Replies

1. 
   fingersandtoes | Nov 23, 2009 12:36am | #1

   Welcome to the world of old metal roofs :). When you think about it, it was a silly way to build. The roof is kept waterproof by several thousand gasketted penetrations that also are subject to seasonal movement. Snap-lock or other hidden fastener systems revolutionized metal roofing. Unfortunately for the rest of us still trying to maintain the old style connections there isn't much I know of that you can do beyond periodic replacement of the screws. Hope some one else has a better solution.

1. 
   cjeffrey | Nov 23, 2009 12:41am | #2

   Change the screw, I have heard some use high quality caul, just a dab on the hole before you put in the screw.

2. 
   AitchKay | Nov 23, 2009 12:50am | #3

   One of my first jobs, back in ‘73-’74, was building a couple of pole barns. When we started, the nails we used were Led-Heds, which had solid lead washers. You think yours are a PITA! A marginal seal from the get-go, and zero resiliance/springback. You’d have to go up as the wood dried out, and tap down every single nail.

   By the time we finished the second pole barn -- a real monster, 140’ long, with 85’-long FREESPAN 2x trusses, the industry had switched over to neoprene washers, which were much more forgiving. Still nails, though, hand-driven, every one.

   Yours are screws, which makes your job a piece of cake, comparatively. And I’m afraid you’ve answered your own question -- replace ‘em.

   I wouldn’t try to replace the washers only, and I wouldn’t do it selectively. Get up there, work your way across the roof section by section, and replace every screw: your labor getting up there is worth way more than the cost of the screws.

   I’ve not heard of using a sealant as well, but if it was compatible with the washer material, it might not be a bad idea -- that’s really an Ag-style roof system, not really meant for residences. Don’t use any sealant, though, until you’ve cleared it with the screw manufacturer.

   Good luck,

   AitchKay

3. 
   coonass | Nov 23, 2009 12:51am | #4

   Kroc,

   Use the right screws and it should be good for many years.

   http://www.bestmaterials.com/SearchResult.aspx?CategoryID=842

   KK

4. 
   Piffin | Nov 23, 2009 01:09am | #5

   I have a few thoughts on this.

   You leave some open questions in my mind - first is that you say the roof metal is screwed to the rafters. I have never seen that one.
   My own house has purlins running perpendicular to the rafters and the metal is screwed to those, but I can't imagine what is holding the metal up if the only fasteners are int e rafters and there is no decking. If that truly is that way it is built, it's time to take it all off and rebuild it.

   #2 thought - I learned a long time ago after a few metal roofs to use the larger shank screw with the 5/16" head, rat6her than the 1/4" head with smaller shank that most use. The amt of displacement of wood is much larger so it holds better and there is more shank surface area for more friction holding also.

   Now then, you say self tapping screws. That suggests that you have screws made for metal to metal attachment as in metal buildings. The screws made for metal to wood are self drilling but not self tapping. Maybe you have the wrong screws and that is why they keep loosening up.

   I have not had a problem with washers drying out from heat or age, but I have seen a lot of screws over driven so they crack almost immediately from pressure, so maybe they are installed too tight. How hot is your climate and how old is your roof? Cheaper screws from china might be more prone to cracking too though.

   Alas, since I am not there and cannot see any of this, I don't know if we have a problem with semantics or something else, but you have some clues top start with now. Hope this helps..

    

    

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5. 
   Piffin | Nov 23, 2009 01:13am | #6

   also, how steep of a pitch is your roof?

    

    

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6. 
   Piffin | Nov 23, 2009 01:23am | #7

   reading this thru, I see mention of old leadheads, which were installed on the high spots of corrugated metal roofing.
   This older practice has lead some to mistakenly use screw and washer type fasteners in the high points of the newer type metal roofing. This is wrong tho. The screws must be used on the flats, not the ridges. Placing them on the ridges will result in loose and leaking screws.

    

    

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   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
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1. 
   frammer52 | Nov 23, 2009 01:33am | #8

   Beat me too it!

1. 
   Piffin | Nov 23, 2009 01:39am | #9

   but look how much speculating on insufficient information I had 6to do to beat you! 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

1. 
   frammer52 | Nov 23, 2009 02:44am | #12

   Yeh, you had a head start, I wasn't on when you were speculating. 

