Got A Question For The Roofers...

Mudd Dogg

Got a question for the roofers of this board. When installing a metal roof over shingles, are 1X stips of lumber needed between the shingles and the metal roofing. Meaning are they required or not. My brother in law has never done a metal roof in his life and insists that they 1X strips are not needed. If it was his house I wouldn't care, I can't stand him. But he's renting it from my other brother in law which I do like and I don't want the other one to mess up his house for he is trying to sell it.

Any advice would be appreciated.

indm45

yes mudd tell they are required,for1 it lets the roof breath between the meatal and shingles. also it gives a better strength for screwing or nailing, and helps the fastning of these to look uniform and more eye appelling, tell him not to do it half ass

AaronB.

I have no idea, but if I had to bet money on it, I would say go with the first reply.

Pgriz knows metal.

__________________
http://www.roseroofing.net/
Seamless Industrial and Commercial Roofing Systems, Residential Repair. For Those That Demand Quality!
Free roof inspections within 12 miles of our locale.

red_cedar

Depends on the kind of system it is. Shingles, Panels ?
Some are ok to install over purlins( wood or metal ) while others are not. Best to check with the manufacturer on what their system can and cannot be installed over.I just put 1x4's on a roof I am the process of doing.
The system is a vertical panel with concealed fasteners. This particular sytem I can do that because of the panel design and thickness of material. In this case 1x4s are used only because in the course of removing the old roofing, the substrate ( plywood ) appears as though it wouldnt have much holding power for the screws, other wise I would have put it on the plywood with an underlayment. Other vertical panels systems can go over the shingles
or over the 1x4s or 2x4's. Existing conditions play a part in it also, its not a one application fits all. IMO. check with the manufacturer and follow their installation recomendations. Hope it helps.

Glasshousebltr

It's been my experience that the more air between the shingles and metal, the better. From what I'm told the trapped heat can bake the shingles bad enough to force the metal up between the seams and give you an ugly roof in a few years of temp fluctuations.

Bob

__________________
Bob

pgriz

Most panels are installed over furrings, while most shingles will be installed directly on the sheathing. As Red_Cedar said, you have to check with the manufacturer of the system you are using.

Personnally, I don't like the practice of only using horizontal furring strips, as the air cavity they create does not actually help with ventilation since air needs to rise by convection. The better practice is to place 2x4 vertically, then lay 2x4 horizonally on top of them. This creates a vertical air channel for allowing air flow. Of course, you need to make sure that the inflow at the bottom is clear, and that there is an appropriate vent (ridge vent or vent cavity) to allow the warm air to get out.

tinner666

It's seldom mentioned, but the expansion/contraction of the metal directly on shingles will sand holes through the metal.

Grumpy

Tear off the old roof.

GunnCon

Grumpy you are 100% correct.
I would never install metal over existing asphalt shingles. I always tear off the shingles to inspect the sheathing and thats very important. When I see a roofer go over the existing roof I would have to question why? Well I don't really have to question it I know why.

AaronB.

I know why too....cheap azz homeowners or lazy azz roofers.

__________________
http://www.roseroofing.net/
Seamless Industrial and Commercial Roofing Systems, Residential Repair. For Those That Demand Quality!
Free roof inspections within 12 miles of our locale.

tiny

Well i was waiting to see if any body would mention the expansion contraction over shingles . tear it off then grace or another smooth icws as far as air flow do as suggested and profile vent cap we did a huge job in 2002 546 sq and it is a thing of beauty . except for the color seafoam green yuck!!!!!

tooldude58

Sounds like metal roofing is another animal entirely! Dan-o

Grumpy

Each type of roof is totally unique however I think you will find overall quality conscious roofers always want to tear off regardless of what type of roof system it is. Infact the ONLY roof system I am willing to lay over, and warrant, is flat roof systems.