Replacing a wall with a beam: Wood or steel? 1

[joeldm]

I am removing a 14' wall section between two rooms. That wall sits on a 4X10 timber that spans 14' and sits on a brick colum on one end and is attached with a hanger to a 12' long triple 14" LVL that holds up one section of the back of the house that I installed a few years ago.

I built a new addition that is three stories off the back wall. The base story is concrete and rebar filled cinder blocks on which I have traditionally framed a 2-story addition, using LVLs and wood I-beams, kitchen and master bedroon above. The 14" beam was part of that work.

The new top floor sits over on the existing (50 year-old) house's ceiling framing by about 6 feet and is over the rooms where I want to remove the wall, running from room to room. The recent construction's top floor's front wall, which supports one end of the hip framed (38 deg) roof, sits on an 11-7/8" double LVL that runs 24' from the outside wall and sits (perpendicular to it) on the wall I am removing. The framing in the new addition runs in the same direction as this 24' LVL beam and does attach to it. The framing in one of the two bedrooms where I want to remove the wall sits on that divider wall and in the other runs parallel to the wall I want to remove.

So the beam I am proposing to replace the dividing wall with support s one 12X12 floor system (bath and closet), the midpoint of a wall that spans 24' (the outside points of which run down the outside walls of the structure and onto the foundation) and that sits on a doubled 11-7/8" LVL. And that 24' wall supports the rafters running off a hip roof under which there is an attic with storage and the HVAC system for the top floor.

Ideally, I'd like to embed the beam in the ceiling, but the old construction portion of those two rooms above is 2X8s and so only a 7-1/2" beam is possible.

I have already purchased two 11-7/8" LVLs that I was going to run UNDER the ceiling withough cutting it into the ceiling above, but am wondering if I can rip those LVLs down to 7-1/2" and sandwich them around a center 2X8 and either side of two 1/4" X 8" steel flitch plates, wood/steel/wood/steel/wood bolted together in a 5-1/2 or 6" wide beam (depending on whether or not ripping the LVLs which I can't return makes sense). If I can't use the LVLs I assume I could use three 2X8s?

Is this a substantial enough beam to replace the wall and 4X10 (which appears not to be deflected)? Or must I use an LVL beam UNDER the ceiling to carry that load and how should I size it?

Thanks,

Joel

 

[dougantholz]

Joe,
there is a lot of detail in the question that you are asking. I would get a professional engineer in your area to come and take a look at it. The problem is too complex for this forum.
If you want, you could engineer it yourself, but it sounds like you aren't confident in wood design. Ask someone who is. Maybe you could work out a quid pro quo.
Doug

 

[joeldm]

Doug,

When I finished typing this I was sure it was too complex for a word description. I've been a renovation contractor for some time and I feel relatively confident of the sizing of the beams I've chosen, especially given that the same wall has been holding up that new addition et al for the last 3 years without a sag and it is held up by a 4X10. So, a double steel flitch plate sandwiched ought to do it or the 12" LVLs. But sometimes it makes sense to get an engineer's input, especially in such a scenario.

But one question I do have about LVLs, I've been told that if you rip an LVL, you destroy it. In other words, you can't rip LVLs like you can a 2X8 and still have a usable timber. But aren't LVLs run and then ripped to size at the factory? And if so, in a dry application as required, why would resizing the beam destroy it? I realize that it would reduce the weight-bearing load, but isn't it in much the same way as ripping dimenional lumber?

Thanks!

JoeL

 

[dougantholz]

Joel,
I'm not an expert in LVLs (this is a steel forum anyway) but if you rip an LVL perpendicular to its laminations so the depth of the member remains the same, then you have reduced capacity because of the reduced section. If however you rip along a lamination, then you have a piece of wood with properties very unlike the original lumber.
The top and bottom laminations on an LVL are usually made of higher grade wood than the infill laminations. This is because these are the areas with the highest stress during loading. I believe that in the manuf. process, LVL's are made to depth, then cut to length.
Hope this helps.
Doug

 

Hello joelmd,

In regards to your question about ripping an LVL. I am the Manager of Engieering Services for the largest wholesale distributor of engineered wood products on the east coast for Willamette Industries. You can in fact rip an LVL down to change the depth without destroying it's material properties. For example a 9 1/2" deep LVL from the factory will have the same strength as an 18", 16" 14" or 11 7/8" LVL that has been ripped down to 9 1/2". The same however does not hold true for a Glulam product which is an entirely different animal. LVL is manufactued from the plant in sheets typically 1 3/4" thick 60' or so long and about 8' wide. It is then ripped down at the plant to obtain the desired depths. Glulam beams are manufactured by stacking 2x4 or another width material one on top of another until the desired depth is obtained. If you rip a glulam down you do in fact alter the material properties since the top and bottom laminations are typically a higher grade material whereas LVL is uniform throughout. I hope this sheds a little light on your question.
In regards to your question about whether or not a particular size beam will work. If consulting a PE is not in your buget. You might try calling your local lumber dealer that sells engineered wood products. Many have the means to size LVL beams. I do this frequently over the phone. You will need to give them your span length as well as the lenghts and use of any joist or rafters bearing on this beam. a sketch over the fax machine is often helpful to since most of us engineers are more picture oriented than word.

Good luck and God bless........DesignerK

 

[rutherfordfish]

I am the owner, acting as general contractor of a 1910 Craftsman style home on an island near Seattle. The living room is 19'8" long X 16'9" wide. My question is about deflection in the ceiling. the joists in the ceiling bow about (1.75&quot 1" 3/4 inches. They are 2X8 quater sawn old growth fir floor joists, 24"OC for the bedroom above.

Am I better off sistering the existing joists above the ceiling or dividing the spans in 1/3'ds with a pair of steel beams from below the floor joists / cieling?

The problem is aggravated by the Lowish ceiling in the liv room it is 7'9.5" (93.5&quot. so any steel beams would have to be trimmed out with wood and shouldn't porject below the ceiling more than about 3.5" for aesthetics. Can steel I beams be "notched up into the 2X8 floor joists to address the aesthetics?

Thanks for any help.
Rutherfordfish