Second Floor of Shop I-Joists or 2x12 Lumber

[Larry Edgerton]

I have installed thousands of feet of TJI's and for my own house I used hemlock. I just like wood better for many of the reasons listed.

Keep in mind that the install will be a mornings work, and then it is just a memory. Don't let one short, fleeting period of time affect your decision.

[Randy Cohen]

I used i-joists to frame the floor in my house. they are 32' long and 12" deep on 19.2" centers. they were very easy to install. the floor is very solid feeling. there is no blocking used along the span. the utilities were very easy to run. the parallam in the middle was pretty heavy though.

[Dave Sepucha]

From an engineering perspective, I think I Joists are great. They are very easy to work with not to mention light. They can have a bit of springiness (bounce) in floors but don't thing that would really be an issue for your install.

But I believe Jason is right, they can apparently burn VERY fast. I was doing some research on them and came across some of the articles from fire fighters. If you do have a fire, one could argue that the damage is done. But if you have I-Joists the structure apparently won't last long. I have no first hand experience with fire and I-Joists, just relaying the info I read.

So it's a trade off. FWIW, I have I-Joists throughout my house.

[Tom Godley]

So you have a span of less that 16" feet -- maybe 14.5 ?

This will act much different than going out 20' without any support -- This is what happens when you have a double garage with only one door.

[Andrew Joiner]

Jason,
Have you seen this classic photo? Says a lot for solid wood.


Here's more:http://www.softwood.org/AITC_eVersion/EN/p3.htm


Steel beams have melted and collapsed over charred timber beam, which, despite heavy damage, remains in place.

[Andrew Joiner]

I have installed thousands of feet of TJI's and for my own house I used hemlock. I just like wood better for many of the reasons listed.

Keep in mind that the install will be a mornings work, and then it is just a memory. Don't let one short, fleeting period of time affect your decision.

Thanks Larry,
From reading your posts in the last couple months I'd say we have a lot in common.
Your insulation experiment sounds great. Sounds like you went against the norm based on your own experience and won. Good for you!

When I was a kid apprentice in a millwork shop I'd always wonder why the "industry" did things the way they did. Yup sales, marketing and politics kinda complicate common sense. When I had my cabinet shop I saw a lot of gimmicks and trends come and go.

So when you said" for my own house I used" my ears perked up. I designed my house and the shop we're talking about. I built all the "inside",subbed out the framing. Because of zoning and the very unique design I got into some new material choices. When ever I could I'd choose simple time proven materials. That is best warranty you can get. If it works don't fix it.

Now I do respect technology and testing. I did use I-joists in my roof since it was the best choice for that span.

[Jason Beam]

huh! Check that out :P

I hadn't seen that one before. I have seen a few shots of the osb web having been burnt out completely and entire surface sagging dangerously (feet, not inches). Those were shot by firefighters. I believe they even mention them when training new firefighters, but can't say for sure.

Tried and True for me

Jason,
Have you seen this classic photo? Says a lot for solid wood.


Here's more:http://www.softwood.org/AITC_eVersion/EN/p3.htm


Steel beams have melted and collapsed over charred timber beam, which, despite heavy damage, remains in place.

[Andrew Joiner]

I would add to all the above...Whichever way you go, install a center blocking or even two rows of blocking between ALL joist. You wouldn't believe what a difference this will make in the bounciness of the floor. I personally feel the I joist will carry your span MUCH better than the 2x12 and will definately provide a more level floor. I have framed with both. I joists are simple to install. I'll also add that if you make your own beams, add a plywood piece in between the 2x12's. This will help to fir out to proper thickness and increase the stiffness a lot. Russ

Mike Guertin (who I like) writes a lot of articles on framing. He says:
Solid-wood joist blocking will sometimes help reduce bounce, but the joists and the blocks need to be dry and the blocks must fit very tight. I purposely cut blocks a whisker too long and sledgehammer them into place. Nail them in a straight line, not staggered. You can add one, two, or three rows of blocking to help stiffen the floor.

I also found this on a deck site.
Solid Blocking: Blocking keeps taller joists from twisting onto their sides when heavily loaded.
By 2003 International Building Code (IBC), blocking is required every 8 feet for 2x10 and taller joists.

