Repairing leaks on a barn roof
Hi, I'm not a roofer, and I'm not even in construction, but I hope someone can here help me. I have a horse stable (but no horses) that is 37' x 37' and a roof made of steel panels (similar to the screenshot I have attached below). The barn is probably around 40 years old. It was here when we bought the place 30 years ago. I now use it for a workshop.
The steel sheets are probably something like 25 feet long and attached to the rafters with nails with neoprene washers, as well as with some screws in certain places, also with neoprene washers. Over the years a lot of the washers had deteriorated, causing leakage, which has been getting worse.
I asked a friend who had been in construction for advice, and he suggested that I cover all the nails with elastomeric caulk, which I did. I also replaced many of the nails that had rusted out or were missing altogether with long screws and neoprene washers, and covered them with the elastomeric stuff. Every screw or nail is covered.
After a couple of weeks and a couple of moderately heavy rains, it appears that the leakage has stopped, but I am not real sure if the caulking is holding up like I hoped it should. It may just be my imagination, but now I am wondering if I got good advice from my friend.
So my question is, was the elastomeric caulk the right choice? Or is there something better? If I need to redo it, it needs to be done pretty soon, because I am nearly 70 and I need to get it done before I'm too old to do it.
I really appreciate any advice I can get.
First of all, it's good that you don't have any active leaks, which makes this all less urgent.
Please keep in mind that without actually seeing the roof, my opinion will have limited value for your specific situation, but I can tell you a few things based on best practices for metal roofs. After reading what you wrote, I do have a few thoughts.
1. If you have forty-year-old galvanized steel panels in place, and they are in pretty good condition (no corrosion), you could probably get another 20 years of service out of the roof. I don't know if your roof is just galvanized or has another coating on it, but 20 more years is a reasonable expectation if there aren't any current issues with the coating/protective layer.
2. The proper maintenance/repair procedure for failed washers at metal roof fasteners is to remove and replace the fasteners. Typically you replace the fasteners using the same holes, but using a fastener one size bigger than the existing fasteners. New fasteners with new washers should perform well for at least 30 years. That probably would have gotten you to the end of the useful life of the roof.
3. The fact that there is now caulk covering the heads of all the fasteners is a problem. If you try to remove the caulk in order to remove the fasteners, you are going to scratch and damage the protective coating on the steel roof panels. Scratching the coating/protective layer around all the fasteners would probably lead to serious corrosion pretty quickly.
A) If you still want to remove and replace the fasteners, you'd have to be extremely thorough when you remove the caulk. You'd have to remove all traces of it in order for the new fasteners to be installed properly. You'd then have to apply your own protective coating to the areas on the roof panels that you just scratched at those locations. Rust-Oleum makes a few different products that would work. This would be difficult and time-consuming work.
B) You leave the caulk the way it is and treat it as an on-going maintenance item. Exterior building sealant can last anywhere from 5 to 20 years, depending on a few different factors. (Building sealant is always a maintenance item and should be avoided if possible.) I don't know what kind of sealant you used, silicone lasts the longest, up to 20 years. Polyurethane sealant, on a roof, usually lasts 5 to 10 years before it needs to be replaced.
Old caulk is a lot easier to remove than new caulk. You could remove and replace fasteners as each one becomes a problem. Of course, this doesn't help you get a solution in place quickly like you want to.
I'm guessing you're looking for advice from other sources as well, so I want to say that if anyone tells you to cover the fastener heads with a roof coating or a roof repair tape, that would be a bad idea. The tape will end up with pockets of air around the fasteners. A coating will normally delaminate around the fasteners and also end up with pockets of air underneath it. Moisture will accumulate in these air pockets and corrode your roof over time. I've seen this happen fairly often.
I wish I had a simple recommendation for you. Hope this helps. Let me know if you have any follow-up questions!
Thank you Jack, this is some very good information.
I can't tell by looking if the steel panels are galvanized. For a long time there had been trees overhanging the roof and leaves had been accumulating for years, but I trimmed back the trees (or removed them altogether) and cleaned off the leaves. It looks like the areas under where the leaves had been are a little corroded, but it doesn't seem to be really damaged.
The sealant that I used is APOC #264 Elastomeric Roof Patch in the caulking tube.
You had mentioned that 'Building sealant is always a maintenance item and should be avoided if possible.' Can you expand on that a little?
Because of my ignorance, I have not been very attentive to the condition of the roof, and only when the leaks got really bad did I realize I have a big problem. I hope that I have caught this in time.
Thank you again!
So that APOC sealant is a polyurethane/acrylic hybrid, and I'd expect it to last 10 years at most. A silicone sealant is preferred on metal roofs because it adheres well, is more UV resistant, and stays flexible longer than most other sealant chemistries. Silicone sealants also don't stick well to other sealants, so you can't use one now.
I think you're pretty much stuck with what you've got in place at this point.
On the bright side...
The average life expectancy of a steel panel roof is 40 to 60 years, so you've gotten a decent amount of service out of your roof. It's good that you cleaned the leaves off and trimmed the trees back. You might even consider wire-brushing the corroded areas and then painting them with a rust-inhibiting paint if you want to try to get a few more years out of the roof.
As far as what I was saying about avoiding sealant if possible..
People often use sealant because it's a cheap and quick solution (at first).
Sealant always degrades and fails and eventually leaks. It has to be replaced regularly, whether it's every 5, 10, or 15 years, it's always an ongoing maintenance item. It's simply a good idea to avoid creating maintenance items if possible.
An example would be replacing the fasteners on a metal roof when the washers fail instead of covering them with sealant...
Other situations include roof penetrations (like when a cable or conduit runs up through the roof. It would be better to install a gooseneck flashing, which doesn't depend on sealant, instead of just sealing around the hole) or roof membrane terminations at walls (it's better to run the roof membrane up and over the top of the wall instead of depending on sealant to keep the edge of the roof waterproof). Permanent, maintenance-free solutions are always better if they aren't too expensive.
I won't keep going on about sealant and run the risk of putting you to sleep, but I do discuss avoiding sealant in at least a couple of articles. Pitch Pockets and Tilt-Up Walls off the top of my head.
Hope this was somewhat helpful!
Jack, I really appreciate your help with this. I sorta feel like my patching might be inadequate, since I did not use silicone. I am tempted to scrape off the elastomeric and start all over again. But I will at least do any further patching, if it becomes necessary, with silicone. Do you have a specific recommendation what kind it should be?
I want to make sure the barn is structurally sound for as long as possible, and let it be in good shape for the next owners when we are ready to sell the place. That won't be for a while, I hope, but I still feel like it should be in good shape.
Thank you again!