Use Foam to repair 90yr leaking tin roof on warehouse in FL?

We have a large warehouse with a 90 year old copper clad tin, standing rib roof that leaks like a sieve. We are in Central Florida and are trying not to sell the farm to re-roof the thing!

Do any of you have any experience in coatings like the foam coating w/ Elastomeric? It sounds good to us, though it is extremely expensive, around $150,000.00. We just do not know how it will hold up to the Florida heat.

Our building is an old citrus packing house. The roof is not flat, but there is not a very high pitch. There are 15 skylights that will have to be replaced. The building is around 25,000 square feet.

We have spent hundreds of hours trying to patch this roof. We’ve used Silver Dollar coating, painting all the roof two or three times. No success. We have used Elastomeric patch. No success do to the seemingly miles of 1.5" standing rib joints that could be leaking. It seems like a football field in size, when you are up there and it is an endless job of scraping, patching and coating. So we are thinking that the foam coating, that would be topped with the UV blocker Elastomeric may be worth it. However, we really do not know how many years it could hold up in the Central Florida heat. Our fear is that we would spend the $150,000+ and then it would start cracking in a couple of years.

I’d love to know about any of your personal experience with it! Thanks ahead of time for any input whatsoever!

How much for a new metal roof around your parts?

It has been a year since we have had an estimate on replacing the roof. The foam is around $6 a sf, the new roof (last we checked) would be around $8 a sf, however, with the foam, you would not have to replace the wood that has deteriorated from years of leaking, only the skylights. I noted the roof as 25,000 sf… the part that we need to repair is around 16,000 sf.

and this is good…How?

The cost. The wood that frames this building is aged and hard, like iron. We do not fear the structural integrity of the roof, even with some decay. So we can justify coating it. We cannot replace it right now!

You could use a 3.0 pound foam for the roof, and add a reflective coating if you are looking for the added R-value. If not, then you may want to just look at something like HydroStop.

Thanks Cerberus! That is what we’ve been advised so far, I just needed to try to get other opinions, it too is quite expensive on such a large roof. Have you ever seen the foam and UV coating work for very long on a roof in hot weather?

Well, we have a fair amount of acrylic-coat polyurethane foam roofs here in Houston, and it gets pretty hot here 9 months out of the year. :mrgreen:

Do you need the R-value? If so, then go with 3# foam and acrylic, but have the contractor use a urethane coating in lieu of acrylic in areas that tend to pond water; you may even want them to coat the inside of your gutters if they are rusting out, though that can get costly. If you do NOT need the R-value, then I would recommend a product like HydroStop (gaf.com/Roofing/Commercial/P … brane.aspx).

Just remember, urethanes hold up to ponding water much better than acrylics, which tend to crack and peel when exposed to ponding. Urethanes cost more of course, so just don’t think urethane is the way to go unless you are prepared to pay the difference between them and acrylics.

Be forewarned, if someone sprays foam on the outside of your roof, it will be lumpy like snow and not perfectly level and flat. So, if you want the R-value and aesthetics are equally important, you may just want to spray foam on underside of roof deck, and coat the top side of roof deck with HydroStop. If you go this route, you will likely want to use 2# (1.8#) foam on the underside of roof deck, just realize that it is closed-cell foam and you won’t realize you have roof leaks so it is important that you properly repair the metal roof.

I’ll let you digest all of that, do a little homework, and then I suspect you’ll be back with some more questions! :mrgreen: Just note and remember, I am not trying to sell you anything, and I don’t represent/peddle any particular roof system or manufacturer. In other words, I’ll look at your problem and give you the best solution in my opinion; whereas, a single-ply roofer/manufacturer will try and sell you single-plies, a metal roofer/manf. will try and sell you a new metal roof, and so on . . . I have no ties, so I try to pick the best product for the application. I mention this because you are most likely to go ask your roofer questions, and you may even trust him more than I because you are talking to him in person. So, do your homework and know what you want before someone sells you a roof THEY want to put on.

And as always, photos would help! I’d like to see the condition of the metal roof (overview), close-ups, and the seams. I’m assuming you have standing seam arch. panels over steel framing and purlins. If you have 5v-crimp over plywood or some similar configuration, it will make a difference in what you should do.

I have a real good friend of mine down in fl. that is certafied with hydrostop, pm me if you want I could give him a call and have him take a look at it.

I would have to ask how often it has to be recoated,because that will be added cost down the road to maintain the warranty.Can this roof be retrofitted with metal hat channels and an r panel roof system installed? I would believe if so it would be much cheaper if your deck is solid i see why not,we do a lot of retrofits.They are light weght and actually reduce roof surface temps because of the airspace.

How do you find your leaks? :o

When we install a retrofit roof there is no leaks,i give a 10 year labor warranty on steel. :roll:

You mean as far as you know you have no leaks. I’ve seen metal installed over a built-up roof, and you talk about a mess. Every time the metal roofs leak, they drip onto the underlying built-up roof, the water then migrates to a place where it can either pond between the two roofs or leak in from the built-up roof. A true mess and a disaster waiting to happen if the water collected between the roofs puts stress on the roof framing.

I’m just not a big fan of hiding one roof beneath another. You either won’t know you have leaks, or you’ll have one that is hard to identify. I know, because it is part of what I do for a living; roofing forensics.

Been retrofitting roofs for over 20 years no problem here,we also know how to install metal roofs.Ive been in this business for 30 years but i guess i know nothing.I guess the millions of dollars in roofs i have down count for nothing.I dont hide my identity on here,you click on my website.

I would shop around for a spray foam roofer if price is a concern. The Florida heat shouldn’t be, as like you said the UV top-coat keeps most of the potential heat away from the foam in the first place, and there are foam roofers operating in FL who do this every day. All the best with you and your roof! We’re here to help.