I live in Chicago, across the street from lake Michigan. I'm in a high rise condo and have a concrete sub-floor. I am getting Mirage engineered wood and am trying to decide between 5", 3 5/16, or 2 9/16. I do not like to use my air conditioning in the summer. My floor guy say's not to do the wider planks due to cupping. I know all about using a moisture meter before the install. What if I have a relative humidity reader in my condo, and use a humidifier and a dehumidifier both. Will I have a cupping problem??? I love the 5" planks. What do you think??
Donna

A 5" engineered is way more stable than a 3/4" x 5" solid. You would still need to maintain the Rh between 35% to 55% year round. Make certain that you have lightweight concrete and not a "Gypcrete" substrate. Use a 100% moisture-cured urethane adhesive if you are gluing it down, but check the instructions for the specifics on that.

Jerry
I'm not sure about the concrete, but the glue is T55 Sika.
Donna

I don't see any problems with this scenerio using an engineered hardwood.

Thanks Guy's,
I'll find out about the concrete and let you know.
Donna

With that SikaBond junk, you better use a ½x½ square notch. That stuff does not hold its ridges, and drops flat on the floor, less then an 1/8 film of adhesive, if you use a 3/16 V notch, and you will be weighting and fighting hollow spots, even with the substrate prepped to flattness specs.


I also advise to use a respirator, when and after spreading. It will burn your eyes!!!

It is always best to check for sure. If the poured floor is a Portland Cement (concrete) base thats good. If it a gypsum base (gypcrete), you will have seal it with an Ardex product made for that. I don't recall the specific name of it, seems like Ardex GS4 or something. Perry knows

Perry:

Any adhesive will not hold it's ridges if you install into immediately and roll it or walk on it. I don't understand your reasoning as you've mentioned this before. You're bringing up a non issue from my experience.

I can show you a picture of BST that was spread and it is holding it's ridges. I can show you pictures of Parabond 4002, holding it's ridges. I can show you Taylor 2071, holding it's ridges. I can tell you right now, before you can get all the way across a 11x3 foot spread, SikaBond T55 will be flat as a pancake where you started spreading.

The ability to hold ridges, lessens the chance of hollow spots. That is why the adhesives that say it does not need to be rolled, hold their ridges better and make more contact with the board, when you place it.

If the spec is 1/8 in 6 feet, and the adhesive falls flat to an 1/8th or less, then can you see where 1/8 in 6 wouldn't be enough, no matter how you rolled it. As that adhesive flows so good, it flows right back off the board, leaving a hollow spot. That stuff won't grow legs when placed, unlike BST and Parabonds 4002.

That is why after sceeding the big low spots, I skim coat the entire floor with a 2 foot flat trowel. Because I've run into BEST and it's falling ridges before.

Oh, I get it now. You're referring to what the adhesive looks like before you install into it. I got it mixed up when you used the same reference in that nasty removal recently. Yes, that does sound odd. I wonder why? What does the manufacturer say?

Hey,
You guy's are making me nervous. My floors are going in on Monday morning. The distributor said that this glue is harder to work with than others and has to be wiped up immediately. They said for a high rise on the 18th floor, this glue is the best because it moves with the floor. Just tell me, should I use it or not? If not, which one is best. My installer is very good, only sells and installs floors.
Donna

There are better adhesives then SikaBond, but hey, if they want to get high smelling the glue, while their eyes burn & water, then have to worry about hollow spots, I say more power to them.

"I don't like to use my air conditioner in the summer".
yes, you will have problems.. gaurenteed

Mirage 5in is on a 9ply Baltic Birch chassis. It is about as stable a product as you are ever going to find this side of plastic. Sika has a system for use in multi-family installs that uses beads of adhesive. My guess is thats what is being used. Nothing else makes sense since Bostik is the only adhesive BoaFranc recommends.