Pole barn question

TomDavis · Aug 10, 2015

For what it is worth.
Our advice comes from a wide range of experiences. All that really matters is that you feel like you did the right thing based on what you knew and understood at the time. Who cares what we think or what you decide later. Chalk it up to experience. All that matters is you do not want to regret what you decided because you did not follow you intuition.

GLyford · Aug 11, 2015

For those places where tin might touch pressure treated wood, there are several things you can use. You can use that peel-and-stick flashing like they use around doors and windows. You could also use strips of tar paper or rosin paper...if you read the fine print on some of the commercial flashing for deck ledgers and such, they recommend tar paper, so I suspect it would work for siding, roofing, and drip edge type stuff too. Galvanized, coated or stainless nails, screws and bolts, of course.

For appearance boards like rake boards and eaves, you can use the plastic stuff, like Azek or Veranda. I'm gradually converting over all trim on my house to it as I need to replace pieces. It's pricey, but never needs painting and won't rot. Beats the hassle of replacing the same stuff over and over. Ladders don't seem to get any shorter or more stable the older I get. I've also covered the face of my rakes with the wider drip edge on a shed, it worked pretty slick, and was cheaper than the plastic trim.

For decay at ground level, there are sleeves for posts where they go in the ground, to keep that 6-8" above/below ground level rot from happening. I've also heard of painting tar on that zone of the posts. I don't know how well it works, but I'm trying it on fence posts I'm replacing...will let you know in 10 to 20 years how well it holds up.

I'm with Tom...do what feels right, and be willing to live with consequences if it doesn't work out. I think they call that life...

rickyb01 · Aug 11, 2015

Thanks guys and I was never going to use treated trusses but the 2x10's that hold the trusses up I think will be treated. Rick

TomDavis · Aug 11, 2015

I also have some rot on the ends of the rafters even though the tin extends beyond them abut 2". The rain still kept them wet so they are rotting. At that point there is a 1x4 runner that the tin is nailed into. I worry that is a weak place and would be where a hgh wind would start pealing off the tin. I will some day add a treated 2x4 about 3' long to the existing 2x4 and nail the 1x4 to that solid 2x4. You could add a weather proof cap of one of the materials cited by GLyford above although I am not familiar with them. Perhaps he will offer an idea for a cap covering 6" or so of the end of the rafter. Alternatively could also nail on a treated 1x4 as a facia and paint it. Then you enclose an area, add a heat pump, the wine/beer refrigerator and PC with wifi so you can check on your buddies here at the forum. Here is my old pole barn.

mx842 · Aug 11, 2015

LD1 said:
Treated dont necessarily mean more insurance.

Treated eats metal that isnt properly coated. So you have to make sure you use all the correct fasteners. Then the issue where metal roofing or trim touches the treated lumber....

It don't mean that termites wont eat it either. My wrap around porch has salt treated 4x6 post every 10' and not long ago I was spraying weed control around the edges of the house and I noticed that they had started eating a couple post. On one of them they had eaten the post all the way to the deck and started eating a 2x6 joist headed for the house. The other one was left only as a shell about half way up to the deck. They screwed up and ate all the way to the outside of the post in a couple places and that's how I spotted them. The really bad one looked like a perfectly good post until I stuck a screw driver into it to check it. The screw driver almost went all the way through.

So far i've only found two post that had them in them. But they had already eaten all the 1x4 salt treated boards that I used as expansion joints for my cement patio and side walks around the back of the house. I've really looked close under the house and have seen no signs where they have started working their way to the walls inside the house. When I built my house everybody asked why I put termite shield ( thin aluminum sheet medal) on top of the foundation where the floor joist band tied to the foundation. They said that was old school and that termites wouldn't eat today's salt treated material. That was over 20 years ago and I guess I got some of the old school salt treated material because they sure seemed to like my post and expansion joints.

GreenYellow · Aug 11, 2015

IMO, treated rafters or trusses on a polebarn may actually cause more problems than using untreated. If the treated lumber is in contact with the metal roofing, it rust in no time. Your fasteners (screws) for your metal roofing will rust 10x faster. Also, treated lumber (in general) is more likely to warp than untreated because of the higher moisture content when new. Usually treated lumber is a lot wetter than untreated when you buy it. Sure, it could be dried, but it's very time consuming and it's heck trying to keep it straight. If you put wet (fresh) treated lumber up against a hot metal roof (as a truss), you can guarantee they'll curl up like a potato chip in a week or two.

No question, I'd go with untreated for everything except the posts.

GLyford · Aug 11, 2015

If you already have a 1x4 fascia (or 2x4 subfascia) across the ends of your rafters, the easiest way to protect it is piece of drip edge. I've actually run two on some stuff, one over the sheathing overlapping the fascia, with the shingles on top (no reason you couldn't run it under tin just as easy) in the "traditional" use, and the second flat on the face of the fascia to cover it. The regular stuff will cover a 1x,
Amerimax Home Products F4-1/2 White Aluminium Drip Edge-5505400120 - The Home Depot
This is made in a couple of different widths, so you may be able to come up with something that will work depending on if you are trying to cover a 1x4, 1x3, or 1x6.

and they also make a deeper version just for wrapping around a 2x.
Amerimax Home Products B5 1/2 Aluminum Drip Edge-5500300120 - The Home Depot

I know different areas of the country carry different things, but if you poke through the flashing department you may still find something you can adapt in slightly different ways to protect stuff. Get a roll of trim coil and bend it between a couple of clamped boards if noting else.

This is the plastic trim stuff:
Veranda 3/4 in. x 3-1/2 in. x 8 ft. Cellular PVC TRIM-H190LWS6 - The Home Depot
They have other sizes. Very easy to work with regular wood tools, and I've even carved it to fit with a utility knife for the odd spot while up on a ladder...and it doesn't split.

Here's my current project, used a bunch of the stuff: