It would depend on the type of metal roofing. It appears you are talking about thru-fastened panels with exposed fasteners rather than a system with hidden fasteners like standing seam. Exposed fasteners can have the problem you mentioned.

In any case I would apply Ice & Water Shield under the entire system.

There are literally dozens of types of metal roofing, from the exposed fastener panels you're referring to, to standing or snap lock panels, to metal shingles, shakes, and tiles. What do you want?

Better to get the hidden fastener roof, but if you do get exposed fasteners, you are supposed to replace the fasteners about every 10 years. Also the fastners need to be tight but not overtightened, see page 11 http://www.menards.com/main/store/20090519001/items/media/BuildingMaterials/MidwestSteel/Install_Instruct/ResRfHH8-24-15Low.pdf

Best to install exposed fastners with a drill that has torque settings and figure out the correct torque so it is tight but not overtight.

yes neoprene gaskets will degrade in 10-15 years or so.

and will have to be changed.

you want the gasket to 'plump' but not flatten out.

torque drill is best as stated above.

best of luck

I assume the metal roof with the hidden fasteners on the panels is more expensive than the exposed fasteners. Do you know if it is more cost effective to get the hidden fasteners initially than changing out exposed fasteners every 10 years or so?

It will be less of a pain, the hidden fastener system will require not much maintenance and should last at least 50 years.

It of course all depends on the roof, manufacturer, style, thickness, etc. "Many" ( I don't want to say most or all), exposed fastener panel systems are specifically made for agricultural style buildings and are thinner than the panels used on snap-lock residential systems, the paint is thinner and not applied the same way, and the details and accessories were cheaper/different. When I went to classes and installed them (more than a decade ago), metal residential roofs in my area were about three times more than an agricultural, and could get more expensive from that. I can tell you that the roof on my cabin (in a heavy snow-load area), in metal was 5x what good shingles would have cost. That was a nice roof.

standing seam roofs quite a bit more expensive in my

area also. another problem is workers aren't experienced

in standing seam, again may be a local issue.

we recently changed the screws on a metal roof. 15 year

old roof no leaks. just time to change the gaskets.

I have to say we have been keeping an eye on the

gaskets for the past few years...1500 sq ft house 4/12 pitch

took us two mornings.

what location OP? and what color metal roof?

I vote white first, then reflective.

best of luck

A standing seam roof, concealed clip/fastener, will be more expensive initially, but can cost less over the life of the panel. It is also a more substantial material than most R-Panel systems as well.