I have a raised ranch with a finshed basement that has a garage in one half and a large den on the other half. The den has a 17′ beam in the center of the room with a supporting lolly column in the center of the beam. The beam is made of triple 2×12’s that run the entire 17′ length and there are 2×4 nailers that support 2×8 joists. The basement is 23′ from front to back of the house. The main floor is 26′ front to back with 18″ cantelievers along both the front and back walls. The area over the beam is a single large room with cathedral ceiling so no load bearig walls rest directly over this beam.
I want to remove the supporting column. I spoke to an architect who recommended adding a 1″ steel flitch plate and another 2×12 to the existing triple 2×12 beam all through bolted together. I would need to put up a temporary supporting wall, remove the 2×4 nailer, trim about 2 1/2″ form each of the joist, add the flitch plate and 2×12, bolt it together and then reattach the joists to this beefed up beam.
I had a contactor in to quote this and after a few days, he came back to me and said he checked with his engineer and both agreed that there was no reason for the flitch plate and extra 2×12. He said all I needed to do was to put 2 through bolts (top and bottom) every 12″ along the length of the beam and replace the 2×4 nailers with metal joist hangers.
The contractors suggestion is certainly less work and less $$ and I can do it myself but…. Will it support the house?
Replies
barry.... go for it....
BUT first.. tell your contractor that you will pay his engineer for his Report. .... and....
have your contractor incorporate his Engineer's beam calculation in his contract .
The Architect may have been spec'ing overkill..
or the engineer may have been shooting from the hip..
if he's will to put his stamp on it , he's not shooting from the hip...
as such his professional fee is worth it to you
Your architect's suggestion sounds far more realistic. I don't have a code book in front of me, nor am I going to waste the time doing the calcs when I don't know all of the loading involved with that beam, but 3 2x12's surely sounds very light for that situation.
Just remember, you're family's lives are relying on that beam, so who do you want the believe- the architect who has had structual design courses, or the contractor who "may" know what he's talking about? As Mike said- I'd go with whoever can provide calcs to back up his assumptions- the building department will want them anyway.
Bob
17' span?
3 2x12's?
good luck.
Don't forget to add in the cost of putting netting around any nearby stair openings, etc., cause it's gonna be a blast for the kids to have a family room sized trampoline.
no way that's enough
find a new engineer
Bing
If it were my job or home, I would go with something stronger, like the flitchplate or an I-beam. Let us know what you decided on.
Barry,
It doesn't seem right that you would have a contractor spend the time to give you a solution that he spent time discussing with his engineer only to have to run off and do it yourself now that he has come up with the solution.
Either hire the guy. He has already saved you money by his experience (assuming he is correct). OR pay him for his time. Ask him what he would charge you for his time if you did the job yourself and be sure to explain to him that you are seriously contemplating doing this yourself.
http://www.peteforgovernor.com
Edit-add this - The 'engineer' in the original post advocating simply adding thru bolts is , IMO, incompetent.
Lally out, beam strength relative to load = only 1/4 what it was before, deflection is trampoline like 8 times more. So, you need to quadruple the beam strength to have the same safety margins you had before. IMO, vertical flitch plates are a waste of good steel - good grief, a 734 pound flitch!!.
You can double beam strength by adding a flat plate on the bottom, see current thread "beam sag #2 to castenana" for typical install on a garage beam. To trple the strength, you need to do the calculations #), a flat plate (I'd guess an 8" wide 1/4" thich plate , 122#) on the bottom of the existing beam with lots of 7/16" lag bolts is a lot less work that other methods discussed - ps, put the lally back under the plate while you install the bolts. Pix is of 6" by 1/8 thick plate install on garage to double strength of 16 ft long 6x14 beam)
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Edited 8/30/2005 7:52 pm ET by junkhound
You called it! There is probably no engineer at all. ...that's not a mistake, it's rustic
Thanks for the input! Putting the steel plate under the beam seems like a good idea. How would I go about calculating the width and thickness of the plate? Would having the plate any wider than the beam it will be attached to really give it any more strength?
Since there is no load bearing walls on top of this beam, I have no fear that removing the lally will cause any structural failure (the house will not fall down). Seems like deflection is my biggest potential issue here and I want to avoid any trampoline effect in the room above this beam.
How would I go about calculating the width and thickness of the plate?
You have missed something that was said at least twice in previous answers. Pay a competent person to design the solution, and get it in writing with either an engineer or architect stamp.
Junkhound is an amazing person. Do you think you could figure out the bolt pattern? The letter from the engineer will tell you all you need to know.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
The straightforward theory is outlined in "Strength of Materials", Timeshenko and Young, Van Nostrand, 1935, rev 1962 (my first structures textbook, you can probably get similar text at the library, look in the indexes for "built up beams"). For your own house it is feasible to DIY IF you are willing to educate yourself. You do have one serious complication since there are 3 2x12s vs a single 6 by 12 in that the shear between the steel plate and the 2x12s has to be uniform, so you will likely need 3 parallel rows of lag bolts. If you cannot accurately drill and place 7/16 bolts in the center of the 2 bys, then you will need to drop to 3/8 lags otherwise the shear interface to wood for 7/16 actually are 'weaker' than the 3/8 per bolt. You need a drill press otherwise drilling the # of holes needed would be arduous, likewise a good 1/2 drive drill or impact wrienc for driving the bolts. If you do the calcs, be sure to span the 2x4 ledgers with the steel plate also and tie to those also, there will be a benefit and thinner steel plate. Use the existing lally below the steel plate in the middle and jack it up about 1/4" in center span before bolt install, then you will get good results.
