Attic acess clearence?

[jxofaltrds]

Re: Attic acess clearence?

Drill what!

I hope you do not drill trusses.

Mike P.

 

[iwire]

Re: Attic acess clearence?

Drill the truss, well the electrical inspector may accept that but I doubt the building inspector will.

 

[ryan_618]

Re: Attic acess clearence?

Originally posted by macmikeman:
[QB] You can allway's drill thru the trusses (I'd keep it to a 1/2" hole) and run the wires thru the holes.

Please, PLEASE do not drill trusses!!!

Trusess are not permitted to be: drilled, notched, bored, altered or looked at the wrong way! When I inspect a job with a drilled truss, I have the GC get a fix from the truss engineer to address it. So far, there has been a fix required every time, and every time the electrician has had to remove his wires so that a scab board could be applied to the truss.

 

[pierre]

Re: Attic acess clearence?

Hot off the press from the ICC residential building code of NY.

R802.10.3 Alterations to trusses. truss members shall not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of a registered design professional.

Also;
R602.6 Drilling and notching-studs.
R602.6.1 Drilling and notching of top plate.

There are many restrictions that sometimes we find out the hard way.

When I was a first year apprentice, I was asked/told to drill the floor/ceiling joists for the HRs across a residential building. I was only 3 days on the job and I wanted to impress the foreman. So I drilled the holes as fast as I could, all the way across the first floor of the house. Well... they had to replace every joist I drilled. Needless to say I will not forget what my foreman had to say.

Pierre

 

[Guest]

Re: Attic acess clearence?

From a layman's standpoint I would understand not drilling through trusses if trusses were made of clear lumber. Most trusses are made of construction grade lumber and that lumber is allowed to have knots up to 1". Is a 1" knot much stronger than a 1" drilled hole?

Glu-lams are another story.

Pierre said:

When I was a first year apprentice, I was asked/told to drill the floor/ceiling joists for the HRs across a residential building. <snip>Well... they had to replace every joist I drilled. <snip>

What made these joists special? Or, did you drill in the restricted portion?

Oh, and what did that foreperson say?

I knew a first year carpenter apprentice who was told to cut off the rafter tails on a house. He did just that: he cut them all off flush-- instead of to a stringline 24" out.

 

[pierre]

Re: Attic acess clearence?

Wayne

I drilled too many holes and degredated the integrity of the joists.

If you were to listen very closely, I believe you can still hear my foreman.

I went to driving groundrods after that. It was about 10 derees outside and I was sweating my ... off for a week. I had to drive 32 groundrods with a 16 lb sledge.

Pierre

 

[jxofaltrds]

Re: Attic acess clearence?

"From a layman's standpoint"

Wayne

Because those are the rules. Almost any other thing else can be drilled "IF" allowed by an engineer.

I would bet you the truss would never fail but what IF.

Drill in to a parallam or microlam and see how fast everyone gets up your butt.

Mike P.

 

[ryan_618]

Re: Attic acess clearence?

Originally posted by awwt:
[QB] From a layman's standpoint I would understand not drilling through trusses if trusses were made of clear lumber. Most trusses are made of construction grade lumber and that lumber is allowed to have knots up to 1". Is a 1" knot much stronger than a 1" drilled hole?

Perhaps the answer to your question is in the question itslef..."from a layman's standpoint". I am not interested in layman's standpoints, only structural enginner's standpoints. No offense.

 

[iwire]

Re: Attic acess clearence?

Wayne I agree that the knots are not any stronger then a drilled hole, but we have to think of these holes as "factory approved".

I have no doubt that someone at the factory grades the lumber and knots over a certain size get tossed.

Something else to think about is the knots are random but when you run a wire the holes are in a straight line, you make a week spot all the way down the line.

 

[russellroberts]

Re: Attic acess clearence?

Mike P said"Drill into a paralam or microlam and see how fast everyone gets up your butt"

I drilled into a paralam several years ago.Found out real quick no one has much of a sense of humor about it.

Russell

 

[big john]

Re: Attic acess clearence?

While I can understand not drilling into engineered wood products without an engineers consent, I don't understand what makes sawn-lumber trusses any different from any other structural member.

What I've always been told, and it has been reaffirmed in answers I got to a question on this forum, was that you could drill/notch almost any milled lumber as long as you did not remove more than 1/3 the depth of the piece of lumber. I know different rules apply to different pieces, but that seems to be the general rule of thumb.

Why would it be expressely forbidden to drill roof trusses, but it's perfectly acceptable to drill floor joists?

Thanks.
-John

 

[ryan_618]

Re: Attic acess clearence?

