TIL the hard way why you shouldn't rush your mortar mix on a humid day...

I was laying brick on a retaining wall for a backyard patio job over in Greenville last June. Humidity was around 80% and I kept adding more water to my mix because it felt stiff, trying to get it done before lunch. By the third course, I noticed the bricks were sliding around when I tapped them with my trowel... the mortar was too wet to hold. I had to pull up two whole rows and start over, cost me about an hour and a half. Has anyone else dealt with mortar slump in high humidity like that?

2 comments

2 Comments

lane.angela1mo ago

Over 80% humidity kills any chance of proper set time.

noah9141mo agoMost Upvoted

... I'm not buying that humidity alone is a dealbreaker. Sure, if it's raining sideways or you're in a literal steam room, yeah, concrete won't set right. But 80% humidity? I've poured decks in the middle of a muggy July afternoon and watched the mix stiffen up fine. Usually the bigger issue is direct sun or wind drying the surface faster than it can set. If you're worried about humidity, just mist the slab after you finish and cover it with plastic. People act like a little moisture in the air ruins everything, but it's really not that serious. I think the whole "high humidity kills set time" thing gets way overblown by guys who are just looking for an excuse to blame the weather.