Getting ready to order my roof metal for my steel truss 38 x40 pole barn and would like to know what ridge gap is recommended to properly vent my barn? The way the steel truss roof purlins are spaced, I have from 0 to around 10in for ridge gap adjustment. I'm in florida and it's hot and get lots of rain.
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What size ridge gap on Pole Barn?
- Thread starter jdeshong
- Start date
Musicinabottle
Banned
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- Jul 24, 2016
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If you get a lot of wind and the roof pitch is low, then I'd put "C" metal at the top of your metal to prevent wind from blowing water under the ridge cap. Generally you leave a 2 inch gap with screen material to prevent bugs from entering and what we call in our area "universal ridge cap" . It's something on the oder of 6 inches each side. You can have something bent even more if you need.
bpjr
Well-known member
You can get different width caps so make it as wide as you can for good venting. I've seen
12" wide caps that let you have a really wide vent gap. My shed, house and commercial building have approx 4" wide gap with 8" caps. Use the plastic material that looks like a scotch brite pad to keep the wind from pushing water in. It still vents. In the last hurricane I checked to see if water was getting pushed in and not a drop at 80 mph but plenty of air flow. I'm on the east coast of central Florida.
12" wide caps that let you have a really wide vent gap. My shed, house and commercial building have approx 4" wide gap with 8" caps. Use the plastic material that looks like a scotch brite pad to keep the wind from pushing water in. It still vents. In the last hurricane I checked to see if water was getting pushed in and not a drop at 80 mph but plenty of air flow. I'm on the east coast of central Florida.
Marctrees
Well-known member
You can get different width caps so make it as wide as you can for good venting. I've seen
12" wide caps that let you have a really wide vent gap. My shed, house and commercial building have approx 4" wide gap with 8" caps. Use the plastic material that looks like a scotch brite pad to keep the wind from pushing water in. It still vents. In the last hurricane I checked to see if water was getting pushed in and not a drop at 80 mph but plenty of air flow. I'm on the east coast of central Florida.
bpjr said it right overall, but I'm pretty sure he has more moverhang than he described.
4" gap w 8" cap is less than 2" overhang.
We have about a 7" gap, and a 24" cap.
Again, keep in mind, any metal building supply can make a ridge cap of ANY width, then you use the "Coarse Scotch Brite" type of closures to permit air flow.
Couple different kinds on market, but they DO call that formed material for the different R panels "Closure" ?strip? I think.
Marc
Last edited:
I checked again and actually have a 7" gap between my roof purlins which are ran horizontally. If I overlap 3" on each side i would only be able to have a 1" gap. Do the ridge screws have to hit wood? I would like to leave the 7" gap but the ridge cap would just be screwed down on each metal rib without hitting wood. Thanks for the advice.
joe_padavano
Well-known member
Every single manufacturer of metal roofing and siding panels publishes a manual that tells you specifically how to install their product. They also sell ridge caps, vents, drip edges, etc, etc to properly detail these features and avoid leaks. The manual for your selected roofing product will tell you exactly how much gap to leave and how to properly install their compatible ridge cap and vent system.
No manual on their site, the sales guy said I could screw the cap down between the purlins but he didn't sound too confident and would like to know what others have done with no problems. I'm sure I'll get some "instructions" with the delivery of the panels but I can't buy them until I figure out the exact length I need which is related to the ridge gap.
I checked again and actually have a 7" gap between my roof purlins which are ran horizontally. If I overlap 3" on each side i would only be able to have a 1" gap. Do the ridge screws have to hit wood? I would like to leave the 7" gap but the ridge cap would just be screwed down on each metal rib without hitting wood. Thanks for the advice.
I realize this is old and your build is done, but for someone down the road.... I used stitch screws to attach my ridge caps to the steel roofing panels at the rib (not through to the wood). Worked great, no issues. If ribs are 9" apart (common) thats a lot of screws holding it on, also makes it pretty easy to remove if needed.