Support Beam - Residential
Support Beam - Residential
(OP)
I work mainly on concrete and steel commercial office building design and haven't had too much experience with residential single family homes, but how hard could it be, right :)
So, I was asked by a friend to review some preliminary architectural drawings that he is planning on using (eventually) for his home addition/remodeling. Currently in the garage there is a existing steel pipe column supporting a two-span steel beam, 12'-2" +/- each span. The far ends are supported by exterior CMU bearing walls (mostly above grade). The steel beam supports the existing 2x10 floor joists for the kitchen.
My friend (and his architect) want to remove the pipe column and steel beam and replace with a stronger beam to span 24'-4", thereby having a column-free garage. Obviously, there will be temporary shoring issues to deal with, but that aside my question is this: if headroom is not an issue, is there much of a cost difference in going with a larger steel beam vs. an engineered wood product (glulam, LVL, I-joist, etc.)?
How does the decision of beam material effect the pocketing of the beam into the existing exterior CMU wall? By this I mean, do I need to recommend dampproofing/waterproofing around the ends of the beam or anything else to prevent deterioration?
Any advice would be appreciated.
So, I was asked by a friend to review some preliminary architectural drawings that he is planning on using (eventually) for his home addition/remodeling. Currently in the garage there is a existing steel pipe column supporting a two-span steel beam, 12'-2" +/- each span. The far ends are supported by exterior CMU bearing walls (mostly above grade). The steel beam supports the existing 2x10 floor joists for the kitchen.
My friend (and his architect) want to remove the pipe column and steel beam and replace with a stronger beam to span 24'-4", thereby having a column-free garage. Obviously, there will be temporary shoring issues to deal with, but that aside my question is this: if headroom is not an issue, is there much of a cost difference in going with a larger steel beam vs. an engineered wood product (glulam, LVL, I-joist, etc.)?
How does the decision of beam material effect the pocketing of the beam into the existing exterior CMU wall? By this I mean, do I need to recommend dampproofing/waterproofing around the ends of the beam or anything else to prevent deterioration?
Any advice would be appreciated.






RE: Support Beam - Residential
A wood beam would have to be supported on treated wood on the CMU to avoid moisture damage or rotting.
The removal of the column means that you will now be depositing around twice the original load on the CMU walls and thus on the footings below - could be a problem - you'd have to check both the wall stability, masonry bearing, and footing strength and sizes.
You'd have to price out steel vs. wood for your locale.
RE: Support Beam - Residential
Removing the central column is possible only if the remaining supports have adequate support to receive the larger load.
On the dampproofing/waterproofing issue, you should follow recommended procedures.
BA
RE: Support Beam - Residential
RE: Support Beam - Residential
But whether the beam winds up being steel or engineered wood, I think it should be designed with support only at each end. I have a hard time convincing myself that the 2x10s bearing on the beam will provide lateral bracing. Agree?
RE: Support Beam - Residential
There are wood beams resting on interior pilasters or pocketed into
CMU's all oer' the land. If the beam is not exposed to weather, moisture will not likely be a problem.
If the increased reaction on the wall is problem, you may consider constructing a new pilaster or post inside he existing wall ...this will also make erecting the new beam much easier.
This will require a footing check or pouring a new small footing.
RE: Support Beam - Residential
This can be achieved with a wideflange by bolting ledgers to the web of the wideflange
RE: Support Beam - Residential
Resting the 2x10s on the new beam should laterally brace the compression flange of the new beam.....doubt it will ever see uplift ...Unless the homeowner has a Blown Hemi and revs it up in the garage
RE: Support Beam - Residential
I agree with Hokie here to replace the steel with steel. If it was designed by an engineer (I realize that I am being idealistic here) the steel was used for a purpose initially, probably high loads, and deflections. Stay with it.
Could have also been that the framing contractor had a couple of old steel beams laying around and wanted to save some money. Seen that happen too.
As for the top flange lateral support issue, that has been discussed here in the forum many times. Personally, if the joists rest on and are are nailed to a wood sill plate that is bolted to the steel beam, considering the stiffness of the diaphragm, I believe that the required lateral support to the top flange can be provided at every joist.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Support Beam - Residential
You have learnt the important lesson about domestic building, it definately can be more complex than most commercial buildings as the structural systems are not as defined and they involve all the major materials.
Personally I would agree with the comment above that the steel would be a better job due to:
shallower depth therefore more headroom
Lower long term deflection
Less end bearing issues
Sometimes the up front costs are only part of the issue and I would expect that the cost differential would not be much.