Building a wood shed, vapor barrier???

True

 

Could you use non-treated SPF for the purlins, and avoid the problem, plus save some $$? It's under the roof, and not in ground contact, so the only concern should be insects, if I'm thinking right.

 

There is no problem anyway. As stated above, the steel is screwed to the bottom treated skirt board on nearly every pole barn built. It's a non-issue, especially if it's Galvalume steel

 

True. As long as it stays dry, galvanic corrosion can’t happen.

 

That's kind of always what I thought also. I've pulled regular nails out of acq lumber that was inside the barn 5 years later with very little rust on them. but regular nails in acq lumber that remains wet will not last long at all

 

Going with treated lumber because of the bugs, Carpenter bees the size of helicopters!!!

 

carpenter bees don't "eat" wood, they just drill it. Not sure treated wood is going to provide any significant benefit. The carpenter bees around here are a huge issue on exposed wood. Well, the bees don't really do all that much damage, it's the red headed woodpeckers that go after the bee larvae. They'll dig furrows a foot long all over the place. They do make a paint that is supposed to prevent bees but I haven't tried it. I wouldn't use treated for that application.

 

is ACQ the standard treatment process? There are many here and some demand stainless steel, others class 4 hot dipped galv and there are even some where bog-standard zinc chromate is fine.

 

No need for pressure treated anything except poles

 

I took some pics tonight of our woodshed I redid that was ready to fall over. Has a tin roof overhead. I sank some poles in and cemented added sides used milled lumber.Left the west end open. Had to dig it out filled it with sand had black dirt. It can hold close to two years worth under it.

 

Granted, a shed may be a different proposition for many but they tried that line of reasoning here years ago and it has cost the country billions of dollars in re-dos and legal fees and resulted in suicides and/or financial ruin for many. The reasoning being the framing wasn't supposed to get wet so should not need to be treated beyond just boric. Big mistake. I walked from a few jobs back in the day when they wouldn't stump up a grand or so more for pressure treated framing. Many thought I was a fruitcake.

Only one of those times did I ever find out they became yet another 'leaky building' statistic but I think that was only partially the fault of the choice of framing materials (boric was considered 'good enough to meet code' back in the day). The rest of the blame, in that case and many others was the builder doing crap work, inspectors not doing their jobs either, architects following Mediterranean wankfest designs not suited to NZ, and lastly but by no means least, the clients choosing anyone who would tell them what they wanted rather than needed to hear especially if it saved them a few thousand dollars off the initial cost of the job.

Personally, I just won't build anything that has the potential even if not the intent at the time, of becoming a habitable space, with anything but pressure treated framing. Where I'd call it overkill is on internal walls that will not see any plumbing.

 

That's crazy. Are you in a really wet climate in NZ? Here in my part of the US, there are buildings 150 years old or older that have no rot or pest issues, so long as the wood framing is not in contact with the ground, and has a dry roof over it. Of course, a lot of the local framing timber in this area was hemlock, which does have some natural rot and pest resistant properties.

 

Pine framing, wet climate, nearly everywhere is within 2 hrs of a coast.

 

Rough cut hemlock, naturally big resistant, keep off of ground contact will last a long time

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Used to ship hackberry to Saudi Arabia for them to use to build in the desert in the late 90's! Never rains there!