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I have this drawing for open up the living room wall. The architect is proposing a 5-1/4x16"x16' lvl beam with 5-1/4"x7-1/4" column on each side and adding 2x8" blocking btw. joists to support column but would not explain anything.

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what is 2x8 blocking referring to?

structure that prevents the joists from twisting, a solid piece of wood, often the same material as the joists themselves, is installed perpendicular to the joists without any gaps (e.g. I joists would use a piece of I joist for blocking)

or additional vertical members (2x4's) to carry the load from the beam up to another load bearing object above the floor (e.g. a new column)

if it's the later, what's benefit using the block to support the column? wouldn't be better for the column to go straight down through the subfloor and rest directly on the existing beam?

thanks

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This is the reason for the blocking:

"additional vertical members (2x4's) to carry the load from the beam up to another load bearing object above the floor (e.g. a new column)"

In other words, it's a complete load path from the beam to the foundation

if it's the later, what's benefit using the block to support the column? wouldn't be better for the column to go straight down through the subfloor and rest directly on the existing beam?

Depends on what you mean by better.

Better related to the load path? Yes, in that all the pieces will be imperfect and have a little gap between them that has to close up before the load is applied. Note that wood has more strength along the grain so install the wood blocking vertically, not horizontally as most other blocking.

Better related to buildability and cost? No. It is done this way for a reason. It is much easier and therefore faster and keeps costs down.

This is an extremely common detail and if you're architect and engineer are doing their job correctly, then there are no issues.

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  • thanks for answering the question. – user3698061 Sep 15 '20 at 5:35
  • thanks for answering the question. I have a 6x8 wood girder beam in the basement that will support the two new 5-1/4"x7" columns on either side. in terms of load path, how is this better than resting directly on beam? resting column on couple 2x8" block that support 16' beam with 1000lbs/foot load seems very brittle. how is the nail going to hold together the 2x8 with a such load? do you have method how to build the blocking and securely place on top of basement beam which will support the new column? – user3698061 Sep 15 '20 at 5:47
  • "in terms of load path, how is this better than resting directly on beam?" => As I noted, it's not better. But you don't need to allow for the full load that at 5-1/4x7 can carry, only the design load. Wood is very strong ALONG the grain. The crushing of the supporting beam, loaded perpendicular to grain, is the controlling item. Your engineer has taken responsibility for considering such things -- "resting column on couple 2x8" block that support 16' beam with 1000lbs/foot load seems very brittle." => your little 2x8 block of Hem-Fir #2 can support approx 14,000 lbs so... (more follows) – Ack Sep 16 '20 at 0:22
  • " how is the nail going to hold together the 2x8 with a such load?" => I don't know what you are asking. -- "do you have method how to build the blocking and securely place on top of basement beam which will support the new column?" => Yes I do, because I am both an engineer and a contractor (either is enough). These types of questions is why you hire someone. These types of questions is also why your architect "would not explain anything." He makes more than a contractor, and you want his time for free – Ack Sep 16 '20 at 0:24

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