    

1. 
   cjeffrey | Nov 23, 2009 03:08am | #13

   The metal roofing we use around here usually on sheds & barns, uses a screw with a neoprene washer. You screw beside the rib on the flat. So the metal is tight to the wood and the washer tight to the metal. If you screw in the top of the rib the rib can flex. Do not over tighten as they are kinda like a gasket on a car and can leak if over-tightened.I never use the torque settings on the drill. I have seen guys do that. The washer is tight to the metal and the drill kicks out, but the metal is not tight to the wood strapping. I use variable speed cordless drill and pull the trigger enough to set the screw. Also pre-drill all holes. The best bit I have found was suggested to me by an auto-body guy. They are 1/8" and double ended. Usually drill through up to 15 sheets at a time. I found regular bits broke easily these are shorter and tougher.

2. 
   Piffin | Nov 23, 2009 02:22pm | #14

   "The washer is tight to the metal and the drill kicks out, but the metal is not tight to the wood strapping."Not if you hold the gun right. Use proper setting on a Tex screw gun and get some pressure behind the gun and it will do better work three times faster than a drill. 

    

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3. 
   cjeffrey | Nov 23, 2009 04:50pm | #15

   I have not heard of a 'Tex screw gun', I did a google search and did not come up with much. One I saw was a "tek' it seems it is sorta like a drywall screw gun?

4. 
   Piffin | Nov 23, 2009 05:49pm | #16

   yeah, tek gun.way the adjust works is by depth of screw set rather than torque, which varies if you hit a knot or denser wood. It's made for steel buildings and metal roofing.A lot of leaks at fasteners are from using wrong gun and ending up with under-driven or over-driven screws. 

    

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5. 
   cjeffrey | Nov 24, 2009 05:28am | #17

   Never heard of it before, did a little Google searching. I need to see one and try it out. I'll talk to my metal roofing supplier. I usually do 2 ro 3 metal roof a year.

6. 
   Piffin | Nov 24, 2009 06:02am | #19

   I did a couple hundred once upon a time. I use a Milwaukee. 

    

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2. 
   Karl | Nov 23, 2009 01:54am | #10

   Piffin, You have me intrigued here. I am getting ready to screw down corrugated 26 gauge on my barn roof and looking at instructions online I read to screw the troughs on eaves and endlaps and screw the peaks in the "intermediate" areas.
   http://www.unioncorrugating.com/corrugated.html
   The instructions I refer to are a pdf file I downloaded from this website.Anyhow, I hear you saying that with neoprene washer screws you should screw into the troughs of corrugated roofing NOT the peaks of the corrugations.Or Are you referring to flat metal roofing that has sharp V's folded into it?Thanks,
   Karl

1. 
   Piffin | Nov 23, 2009 02:25am | #11

   I am referring to the newer "propanel" style with about an 8" or 11" flat and a 1" ridge, not corrugated.Definitely use the manufacturers recommendations. 

    

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3. 
   AitchKay | Nov 24, 2009 05:59am | #18

   RIGHT! We had learning-curve problems while changing over from the Led-Hed brand on the ridges (where they were up above most of the water) to neo washers tight to the purlins (where they were squeezed for a tight seal) -- BITD, we didn't get a whole lot of spec sheets, so, like a lot of guys, we made the very same mistake Piffin refers to.Piff -- do you folks currently use Ag products, or are there exposed-fastener products similar to those discussed here that are currently approved for residential?AitchKay

1. 
   Piffin | Nov 24, 2009 06:06am | #20

   Not sure what you mean by "approved"?99% of my metal roofs was on residential. A lot of it on FHA financed homes and condos.Brand names i've used:
   Pro-Panel
   Regal Rib
   McElroy Metals
    

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

1. 
   AitchKay | Nov 24, 2009 07:05am | #21

   Not exactly sure myself -- I guess I meant local-code approved. But thanks for the brand names -- a tour of their websites will surely help to inform me.AitchKay

7. 
   Schelling | Nov 24, 2009 02:53pm | #22

   Good suggestions about the screws.

   One other problem that I have seen from metal roofing attached to purlins was condensation on the underside of the roof in cold weather. When the roof heated up by the sun, the frost would melt and cause water to drip into the house. This was not a huge problem but we did pull the roofing off and lay plywood sheathing and tar paper under it when we were doing a related project.

1. 
   fingersandtoes | Nov 24, 2009 07:31pm | #23

   Good point. Most manufacturers recommend installing over sheathing now. Sheet underlayment such as Tri-flex works better than building paper which can get too hot and adhere to the metal roofing.