Just found out how much a bad glue line can actually shrink a floor

I was reading a 20 year old technical bulletin from the adhesive maker Bostik, and it said a 1/32 inch gap in spread can shrink to over 1/8 inch as it dries. I saw this happen on a glue-down LVT job in a Tampa strip mall last month where the tiles started telegraphing the trowel lines after a week. Has anyone else had a floor fail from adhesive shrinkage like that?

3 comments

3 Comments

abbyk103mo ago

Wait, hold on. That sounds like blaming the glue for a bad install. A 1/32 gap shouldn't just magically appear if you're troweling right and putting the tile down while the glue's wet. That Tampa job? I'd bet money the guy let the adhesive skin over before he laid the tile, or he used the wrong trowel. The glue does what it does, it's on us to follow the directions.

phoenixgonzalez2mo ago

Man, reading that makes my one DIY bathroom floor look like a modern art project. @danielm48 is right, you don't see the problem until it's way too late.

danielm483mo ago

That Bostik bulletin is no joke. I saw a 3,000 square foot office glue-down in Phoenix fail in under a month because the crew was troweling too fast and leaving those tiny air gaps. By the time summer hit and the AC dried everything out, the floor looked like a washboard. @abbyk10 is right that it's an install problem, but the glue shrinkage is the hidden force that makes a small mistake into a huge, expensive one. It's not magic, it's just chemistry you have to respect.