Glue and more glue!

19 years ago

My installer stared putting down my 4" unfinished red oak (on plywood subfloor) today. My contract calls for installation based on manufacturer installation specs. They are using Bostik's best and 6" nailing. Bostik's Best calls for 1/4 x 1/4 x 1/4 trowel for unfinished 3/4 hardwood. The installer is saying he can't use that much glue since it makes the wood hard to install and get close joints because glue gets in the joints. He uses a smaller V notch trowel that does not apply as much glue.

Bostik's has said that if there were no nails being used that it would be inadequate glue to get the required 95% coverage... and although 95% glue coverage with nail use would not hurt, it is not as critical.

So, for those of you who are professional installers, if this were your home, and knowing that glue with 4" boards and nails is probably overkill anyway... would you be comfortable with the lesser amount of glue (about 1/2 of what would be there with the proper trowel) and the finished product or would you require that they use the proper amount? My only concern about holding them to the proper amount, is that the specs on tehBostik sheets and can are ONLY for glue ONLY applications... and that the extra glue with the nails is actaully going to cause some problems getting things tight and give me a worse finish overall as compared to just lettig them put it in as they say they have done for 20 years!

Advice greatrly appreciated... they return at 7am...

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Comments (9)

glennsfc
19 years ago
Glue and nail installs are very rare indeed. The glue and nail schedule sounds good to me. Bostik's Best is an unbelievably strong polyurethane adhesive. The fact that the boards will get locked in and down immediately and will stay down as the adhesive cures leads me to believe that the adhesive will perform the job as expected. Having worked with Bostik's Best, I am confident that the trowel configuration they are using is sufficient...and it is probably what I would choose if I was doing your job.

Another thing here is a 1/4" X 1/4" square notch trowel will place too much adhesive on the substrate in a glue/nail installation...glue getting into the tongue and groove space would just be one problem you would have.

In my professional opinion they are doing a professional job.
jscozz
Original Author
19 years ago
Thanks, glennsfc.

I appreciate your opinion...

Instead of him just using a smaller v notch trowel like this:

/\/\/\/\/\/\/\/\

he is using one like this:

/\__/\__/\__/\__/\__/\__/\__/\__

which I think is going too far... This is less than the least amount on the Bostik can. I did not measure the notch depth... I guess what would be very helpful if a table somewhere that listed various trowel styles and sizes and the corresponding final glue thickness once compressed.

The main thing I want to get out of this is a squeak free, solid floor that has no give in any areas when you walk on it. I am just concerned that if there is not enough glue that it will not contact the wood completely and leave voids that will defeat the whole purpose of me spending this extra $$$$ for the glue and installation.

Jeff
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floorguy
19 years ago
Heck I never full spread when I'm gluing and fastening.

Glue tubes for the caulking gun, and a serpentine ribbon down the back of the plank, and place and nail.
jscozz
Original Author
19 years ago
Thanks, floorguy.

I would almost be happier with a serpentine bead down the plank, since I KNOW there would be FULL contact with the board all along that bead. With the very thin spread with the trowel, I know it is not getting any contact on the recesses on the back of the board... and on the other parts it is a thin strip.

Part of it for me is just the principal also... I chose this installer based on the contract we signed that stated exactly how it would be installed (manufacturer's specs and exact trowel size I specified). If an installer intended to do it however they want anyway they should not sign a contract that states otherwise. I had 3 lower bidders than this guy... If I were to tell a contractor that I changed my mind and will pay $2 less / sq ft... half way though the job, that would never stand... but for him to disregard a signed contract is OK. That probably frustrates me more than the amount of glue. Unfortunately, if I fire him I miss my deadline to move in before Christmas. Oh well..... plus the fact that none of the workers speak a lick of English frustrates the hell out of me when I can't communicate with people.
glennsfc
19 years ago
The larger teeth spread further apart is the correct trowel for some wood installs.

I never guarantee a squeak free installation regardless of the installation method employed...to do so is unrealistic.

You're going to have to make the call here with your job.

Best of luck.
jscozz
Original Author
19 years ago
In looking into thing more... the flat top v notch they are using has a spread rate of 34.2 sq ft / gal. The recommended square notch trowel has a spread rate of 12.8 sq ft / gal. That is almost 1/3 the recommended glue.

I think it is really a matter of the crew complaining to the boss that it slows them down and it will take them longer to install it.
glennsfc
19 years ago
It is sufficient glue in my opinion. Have them place a plank in the adhesive and then lift it to see what the coverage is. If the adhesive ridges are transfered to the back of the plank, then that is enough in my opinion.
oruboris
19 years ago
If they used the quarterxquarterxquarter trowel, you'd have an eighth of an inch of glue between the floor and sub-- sounds like way too much, to me. You could use that trowel to set tile...
floorguy
19 years ago
Ummmm,

Are you sure you got that right?? 12, foot a gallon????

Who is supplying the glue???

That is a lot of glue. I would be at the 40 ft. per gallon rate, if that, if I were also nailing. Those boards are getting in the glue, where it counts.