Hi Guys,

I'm being asked to install a solid 3/4" x 6" wide walnut plank floor. It is already been scraped and distressed but is UNFINISHED. Since it is a 6" wide solid, the idea is to glue and blind nail. At first, the owner wanted to full trowel with Sika but since it's unfinished and little to no sanding will be done, I think that method would be way too messy and I'd end up with glue on the surface, which would affect the way the wood takes the stain. So I think using cartridges/tubes would be neater. The plan is to apply 1/4" beads across the backs of the boards every 8". I just need to know which adhesive would be the best one to use. Bostik's? Chemrex? PL Urethane? Something else?

PL Urethane, Works for me.

I've been using the Sika adhesive in tubes. They have a pneumatic and a manual gun. You might consider the pneumatic. It is a great system.

Would you install the wide plank unfinished walnut without the glue ? Just using the aqua bar as underlayment and stapled ?
I have similar job and some rooms are over 50 foot long .
Owner believes that the glue is not needed .[/i]

the carlise job im biding on (over radiant) they say 3/8th beads of pl400

PL 400 is all i ever use , and they carry the large tubes at the local HD for around $4.75 a tube ..
If you have a lot of floor i would use the pneumatic gun like Barquios suggests ..

Anyone did use this brand ?
Lowe's has it , and it comes in the large tubes too .
However I was unable to get the pneumatic caulk gun , at least not the one for the 29oz tubes ..
There is some online , just I wish , I could have one sooner ..

OSI - Heavy duty subfloor adhesive

subfloor adhesives and construction adhesives I found they tend to get brittle ..

Thanks for the responses. I also found the PL Premium Urethane to get to hard and brittle. It does stick like no one's business but with a 6" wide plank floor, I'm concerned about elasticity as well. Spoke with the Sika rep and we're going with their SikaBond T-53 in tubes. The plan is to apply about 1/2" beads every 6" or so. Rep said they does this in Europe all the time and it's called the "Cordon" method. We did consider those large tubes of PL400 but here in CA, all I can get now is the low VOC latex stuff, which can cause cupping, due to the water in the adhesive. But the owner is paying for the Sika adhesive so I don't care about cost. Wish me luck on this one guys. BTW, one thing that is odd. The flooring MC metered out @ around 6 to 7% MC. The subfloor is around 10 to 11% MC. The stuff has been sitting in the house for awhile now. I could have the AC turned on but actually want the flooring to pick up a little moisture; a % or two. Would feel better if it read 8%. RH is averaging 45% and temp around 75. Fortunately, American Black Walnut is fairly stable and we're gluing. We got the vapor barrier installed under the house so we're good there. I was just concerned if I turned on the AC, I'd dry out the wood flooring even more.

Good luck Gary .. Let us know how you make out ..

This message is probably past tense, since you have most likely completed this project by now.
The MC difference between your sub-floor and the finished floor seems to be borderline too high. I think that if possible, if the 10-11 percent moisture content of the sub-floor is stable at that range, racking out the floor on top of it for a few days might help equalize the difference.
If it is new construction, I would delay the install until the difference between the two is less, say within 2%.
As far as glue is concerned, we would normally run a "zig-zag" bead of any good quality urethane adhesive along the entire lenth of each board, nearer to the groove edge.
Sounds like a great project to be working on though. How did it turn out?