How many "sisters" are too many???

[dricci]

Hi Guys and Gals,

Question... for a small cottage 20 x 30 with termite dagage to the ends, some middles of practically every floor joist what if every joist has a new 2 x 10 pt sister? Acceptable to you?

Thx -D

[Marc]

It's a borderline solution, in my humble opinion. One or two sistered joists might be acceptable for reasons of convenience but not the whole house.

Marc

[dricci]

Thank you. Confirming my feeling, not the whole house even if they were done well, just too many. -D

[Jim Baird]

The question with termite damage is just how extensive is replace/vs repair vs sister.

Often replace is just not feasible. I have seen some very creative support systems that do not replace. Short of engineering, which may be very hard to get depending on extent of damage, sistering as well as shoring can sometimes save a building from the wrecking ball.

[Erby]

Why, if it is acceptable to sister one joist (in this case with a complete new joist), is it not acceptable to sister all joists?

Did I read right that they used pressure treated new joists for the sisters?

[kurt]

Why, if it is acceptable to sister one joist (in this case with a complete new joist), is it not acceptable to sister all joists?

I see old buildings where every joist is sistered. Certainly not lovely, but necessary and it works.

[Tom Raymond]

I was recently in a house that had all but 6 of the joists sistered. When those were eaten by carpenter ants they were sistered again. Several of those, half of the band joist and three quarters of the sill plate were rotting again.

That was too many.

[allseason]

Treat for the termites first.

I have four sisters, and four brothers, that's too many.

[Marc]

Sistering a joist does not leave the junction between subfloor members on the centerline of the sister. Works fine for some subfloors but not all.

If the termite damage reaches the top centerline of the original joist, the subfloor might become uneven.

Marc

[Bill Kibbel]

I've inspected probably hundreds of floor assemblies that have had every joist sistered. I get a lot of those "types" of buildings. If it's done correctly, and the issue that caused the problem to the original joists has been corrected, it's not an issue.

Sometimes the sistering was done just to level the floor after the original floor joists deflected. Sometimes it's done to accomodate additional live loads than the original joists can handle.

[mjr6550]

As a few others have said, there is no problem having too many sister joists if the work is performed properly, which it seldom is.

Replacing the joists creates the problem of attaching the sub-flooring to the joists.