Wednesday, October 10, 2012

The Word is Out: Keyed Strutting

Keyed Strutting:

Before nailed-on bridging or blocking was used commonly between floor joists, mortise and tenon joinery was employed, at least in higher class construction. 'Strutting' are strong pieces, usually in 2" stock, tenoned through joists, and so forth, and wedged with a tapered key on each end:



From Corkhill's The Complete Dictionary of Wood (1982). Click on the image for a larger picture.

It appears that the struts are meant to be below the floor joist's upper surface. If, however, the strut is placed level with the floor joists, and thereby carries a greater portion of the flooring load above, then a tusk tenon joint would be a more appropriate connection to employ. In either case, the pair of joists may have to have the struts pre-fitted prior to their placement, depending upon how the joists attach to the sills or plates.

Maybe it's time more of us, ahem, 'strutted our stuff'? har-har...

6 comments:

  1. The top surface of the strut, or bridging as it's commonly called now in modern res. construction, is not "load bearing" in intention. Though having the tops of the bridging in plane with your joist is the norm now, mostly because you would normally use the same dimension materials for the bridging as the joists.It keeps the joists( or rafters, studs) from deflecting as bearing loads are applied. I bet those that cut and fitted these "Struts" would have given much for a nail gun and a chopsaw.

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  2. Matsukaze,

    thanks for your comment. That's an interesting question - how carpenters in the past might have viewed such gear as nailers and chopsaws. I think that carpenters then in some respects were not a whole lot different than carpenters today - - I tend to think that while many of them would have been delighted to toss the old gear out and embrace the new, there would have been a contingent that would have frowned upon such equipment as non-traditional and even scorned those who, perhaps in their view, 'took the easy way out'. And even today with those pieces of equipment widely available and quite affordable, there are still those carpenters who prefer to hand nail at times or use the hand saw. Not so many in N. America it appears, but it seems like whenever I see a show on BBC or Channel 4 UK I can see in scene after scene that the carpenters still enjoy their handsaws quite a bit.

    While the biscuit jointer and Festool Domino promise fast and strong joints, and simpler work processes all around, in my own work I choose to not use those technologies to connect wood together. Every craftsperson comes to some accommodation with the tools available to them, what they use and won't use, and why - whether they do so consciously and with deliberation is another question mind you.

    ~C

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  3. It speaks of an era when craftsmen could be given the chance to learn how, and then spend the time needed to produce things that were more durable, and make a decent wage doing it. The high costs of living have much become a nemesis to the greater degree of patience and care that once also injected artistry into work. Where once boats drifted with the current, now they have to row against it.

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    Replies
    1. Dennis,

      yes, I have found one of the keys to survival has been to keep overhead as low as possible. And all that rowing against the current does put you into incredible shape!

      ~C

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  4. How interesting. It does seem very time consuming. I'm with you, Chris, I prefer not to use biscuit joiners and especially pocket holes.

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  5. Julie,

    thanks for your comment. It is certainly true that keyed strutting would be more time consuming to execute than other methods, and it is also stronger and more attractive visually when done, IMO.

    ~C

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