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Posted by Bobk207 on February 16, 2008, 2:46 am
>
> > Bob,
> > Could you expand on this comment, please?
> > "personally I think some code allowances for holes in joist are a
> > little too generous."
>
> > From your comments, you appear to have run tests.
> > Were the results recorded and conclusions drawn?
>
> From that particular snippet it's unclear whether he means that code
> allows the holes to be too big, or if it should allow them to be
> bigger. I'm old school - if you want holes in your joists, use truss
> joists! ;)
>
> R
To clarify..... some codes (I did a little researching when the topic
came up another time a while back) allow holes that are (IMO) too
large & too close together but its just my opinion
It's been a while since I looked at them but it seems that allowed
drilling & notching of joists varies a lot from place to place
I recall that one jurisdiction allowed something like multiple 2"
hole in a full size (6") 2x6, the separation required was something
like only 1" of meat between the holes! .....That didn't seem all
that large & the required separation was independent of the hole size
which didn't make me feel any better.
Some jurisdictions allowed notches, which is something I would never
do without some sort of reinforcement plan.
Sawn lumber isn't a homogeneous material & putting multiple rather
large holes in it at questionably close separation doesn't seem like a
great idea.
The recent thread about a 2" hole (rather near the end of the joist)
in a 8.6" (?) deep joist didn't seem like a big deal......that's
pretty much why Robert Allison & I said "don't worry" since that was
a pretty big timber & it left a lot more than 2" of meat above & below
the hole.
I've be lucky to have had many opportunities to perform & observe
tests on timber structures & components.
Often if we had a question about how something would perform...we'd
just build it & test it.
I have not specially investigated holes in joist but I'm sure
research / testing has been done on the topic.and it could be dredged
up.
So unfortunately I don't have any hard data to share
I've seen a lot members hacked up (notches & holes; too large, wrongly
placed) so I'm not a huge fan of letting the misinformed loose with
Hole-Hawgs & Sawzalls.
Hopefully I have enough engineering sense & experience to be able to
tell when a hole in a joist is ok & when it isn't.
cheers
Bob
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