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Mike_Dizney 04-24-2012 01:18 PM

Floor joist sister/replace help; 100+ y/o home
My Philly row home, built in the 1890's, is due for some upgrades. My current project is flooring, and more specific than that, replacing or sister joists to make up for a bit of settling.

My joists are 3" thick and 8" high. They go directly into the brick foundation, as it appears the bricks were laid around the joists as the house was built.

I currently have some jacks set up to support a few joists in the rear left of the house, where there appears to be some rot. Also, in the rear right of the house, there appears to be some type of "planking" method used. This method is only used in that small area of the basement.

Some basic questions I have: Can I, or should I, replace these joists? Can I sister them? What should I do about the planking method? Should I just shim the back area of the house to make up for the settling?

Back left of basement where most settling occurred:

Back right of basement. Hasn't settled as much, but has a completely different method of joist support:

Perpendicular beam showing split between two styles of support in rear of house. Planking to right, makes up about a third of the width of basement.

joecaption 04-24-2012 01:24 PM

Not going to like my ansewer, but so be it.
This is not a DIY job.

Mike_Dizney 04-24-2012 01:26 PM

It's not that I don't like your answer, I just want to know why you think it's not a DIY job.

I'm not arguing, I literally just want to know.


sublime2 04-24-2012 02:44 PM

Hang in there.More will be by to give you options,answers.

Daniel Holzman 04-24-2012 03:47 PM

I have inspected a lot of houses that had floors out of level. Old houses in particular tend to have floors more out of level than newer houses, for at least three reasons:

1. The foundation of any house tends to settle slowly over time. The more time, the more settlement. Foundations often settle unevenly due to local soil or groundwater conditions, which can cause one side of the house to be lower than the other side, hence sloping floors.

2. Solid wood beams and joists deflect over time due to load. One of the curious properties of wood is that the ultimate deflection may be as much as twice the initial deflection, and it can take many years for ultimate deflection to occur. So a house with initially nearly flat floors may, over time, acquire a decided slope to the floors, especially towards the middle of the floor, where the bending moment on the joists is greatest.

3. Houses are sometimes constructed using green (undried) lumber. As the lumber dries, it tends to twist in sometimes unpredictable ways. The twist can cause floors to settle or heave in some cases, creating an out of plane condition.

4. Joists and beams which sustain water damage can bend, twist or settle in various ways. An older house is more likely to have had a leak than a newer house, which can cause out of plane floor conditions.

Due to the variety of things that can cause out of plane floor conditions, it is necessary to determine exactly why our floor is out of plane before you undertake a program to bring it back to level or flat conditions. Usually I start with a careful, precise instrument survey of the house to determine the elevation of multiple points in each room, and on the foundation. This usually allows me to determine if the foundation has settled, or the out of level condition is due to framing movement or damage.

Truthfully, if there is no structural damage to the foundation, in most cases I recommend that the homeowner live with the out of level or out of plane condition, since repair is often difficult and expensive. However, if the homeowner insists that they want to "solve the problem", once I have determined the exact cause of the condition, it is generally possible to examine alternatives which may include shimming, jacking back to position, installation of posts, sistering, or installation of other structural improvements to the beams and/or joists.

joecaption 04-24-2012 04:45 PM

I think what this home owner is dealing with Dan is the rot, not just a simple floor sag.
Anytime untreated wood is in direct contact with the foundation like this one is there going to rot from moisture over time.
There also far more likly to also have insect damage since there moist and so close to the most likly place insects are going to come in.
I've seen it many many times.
BY far I've worked on far more 100 plus year old houses then new ones and have seen far to many time the toll fungus, bugs and moisture can do.
It's not a simple job to do and someone that has done this before really should be on site to look it over.

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