First off, let me say that I appreciate this board and everyone who posts here. This is my first post, but I've gotten lots of useful tips and information here. Also, I respect you guys that do this for a living, it's not easy.

I a DIY'er installing Anderson Lincoln plank 3/8" engineered on my concrete slab using Anderson Duck glue. I've only installed 7 rows so far and I'm happy with the the way things have started except for one issue. I'm having a bit of a problem with some of the end joints lifting up off the glue a little bit. This is mainly happening at the end of the room.

Here's what I think I've done right:
1. I've tried to use the straighest planks I could find on the first fews rows
2. I'm using the correct trowel size according to the Anderson instructions
3. I did a fair amount of slab prep so I'm fairly confident as to the flatness of the slab.

So far, I've been compensating by placing some object on the joint to weigh it down so it will set in the glue good. What are some of the reasons that this might be happening (or more precise, what am I doing wrong)?

Thanks for your time,
-Brad

Ends lifting on engineered is a sure sign, the substrate or adhesive, is high in moisture, or moisture vapors.

This happens if you use a waterbased adhesive and not a full urethane wood adhesive. Or if the concrete moisture vapor emissions are above acceptable levels. It looks dry, has caused many wood floors to become firewood.

Put some boards together dry, and check to see if the ends are lifted dry laying them.

That used to happen with Bruce's failed Tribond adhesive of years past. It was always a darned mystery to me. It wouldn't stay down around door casings either. I suppose I haven't provided any help but I'm sure it wouldn't happen if Bostiks was used.

I have had ends lift using Mannington's (which is supposed to be Bostik's dyed green) but only at the cut ends (walls). I suspect either banana boards or a low spot. Had to have the baseboards anchor them down. Get some heavy items to place on those boards while the glue is still wet. Once dry, if the slab is too, they'll be fine.

Thanks for the suggestions. I dry-laid some boards in the main area I saw this happening and they were flat. Interestingly enough, all but a couple of the boards that were doing this are at the end of the room and they are boards I cut (similar to situation Gary described with Mannington). It's also possible the boards I used at the end of the room weren't as straight as I though they were. Anyway, I'll just keep a close eye on it as I go along.

Thanks again,
Brad