House Structural Question

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  #1  
Old 04-22-12, 05:43 PM
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House Structural Question

My house is about 100 years old. It has a basement, and three floors above it. The foundations is made of large concrete blocks, and the main beam in the center of the basement is made of wood. There are five wooden columns supporting the main beam.

On the second floor of the house, there is a noticeable sag in the middle of the house, at one end. The other end of the house is pretty level. The first floor is also pretty level, certainly not as bad as the second floor.

I included some pictures of the main beam and the pillars supporting it in the basement. In the first picture, the beam and pillar appear to be in good condition. This pillar is directly under the part of the house that does not have a sag in the floor.

The remaining pictures are in order, from the one good beam, to the far side of the house. I'm not experienced with structural issues, but I have some concerns about the integrity of these pillars and the beam. As you can see, several of the pillars are cracked from the basement floor to the beam, and the beam itself has some pretty large cracks. Some of these cracks are large enough to put a finger into.

My questions:

1. Is the sag on the second floor likely caused by the condition of the pillars and beam?

2. Are the beam and pillars viable? Or are they in such bad condition that they need to be replaced?

3. I can live with the sag in the floor, and from what I've read, jacking the house to the degree that it is no longer sagging could very possibly damage walls, pipes, etc. So, what can I do to strengthen these pillars and the beam, so that the problem doesn't get any worse? There is a lally column right in the middle that was added before I purchased the home.

4. Do I need to contact a professional?

Thanks very much in advance.



















 

Last edited by WarnLot; 04-22-12 at 06:13 PM.
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  #2  
Old 04-23-12, 12:41 AM
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1. Without being able to do a hands-on review, my guess is the second floor sag is not caused by what's going on in the basement. Rather, there is more likely a problem with the second floor's in-floor support beam (the one holding the floor joists in that floor).

2. If the columns and beams were mine, they would be kept in service with some supplemental help in the form of epoxy injection. A professional outfit would do the whole basement for a few thousand $$$ or more, but there are DIY kits available that would be a small fraction of that cost. The trick is to know what to use where (low-modulus gel with a putty knife for the big cracks and setting plastic injection ports, then low viscosity epoxy for pumping) and proper surface preparation. All moisture insensitive, of course.

3. Answered above.

4. You didn't specify what type of "professional." It wouldn't hurt to get a few quotes from specialty contractors to repair everything you've got, and the quotes should be free. Could be a learning experience for you. Bringing in a qualified professional engineer to evaluate everything (and write a report) would also be a good idea, although be prepared to pay for it.

After the structural issues are settled, redoing the plumbing and electrical would also be money well-spent.
 
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Old 04-30-12, 06:52 PM
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Thanks for the reply.

Would you mind walking me through the benefits of the gel and the epoxy? Do these products bond with the wood and hold them together to prevent further cracking?

Also, is there any benefit to installing more support posts?
 
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Old 04-30-12, 08:20 PM
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When properly performed using the appropriate materials, epoxy sealing and injection will enable your timber members to perform as if they had never cracked and split. There are epoxies available that are specifically blended to bond with wood, and most are moisture-insensitive. The main differences between gel and low-viscosity injection epoxies are obviously the consistency--gel is thick, almost like a paste, and has hardly any exothermic reaction properties, while the injection material is thinner than water, but almost always has a high degree of exotherm, meaning it will heat up while the chemical curing process takes place, and if used in cracks that are too thick, will literally boil itself apart (lots of heat and bubbles, no strength). The gel doesn't do this, and is thus used to first seal the wider crack openings at the exterior surfaces, with plastic injection ports placed every 6" or 8", followed by sequential injection of the low viscosity epoxy into the ports. Based on your pictures, I don't think you would see any future cracking once the members were properly repaired with epoxy. Assuming the applied loads on the members don't exceed their structural capabilities, of course.

Adding more support columns probably won't hurt, but I suspect they are not necessary. It's difficult to assess your situation without knowing span lengths, loads, member configurations and room sizes. Your members are beefy, and have endured the test of time. Keep in mind that only a hands-on site review by a qualified engineer can tell you if the existing configuration is adequate, or requires some additional support columns.
 
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