New 5v tin over old 5v tin?

[coosa]

I have a farm cabin my father and I built in 1979. We used 5v tin and nailed it down with lead-headed nails in the v. I had a limb fall through a panel about 10 years ago, and repaired it by simply laying a new piece of tin over the old and screwing it down. That is the only problem I've had with the roof in 39 years, so I think we got our money's worth.

But it is getting really rusty now and I think I need to go ahead and put another roof on it. My son-in-law wants to tear the old tin off and replace it with a different type of metal roofing. It sure looks like to me that it would be easier and cheaper to just put new 5v tin right over the old tin. I found out when I made that repair that I had to remove the lead heads from the nails, but that was pretty easy. Once the lead was cleared out, the new tin fit right over the old and it was easy to put screws into the rib.

Someone told my son-in-law that we might have a moisture problem if we just put the new tin over the old. Does anyone have any experience in doing it this way, or is it better to tear off the old one and start over? Thanks for any ideas.

 

[Oldoak]

Just had our 40 year old pole building reroofed (metal roofing) last November. Removed all the leaded head nails and old metal before screwing down the new metal roofing. I think it makes for a neater job and allows for inspecting the condition of the wood purlins for any rot. We also install a different style of sheet metal roofing.

I do believe there could be the possibility of a moisture problem from condensation between the two layers if the old metal was left on.

 

[Wagtail]

Fully agree with Oldoak and all of his stated reasons.

Especially if, after all these years, you're getting rust. Times & technology have advanced... the typical metal roof here in Aus is a "colorbond' steel (usually corrugated, but not always so - I had to Google "5v" to see what you were referring to), the coating of which really makes it last.

Heck, the "colorbond" colours are so standard here that house paints are matched to the same shades.

25 year roof on my house. No leaks or loose panels:

 

[coosa]

Thanks, Guys. It sounds like we need to take the first roof off.

Back when we built the cabin, the 5v style was supposed to be a big advancement over corrugated tin. Hardly anyone uses it now, but the panel I bought 10 years ago for the repair was about half as thick as the original. I doubt we can get 39 years out of anything on the market now.

 

[Rustyiron]

Another vote to pull the old roofing. This will also give you a chance to inspect the purlins for any that need replaced. Screwing into spongy or old wood that won't hold a screw.......... Remember your goal of another 39 years.:thumbsup:

 

[Cord]

There are spray applied coatings that can extend the life of the existing roof. The coatings are rubber based and are applied with an airless sprayer. Here's a video that shows the whole process: Easy Metal Roof Repair Using Ames(R) Maximum-Stretch(R) Spray-On Coating - YouTube Just google "metal roof recoat" and you'll get hundreds of hits. If you do decided to pull the existing roof, carefully remove the panels and post them on Craigslist. Last I saw these panels were fetching $10 a piece and up. That rusty metal look is really hot right now.

 

[Oldoak]

Thanks, Guys. It sounds like we need to take the first roof off.

Back when we built the cabin, the 5v style was supposed to be a big advancement over corrugated tin. Hardly anyone uses it now, but the panel I bought 10 years ago for the repair was about half as thick as the original. I doubt we can get 39 years out of anything on the market now.

Something to keep in mind when shopping and pricing new roof steel. Most manufacturers make it in several different gages (thickness), 29 gage being the thinest. I went with 26 gage. Then there are 24 and 22 gage which is getting into commercial grade material and very costly.

 

[Rustyiron]

Something to keep in mind when shopping and pricing new roof steel. Most manufacturers make it in several different gages (thickness), 29 gage being the thinest. I went with 26 gage. Then there are 24 and 22 gage which is getting into commercial grade material and very costly.

And they also have different "thickness" galvanizing with "G 100" being the heaviest coating.

 

[Stimw]

If you want the building to last I would remove the old roof.
I just got my home roof replaced with 29 ga. metal roof.
I priced the metal before I had the roofer do it and this metal is called "Galvalume" and costs $1.44 a linear foot (1' X 3').
It is much better than 5V.
Also they screwed it down in the rib not the flat and he said the engineers approved of this.
My roof is permitted and inspected. Roofer has his own machine to make the panels!

 

[quicksandfarmer]

Maybe I'm missing something, but if you're taking the nails out what's holding the panels on? It seem like it would be incredibly unsafe to be on the roof with all the panels un-nailed. At that point removing the panels is just a matter of lowering them to the ground, a negligible amount of work.