Metal Roof on Shop

Your contractor gave you good advice.

A metal roof will expand and contract alot and that why we install them in the heat of summer in hot climates and dead winter in cold climates as this keeps leakage to a minimum for many years.

What he would do is install a slip sheet (roofing felt) between the plywood and the metal decking. This allows the metal to slip on the felt when expanding or contracting as well provide the needed vapor barrier for consensastion. This is also the reason why a slip sheet is installed on any type of roof, and yes asphalt shingles move.

As Tip stated, a standing seam is the best method of installing a metal roof as theres no screw hole penetrations to create leaks or pull loose. We use a "u" shape strap that goes over the male "L" part of the standing seam and is fasten to the joist/perlins/columns with screws, then a layer of joint caulking, then the female "U" part of the standing seam slips over the male part and the "U" strap, then a button punch (puts dimples in the seam) is used to lock the standing seam parts together. The thinner the metal gauge (example;26ga vs 20ga) the closer the standing seams need to be so the wind doesn't "suck" the metal up off the slip sheet.

The next best is using screws with neophrene washers. This allows the metal pull against the washer and then the washer expands back to it's normal setting when the wind dies down.

The other method is using SM screws without any washer. Although they will hold much better than nails, if your using thin gauge sheeting, the screw head will pull thru the sheeting given enough time.

Never use nails on metal buildings, only screws. As I stated the wind will "suck" the metal outward, doesn't matter if roof or wall metal, and slightly pull on the nail head each time. After a few years the nails really get loose then your sheeting starts coming off if not renailed.

T_Bone

I decided to answer here too keep the info linked together.

It is/is not a specific brand too say. Any metal roof supplier should be able to run standing seams "if" they have the roller dies for making standing seams. You could have to wait until they make a production run this type of decking.

You can also contact local sheet metal contractors as metal roofs are part of the sheet metal trade. Most roofing contractors tho employ sheet metal workers for this type of work as the typical roofer tradesman doesn't like doing fine metal art work.

To shorten the SM contractor hunt, call your local SM Union office and ask for a local contractors that installs standing seam roofing.

After finding a contractor, ask for addresses of installed roofs. Then drive by and look at the finished product from the ground as you can quickly see major flaws,ie; deck buckled/bubbles, standing seam joints not straight, etc.

T_Bone

Now I'm a little confused. Are you talking about a traditional standing seam roof?

I just had 2220 lbs of hard roll copper (16 oz.) delivered for that. All we do is use tongs to form the pans and then seamers to do the double fold, encompassing the cleats. As the seamers are self-aligning, it's all but impossible to do anything crooked. Buckling is usually caused by over-length pans without either the correct expansion cleats, or lateral expansion joints (welts).

Copper price has risen a lot lately, but not as much as steel.

If you buy it locally, you should be able to get hemlock or a similar softwood pretty cheap - better than plywood at about 1/
2 the cost. For that matter, build the whole shop with green lumber - you will end up with a better structure and support your local economy.

As for roofs, a standing seam metal roof will last forever. More expensive to put up, but, unlike other metal roofs, which will leak around screw holes after the neoprene washers dry out (or the nails loosen up), the standing seam has no holes.

Good luck!

The RBoard is a rigid board with a very tough facing on both sides similar to fiberglass. Whatever you choose I would highly recommend you NOT use plywood by itself. You can email me if you have any questions.

JT

If you want a ceiling, the trusses will have to be closer (16" or 2') but won't cost as much per truss and will have to be designed for a roof load (ceilings weigh quite a bit). But with a ceiling, you could put most of your insulating here and have a cozy winter workshop.

Ask around local, what did your neighbor use? Is he happy with it? What would he do differently?
Then check on the contractor, talk to previous customers. How good is he? Does he do quick work or quality work?

In other words, check the integrity of the source of your information (which is impossible on the 'net). Best of luck. Hope it works out beautifully.

It seems better to me to insulate just above the ceiling and restrict the heat from getting to the cold roofing. Would it then have condensation enough to give problems?

I sure wouldn't use plywood directly under the roofing without a moisture barrier of some sort.
I would probably prefer a rubber membrane if I could afford it, although the house wrap could be used from what little I have read of the product.

If it were me, I think that I would contact a maker of sheet goods for such roofs and see what they have to say. They should have the definitive answer.