Yep, those are the fasteners we used for our ceiling nailers, @DeMac. Different supplier but same type of fastener.
Quote:
Originally Posted by Deb&John
These look great, but how did you secure the strips into the metal without creating a thermal bridge? It seems like a screw would condense and potentially rot the wood. I can’t think of any other reliable way to attach them.
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Using furring strips / nailers like this is a way to mitigate / address thermal bridging, not an example of thermal bridging to avoid. Consider one alternative: attaching your interior ceiling directly to the hat channels instead of to furring strips. Each 'hoop' is ~1.5" wide, and on our bus, close to 10 feet long, to/from the tops of the windows. That's ~180 sq in. of surface area per hat channel, or 1.25 sq ft, which is a direct conductive path from the interior metal (which itself has a direct conductive path to the exterior metal).
Now consider the case using nailers. Let's say you spaced them 1' apart, for a total of 12 across the ceiling (pretty dense for purposes of illustrating 'worst case'). And let's say they were 2" (actual) wide. That's 1.5" x 2" for each contact point, @ 12 contact points per 'hoop', which adds up to a total of 36 sq in. So even if the furring strips were made of steel, you'd still be reducing the conductive path from outside to in by > 400%.
But, of course, you're probably not going to use steel for furring strips. Wood doesn't have a good r-value, but it's one heck of a lot better than steel. It would take a bit more math to get a rough idea of the difference now, & I don't feel like doing it, but suffice it to say that you're WAAAAAY better now than you were w/o furring strips at all.
The point isn't to avoid screwing anything into the metallic structure. That's just not practical. By using nailers/furring, you're 'breaking' the thermal bridge... the nailers mechanically attach to the bus metal, and the ceiling (or walls, or floor, or...) attach to the nailers. That's the 'break'.
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