3/4" T&G on concrete

[bobbyt8888]

We've laid the 3/4" hickory Mullican floor on the entire 1st floor (basement below) using staples and glue assist. Now there is a short, narrow hallway that is a step down from the floor. It is 36" wide by 8' long and is on a concrete slab.

How much trouble would I be in if I simple glued it down to the concrete? I know the instructions say not to do this but I thought I could cheat on such a small area. What is the worst that could happen?

Thanks,
Bob

 

[Mark Brown]

If you use a moisture inhibiting adhesive, there is little possibility the worst will happen..... but worst that could happen is complete failure due to imbalance in moisture conditions. The wood likely would swell, buckle and then disengage from the adhesive/concrete through shearing.

BUUUUUUUUT.... in such a small area and the likely hood being very low, I would roll those dice.
Worst case scenario, you are out 24 sqft of wood and a day of labor.

 

[bobbyt8888]

Would the Loctite urethane adhesive that I used for the assist be considered "moisture inhibiting"?

 

[Mark Brown]

No, that is not what you would want to use in a situation like that.

You want a specialty hardwood adhesive. Something like Mapei 985 or Bostik's Best or Bona R851

 

[highup]

No, that is not what you would want to use in a situation like that.

You want a specialty hardwood adhesive. Something like Mapei 985 or Bostik's Best or Bona R851

And for sure, you'd want to use the correct trowel.

 

[Tile Tom]

Like high up said, the correct trowel is the ticket.
It's designed to spread a thin layer of adhesive between the notches that act as your moisture barrier.

 

[bobbyt8888]

Like high up said, the correct trowel is the ticket.
It's designed to spread a thin layer of adhesive between the notches that act as your moisture barrier.

Agreed, I need the correct trowel. Now I just have to find a smaller quantity of the adhesive.

 

[Tile Tom]

Agreed, I need the correct trowel. Now I just have to find a smaller quantity of the adhesive.

I would hit up your local flooring shops. I'm sure one of them would have a partial bucket they would sell you cheap if not just give you.

 

[Dan]

100% transfer of the adhesive from the concrete to the back of the board will be required. Ensure all boards are flat. Absolutely no hump end to end. This is actually one of the big reasons 3/4" solid is not recommended for glue down installations.

 

[highup]

100% transfer of the adhesive from the concrete to the back of the board will be required. Ensure all boards are flat. Absolutely no hump end to end. This is actually one of the big reasons 3/4" solid is not recommended for glue down installations.

Though this isn't something that I do I'd go for engineered for a long before I go for solid. They make engineered with a really thick wear layer if that's a big deal.

 

[Dan]

Though this isn't something that I do I'd go for engineered for a long before I go for solid. They make engineered with a really thick wear layer if that's a big deal.

They've already installed the entire first floor. This is likely an afterthought with left-over material, not considering attic stock.

 

[bobbyt8888]

Thanks everyone. I bought a tub of R851. If I use some now and then again a month or two from now, will the foil keep it usable until then?

 

[Mark Brown]

Thanks everyone. I bought a tub of R851. If I use some now and then again a month or two from now, will the foil keep it usable until then?

The foil wont really help anything. The glue will skin over as it is moisture cured. Usually you peel off a 1/2 inch pancake and what is underneath is good as gold. Unless you really do not use a lot, then it might not even skin over at all and just be good to go.

 

[bobbyt8888]

They've already installed the entire first floor. This is likely an afterthought with left-over material, not considering attic stock.

Yes, that is correct.

 

[Dan]

Yes, that is correct.

I'm guessing this is a factory finished product. IF that's the case, just make sure you will still have enough left over to sock away in the attic or somewhere in the case of some kind of an accident down the road. Very likely color wouldn't match from a new order.

 

[bobbyt8888]

I'm guessing this is a factory finished product. IF that's the case, just make sure you will still have enough left over to sock away in the attic or somewhere in the case of some kind of an accident down the road. Very likely color wouldn't match from a new order.

It is Dan. How do you determine how much enough is?

 

[Mark Brown]

5% would be my target amount of course if you have it you will never need it but if you do not, the first thing that will happen is your fridge will leak and swell all your boards.

Everyone always wants to take back their last 2 or 3 boxes but 60 odd feet of "too much wood" is a lot cheaper than a whole new floor.

 

[bobbyt8888]

These replies lead me to ask a question on board replacement which I will ask in a new thread:

https://www.flooringforum.com/threads/3-4-t-g-board-replacement.6716/post-79379

 

[Dan]

The industry standard figure of 5% should account for culled boards and waste. Everything else leftover should be kept for future needs. Might be a good idea to order another box or two to do your hallway and keep what you already have. If you bought it local, you might be able to source extra product with the same lot number now. Down the road, not so likely.