ACQ Treated wood and Metal Roofing

[bigballer]

I am in the process of constructing a horse shelter and am using ACQ treated wood throughout (posts, beams, rafters), now I am reading warnings about metal roofing/flashing and the corrosions issues when the two meet. my plan was to lay the metal roofing right on top of the rafters and attach with roofing screws. Is this going to cause me big problems? What are the effects and how long does this take? Does the metal roofing rust through? Does anyone have any firsthand experience with this?? Please help, I need to get this in place but don't want to sabotage the integrity of the structure by not doing it right.

 

[SnowRidge]

This product instead of metal might be one way to go until this stuff gets sorted out. You would have to watch out for the fasteners, though. Might have to use their stainless nails.

 

[KYErik]

I have heard about this issue as well and would not want to risk the chance of corrosion, especially with the cost of metal.

Typically, the rafters/roof stringers shouldn't need to be treated (they should stay dry). This will save you some money over treated wood and corrosion won't be a factor.

The wall stringers (horizontal 2X material you screw the metal to) are more tricky. I built an open lean to on the side of my pole barn last summer. If there is a strong south west wind or south east wind, the exposed stringers on the end of the walls could get (if wind blows in the opening). I used untreated 2x4's and applied a wood preservative to the ends that might get wet. I then screwed the metal siding to these untreated 2x4's.

Another option for the side walls is to buy some rough sawn oak to use for the stringers that might get wet and screw the metal to the rot resitant oak.

PS- don't forget to use the approved wood screws/nails for ACQ treated wood

 

[tallyho8]

I have built and torn down many horse barns in the past. When you remove a metal panel off an old barn you can tell where the purlin was. The panel will usually be a little rusted out whether the purlin was treated wood or untreated wood because moisture will usually get in between the panel and purlin one way or another.

Untreated purlins/roof stringers will always rot out much quicker than treated purlins because water will condensate on the bottom of the metal panels and condensate will run down the inside of the roof and settle on the purlins so I always use treated wood for purlins.

My method to help prevent this rusting is to use good old fashioned tarpaper. I cut the paper in strips a hair wider than the purlin and staple them to the top and place the metal panels down on the tarpaper. I like to use galvanized screws with rubber washers on the flats to secure the panels.

One cheap roll of tarpaper will do several barns this way and prevent the panels from ever touching the treated wood. I have found nothing, easier, cheaper or more efficient for this task.

 

[mocassincreekranch]

What Tallyho8 said is dead on the money.

 

[shvl73]

Here is a bulletin from US Steel that goes over this issue.

 

[bigballer]

i picked up some roofing felt today, was looking for snow/ice shield but the place i was at didn't carry it. i also got the spax acq roofing screws. i think this should take care of the potential problems or at least delay the corrosion as long as possible. i appreciate all the responses, great info and i feel much more informed now.