get flandge extenders that screw down to the floor and build up the flange. I trust them much more than multiple wax rings.
Marble saddles can hide a wide reange of height variances when used in the door way. The beveled edge that rises above the tile will also help keep any water on the floor from running onto the floor outside the bath.
As for the kitchen floor, if it's 3/4" step up then you can use a reducer for 3/4" hard wood in the doorway to really soften the step up.
Let your wife help in the tear out and installing the new ply, mixing morter and screwing down backer panels. It might help her to understand the scope of what would be involved in ripping out a tile job. If you are fairly cartain she will want it up in a few years, use galvanized roofing nails to set your cement board over thinset into your subfloor. Makes prying up much easier.
 

Last edited by Tilebri; 12-02-04 at 09:37 AM. Reason: Needed ot add another suggestion
  #8  
Old 12-02-04, 09:46 AM
sharvel
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thanx again tilebri! I do have 3/4" plywood........as you stated they must of done it to match the old hardwood floor....which is now carpeted. The carpet is actually almost an inch uncompressed meeting the plywood now. This makes me think I can get away with a 3/8 " sheet,wonderboard then tile.I'd really like to pull the whole darn 3/4 floor only the toilet flange prevents me from doing so. Can I just jigsaw around the flange and put new 3/4 board down? I'm skeptical with that since the screws in the flange ring will hit nothing and be shall we floating in the breeze. I'm torn really with what method to do. adding the 3/8" and wonderboard may be too much height is a key concern. another big key question here is do I need to put a vapor barrier down?.again if so with what material and between what underlayment???
 
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Old 12-02-04, 10:03 AM
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Let's clarify the verbage. The subfloor is what runs under the studs in the walls. Anything additional layer of wood or cemtn board over that is an underlayment. If you have a 3/4" plywood underlayment over plank subfloor, you are fine to go over that with the backer board. If you want to maintain height to what it is now, you can replace the 3/4" ply wood with 1/2" bc or better exterior grade plywood and set your cement board over that. Yes, you can cut around the plywood under the flange, Just don't cut through you subfloor. If you have only 3/4" plywood and it's not over t-g, then thats when you add 3/8" ply to as an underlayment to strenghtn the floor before adding your cement board. There is no need for a vapor barrier over the subfloor unless you are then stapling down diamond lath and doing a 1 1/4" thick mud floor, which in that case it's only there to help protect the mix from having the moisture drawn out of it into the wood preventing proper curing. If you want to waterproof your floor, you do this after you set the cement board and fill and tape the joints, by painting it with Redguard waterproofing membrane, also a Custom product and keeping in line with their warranty requirements, but it's really not needed.
 
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Old 12-02-04, 10:16 AM
sharvel
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Thanx so much for the support!!!! there is just the 3/4 plywood for the subfloor. It actually butts up to the t&g at the tub edge. Obviously this also seen looking at the floor joist from the cellar. I'm going with the 3/8" ply for a few reasons........1 to cover that nasty adhesive which may contain asbestos.....and 2 to streghten the floor. the sub floor was fiddled with at some point where they actually replaced a 3'x2' secton around the toilet. probably due to a leak and rot I'm sure. so with the additional seams there I think it would be best to put the 3/8" down. my floor may be a tad bit higher than the carpet this way but I'll now I'll have a good floor that will last! again thanx much for the support
 
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Old 12-02-04, 10:18 AM
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Let us know how it turns out. Good luck.
 
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