Residential Second Floor Sag Near Support Beam

[ccg1]

Hello, I'm a civil engineer in transportation/water resources, but I need some advice for a home issue that is out of my field. I'll try to be as specific as possible. Please review the attached diagram for reference.

I have a significant sag in a second floor bedroom (marked BR2 in diagram). The house is 120 years old, and there isn't any reported history of water or insect damage on the second floor (there also isn't any plumbing on the second floor). The house has a basement, and three of the four foundation walls were redone about 40 years ago (the fourth wall is in great shape, and the entire foundation was inspected by a structural engineer in the area before we bought the house). The second floor consists of three bedrooms with a hallway running through the middle of the area, and a wooden support beam running perpendicular to the floor joists runs at the edge of this hallway (see diagram). The first floor living room rests below these bedrooms/hallway and is separated into two areas at this support beam. When we first moved in tothe house in Spring, we noticed that the living room floor sagged in the middle, and we found this to be due to an issue with the floor joists from what appears to be past work on heat vents in the basement. So, we jacked the floor 1/4" every other day and raised it to be nearly level, placing a permanent support post in the basement once we were finished raising the floor. The location of this post would be directly below the second-floor support beam stated above, and it's location is marked on the diagram (this post is in the basement, but I marked its location on both the first and second floors in case it might be relevant).

After raising the first floor, we noticed that the sag in one of the second floor bedrooms (BR2) became more significant, but this was not the case for the bedroom across the hall (BR1), which has a much smaller sag and may have even gotten better. The hallway is perfectly level, and the sag in BR2 seems to be at its largest slope closer to the hallway than the east wall. I'm concerned that there is a structural issue with the joists in this bedroom that could eventually lead to a collapse, but I'm not knowledgeable enough to know. I'm guessing that while raising the first floor did not directly damage the second floor, it may have revealed a problem that already existed and has become more apparent. If I can avoid tearing up the flooring on the second floor, that would be ideal since the previous owner installed new laminate right before he put the house on the market (however, if repairs are required, I'm obviously OK with doing this - I just don't want to tear it up if there isn't a problem). Any help in establishing the issue and potential outcomes would be greatly appreciated. Thanks so much for your help in advance!

 

[Tomfh]

It sounds like you're jacking up both levels without really understanding what's lifting what. It can be tricky with old timber houses. When you jack one part the timber and walls can react in ways you don't necessarily anticipate. Often walls act as deep beams.

Post some photos, including your post under, the sagging floors, the beam including how it's supported.

It's worth having a structural engineer look at it if the house is sagging in ways you don't understand.

 

[HouseBoy]

I don't know if your situation is similar to one I came across a few years ago but.... you might try to make a detailed level survey of the entire house (especially the perimeter). In my situation, I found that there was settlement happening in a location that was not recognized (far away from the "problem" and that was causing the contractor to misread the problem. In our case, we actually lowered the high point in order to smooth out the out of level condition.
The point is that the sag was incidental to some other settlement and the solution was to smooth out the transition so that it did not appear as bad.
Just a thought.

 

[JAE]

For a house that old the wood is permanently deformed due to long term creep in the wood material. Not sure that jacking anything will help.

Check out Eng-Tips Forum's Policies here:
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[jayrod12]

And if you're more open to repairing the ceiling as opposed to the flooring, I would recommend opening the ceiling up in the area of the worst sag and taking a look at the joists from the underside.

 

[ccg1]

Thanks all for your helpful responses!

Tomfh I'm not sure how helpful this is, but here are some pictures. The first two are of the post in the basement (ignore all the "strings" as they are just a part of the ceiling drywall). The third picture is the archway of the living room first floor - the spot we raised the floor is in the archway (look at the previous diagram to see its precise location; we did not see any cracks in any walls after we lifted, and the floor is now nearly level). The last three pictures are of the second floor bedroom in question. The string runs 11.5 feet in these pictures with a 1.5" sag. Again, the hallway is perfectly flat, and the other bedroom (BR1 in the diagram) only has a 5/8" sag at it's worst spot over a similar distance. We aren't worried about the sag if it isn't structurally dangerous - we can deal with the "character" of an old house as long as we know it's safe.

One other thing that might be worth mentioning is that in BR1, most of the deformation comes at the west wall, and in BR2, there is very little deformation at the east wall. This would indicate to me that the east wall, which is NOT at the edge of the house (the first floor extends further but the second floor ends) may be slightly lower than the west wall (which is the very front of the entire house) due to settling over 120 years (and perhaps when the foundation was redone). However, I'm not sure if this is relevant for the sag in question?

Thanks again for your responses!

 

[kipfoot]

My thoughts:
1) call the structural engineer who came out earlier to come back to consult with you on the floor system
2) remove part of the ceiling and wall over the opening near your 'x', as jayrod suggests. This will allow the engineer to get a look at the joist space and the beam, if any, over this opening.
3) As JAE notes, the deflection of the wood may no longer be an elastic state. Pushing up on it probably won't make it spring back to level and will create cracks and popping sounds. Also remember that pushing up from a wood floor is the same as pushing down on the wood floor; any jacking points must be supported below.
4) Ask the engineer to look at the single post you installed in the basement.
5) When a seller puts down a new floor finish, or any finish, before putting a house on the market, my suspicious nature leads me to think that there's an issue that they were trying to mask. Perhaps they simply were trying to make the deformation seem less severe.

 

[Tomfh]

To help understand it better, get a cheap laser and survey each room upstairs and downstairs. I got one and it really helped me understand my house, which has similar issues.

Survey each room. Measure floor height around the perimeter of the room, and at few locations within the room. Plot it on plan. This gives you a good picture of what’s actually going on with the levels.

You will probably have to open the wall and/or ceiling at the opening as others have mentioned.

Question: where are the basement walls?

 

[ccg1]

Thanks for all of the tips everyone - I really appreciate the help! I'm going to get a laser and plot everything out when I get back in town after the holiday weekend.

In the diagram, the basement walls would be at the north, south, and west walls of the first and second floors. The east basement wall is not shown in the diagram as the first floor extends further out east (the second floor only consists of what is shown in the diagram, so all four exterior walls are shown). So, the north/south/west walls of the second floor are all directly above basement walls, but the east wall is not. It's worth noting that there isn't anything special about the first floor below the east wall of the second floor. There is a wall there with a doorway leading to the kitchen on the first floor, but if you look at the first floor joists from the basement at that location, there isn't an extra support beam - it's just the normal joists, although the spacing is smaller at that spot to ensure that a joist runs directly below the wall. If that makes sense.