Replacing girder in basement

[ebaftj01]

I am trying to get my basement finished, and I want to remove 2 brick columns (6'-8" o.c.) which are supporting a full size (not dimensional lumber) 4" x 12" wood beam. There are other masonry columns which support this wood beam also spaced 6'-8" o.c. but I am not touching them. I want to remove 2 columns which will give me a ~ 20' span in the basement from the 3rd column to the outside foundation wall.
The wood beam is supporting full dimension 2" x 12" floor joists (for the first floor). The full length of the 2"x12" joists is 27' and the house spans ~ 30' in the other dimension (that is the length of the 4" x 12" girder in the basement). It is an old big house, 2 floors and a walk up attic.
Now, I did the calculations on the loads for the replacement beam, and I got ~ 2,360 lbs / lf based on the building code in N.Y.C. where:

live loads are 40 psf / 20 psf dead load living areas, (plus 8 psf for partition walls)
30 psf LL / 20 psf DL for sleeping areas, (plus 8 psf for partition walls)
20 psf LL / 20 psf DL for attics , (plus 8 psf for partition walls) and no roof since load travels down to outside bearing walls.
Tributary width of 14.6667'.
I looked up tables for Parallam and I can get a 7" x 16" that will cover the 20' span I am looking to open in the basement. My wife threw in the monkey wrench when she said that she is not looking to give up 4" of head room (since the existing wood beam is 12" deep, and the new Parallam would be 16").
So normally, I looked up tables for steel beams, and that's when I ran into problems, the steel beam tables were telling me to use W14x26 for a tributary width of 16' (inclusive of my 14.667') with a maximum span of 13'7, when I need 20 ft. This is for Fy = 36ksi.
Are there stronger beams I can use Fy=50 ksi, or can I use let's say W10x22 which max span is 11.7 ft and double it up side by side?

Thanks,

 

[mijowe]

You have increased the loads to the perimeter and 3rd column foundations, this could be a problem.

You will also want to check deflections, your existing walls and ceilings could damaged under the newly extended beams.

 

[ztengguy]

I think all W shapes are 50Ksi now, might be hard pressed to find 36ksi. Have you checked deflection? I am thinking that will control with a 10" beam and that span.

What unbraced length are you using?

How are you supporting the ends? have you checked your footing for the new load?

You could use a deeper beam and modify the joists to be side hung from the beam.

Might want to spend the money and have a Structural engineer figure this out.

 

[ebaftj01]

Mijowe, I was going to install 2 new 2'x2'1' concrete pads on 1' of 3/4" compacted stone by the foundation wall & the existing 3rd column, so the new beam would rest on new columns on the new pads.
Ztengguy, maybe the tables I was using were outdated, so I'll look into the Fy=50. I was thinking of doubling the 10" beam, is that ok?
I was going to support the ends on the new columns on new pads, and have the beam rest on a plate, and use clips to keep it from twisting.
I am not sure what you mean by unbraced length? If you mean the spacing of clips, I was going to put them on every other floor joist (32" o.c.).
I was trying to stay away from deeper beams than the existing 12" now, I can even use a 12" steel beam, but I don't really want to cut the floor joists and hang them from the beam, it would be a lot more work.
I am on a budget, and I understand no one here can really provide straight up answers, because they are not providing a service, it's just merely a forum, but I was looking for some guidance. If I was to get a structural guy, is there a reasonable price range I should expect in this region (NYC)?

Thanks,

 

[SteelPE]

Typical solution when a beam does not work..... get a bigger beam. I have W8x67's in my house (spanning 24 feet,I think, supporting 2 floors with a trib of 13'to 14') which is stronger than a W14x26, 6" shallower than a W14x26 but it costs 2.5x more. As others have stated, you need to look into deflection. Also, not sure about what you have going on there..... but 28psf for dead loads seems pretty high for me. Usually you will be around 15psf including partitions.... but you may have something else going on in you house.

Hiring a structural engineer is a good idea.

 

[Archie264]

W8x67's? Wow!

>>>If I was to get a structural guy, is there a reasonable price range I should expect in this region (NYC)?<<<

ebaftj01, I don't know about your area, of course, but in many places there are good sole-practitioning structural engineers who specialize in small projects, turned around quickly, and done very affordably. The trick is to find them. If there's one in your area it would be worth engaging him; he will have seen and know of the typical construction practices and capabilities in your area and can save you a lot of aggravation. You may want to ask around to see if there's such a person in your area. I've heard of NYC and expect that there might be some there. I'm sure there are bad ones too, though, so if you decide to go that route, ask around.

 

[structSU10]

You can probably expect to be billed for $90-$150 an hour I would guess. Depending on the scope, you may be looking at a couple days worth of time. Also fabricated, erected steel costs about $3000-$3500 per ton. It may be less if it is a fairly straight forward beam, but that is a good ballpark. Foundation work can be pricy, and for what you are talking about I think new footings would be larger than 2'x2', considering you can likely only count on 1500 psf soil bearing.

 

[ztengguy]

I think you could get this designed and detailed for under $1000. My opinion, money well spent. its not just something simple like a header over a window, you have multiple floors, new foundations, existing walls, and then serviceability issues. You might save $500 by doing yourself and over engineering, but what happens when a footing sinks and all your walls start cracking.

 

[SteelPE]

Archie.... it's spanning 24' and I might have been a little conservative because it was my house.

 

[Archie264]

SteelPE, Sounds cool. And I hear you about designing for yourself: code proscribed minimums are indeed minimums; not maximums...