i have span tables for dimensioned lumber for rafters and joists. i have span tables for solid beams and glulams. but what i have is a 20′ beam made up of 3- 2*12s bolted together. there is a post 9′ from one end. client wants to remove the post. the clients owned the house 10 years ago and the post was not there then. someone has added it . my tables tell me i can use 2 lvl-3 1/2* 14 nailed together. if so, the 3- 2*12s ought to work? the beam is the ridge. the room is 24′ wide. rafters are 12′ 4*6s, 32″oc. cieling and roofing are t/g 2*6 with roll roofing. this was a common style here 40 years ago, called pierson homes.anyone have tables for built up beams? thanks. paul.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
This spray-foam sealant from Great Stuff offers mess-free, 6-in. coverage.
Featured Video
How to Install Cable Rail Around Wood-Post CornersHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
What species and grade of wood is the triple 2x12-20 foot beam?
I have a set of loading tables for 10 species and 4 grades each.
For example, commonly, in the past in this locality #1 yellow pine is used for beam as you describe. The tables have a listing for an allowable live load of 102 lb/ft at a 20 ft span.
I would say that the post was added for a reason....and it wasn't cosmetic.
Have a qualified resource calculate the loads and resulting required size of beam. Often the supplier of your LVL's will be able to assist you in this problem. If not then an architect or a PE.
Good Luck
........................Iron Helix
the beam is painted. in our area it is likely fir . no way to know if it is sel or #1 or #2 however. yesterday i told the client that the beam ought to be engineered. i have not heard back yet. thing is, the beam had no post before they sold the house so they are inclined to just remove it.
"my tables tell me i can use 2 lvl-3 1/2* 14 nailed together. if so, the 3- 2*12s ought to work?"
First off, an LVL probably has 3 or 4 times the strengthof a 2X12. So no way is that comparison valid.
A 2X12 spanning 20' is almost worthless. It will barely carry itself.
Life is not about how fast you run, or how high you climb, but how well you bounce.
I agree with Boss Hog, the 2x12's will sag under their own weight, let alone adding the deadload of the rafters, then snowload...If i were you i would pull a string along the outside walls the rafters are sitting on, sounds to me like the post was put in to counter whatever sagging may have occurred, which would thrust the walls outward. i think before i replaced the ridge, I would slowly jack it back up to is original position, which may or may not pull your walls back in...
Good Luck!
Are the rafters sitting on top of the beam, or are they nailed to its faces?
SamT
thanks for the responses guys. rafters are nailed on top of the beam. we have no snow load here.
Are you sure that's a triple 2x12? Looks like a cap on the bottom of the beam. Did you look under and see if it's maybe a flitch with a steel plate?
Since the rafters sit on top of the beam could you just add a plate if there is none rather than pull the whole thing out?
the beam in the adjoining room is 4 2*12s. it spans 16'. the cap was added with the post. and i claim Brain Lock. i did not tell the wholestory. should have caught it when fitz mentioned the walls in his post. a 6/12 roof was added on top of the pierson 2/12. that new roof ridge is non bearing 1*8. the 4*6 rafters are now acting as collar ties. whoever added the roof must have added the post-hoping that by supporting the ridge the walls could carry the new load. anyway, thanks and sorry for only half of the story. btw, clients agreed to let me bring an engineer up tomorrow at 3.
Let us know what the engineer says. A lot of these threads end with "consult an engineer", but we never get to hear what the outcome of the consultation was.
met with him today. talking and measuring etc = 1 hour. results asap. i'll let you know.
Solid!
it took longer than expected but the report is back. and it was worth the wait for the owner. the original roof was stripped befor the new roof was added.the tripled 2/12 works fine w/o any post at all. it will be removed and the client will get their open floor space back. and now we can move on the rest of the kitchen. paul.