Did the Architect Specify the right BEAM Size?

[falinatl]

I am a Computer Guy not an Engineer. I hired an Architect and Contractor to renovate my 1930s Bungalow adding a 2nd floor.

I need advice(I am willing to hire an Engineer to come on-site to Consult, I know each situation is different and it's difficult to advise withoout seeing) on whether the Beam installed in place of a load bearing wall between my Kitchen and Den is structurally sound.

Above the kitchen and Den are 2 Bedrooms and it appears all roof load is carried by outside walls. The Beam is made of 3 2"x10" spanning 10'4" supported by 4x4 on each end. The joist above are 14"(16" OC) Engineered lumber spanning 28' and joined over the Beam(each side is about 14'. This has been in place for almost 3 yrs; however where the beam meets the wall(this is an outside wall)I can see just a little cracking at the seams of the sheetrock, nothing major but enough to make me wonder. There are no other signs of problems. The question is does the Beam size etc appear OK? Should I be concerned? Should the fact that it has been 3 yrs give me comfort? PLEASE HELP!

 

[Bobnj]

I have practical experience with moving beams and supporting walls in basements although I am not a structrual engineer. This beam of 3 - 2x10s with a span of 10'-4" is fine. I have seen this in many basements to support load bearing walls. The mistake most contractors make is not place the foot of the load bearing column on a proper footer. Check your to see if the footing looks solid. It shoud be on a 10" thick concrete pad. If it is sitting on the basement slab you won't know what is under it, but if there is no cracking of the concrete where the 4x4 foot is setting it should be ok. If the footing looks ok the next reason for the cracking of the sheet rock is shrinkage of the 2x10 lumber. Green Douglas Fir will shrink form 9 1/2" to between 9 1/4" to 9". This is enough to cause cracking of the sheet rock. As long as your floor remains level I would just spackel the crack.

 

[akastud]

falinatl,

I am a structural engineer, and although Bobnj may have seen this beam work in similar situations, I checked this beam as if you have carpet upstairs (a very light Dead load) and this beam is overstressed per the code by a factor of 1.9. This would be reason for a little bit of cracking on your sheetrock. I would recomend that you hire a registered professional to assess the situation with exact loads, but it looks to me as if a small Glu Lam beam would be more sufficient.

akastud

 

[JAE]

I'm an SE also - I got about 1.8 unity (80% overstressed) based on 15 psf dead load and 40 psf residential live load using Douglas Fir No. 2 and 14' tributary width on the beam.

falintati - you might want to go hire an engineer to check this out.

The 40 psf live load is intended to cover all your furniture weight and other non-connected items that load the floor in addition to humans. Normally you don't get the floor loaded up that much (14' x 10.33' x 40 psf = 5,784 lbs.) so according to the 1.8 unity you've got a SAFE capacity of 15.5 psf live load (= 2,214 lbs on the beam)

SAFE capacity means that your beam is delivering a code required safety factor when it just gets loaded with the 15.5 psf.

FALL DOWN capacity is perhaps 60% to 80% or more higher than the safe level so the beam would theoretically fail at about 35 psf which is about 5,000 lbs of weight on the beam.

All these weights are in addition to the self weight of the beam and floor system.

But still...go get an engineer as you may have to show your builder that what he did doesn't meet code.

 

[falinatl]

Thank you all for your help. I have since realized that there appears the Beam is made of 4(not 3) 2"x10" spanning 10'4". How does this effect the situation?

 

[falinatl]

Thank you all for your help. I have since realized that it appears the Beam is made of 4(not 3) 2"x10" spanning 10'4". How does this effect the situation?

 

[akastud]

As far as code goes, I estimate that you are still about 35% overstressed.

 

[JAE]

4 - 2x10's will simply give you 4/3 more capacity than 3 - 2x10's. Also, your deflection would be 3/4 of the deflection of 3 - 2x10's.