# Primer Cracking on New Construction Ceiling



## GP Painter (Sep 14, 2013)

Last week one of my painters sprayed the ceiling of a new construction home with CHB ... today I'm seeing cracks in the primer. What would cause this?

One thing I'll note is he forgot to turn the heater on that evening, and nights are getting down to mid 20's, days 50 degrees.

Thoughts?


----------



## TJ Paint (Jun 18, 2009)

Too cold + cheap paint = fail.


----------



## paintball head (Mar 3, 2012)

Did he backroll? Just spraying new drywall without rolling will cause that. I was once called to have a look at a full house prime on new DW and whoever primed backrolled none of it, so there were random areas cracking and peeling. I have seen CHB crack in corners where the roller didn't touch.


----------



## GP Painter (Sep 14, 2013)

We have always sprayed CHB without rolling and have never had an issue. After looking at this mess, I'm thinking this employee put the paint on too heavy. Between the that and the cold, it's costing me to fix.

Lesson learned!!


----------



## LIPainters (Oct 5, 2013)

I hardly ever backroll a primer coat and I never have a cracking problem either. I have had a problem though (more like blistering) in low temps and I would bet that was your problem as well. Can crack even more in the heavy spots because they weren't fully dry before it got too cold.

Long Island Painters


----------



## Wood511 (Dec 13, 2010)

Paint is mostly water...so...


----------



## Stretch67 (Oct 7, 2013)

Some worthwhile possibilities for sure...

I most often see this when the substrate is too wet. There is a reason good architects spec that paint doesn't go on until drywall is a 12% relative moisture content or less. The general of course is always pressuring to get it painted while the mud is wet (not to touch obviously, you need a good tester with pins to poke in the gyp) and if they want it done, have them sign a liability waiver. At least that's what I do, and I learned the hard way on a 50 unit three story condo building.

Here's what happens, just say its a knock down ceiling that they just sprayed mud on two days ago. Sprayed Monday, sanded Tuesday, WANT IT PAINTED WEDNESDAY. They've had the windows open and fans going and they think its ready. Well guess what, here in MN in the summers, daytime humidity averages 65-85 percent, no problem. And at night, its even higher (dew on the grass??). So in the early morning when the temp is warming up all the way until afternoon, the drywall is cooler than the ambient temperature, and depending on the dew point, it is more than likely TAKING ON moisture like one giant sponge. Then mid-afternoon/evening the drywall finally warms up to the ambient temp or close, and the ambient temp starts dropping. So while the drywall stays warmer than the air around it, its generally losing moisture/drying. Until about midnight or so, then the cycle starts again. So most of our jobs have DE-humidifiers on them (big ones, sometimes 10 or 20 of em). From April-September here, drywall isn't half as dry as people think it is, and it often takes a good moisture meter to prove it. Winter is a lot drier, so usually don't have too much trouble then.

The reason it cracks (I call it alligatoring) is because too much moisture gets trapped underneath the paint. When the wall warms up, the water/air combo expands (much like ice) creating pressure against the underside of the paint. In order for the moisture to escape, it cracks through the weakest parts of the paint film and is a lotta work to fix. Painting over alligatoring typically just makes the alligatoring worse. You have to chip off the loose stuff, skim coat it with mud, and then paint it again. Making sure every process is DRY before the next one commences.


----------



## Stretch67 (Oct 7, 2013)

GP Painter said:


> nights are getting down to mid 20's, days 50 degrees.


A textbook example. When you walk in at 7 am, the windows have been open all night. Wall temps are 28 degrees, if your lucky. By 9 am coffee, wall temps have risen to 34 degrees and the air coming through the windows is 45 degrees. And the dewpoint on the air coming through the windows is 30 degrees. So while your sitting there having coffee and a cigaratte in the front doorway, the moisture in the air rushing by you into the house is heading directly to the nearest piece of drywall and schlurping right into it because the temperature of the drywall is lower than the dewpoint.


----------



## Stretch67 (Oct 7, 2013)

Wood511 said:


> Paint is mostly water...so...


paint is engineered to be able to handle "its own moisture content" for the most part. ever left a 1/4 inch of paint in the bottom of a fiver to dry? it rarely cracks, and if it does, maybe in just two or three big cracks. usually just one nice smooth 1/4 inch thick slab of paint.


----------



## Wolfgang (Nov 16, 2008)

CHB has a high clay content.


----------



## ewingpainting.net (Jun 2, 2008)

Wolfgang said:


> CHB has a high clay content.


My thoughts too, could be mudding


----------



## ReNt A PaInTeR (Dec 28, 2008)

Most of the time is the painting contractor's fault. around here they cover windows etc. followed by the prep. then they shoot lacquer undercoater, then some starts shooting latex. sand all trim and doors and proceed to shoot enamel. :no:


----------



## canadianpainter (Mar 7, 2009)

GP Painter said:


> We have always sprayed CHB without rolling and have never had an issue. After looking at this mess, I'm thinking this employee put the paint on too heavy. Between the that and the cold, it's costing me to fix.
> 
> Lesson learned!!


Has nothing to do with the cold. The paint was just too heavy.


