01:27AM | 08/18/05
Member Since: 08/17/05
5 lifetime posts
Hey gang, I just bought a 1850's antebellum home, and need some help with one of my rooms.

In one section of the house, under what is one of the two living rooms, we have old termite damage, in some areas going all the way through the original hard wood floors. This is spotty, and can be fixed with about 10-15 planks, but my question / problem involves the floor joist.

Under this room, just outside the perimeter, I have huge 12x12 beams boxing in an area of approx 20 feet by 15 feet, placed upon large CMU's, and according to my inspector, appear unaffected by the termites, then notched into the beams, I have six floor joists which measure 4 inches x 61/2 inches by 19 feet. One joist has almost been entirely destroyed by the little vermin, with the other five showing very minimal damage.

My question is, should I just look at replacing the on one bad joist, and sandwich the others with bolted 2x8's cut to fit, or since there is some sagging of all the beams running 18+ feet which is requiring bracing at the 9' mark, should I pull all six of the beams, and install engineered joist running across the short side of the box, or perpendicular to what they are now? Would sandwiching them and jacking up solve the sag with out having to add a cross brace midway across? There is plenty of room for hangers, so that is not a problem, and either way seems about the same amount of work, so which way do I receive the most benefit?

On such a structural issue, I do not even consider the "original classic" issue, besides the old owners already added vinyl siding, windows and drywall, so to worry about that seems moot. They are really cool beams though, where you can see the hand carved marks for notching them into the larger beams, as if Norm himself did them!

Thanks for your help, sorry I rambled on


Glenn Good

06:03AM | 08/21/05
Member Since: 09/10/03
314 lifetime posts
Removing the floor joists could lead to additional problems as the hardwood flooring is likely nailed through the subfloor into them. In addition changing the direction of the joists could adversely affect the floor as well for several reasons I will not go into detail about here.

Salvaging the joists that are in good condition would be your best bet. The span of over 18’ will require additional support at mid span unless you upsize the new “sistered joists” to at least #2 grade or better southern pine 2x12s. The 2x12s installed at 16” on center (sistered only one per joist or by themselves) should span 18’ 10” without additional support.

If you are installing a new support at mid span the existing joists (that are in good shape) would not require sistering. Only the damaged joists would have to be replaced and #2 grade southern pine or Douglas fir 2x6s will span 9’ 9” by themselves installed at 16” on center.

Sistering 2 – 2x6s to each existing joist would still not be enough support to eliminate the need for mid span support.

When sistering the joists using the lumber size and grade I listed above you do not have to bolt them. They can be securely nailed with 16d common nails in 2 staggered rows top and bottom or by screwing with 3” screws. Using some construction adhesive between the sistered joist will also help eliminate the potential for squeaking.


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06:28PM | 08/21/05
Member Since: 08/17/05
5 lifetime posts
Hey Glenn,

Thanks for the info, that was along the lines of what I was thinking. I wanted to go with 2x6 do to the space constrance, and that would put them about the same size as the original size. At the mid point span I am considering digging a hole on each side of the span, about 2x2x4, filling it with concrete, finding a steel i-beam to span it and using metal house jacks at each end. Would this work, or do I need to look at using a wood beam? If I need to go as thick as a large wood or laminated beam, I might re-think and use the 2x12 instead. Thanks for all the help,


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