I had that same floor in my home, about 900 s.f. of it. I had the right moisture reading and put down a moisture barrier and it still cupped. It wasn't real bad, but I noticed it and it drove me nuts for 10 years. My wife didn't notice it, or should I say if she did, she didn't care. It's a great looking floor, but I went with engineered my second go around.

Tweed11 said:

I'm a excavator by trade but been working for my dad a gc for many years and I am some what familiar with hardwood flooring. I'm installing 3/4 by 5" prefinished oak hardwood floor in my new house. It's a traditional two story with full basement. I live in the Midwest. I plan on subfloor adhesive and staple every board. When I mean subfloor adhesive i mean putting a thin bead in the middle of every board then staple. Was told by flooring guys it helps with cupping. Is my process right Any info would be greatly appreciated.

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How long do I let it acclimate before installing or how do I know it is acclimated thanks.

The rule of thumb is 72 hours but this is ultimately meaningless. Local conditions determine when the floor is ready. Moisture reading differential should be 2% or less. calcium chloride test or the plastic vapor test for basment slab.

You can trowel moisture barrier/adehesive like ms + but it gets expensive if applied according to manufactirers specs. Like a buck a foot in glue.

Ive never had a floor that was visibly dry and above grade fail to come in around 6-8 % and i live in the pac nw. Lumber from my distributer is usually about six.

I just read the instructions and went by that. I'm sure you can find that info online. :thumbsup:

Tweed11 said:

How long do I let it acclimate before installing or how do I know it is acclimated thanks.

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Stick a moisture meter in the back side of the flooring. Don't have one, then let it sit for a week. I've never heard of a line of glue down the middle. I've put glue lines across the width though every 1' or so.

If it's an existing house, and not new construction, that is in your favor. If it were my house I would glue 5" too. I don't think letting prefinished flooring acclimate does a hell of a lot but I do it because that is whats specified. How much acclimation is really happening unless every box is opened and all the wood spread out?

Adhesive does nothing to prevent cupping. How could it? Grab some dried adhesive and see if it will stretch. Folla?

A bed of adhesive can act as a vapor barrier if it's 100% coverage, but the the easiest thing is to just staple the piss out of it. Do a 3 inch schedule and it will stay flat. Nothing beats a mechanical bond. Steel is stronger than wood. Adhesive isn't.

Acclimation is a myth. You can acclimate for temperature, but you can't acclimate for MC. Want to acclimate it? Rack the whole job. Then come back the next day. Maybe it's at 8% now. Maybe it's at 12. Either way, you've done nothing. If it's at 12, you'll break your arms trying to get it together. If it's at 8, it was going to be at 8 anyway. The whole thing is a fool's errand.


Acclimate the friggen' house.

Tweed11 said:

How long do I let it acclimate before installing or how do I know it is acclimated thanks.

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I'm open to being educated. How can adding an adhesive not help a 5" wide piece of oak stay flat (or flatter)? What's the science behind your statement?

I already told you the "science", but I don't mind repeating it.

IF you full spread with a urethane adhesive, you'll create a true moisture barrier. Messy, but it works. Thing is, if you're just squirting it in spots, it's worthless. Why? Elongation. Adhesive manufacturers actually tout their products' elongation properties as a point of pride. Bostik's Best is around 300%. Pretty good for controlling lateral movement, but awful for cupping (if you're squirting it in spots). Why? Because the stuff will stretch like a rubber band allowing the wood to do whatever it wants to do.

I'll gladly explain this further if you need me to.

I follow what you're saying. Thank you for responding.

No sweat. I live to serve.

There was a time when acclimation meant something. Now it's become this retarded gospel of doing whatever the machine says to do for the sake of avoiding potential litigation. Lawyers. ugghh.

