On Sun, 23 Jun 2002, Randall Young wrote:
>
> Thanks for the thoughts, Peter.
>
> > The cracked appears, from your post, to be 6 feet from the wall.
>
> My apologies, the break is actually near the center. It's probably 2' long
> and runs at an angle. The new 'sister's would overlap it by several feet,
> although I'm really expecting the new wood to carry the whole load. It's
> just easier to leave the broken one in place than to remove it (and have to
> support the floor above it). I'll make them longer, if Home Depot has them.
Make them as long as you possibly can.
> > Rather than bolt which would compromize the strength of the joists, I
> > would use wood glue to laminate the sister joist in place. Wood glue is
> > stronger than wood and bolt holes would compromize the strength of the
> > joist.
>
> I'll agree glue is stronger than wood, but I'm not convinced that in this
> case it would result in a stronger joint. Glue will concentrate the force
> at the face of the beam, while the bolts will distribute it through the
> beam. Wood is weakest in tension, so it will start breaking right at the
> glue surface and continue across the joint. The clamping force of the bolts
> will also result in significant friction at the face, likely nearly as
> strong as the glue.
Remember to use large washers to distribute the clamping force on the wood
face. More than a couple hundred PSI will crush the wood, causing a loss of
strength. 1" fender washers around 5/16" bolts is probably how I would do it.
david
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