If you do not already know (b*h^2/6)*sigma = moment = wl^2/4 off the top of your head, you have a LOT of self-education to accomplish for DIY on this project.
Edit PS: Once did a hand calculation (no computer spreadsheet) years ago for brother's house, 36 foot built up wood beam of 2x6s and 3/4 plywith embedded electrical and plumbing - calculations took 6 hours by hand with just a calculator (early 1970s). There are structural FEA software programs that will do it all in a few minutes, they only cost a few grand up to $40K! kinda like the truss programs Boss Hog uses everyday.
Edited 8/31/2005 9:38 am ET by junkhound
"Since there is no load bearing walls on top of this beam, I have no fear that removing the lally will cause any structural failure"
Well, that statement just confirms my thought that you have no idea what the h**l you're talking about. There may not be a wall directly above the beam, but half of all the floor load on the joists that are tied into the beam is being transfered to that beam. Given that, if the excessive load caused by the increased span exceeds the allowable bending stress of the beam, there WILL be a structural failure- your first floor, furniture, and family will quickly be sitting in the basement.
PLEASE do not not attempt this yourself- pay an engineer a few hundred dollars to sign and seal the calculations and size the beam. You can't possibly put a price on the damage that could occur otherwise.
Bob
PS- As Pete said- if you never had any intentions of hiring the contractor who gave you the info (albeit wrong), it was pretty sleazy to bring the guy in and waste his time as your "unpaid consultant". And people wonder why contractors charge "too much"- maybe it's to cover the time wasted dealing with homeowners who spin their wheels like you did.
I completely had intentions of using the contactor. Although I am a very experienced DIY'er, I have not done any significant structural work other than deck building. I know my limitations, that's why I called a contractor to come and give me an estimate.
The contractor left me a voice mail telling me that I did not need the flitch plate and should be able to do the work myself.
Since the architects recomendation and the contractors suggestion were so different, I decided to get more opinions by posting this on Breaktime. I am also planning on calling 1 or 2 more contractors after I discuss the various suggestions and comments I have seen here with the architect that made the original flitch plate recomendation.
barry .. are u a bleedin idjit ?
what do you think the architect is going to tell you ?... exactly what he already told you..
if you want a different solution.. go to a different source.. a Structural PE..
stop wasting time.... you need a beam calculation....you already have one from your architectMike Smith Rhode Island : Design / Build / Repair / Restore
LOL i was thinking the same thing.. why not get it right from the horse's mouth.. the PE..
For fun, I'll add another good DIY method that insurance companies typically give farmers to relieve sagging barn timbers when space is available. A cousin in ND got a kit like this from the insurance company as part of a claim settlement after a storm in the 70's, don't know if ins companies still do this.
Inverse truss fix: 1/2" dia or 3/4 dia plow steel wire rope with a suitably sized (typ 7/8" threads, forged ends) turnbuckle and 2 big forged eyebolts. Drill vertically thru the ends of the beam and install the eyebolts (usually 3/4 dia HS bolts) with special split bridge washers trepanned into the beam. Bolt a 1 ft high standoff to the bottom of the beam (part of typ. ins company 'kit') and using appropriate wire rope clips, attach the wire rope and turnbuckle over the standoff to the eyebolts in the beam ends. Tighten turnbuckle until the beam sag straightens out.
"I have no fear that removing the lally will cause any structural failure (the house will not fall down). Seems like deflection is my biggest potential issue here and I want to avoid any trampoline effect in the room above this beam. "A trampoline floor IS a structural failure. The whole house falling down would not happen - true, but that is not the standard for defining what failure is.As the floor bounces up and down, the joist to beam connections will work loose. Any deflection and vibration beyond established and permitted limits IS a Failure!Count me in with those who severely doubt that simply adding bolts will do anything for you. Also. I doubt that the contractor truly had a licensed engineer in on htat, mike tactfully had a way to call him on it by requesting the stamped plan.I even question a portion of the architects suggestion. He specs whjat to add, but placing that flirch on one side would create an uneven stress within the beam, making it want to roll. It is generally speced to be installed as close to the center of the built up beam as possible, meaning that the right place in your assembly would bee with two two bys on either side.you should also look into a paralam or LSL beam. I'm thinking a total replacement with a 5" x 12" will more than do the job and save a lot of labor grief. That all depends on the insert locations etc which I can't see form here.
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Good point on the one-sided steel flitch- I was thinking the same thing, but was also thinking the architect had taken that into account. Scary assumption, huh?
Bob
Maybe he took the magneetic field of the earth into account. Odf course, we can't do that since we don't know the current alighnment to said field;)
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Barry,
Have you considered replacing it entirely with a steel I-beam? Less depth, and cheaper if you DIY it, especially if you buy one "used". I think I paid $275 for a 26' x W10x26 ( 26' long x 10" high and 26lbs/ft) about five years ago to replace a load bearing wall in my house. Stronger than tripled 18" engineered wood beams which was my other option and cost three times the price.
WSJ