Headers
mrbreadpuddin
| Posted in Energy Efficiency and Durability on
My balloon frame house has no headers, board sheathing, a single top plate, and the rafters do not fall over the studs, but there is no deviation in the top plate. Is it be possible with plywood and rigid foam to build a header with as much insulating value as the rest of a wall by leaving out the 2x material?
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Replies
William,
Q. "Is it possible with plywood and rigid foam to build a header with as much insulating value as the rest of a wall by leaving out the 2x material?"
A. First of all, a header "without the 2x material" will never be as strong as a header built the usual way (with double 2x6s, 2x8s, or 2x10s, depending on the span).
There are a lot of creative ways to build a header, including ways that include rigid foam. Of course, if you aren't an engineer, any creative headers need to be checked by an engineer.
Whether your headers have a higher R-value than your wall depends on whether your walls are well insulated or poorly insulated.
Finally, not all exterior walls require headers. In most buildings, rough openings on gable walls do not require headers. When in doubt, you really need to consult an engineer.
There's no chance of my making the engineering fee back on energy savings, but on a theoretical level this seems to be an area where "smart framing" could be smarter.
William, I have read accounts(JLC I think) where the builder had an engineer "engineer" headers using the structural sheathing... your current wall seems to work because the board sheathing is working like a header...."strength in depth"
Companies that make Structural Insulated Panels often sell insulated headers for which they publish load charts. They also have load charts for headers that are formed by cutting out a rectangle but leaving part of the panel in place as a header. I'm not an engineer, and am not qualified to give any recommendations, but such a load chart might give you a good upper bound on the maximum strength you can expect from a home-built header if it was laminated correctly with the correct foam and the correct glue.
Search for "header" in this PDF to see some examples in Tables 7, 8, and 9.
http://www.premiersips.com/brochures/PremierDesignManual.pdf