----------



## Damon T (Nov 22, 2008)

Sounds like mud-cracking. I had that happen when we hired a guy from Florida who was used to putting multiple coats on really quick. Well paint doesn't dry as quick in Seattle and the pro mar or whatever it was mud cracked / alligators big time. And as noted adding more paint didn't really help. 
All that moisture talk was very informative. I've never taken a moisture content of mud before. It makes a lot of sense. We had an issue recently where the GC installed new soffits and fascia, they were gonna put on a new roof but hadn't gotten it on yet when the rain came and caused a bunch of the new soffits to get wet, and warped some framing. They left a lot of the soffits up, and a couple weeks later even after the roof was on the MC read anywhere from 20-27%. I had left the jobsite a week earlier because the ratings were too high, and when I came back the next week they were still up there, but the project lead said paint it, they wanted to get their scaffolding out of there. So I let them know any failures will be on their dime, not mine. 
Moisture meters are a must have! I like the one I have now that doesn't require pins.


----------



## Stretch67 (Oct 7, 2013)

Damon T said:


> So I let them know any failures will be on their dime, not mine.
> 
> 
> Moisture meters are a must have! I like the one I have now that doesn't require pins.



Letting them know on paper is the only guaranteed way imho, and when you do you'll all a sudden notice a LOT of reluctance to proceed, and a LOT of hustling to the rental mart for some dehumidifiers. :thumbup: It's funny, I'll explain to the super or the pm that I don't recommend painting cause it's too wet, they'll just say "Oh go ahead get er done we'll cover it if it goes south." Then as soon as I whip my liability waiver outta my binder, they're hemmin an hawin all the way to the rental mart.

Keep in mind, the pinless ones often take readings up to around 50" in depth and just report the wettest point or calculate an average every inch or so... that's why I like the pin ones, yeah it makes little holes in the wall, but you for sure know what you are reading. Sometimes I have checked the same exact spot with the pinned meter and the pinless meter, and the readings are significantly different, just sayin...


----------



## ProWallGuy (Apr 7, 2007)

Last Craftsman, is that you?



bryceraisanen said:


> Some worthwhile possibilities for sure...
> 
> I most often see this when the substrate is too wet. There is a reason good architects spec that paint doesn't go on until drywall is a 12% relative moisture content or less. The general of course is always pressuring to get it painted while the mud is wet (not to touch obviously, you need a good tester with pins to poke in the gyp) and if they want it done, have them sign a liability waiver. At least that's what I do, and I learned the hard way on a 50 unit three story condo building.
> 
> ...


----------



## WisePainter (Dec 27, 2008)

Wolfgang said:


> CHB has a high clay content.





canadianpainter said:


> Has nothing to do with the cold. The paint was just too heavy.


Yes.
Primer isn't really temp affected.
But if applied to heavily and it has a high clay content, it will dry like a desert river bed.


----------



## mustangmike3789 (Jun 11, 2011)

bryceraisanen said:


> A textbook example. When you walk in at 7 am, the windows have been open all night. Wall temps are 28 degrees, if your lucky. By 9 am coffee, wall temps have risen to 34 degrees and the air coming through the windows is 45 degrees. And the dewpoint on the air coming through the windows is 30 degrees. So while your sitting there having coffee and a cigaratte in the front doorway, the moisture in the air rushing by you into the house is heading directly to the nearest piece of drywall and schlurping right into it because the temperature of the drywall is lower than the dewpoint.


 if the dew point temp is 30 and the wall temp is 34, that gives you a surface temp 4 degrees above the dew point when 5 degrees is the normal recommended spread. with a 4 degree spread, moisture will not condense on the wall. the wall temp will need to be at least 30 or lower before moisture condenses on the surface.
the dew point temp is the temp at which moisture in the air will condense, if the surface is above that, evaporation is happening. if the humidity is high too, the evaporation will be slowed down because the air is highly saturated and can not hold much more moisture or allow rapid evaporation to happen. this is why the 5 degree spead is the norm. if the surface temp is allowed to rise 5 above the dew point, this should give enough time for any residual water on the surface to evaporate depending on relative humidity. 
if the drywall did hit the dew point temp at some point before or after painting, moisture would be present and absorbed into the surface. if it happened before painting, the drywall could have absorbed moisture and the paint applied over that may blister or wrinkle while forming a film. if it hit the dew point after paint was applied, (depending on the paint and how long this time period was), moisture would have collected on the wet paint film which could cause runs/ streaks, improper curing, amine blush (epoxy) or the ethylene glycol will not evaporate off of the surface at those temps.


----------



## Oden (Feb 8, 2012)

canadianpainter said:


> Has nothing to do with the cold. The paint was just too heavy.


Mil cracks we call them. Sometimes we get a little crazy with a gun with a big or blowed out tip. No biggie. just Samd it off a bit and recoat usually. If it's real bad, skim it with mud. You know you did it if you did, cause when you backrolled the material- well you could telll.


----------



## Paradigmzz (May 5, 2010)

USG Tuff Hide. Fix it and get a level five all in one swoop.


----------



## Damon T (Nov 22, 2008)

ProWallGuy said:


> Last Craftsman, is that you?


I miss Last Craftsman. That guy had some good tips.


----------

