Rough Cut Strapping Material
pietrasm5
| Posted in General Questions on
Any reason why I couldn’t use rough cut material from a personal sawmill for strapping material used in a rain screen assembly?
Along those lines – I was also considering using white cedar (planed on one side) from the same mill for soffit material. I’m assuming that would be okay?
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Replies
pietrasm5,
Practically no reason not to I can think of, but check with your BI. Our code precludes ungraded wood in construction.
Wood really needs to be heat treated to ensure all the pests (such as the powder post beetle) larve are killed, should they exist in the wood. That's one of the benefits of kiln dried lumber, besides the obvious low moisture content. It also sets the sap so that it doesn't run. You run the risk of oil/sap leeching into the siding if it's not dried. That can probably be mitigated with an oil based primer though, just be aware that it could happen.
Rough-cut lumber can vary dimensionally more than planed lumber, depending on how knotty the wood is and how sharp the saw blade (and sawyer).
We are allowed to use visually graded lumber here in Maine (at the code official's discretion) but like Malcolm says, check your local requirements.
Kyle's point about insects is warranted as well; if you don't end up heat-treating your lumber, you might consider spraying it with Timbor, a borate solution, to kill boring insects.
I used sawmill lumber for a lot of my house, including the strapping. Thickness varied, so I ran it through my portable planer to get a uniform thickness. I liked using 1x3s as they were close to full 3" wide which were less likely to split and gave a larger backing for siding.