Metal roof correct instaltion

What did I do wrong? Here are the details. gabriel roof—pitch 4/12----perlings were placed over existing asphalt shingles perpendicular to the rafters on 24 inch centers. They were 1x4 rough sawn pine. They were nailed to each rafter. The pine was not kiln dried however I felt it had been correctly air dried.—The metal panels are 3ft wide and 23ft long. The gauge of the metal is 26ga. There are 17 1/2 panels on each side of the house.There are 5 ribs running the lenth of each panel.Two screws were placed on the flat part of the panel on each side of the edge ribs where the panels over lapped and one screw placed next to the remainder of the ribs, except at the frist and last row at the eve and ridge where two screws were placed on all five ribs. This was the manufactures recommendations. The screws used, provided by manufacture, were 1 1/2" # 10 with a metalcap and rubber washer. Their instructions were to torc the screws down to a point where the rubber washer just began to expand and stop. I used an electric drill for this task.
The house uses ridge vent ventilation with more than ample vent openings as told by many knodledgeable contractors. Ridge cap, drip eve and rake edges were provided by the manfacture and installed using their instructions. I have found no visible evidence of a leak within my attic at any time. The problem I am having is the screws keep backing out and allowing water to leak around the screws. The problem is bad with at least 1/3 of the screws involved I know the perlings are rotting bad. I want to correct this by taking the panels up replacing the perlings and screws. Will this correct my problem. I live on the Mississippi gulfcoast where the temperatures reach over 90 degrees more than half of each year. The west side of the roof seems to be worse than the east however both sides need attention. I can find no industry standards any where. The metal roof alliance at has a forum similar to yours and usually refers the home owner to manufactures recommendations.
THe metal roofs withstood hurricane Katrina very well and there are a great many metal roofs going back over the existing shingles. Also I am not the only one with this problem of the screws backing out. Thank you for takeing the time to read any suggestions will be helpful.

You should have used a 50yr shingle in the first place metal looks terrible on residential house to be start with

BAcking out? Are you sure? Any other possibilities? Is there any possibility that the purlins cracked while installing? Into wood…were these self-tapping screws? Did you mill your own lumber?

Where the wood is not water rotted the screws can be tightened several
turns. I am sure the wood did not split during installation. There was over
1000 Lf of lumber that much could not have split. The wood was purchased at a reputable local mill. The metal was drilled prior to installation 5/32" drill and #10 screw supplied by roof vendor.

Thank you for your time

What type of screw? The only time I have seen this was when self tappers with a fine thread were used on wood, and the drilling action of the screw bored a hole too large for the thread to grab. This was not fastener backout, though. … /screw.jpg

Aaron, the above link should bring you to picture of an example of the screws used for the installation.


You have GOT to be kidding me here… this guy has a structural question & you’re giving advice on [correction] ***telling him ***what his favorite color should be? I sure hope you had a bit of sarcasm in that post (not evident) because that’s a lame response IMO.

& If we’re going to talk metal in appearance, you should come down to Texas where all of your BETTER built houses have some form of metal roofing; standing seam, exposed screws, snap-lok, 5V crimp, etc.

IIRC, in Texas, insurance is supposed to give @ least a 28% discount on “winstorm” policies as well as the same % discount on a deductible should you actually HAVE to file a claim (provided you use the correct mil thickness).

----------Sorry for the ThreadJacking, but I couldn’t let that slide.

I know a lot of people do put metal over existing shingles, but IMO it’s a bad choice because you never really do get an idea of the roof deck condition should you actually need repairs to it.

Plus, (here in Texas, anyhow) the cost to remove the old shingles isn’t too bad… on a ‘normal’ pitch house, it’s around 20.00 - 30.00 per square max.

hello jayman,
yeah you wont be refered to no manufacture specs here.

first let me say
uh mr swamps of jersey , your litttle 50 shingles are gonna be layin in the gulf of mexico, soon after they are put one mr. jaymans house.
if you have the money and you live on the coast you put metal on
your house.
its the only thing that hold up to the hurricanes.

now that school is out ( thank you mr ranch hand roofing for assisting),
on to the problem at hand.

mr jayman.
did we go and put on a dark colored metal, on our house, that exspands and contracts to such a point that it helps pull out the cheap ass screws that you have used?

dont be alarmed if i am rite.

take off your panels, fix any of your 1x4 or just get rid of em alltogether,
dont need em.
then replace and use a stainless steel # 10 pointed (no selftapper thank you Aaronb), 1/4" hex head and use a seperate stainless steel rubber bounded 3/4" washer. get rid of the drill and use a screw gun
you can fin all this via internet.

i have spoken.


at such

  1. I would never recommend exposed fasteners.

That said,

It may be possible that the purlins you ran perpendicular to the rafters, being only 1" thick, are not allowing the space under the metal to breath properly.

i own a roofing company in mobile alabama 30 minutes from you
and as far as wind goes you have one of the best roof designeds
out there i believe you will find that what is happening is that the wood you have purchased from the sal mill has shrunk quit a bitt my step father /partner also has a sal mill and cutes a lot of cypress takes forever to dry