Adhesive didn't set - so where did I go wrong?

[harderthanitshouldbe]

I'm tiling a small (4' x 5') utility room. Just a water heater and boiler in the room. I put a piece of 1/4" birch on top of the 3/4" floor that is nailed to the floor joists. I wanted the birch for added support, along with not wanting to apply adhesive directly to my subfloor should anything go wrong. Down went the 1/2" wonderdboard, then a layer of ACRYLPRO adhesive, then the 12" x 12" glazed porcelain tile. This was last Tuesday. Most of the tiles around the edge have set pretty firmly, although they can be lifted with the point of a trowl, but the row of two tiles down the middle of the room aren't stuck to anything. The AcrylPro has the consistency of plumbers putty. There are spots that stick to the tile, and spots that stick to the wonderboard, but never the two spots together. Even the AcrlyPro that is stuck to the tile or wonderboard comes right up.

I know I'm going to have to take up all the tile, and probably the wonderboard too. I'm not asking how to fix what I already screwed up, but rather asking how should I do it next time? I guess knowing what went wrong this time would be good too! My only consideration is my water heater. I can handle a couple of days with just cold water, but the less the merrier! With any responses (yea - I'm up for ridicule too ) please keep the water heater in mind with suggestions on how I can get it back on the new floor asap. It's easy enough to remove, if I can have it in while I wait to grout.

Thanks in advance for your help. I learned long ago not to trust the home depot guy (yea - that's what you need - right there...) but I thought I read the instructions on all the ingredients enough to make sure they all went together - guess not...


Michigan
mild humidity (not Florida - not Arizona)
Temps in the 70's to mid 80's

[Shawn Prentice]

Use thinset (not the premixed) next time instead of mastic, which is what Acrylpro is. Versabond will work for you and it's made by the same company, Custom Building Products, and probably in stock at HD. Or Flexbond or Megaflex will be even better, but more expensive.

Thinset over the subfloor, then the wonderboard, then thinset, then the tile.

The 1/4" birch does nothing for adding strength. As long as your joist span, depth, and spacing meet deflection requirements for ceramic, then the 3/4" subfloor will work by itself.

You should be able to clean those tiles of and reuse them. Clean them good.

Follow the manufacturer's directions of every product you use.

[harderthanitshouldbe]

Thanks Shawn!

For Megabond, I found the following link. (add the [http dot slash slash www dot] as I am not allowed to post links!) It says I'd need to mix and additive to this for my porcelain tile. laticrete.com/homeowners/products/thin_set_mortars_adhesives/thin_bed_mortar.aspx

For FlexBond, I found this link.
custombuildingproducts.com/ProductCatalog/SettingMaterials/LatexPortlandCementMortars/FlexBondFortifiedThinSet.aspx

This appears to be the easier of the two, but what are your thoughts? Not to say "moneys no object," but really, I've already ate the money and my time / labor to do this once, so... you know what I mean!

Off subject a bit,
As far as support, I have doubled 2x10's running a 13' 8" span spaced at 12"o.c. in this portion of the house. This seems like over kill, as a single 2x10 spaced 16"o.c. meets code. The birch was result of listening to a home depot guys. He had me lay the wrong adhesive for a linoleum floor. The adhesive did adhere extremely well to the plywood subfloor, but allowed all the nail heads to bleed though the linoleum. I was then stuck with a very poor looking pattern in my floor, and a not so flat subfloor to work with the second time. In my current situation, I figured that the birch would smooth out imperfections in the old oil soaked subfloor (from the old oil burning furnace) and prevent stress on the wonderboard.

Thank you again for your advice!

[bbcamp]

If you don't use thinset under the backerboard, pull it back up. You need thinset under the backerboard to fill any voids between it and the subfloor. Pull the birch plywood up, too. It isn't doing you any good, and may cause a problem if the glue is not waterproof. Then set the backerboard back down using any type of thinset except premixed. Tape and mud the backerboard joints using the same thinset you will use to set the tiles. You don't need a super-duper thinset for this. Versabond will do fine, but at about 1/2 to 2/3s the cost of either of the thinsets you named.

[harderthanitshouldbe]

First - this is a great forum! Thanks for the recommendations and advice!

While looking at the FlexBond site, I came across the SpeedSet mortar. (custombuildingproducts.com/ProductCatalog/SettingMaterials/RapidSettingMortars/SpeedSetFortifiedThinSet.aspx?user=arc&lang=en)
Is this an option open for me? I understand a very short working time may mean I waste some product, but the thought of pulling the water heater on Saturday morning, then removing everything and starting again, with the possibility of setting the tank back in Sunday morning appeals greatly to me, and the family!

just so I'm clear...

I cannot get the oil out of the subfloor. This is heating fuel oil that (sprayed / splashed / or however) got on the subfloor from the original boiler years since past. Seems to me that this will affect the bond between the subfloor and the Wonderboard? Should I put down something, if not the 1/4" Birch (I used Birch as it is supposed to be superior to luan) ?
Bob, Is it the water in the thinset that you are concerned about interacting with the glue in the Birch plywood? I can see your point, but with the oil on the subfloor... any thoughts?

THANK YOU all so much for the feedback!

[bbcamp]

Oil on the subfloor will not have any effect on the thinset under the bakerboard. The thinset is a filler, not a binder. The screws bind the backerboard to the floor.

However, if you still want to put something down over the plywood, use 3/8" Exterior rated plywood with no face grade less than C, or use an Exposure 1 rated OSB. Both will not delaminate due to contact with wet thinset.

[Shawn Prentice]

Sorry, I meant Megaflex, which is Custom's premium modified. Anyway, Versabond will work. Personally, I overkill my jobs and have used Megaflex under and over many cbu installs. But, it costs about 4 times as much as Versabond.

Speed Set. Well, there's a learning curve to that. It sets up quick, so not much time to work with it and it's not something I'd recommend to a novice. But, the tile can handle light traffic in a few hours and can be grouted then as well.

[harderthanitshouldbe]

Shawn, Bob, thank you for all the advice. I now think I've got a good handle on some of the "why," not just the "how." It makes a bit more sense.

Anyways - I'm diving back in Saturday morning, so I'll let you all know after a hot shower how things are going.

Can't thank you guys enough.

[Kman]

If it's worth the extra cost of the speed set, you could do the tiles that will sit under the water heater with it. It would probably still take 3-4 hours before you could safely put the water heater back, but maybe you could do that little section by itself first, set your water heater, then continue on. At most you'd be without water for only part of a day.

[harderthanitshouldbe]

Worked GREAT!
I pulled up everything. I put a layer of FlexBond under the new WonderBoard, cut the new tiles, and set them late Saturday afternoon. I waited 24 hours, then grouted with Polyblend sanded grout. I wiped everything down at eleven Sunday night, and installed the water tank this morning at eight. Floor feels so firm and sound!

Using these methods, I wouldn't feel apprehensive about doing another, and larger room. I can't imagine using the SpeedSet! That stuff must take a real master to use, as the FlexBond set up plenty quick for my pace.

Thanks again for the help from true tile masters!