Our garage is a steel building with a corrugated steel roof with 6 translucent panels for skylights. It is approximately 14 years old and i can see that it is leaking at the screws. There is discoloration on the metal joists where they are screwed in with the rubber-washered self-tapping screws.
I have a few questions:
I'm going to replacet the screws. Suggestions on which ones to get? on how to install them?
I also see some areas where they used a sealer for different reasons. A few places where they ran a screw and missed or stripped and they plugged the hole, they used it around the translucent panels and around the vents on the top of the roof.
What is the best stuff to use?
I am in southern california near the ocean where it isn't too hot, but it sees a lot of sun.
The last related question is that I see drops on the ground under the skylight panels in the morning. I don't think they are all leaking but could be. I wonder if it is condensation and if so, any way to prevent it?
HD or Lowes has screws with their corrugated roofing. Nothing special. 1/4" head, rubber washer.
I would imagine that a couple quarts of flex seal or Karnak or Henrys and a paint brush would have a quicker result, especially if the steel under the screw is rusty/pitted. If the steel under it is compromised, a new screw might not fix it.
Are the corrugated panels painted or galvanized steel?
My gut response is to encapsulate the screws with a good quality silicone sealant (like Dowsil 795 - not cheap but worth the premium) - definitely do not use urethane due to UV exposure. But don't seal to rust. And the translucent panels may require a primer to get a good bond. I'm pretty sure that a local Dowsil tech rep will come and help you with product selection if you ask.
If you've got screws backing out there is a good chance the shafts look like an hour glass from friction. And the threads have likely wallowed out the wood - meaning you will need to replace with a larger screw in order for the new one to bite.
Luckily, the metal seems to be in good shape up top.
What's the best material to get? I see stainless, zinc, galvanized and painted. I don't think painted is the best, but I don't think I need to splurge for stainless...
The heads of the current screws are 5/16". Is the size of the wrench needed the size of the screw? ie I need a 5/16x2" screw?
edit: looks like I need #12.
also, can i just replace the washer?? the screws with washers are going to be around $600. I'd be happy to just replace the washers if i could.
edit: it looks like I can get a lot cheaper if i don't get self-drilling which I no longer need as they've already been drilled.
https://www.lowes.com/pl/Advanced-sealant-Np1--Caulk-Caulking-Paint/4294729414?refinement=2818397894,3704070910
This E36 M3 is on a whole other level from "caulk". Use it and be sealed till doomsday. I recommend using an electric caulking gun, it's thick.
And yeah, if you just want to replace the little rubber washers you can do that as well.
Check menards for screws, they ship and they sell metal roofing screws in bulk bags
The chances that you will be able to put the same size screw back in an old hole is pretty slim. You'll likely need to go one size larger depending on the gauge of the purlins you're screwing into. Rust, wiggling, expanding and contracting, etc have made those holes bigger. If you simply put the same size back in and it tries to cut new threads, it won't hold.
That's one of the reasons I suggested sealing what you have. Dad's Morton steel barn was built in 1978 and about 20 years ago he had to re-seal his screws. Morton strongly suggested against removing the old screws as it just opens up a can of worms; broken screws, rusted holes, etc. Instead, he just painted all the screws with liquid rubber and it hasn't leaked since.
Former metal roofing manufacturer here (note: Not installer/repairer).
I'm pretty much with the consensus here. Seal that crap.
Your 5/16 head says you're already up from the other common size -1/4" head. Screwing into metal "rafters", as I understand you're doing means you better go up a size, but you'll end up in the same place eventually. $600 for screws sounds steep to me.
What you have going against you , living in a desert is large, quick changes in temp. The amount a panel shrinks and grows from coldest to hottest is huge, and it gets worse the longer that panel is.
The leak at the skylights is likely due to the two expanding/contracting at different rates.
Whatever caulk you get, it must remain flexible. The stuff KYOffroad posted looks good, as do many other somewhat expensive brands. You'll get a lot more bang for your buck just caulking it up.
There's my geek out. Hope it was helpful/not preachy.
Turns out the screws I first found were stainless, thus a lot more $$. So I found and already ordered some replacement, one piece (not separate washers) galvanized roofing screws. $200 shipped.
I think I'll get some of that sealant KYO linked and put a dab in as I put the new screws in.
And get new sunlight panels and seal them with that sealant.
If I am finding that they aren't going in, I'll step up to the larger size.
KyAllroad (Jeremy) (Forum Supporter) said:
https://www.lowes.com/pl/Advanced-sealant-Np1--Caulk-Caulking-Paint/4294729414?refinement=2818397894,3704070910
This E36 M3 is on a whole other level from "caulk". Use it and be sealed till doomsday. I recommend using an electric caulking gun, it's thick.
And yeah, if you just want to replace the little rubber washers you can do that as well.
That's a single component urethane sealant. I would not use it on a roof.
https://www.pcmservices.com/blog/2013/06/12/building_caulking_silicone_polyurethane_sealant/