The answer to that is that they are an engineered member, not just a piece of wood. A joist or rafter is a standard piece of lumber with sizes depending on the span, spacing, snow load and a couple other variables. In other words, you or I could look at a span chart and come up with a joist that works.

Trusses, on the other hand, are quite different. These guys can span over 40' and do it out of a 2X4!!! They are not a "one size fits all" application. Because of this, every single truss you have ever seen or will ever see was specifically designed by a person that probably has about 10 years of school under his belt. Each truss is different.

 

[iwire]

Re: Attic acess clearence?

John I think one of the main differences is that the bottom cord of a truss is under tension (being stretched)

Most building lumber is under compression like wall studs or being bent like floor joists.

I do not believe any building inspector is going to be happy to see a notch in a floor joist the bottom half of a floor joist is also under tension.

If you notch a 2" x 8" two inch's it is now only as strong as a 2" x 6" it is unlikely the builder used larger then required floor joists so now you have a violation.

A hole through the center has much less effect.

 

[bennie]

Re: Attic acess clearence?

John: The difference is in the weight loading of a truss versus a joist.

 

[roger]

Re: Attic acess clearence?

John, one reason is, roof trusses are engineered for geographical snow or enviroment loading and are not designed to be altered.

Floor joist are designed the same for the structure regardless of area.

Let's say you buy a Barn print on a world wide market, you will notice the truss design is either not included or there will be numerous designs included.

If you told the local truss designer you wanted the design to include strength for drilling into any part of the truss, they could accomodate you, and actually write you a disclaimer to the effect.

Roger

 

[tonyi]

Re: Attic acess clearence?

Originally posted by iwire:
I do not believe any building inspector is going to be happy to see a notch in a floor joist the bottom half of a floor joist is also under tension.

A 100+ year old commercial place my dad bought some time ago had numerous mods over the years. One was to extend the foundation out along one wall for an addition. The existing joists were old rough cut 2x12 and plenty sturdy...until the guys who did the foundation extension (50-70 years ago) notched'em at the ends to where they were only about a hands width wide sitting on top of a brick wall built between the old and new sections.

I was down in the basement one night with my cousin (a plumber) changing out the old boiler and a karate studio above had a class going. I looked up after a particularly loud thump and the floor was heaving up and down a good 3" as they bounced around. That whole row of notched joists had cracked right down the line where they'd been so deeply notched. The floor may as well have been framed with 2x4's. The karate studio guy said the floor had always seemed a bit springy since he was there. Until I put some lights in the basement it had been dark as a cave, so I guess nobody ever noticed or cared... I love old places, you never run out of things to do

 

[iwire]

Re: Attic acess clearence?

Tony when I posted I was thinking of notches in the middle of the span, I had forgotten about notching the ends.

All the floor joists in my 80 year old house are notched as you describe and sure enough some are split.

 

[robc]

Re: Attic acess clearence?

Our one contractor here in NJ, SGS "DR Horton" will fine any contractor for drilling in any truss,laminate beam,and TJI beam. Even though on the TJI there is the knock-out in place by the factory they are still restricting us on use.


As far as my Inspector is concerned, Today "monday " on met with the code enforcement official from the township and I was not the only one complaining about the new inspector, I went over the code-book with COE and he came out later and looked at the jobs and white stickered them all
Thanks for everyones 2-cents out there, I just joined this site the otherday and I think its the best out here.

Rob

 

[ryan_618]

Re: Attic acess clearence?

Rob: You're welcome.

BTW: Don't be a stranger!

 

[tonyi]

Re: Attic acess clearence?

Originally posted by iwire:
Tony when I posted I was thinking of notches in the middle of the span, I had forgotten about notching the ends.

All the floor joists in my 80 year old house are notched as you describe and sure enough some are split.

Yep, its a bummer. I fixed ours by pouring some footers along the old brick wall, then building fascad style 6" block wall up against the old brick until it was just underneath the cracked joists. Then I jacked'em back into place until the cracks were closed up again (shot some glue in too before the final cranks on the jacks) and lifted'em up maybe an extra 1/16" and shimmed/blocked up from the new fascad wall underneath'em. Then I took a wire brush and cleaned all the crap off'em good and glued and nailed some 12" X 3-4' long plywood scabs on both sides to firm up the cracked area and set'em back down on the new wall. If everything had been nice and open, some sisters and fabricated "U" straps would have been a more straight forward, but this place was chock full of wiring and plumbing that would have had to be moved to slip sisters in. Shutting down the plumbing and electric in an occupied commercial building for any length of time was the wrong answer. I needed something that could happen in real-time with no impact on the tennents.

The town's building codes dude didn't have any problem with the way I did it.