the_olivia•15d agoMost Upvoted

I finally stopped using expansion joint filler the old way

Been watching guys at the supply yard grab that grey foam backer rod for control joints. They jam it in halfway. No depth gauge. Just shove it in. Then they squirt sealant on top. Two months later it's all cracked out. I measured my last driveway job. 1/3 depth max. That's it. That's the rule. Sealant needs room to flex. Why does nobody check this before pouring money into caulk?

3 comments

3 Comments

emeryj6615d ago

1/3 depth max that's the rule" - exactly this man. I've seen guys use backer rod as a space filler instead of a depth control tool and it drives me crazy. The whole point is to let the sealant stretch and compress, not just sit there like a brick. If you pack it too shallow the caulk has no room to move and it just rips apart at the edges. Plus the backer rod keeps the sealant from sticking to the bottom of the joint which is another thing people forget. It's not just about filling a hole it's about engineering the flex.

the_christopher15d ago

Nah, sometimes you just gotta fill the void and move on.

claire_grant3413d ago

Why does nobody ever read the damn instructions on the backer rod packaging? I swear it's right there in plain English but guys just wanna jam it in and move on. I've been doing this long enough to know that shallow backer rod is a guaranteed call back in six months. The caulk needs that room to breathe and move, especially with temperature swings. It's not complicated, it's just basic physics, but nobody wants to slow down and do it right the first time.