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-   -   Yet another beam support question (http://www.houserepairtalk.com/f32/yet-another-beam-support-question-2998/)

MelodyLeanne 10-25-2007 11:10 AM

Yet another beam support question
 
Ok Ive read ALOT of the threads here having to do with moving columns under the support beam in the basement... Here is my question, although I think I may already know (and not like) the answer.
I have a Cape, built in 1926 with a concrete foundation, 40' long from front to back. The main support beam runs smack through the middle of the ceiling in the basement, with a steel post 10' from the exterior wall, another at 10', another at 10' then the exterior wall for a total of 3 steel posts. The footings under the posts are only 12"x12" but I have no cracks in the floor. The beam itself is three 2"x12" put together, staggered. The basement has been completely framed, with a 2x4 framed wall under the center of the support beam to divide the space in the basement from utility area and what Im hoping will be finished space. This wall is approximately 15 feet long, and goes from the first steel post to halfway between the 2nd and 3rd steel posts, where it stops at the stairs. What I would like to do, is add two more posts, equal distances on each side of the 3rd post, then remove the old 3rd post from between them. This would give me 4 support posts, beginning with a post 10' from exterior wall, 10' to a post, then 5' to a post, another 5' to a post, and 5' to exterior wall. The load bearing wall on the first floor of the house is directly above the beam, running the entire length of the house, with 2 standard doorways. The second floor of the house has two walls going perpendicular to the main beam, separating the bedrooms from the stairs. The brick chimney runs up beside the stairs. My roof is not trussed, and there is nothing but insulation in the attic crawl.
Will this compromise the structure of my house? If not, do I have to pour footings, or can the new posts be attached to the beam and the concrete floor? Do I have to use steel, or is a 6" x 6" wood post sufficient? And lastly, Ive seen this question asked, but not answered. Where do I find a structural engineer???
Thanks!

glennjanie 10-25-2007 01:16 PM

Hello Melody:
Your proposed post spacing will not put you in danger as long as there are not 2 splices in the 2 X 12 between any two posts. In my basement, I had to add 2 steel posts to hold up the ceramic bath and a half. The old style ceramic tile that has concrete behind it (HEAVY), plus the Plumber had cut a joist in two and didn't block it. Rather than break the concrete floor and go through the footer deal, I laid a 12 to 18 inch 4 X 6 under the posts to distribute the weight over more space. It hasn't cracked yet, after 15 years.
The 6 X 6 post will be sufficient and will cost much less. Steel posts turn loose quickly in a fire anyway. I know a structural engineer but he is in Kentucky and you would not want to pay the mileage to get him there. I would Google an engineer's association or look in the Yellow Book.
Glenn

MelodyLeanne 10-25-2007 04:04 PM

Thank you! Im glad to hear that. I was hoping it would be ok, couldnt figure why it wouldnt work, but wanted another opinion besides the guys I work with. I was thinking about a steel plate under the posts, but perhaps your idea of a 4"x6" is just as good.
Thanks again, Im off to the local lumber store tomorrow! I really need to buy a truck (mine's totalled but thats another story!)
:D

mudmixer 10-25-2007 07:49 PM

Apparently, all your posts on on footings. Just because you have not ghad slab cracks is meaninless since there is no load on a floor that can cause a crack (only a framed non-bearing wall).

You can possibly expect to see some cracks in your 80+ year old house when the posts carrying the loads are removed and replaced. They should not be large IF the new posts are installed properly AND have good bearing.

That said - You have no idea of the thickness and strength of the existing slab. It works as a slab, but may not work when it comes to supporting a post. A 12" piece of 4x6 on old, unknown concrete is not equal to a 12x12 concrete footing poured on good soil. You may have a 2" thick slab with air voids under it because the soil was not compacted.

You are talking about removing one good properly built post and replacing it with two more on a slab of unknown strength. Old basement slabs are notoriously built just to cover the dirt since no one in 1926 planned on making a new space and putting posts on the floor.

With the wood, you are not doing it right and could potentially have some major problems in the rest of the house. - What if the post punched through the unknown floor and permitted a deflection of 2"?

You admit you already know the answer and do not like it. Just because someone has had good luck does not mean you will be as lucky. - You should put in new concrete post footings. It is cheap compared to the problems upstairs.

inspectorD 10-26-2007 08:10 PM

Yup
 
I have to agree with you mudmixer.
If you need footings rent a concrete saw or buy a diamond blade at the lumberyard for your skill-saw...they do the trick.
Then pour yourself some inexpensive concrete...walla ///done!:D

Make sure you support under any beam seams or joints....this was engineered for your home. I see to many things done half -arsed and then folks try to get a home inspection...and I show up.:D

Then you fix...again....costs more money...and so on ......:)

To many variables to know without seeing it ..just trying to save you grief later on....it will come.;)

glennjanie 10-27-2007 12:28 AM

Its your call now Melody. My answer is an opinion and the other guys are talking 'building code' language. They are correct and I have shared my experience.
Glenn

inspectorD 10-28-2007 07:43 AM

Thanks Glenn
 
I just want to thank Glenn for sharing his experience with all of us here. Just because He gave a different answer Which was not code language does not mean it will not work. I have seen many things in my opinion should not be working...yet there they are 50 years later still functioning away..good as can be.

That is how we discover new techniques and failures.
I just wish more folks on this forum were willing to share their experiences and not be afraid of the rebuttal's you may receive.

This is how we learn from others...by putting all our harebrained "Ideas" out there and see what flies.:D

Thank you Glenn for your alternative options. If someone is not going to do it to code...at least they may follow the other idea which may be outside the box, and not get hurt.:)

Keepin it "real" out there.;)

MelodyLeanne 04-07-2008 08:46 AM

Hey guys, sorry I havent been around to thank you for your advice, the construction project went well. Just so you know, I did not end up pouring footings for the new posts, and here's why:
I drilled into the floor to anchor the bar (an L shaped 4"x4" construction with a thick pine top). I got down the whole 6" of the drill bit and STILL had not hit dirt. I have no clue how thick the basement floor really is, but a neighbor who's house is almost identical, and according to town records had the same builder, put an addition on the back of their house. The property was excavated and to make a long story short, their basement floor ended up being almost 11" thick.
I used the 4"x6" lumber, and fastened them to the concrete with 6" of screw going into the floor. It was not easy drilling it. I filled the hole with hydraulic cement and screwed in the fasteners while still wet. It will be a major project if I ever have to pull it out. Its only been 5 months, but nothing has moved, twisted, bent or cracked. I certainly hope I dont have to come back and say you guys were right, but if I deserve a "told ya so" I'll accept it graciously.
THANKS!!!
When I removed the old footing, it was only 2" thick, full of rocks, and it was on top of cement.....

guyod 04-10-2008 02:42 PM

Cement must of been cheap back then...
I hope they had cement trucks back then too
Sounds like you have a solid house.
Glad everything worked out...


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