4.5″ deep 2.5″ radius holesaw hole in bottom plate of 2×6 struct wall into top of 4 member 2×10 beam
Don’t you love rookie plumbers?
What do you do?
The beam is supporting the 2×6 wall which supports the gable side of a shed style roof.
My thought is that the most important parts of the beam (built up joist) are the top and bottom that are under compression and tension and given the bottom plate is 1.5″ deep, there is likely 3″ of the top of the 4 member beam missing in a 2.5″ radius… so at least 2 of the 4 member beam is missing 3″ of depth from the topside.
All the joists (2×10) that hold up the floor above are hangered into this beam.
House has been up for a year and a half with no obvious settling. My worry is that it isn’t the general cause where this fails, it will be when there is an earth quake and I worry about a catastrophic failure that leaves no warning.
Thanks,
Max
Replies
Most overspanned beams and joists don't fail catastrophically, but cause problems way down the road as the wood slowly develops a droop in it. Without knowing what the lengths and loads are for your situation, and the distance the cut is from the end of the built up beam, it's hard to say if you have a problem at all.
Personally, I'd epoxy in a wood plug and not worry about it.
Inline image didn't attach
Here is the foundation plan.
Epoxy is harder than the wood - since the top is in compression it would serve that purpose as the beam were to sag more over time.....but now I don't think that's even a question.
Since your hole isn't in the middle third of the span I wouldn't even do that if the orgininal beam was sized correctly. Overspanned beams sag most in the middle with the ends remaining relatively straight over time - meaning most of the stresses are placed on the wood in the middle third, where you have good wood.
Even so, a 7' span isn't very long so I'm betting you're not even technically overspanned with the missing wood - what's your snow load? How much of the roof is supported by the wall sitting on top of the beam? How long are the floor joists attached to the beam? Joists attached to one side or two?
I'm guessing the framers went with 4 layers of 2x because it makes up the full width of a 2x6 post or plate, and used 2x10 because the floor joists are 2x10, not because the short 7'2" span required it, but in high snow load areas there can be a lot of weight so it's hard to speculate, but that's my best guess so far until we hear more details :)
Actually, the beam is hollow and that's where the stash is hid. The plumber was looking for it.
He must have given up... and only 6" from his goal.
...
From what I see you have 7'2", but that's to a point 6" outside of the 8" wide foundation wall, which brings the actual span down to 6', but there's an offset on the other end that adds probably 5" to the span so you're 6'6"
With span tables it's fairly easy to see if the original beam is sized correctly.....but that depends on your snow load....
edit: Even at 50lbsqft snow load it sure looks like your beam is sized correctly - so it comes down to the placement of the hole - if you are really concerned about it, most any residential structural engineer will take a look at it for $500 and give you a document with their offical oppinion. They can be more specific since they will look at the beams and were the hole is and do the math based on more specific details - my guess is they would say your beam should be fine - if the $500 is worth peice of mind only you can say.
You can ask a building offical, but they will most likely defer to an engineer, although I have had some who love crunching numbers and a plan reviewer may or may not tell you what you want to hear, right or wrong.
Snow loads - Joists
Thanks for the replies.
Here is the snow load. Yes when I measure in the basement the actual span is closer to 6' and I also agree that based on a 6' span the 4 member 2x10 is likely overkill. Though I am not sure if a 4 member 2x6 would be.
Joists are on both sides of the beam with a 10' span on the right side that supports a suspended garage slab and an 8' span on the left.
If you measure the distance to be 6' then two 2x10s and two 2x6's are enough that I wouldn't lose any sleep over it as it is. If you want to put your mind at ease a trick is to add a light strong stringline - say 80lb spider wire fishing line, with somethingt the weight of a claw hammer on one end - I put a 1/4" drive screwdriver bit under each end to keep it off the beam exactly 1/4" - over time you can accurately measure the actual deflection of the beam to the nearest 1/32". If in a year if you see it deflect that much I'd be suprised - it probably is going to last longer than all of us :)
It just hit me that you said 2.5" radius - a 5" hole?! If it's a 5" diameter and the tops of all your 2x10s are hacked down to 2x6 then yes I'd replace them, but if it's a 2.5" diameter hole I'd feel fine as is. :)
meant diameter....
Thanks for the replies !
How would you drill holes for wires...
How would you drill holes for wires where you want to run the wire from the 2x6 wall that sits on the beam down to the floor below where the beam is. Would you drill diagonal and try to pass through as little of the beam as possible? or would you do something different?
It's common practice to run the wire close to the edge of the bottom plate with a nail plate for protection - wires miss the beam completely with very little angle to the hole.
Not sure how that would work given.
The bottom plate is 5.5". The beam is 6". No way you are getting into the wall cavity without going through at least 1/2" width of the beam.
If the top edge of a beam is clipped 1/2" for a small hole it's not normally considered bad practice - of course a 3/4" hole from top to bottom of beam so wire comes up the bottom is not a good idea.
As often as not the beam is not exactly centered under a wall so the beam is missed completely if someone takes the time for a quick look.
If for some reason a wire has to miss the beam altogether (say it's a wide steel beam) then the wire is simply run along the wall to a wall that's not over a beam and it does down from there, or it's run up the top plate over and back down. Wires are pretty easy to route just about anywhere.