Whatever you do, please dont "staple the piss" out of your floor. Follow the nailing pattern that the manufacturer recommends and if you need to use adhesive as well (sometimes this is recommended for wide width solid flooring) use a trowel and not a caulk gun. Also to properly acclimate your floor you may need to unpackage it and lay it out. Moisure goes from wet to dry so it will migrate to the dryer wood and equalize. The important thing is that the difference between the two is generally not more than 2 or 3% (check with manufacturer again). Check it with a pin meter into the face of the flooring, not the back, and keep it in the same grain line. A reading taken across grain can throw off the accuracy.

Im not sure I agree with that coffer. I talk to old timers fairly frequently that say theyve never acclimated a thing nor tested for moisture. Luck will only take someone so far. There is a science to things.

ccoffer said:

No sweat. I live to serve.

There was a time when acclimation meant something. Now it's become this retarded gospel of doing whatever the machine says to do for the sake of avoiding potential litigation. Lawyers. ugghh.

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Acclimation is not a myth. If your flooring is not at the right MC when you install it, it will move, cup, warp, etc. There is proven science behind it. Look up acclimation, relative humidity in wood, and wood movement through changes in moisture content.

Old timers might not have acclimated becauses not all houses had AC or were as airtight and dry, so it wasn't as much of an issue. Flooring wasnt as wide, also reduceing the effects. I have seen plenty of crappy flooring installations from back in the day.

There is such a thing as acclimation , but NOBODY does it. Unless you're taking it all out of the boxes and stickering it, you aren't acclimating anything but the cardboard boxes. Another thing is seasonal fluctuations. Acclimation does absolutely nothing to counter this. More nails will. I've always found it hilarious that NOFMA recommended the same nailing schedule for 1-1/2 inch strip as for 9 inch plank. It's patently stupid. (Manufacturers all defer to NOFMA /NWFA by the way) I personally don't care what anyone else does, but the wider the solid product, the more staples I'm putting down. Relying on anything else is just wishful thinking.

An example I often use for the purpose of these discussions is Mirage. I've ben to their facility in Quebec and it's impressive as hell. they're people are what really impressed me the most. Everybody there is just a font of knowledge. Now they specifically tell people to NOT acclimate other than for temp. Why? Because you'll ruin the wood if you do it in a place unsuited for wood. That's really what it gets down to...the environment, not the product. Unless you're in some freakish place like Arizona or New Mexico, you aren't going to be drying the wood out any more by acclimating it. If you're in a place that's reading 12 -14 %, guess what, it's not a suitable environment for wide solid wood. Sorry, them's the breaks. So what to do? Get the wood wet? No. Dry the dang house out. The bottom line on acclimation can be seen in the dual reccommendations most everyone copies and pastes from NWFA. On the one hand, they say to "acclimate" by dropping the material off a couple days before you install. (aka, Jump through a stupid hoop) and then immediately after that they go on to describe the environmental requirements. They are between such and such degrees and such and such RH (45-55%, i seem to recall) well guess what. If you refer to the US Forestry Service matrix showing MC at various temp/RH combos, what they prescribe just happens to land right around 8%. 8% is what the wood (all wood) is when it shows up in the box. So, in short, they require you to have an 8% environment and also to acclimate the 8% wood to the aforementioned 8% environment. It's a joke.

Agree 100% with Chu. Working in South Florida in the homes of elderly who insist on keeping it 85 degrees and 70% humidity will learn you a lesson or three in wood science, salespeople ignorance, and futility. Engineered products give you a higher margin for stupid but it's still wood.

When the wood wants to expand that beat of adhesive is not gonna stand aganist the force of expansion. In order to prevent moisture transfer from subfloor it really needs moisture barrier like Aquabar.If you use adhesive you can not use barrier unless using liquid barrier like Bostik MVP. In some cases the subfloor acts like carrier of moisture to wood. Like ply getting moisture from basement and serves to the wood.
Since the top surface is coated the moisture going to wood is very limited. Only time wood gets moisture when it shrinks and moisture goes between openings.
If you still want to glue for each board use MVP and staple.

ArtisanRemod said:

I'm open to being educated. How can adding an adhesive not help a 5" wide piece of oak stay flat (or flatter)? What's the science behind your statement?

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