48x39x14 shop build
- Thread starter ovrszd
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Citydude
Elite Member
Nice job Richard! Very nice building.
JohnBuffaloMN
Silver Member
First - thanks for the over the fence look at your new shop! I know almost nothing about building construction. Is the metal ceiling with no vapor barrier the "standard" way to insulate the ceiling? My shop ceiling was sheetrock with insulation blown in on top of it without a vapor barrier. Condensation brought the whole mess down in big wet clumps. I think I had water pooling under the concrete floor causing the condensation, but I'm hesitant to put up a metal ceiling and heat the shop for fear of ending up all wet again - even with vapor barrier.
EddieWalker
Epic Contributor
Terms can be confusing. What is a vapor barrier?
How far apart where your trusses that the sheetrock was attached to?
How did you vent your eaves and peak?
Condensation is pretty easy to deal with using air flow. To get that wet up there, something else was very wrong.
JohnBuffaloMN
Silver Member
As I understand it - a vapor barrier is usually polyethelene or tyvek - something that prevents the passage of moisture.
I'm guessing they are standard trusses - 24" on center? I don't know, but could measure them.
The peak and eves are steel over wood 2x4 construction with enough light coming through the holes I doubt vents would add/improve anything.
EddieWalker
Epic Contributor
Sheetrock on 24 inch centers needs to be 5/8" thick.
If the metal was open on the eaves, and there is a ridge vent, then the air flowing in from the eave, and then because it gets so much hotter once it gets into the attic space, it goes up to the ridge vent, which keeps the underside of the metal dry. This is long proven, keep it simple technology that works.
Since you say that your insulation got so heavy that it caused your sheetrock ceiling to collapse, then you either had a leak, a lot of leaks, or no air flow from your eaves to your peak.
Adding plastic or tyvek to the underside of the roof would have made this worse. If it was under the metal, and over the pulins, then the metal itself would have stayed dry, but the underside of the plastic would have created a massive amount of moisture.
I have seen plastic used under the insulation and above the ceiling before on a church gym with a basketball court. There, they had a guy that they where paying to clean the gutters, but he never did. Over the years, the gutters became so full of leaves that had decomposed into dirt that when it rained, the water ran from the top of the debris under the roof and into the building at the eaves. It settled on the plastic, where it just sat. It would get so full, then no more water would get into the plastic, and then it would just run out over the sides of the gutters. One day the plastic started to leak a little bit and a lady walking in the gym for her morning exercise, slipped, fell and hurt herself. I was hired to fix it. I cleaned the gutters and drained the water out of the plastic. I used a lift, I poked a hole into the plastic and I filled up dozens and dozens of five gallon buckets with water from the plastic.
If the metal was open on the eaves, and there is a ridge vent, then the air flowing in from the eave, and then because it gets so much hotter once it gets into the attic space, it goes up to the ridge vent, which keeps the underside of the metal dry. This is long proven, keep it simple technology that works.
Since you say that your insulation got so heavy that it caused your sheetrock ceiling to collapse, then you either had a leak, a lot of leaks, or no air flow from your eaves to your peak.
Adding plastic or tyvek to the underside of the roof would have made this worse. If it was under the metal, and over the pulins, then the metal itself would have stayed dry, but the underside of the plastic would have created a massive amount of moisture.
I have seen plastic used under the insulation and above the ceiling before on a church gym with a basketball court. There, they had a guy that they where paying to clean the gutters, but he never did. Over the years, the gutters became so full of leaves that had decomposed into dirt that when it rained, the water ran from the top of the debris under the roof and into the building at the eaves. It settled on the plastic, where it just sat. It would get so full, then no more water would get into the plastic, and then it would just run out over the sides of the gutters. One day the plastic started to leak a little bit and a lady walking in the gym for her morning exercise, slipped, fell and hurt herself. I was hired to fix it. I cleaned the gutters and drained the water out of the plastic. I used a lift, I poked a hole into the plastic and I filled up dozens and dozens of five gallon buckets with water from the plastic.
JohnBuffaloMN
Silver Member
Thank you Eddie, I appreciate your input - the more I'm learning about it, the more I think there was water under the concrete floor that was causing the problems with high humidity in the building. The sheetrock ceiling may or may not have been adequate, but again the ceiling was bowing down and blowing out from the moisture and it wasn't from a leaky roof. I made sure the foundation was draining good around the building after I started seeing the underside of benches "sweating" thinking that had to be from the floor, and the sheetrock ceiling was history by then... after a couple of years it seems to stay dry in the building now. I'm pining for my heated shop again after following this thread, but maybe overly worried about a problem that's no longer a problem.
OP
ovrszd
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Good discussion guys.
It's critical that the humidity in a building is controlled. First line of defense is to not allow any outside moisture to come inside. Thru roof leaks, moisture under the floor, poor ventilation, etc.
Eddie described a "worst case" scenario.
John described a known moisture issue under his concrete floor.
Both of these create problems that will come to boil at some point.
In my case, I believe my floor will stay dry. I believe my Soffit vents and Ridge vent will work together to control moisture entrapment on the underside of my roof metal. I believe my attic will stay dry as long as there are no leaks caused by screws improperly installed, etc.
If these situations stay constant and effective a moisture barrier is not needed between the ceiling metal liner and the insulation. There should be no moisture transfer there to control.
I believe my humidity in the building will be very low. Only increased by parking "wet" vehicles in the shop. Without that added moisture I believe the humidity will be on the low end of the comfort scale. I'll heat the building this Winter. I'll put in a cheap humidity gauge and report the findings.
It's critical that the humidity in a building is controlled. First line of defense is to not allow any outside moisture to come inside. Thru roof leaks, moisture under the floor, poor ventilation, etc.
Eddie described a "worst case" scenario.
John described a known moisture issue under his concrete floor.
Both of these create problems that will come to boil at some point.
In my case, I believe my floor will stay dry. I believe my Soffit vents and Ridge vent will work together to control moisture entrapment on the underside of my roof metal. I believe my attic will stay dry as long as there are no leaks caused by screws improperly installed, etc.
If these situations stay constant and effective a moisture barrier is not needed between the ceiling metal liner and the insulation. There should be no moisture transfer there to control.
I believe my humidity in the building will be very low. Only increased by parking "wet" vehicles in the shop. Without that added moisture I believe the humidity will be on the low end of the comfort scale. I'll heat the building this Winter. I'll put in a cheap humidity gauge and report the findings.
JohnBuffaloMN
Silver Member
Thank you again ovrszd for the opportunity here. Nice drone work BTW
ultrarunner
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Great space you have created and I thoroughly enjoyed seeing your progress pictures...
Very well done!
Very well done!
