Metal Roof questions... 2019.

[ultrarunner]

The old 1860 Barn is all redwood board on the sides and tin roof with nails and lead washers... never noticed any condensation under the metal roof but the barn is quite airy...

I was told the metal roof was put on in the 1940's... it looks well weathered but keeps the rain out.

 

[Rustyiron]

There have been MANY improvements in materials, design and techniques.
Coatings (paint) have improved dramitally in long term performance and colors.
Concrete post bases (Permacolumn) has eliminated placing wood posts in the ground that will eventually rot.
Laminated posts that are and will stay straight.
Laminated (Lvl's) header and structural members that can increase spans or simplify construction.
Yes, some screws are better with the cupped washer, but an installer can still tighten too much and damage the rubber seal.
Advanced fasteners, mainly timber screws has improved holding over pole barn nails and lead to a stiffer structure.
There are several that make an under the panel or applied to the panel material specifically to handle condensation and that's just off the top of my head. I might argue that the old galv. was heavier, although one should seek out a G 100 rating if they are going galv. on the roof. For the cost, I like to use Tyvek (white in color) under the metal. Metal leaks a lot of air and it also looks very nice from the inside, adds a lot of brightness.
I'll look for a link to a trade mag. I get. (Frame Building news)

 

[Arky217]

Number 1: If you don't want it 'raining' inside your barn, you need to either put
the metal over osb or plywood or else put insulation on the underside.
If you go with osb or plywood, first put down a layer of synthetic felt.

Number 2: If you're going with 'barn panels' or corrugated metal panels,
put the screws in the ridges and not in the flats unless you just like
repairing leaks a year or so down the road.

Number 3: Spend just a little more and go with the hidden fastener type
panels such as HLok (16" width). They really aren't that much more
expensive and will last all your life without ever having to worry about leaks.

 

[ultrarunner]

"Raining" must depend on location?

 

[newbury]

"Raining" must depend on location?

Depends on your climate. Here in Mississippi before I had the roof replaced I could depend on rain showers inside if the prior day was hot and humid and the next morning was cool. The wet air would condense against the ceiling and I would often get "morning showers" inside. Used up a LOT of plastic and Fluid Film protecting equipment.

 

[drssg]

Depends on your climate. Here in Mississippi before I had the roof replaced I could depend on rain showers inside if the prior day was hot and humid and the next morning was cool. The wet air would condense against the ceiling and I would often get "morning showers" inside. Used up a LOT of plastic and Fluid Film protecting equipment.

It’s a different situation, but when we first bought vacant land, the first structure we put up was a small vinyl covered shelter to keep my tractor out of the weather. With all the condensation, I sometimes thought the tractor was just as wet as if I stored it outside.

 

[montanadave]

There are sound-dampening paints/coatings available. I looked into them for a plan I had with an outdoor patio area covered with a metal roof (never built it, went with another design). Never did explore the actual cost of this product (Noxudol 31 Product Information | Best Rust Protection for Cars Noxudol). It might be cost prohibitive for a home-owner on a larger scale.

I'd find a local steel roofing and siding manufacturer and listen to their tech support people.

 

[EddieWalker]

There is a line between building it well, and wasting a lot of money without any noticeable difference to the end product. First thing you need to do is talk to your metal roofing supplier. This is where a lot of people go wrong. Do not buy from a national sales company that is just buying from the manufacturer and adding fees to it without any support or hands on experience. Since I don't know your area, I can't comment on who to buy from, but that needs to be your main focus. Here, I have a company caller Mueller's that manufacturers all their products. When I need metal for a roof, I go to their office and talk to the guys there that know their products. They sell very good quality screws and from what I understand, they are the biggest metal roof supplier in this part of country.

My house has a metal roof. Most of it is over 2x4 purlins on the flat with trusses 4 feet apart. My purlins are 12 or 16 feet long except a few that are only 4 feet long where there was no other option. My porch has rafters 2 feet apart and OSB over them, then 30 pound paper on top of the OSB, and then my metal on top of the paper.

When I build my barn I will put my trusses every 4 feet with 2x4 purlins every four feet on the flat, and then attach my metal to the purlins. I will have open eaves for and a ridge vent to get maximum air flow. Then I will install metal on the ceiling and blow in 2 feet of insulation to get R60.

 

[Diggin It]

When I build my barn I will put my trusses every 4 feet with 2x4 purlins every four feet on the flat, and then attach my metal to the purlins. I will have open eaves for and a ridge vent to get maximum air flow. Then I will install metal on the ceiling and blow in 2 feet of insulation to get R60.

I'll be doing very similar on my shed, but will not be adding paper or insulation of any kind. Care I not one iota about a few morning dribbles or sounds. As I mentioned on my shed thread, I may be doing a temporary covering to get it in the dry before I add the metal at some later stage. If I do so, I'll probably leave it in place and put the metal over it.

On the house, I'm doing 1x4s nailed through the shingles, then screwing the metal to them. If the screws end up leaking some day, there is a very good chance I'll never know it.

 

[tcreeley]

My metal roof on the barn here in Maine is just on 2x4's on top of 2x6 rafters. The 2 story barn is well ventilated - eaves and cupola. Never a moisture problem any time of year.