Blocking will add to my labor time, and the I-joists don't need it,but I have lot's of time. I've used blocking in the past because it does make sense.

[Andrew Joiner]

My site built beams are 14' long. They are like oversize headers and will be within my existing pole barn like walls. The beams will really only span 7' . I can block them down to the floor every 3 or 4 ' if I need to.

It's a question of time and material. 1 big beam spanning 14'. A thiner beam spanning 7' and center blocks acting like a post. Or lots of blocks acting like studs and the beam would be more like a top plate.

Remember my existing walls have horizontal 2x6 girts, not vertical studs.

Yes my Fir 2x12 joists will span 19' and they will rest on the beam/headers.

[Allen Schmid]

Andrew (and Jason),
Thanks for thinking of the firefighters in this equation...we have all just accepted the fact that most (if not all) new construction is being done with the lightweight floor trusses. Heck, they are so common that you are even finding them placed as roof trusses in some instances. In many cities across the country the code now states that there is a marking placed on the outside of commercial/large residential buildings to indicate lightweight trusses have been used. The fail rate during testing is almost a moot point as failure is going to occur with fire impinging on/into the joist space, it is always a guessing game as to how long the product has been under assault. Some people I know have not used the LWtruss because of their concern. With standard response times and the amount of heat these fires are generating these days we all presume the worst and hope we can make progress at a fire with the least amount of danger for firefighting brothers and sisters.
Jason, nice job on finding the NFPA info and testing.
Andrew good luck on your project.
Allen

[Anthony Smaldone]

I'm a Lieutenant in the FDNY. Let me say, if we were able to, we would ban Wood I joists from ever being made. They fail within min. of being exposed to fire. They are very dangerous to the fire Depts. throughtout this country. Main reason being, We do not know which buildings have them and which do not. They have killed and will continue to kill us.

[Larry Edgerton]

[quote=Andrew Joiner;1023754]Quote:


Mike Guertin (who I like) writes a lot of articles on framing. He says:
Solid-wood joist blocking will sometimes help reduce bounce, but the joists and the blocks need to be dry and the blocks must fit very tight. I purposely cut blocks a whisker too long and sledgehammer them into place. Nail them in a straight line, not staggered. You can add one, two, or three rows of blocking to help stiffen the floor.

The traditional method is solid at each end from the bond to the first joist, and then X bridging across the span. It is nailed on the top, and the bottom is left to be nailed after the rest of the weight is put on the floor, and things have settled, dried and shrunk into place. It is nailed just before being covered. Solid blocking will not be as strong as bridging as it will not fit as well, especially after shrinking,no matter how big a hammer you use.

The idea of bridging is to stop deflection, where sag starts, and to spread the weight out over several joists at any point.

I don't think much of the metal X bracing that is on the market. Another positive for X bridging is that no holes need to be drilled for wiring, etc.

[Darius Ferlas]

I asked our Chief Building Official where I work (a municipality), and the Fire Chief.

This is a gist of what they said:

CBO- good strength and span. Sometimes issues with delamination of elements, depending on the manufacturing process. Delamination is a concern especially when the joists/rafters carry a ceramic tile floor. His preference is webbed wood joists.

FC: firemen won't even try to walk on floors in a burning house where floors are known to be made of I-Beams. Too risky for them. His preference (to be expected) poured reinforced concrete

[Jason Roehl]

One thing I haven't seen yet in this discussion is the difference in feel between the two floors. An I-joist floor can be made very stiff (low deflection), but will still bounce due to the lack of mass--it will vibrate for some time after all motion on it has ceased. Solid lumber has more mass, but is more flexible, so it takes a much larger 2x to achieve the same lower deflection as an I-joist. Due to the higher mass, however, vibrations are dampened.

If someone has a china cabinet in their dining room, I can probably tell how the floor is constructed just by walking through the center.

[Rick Lucrezi]

I did not read all the replies so if I parrot some one else I appologize. The fire thing kinda lost me. Any way, I am builder and I will advice against the sandwhiching of the 2x12s. 20 years ago or beter we had great lumber and it was possible to get quality select 2x12 and with good wood its ok to make beams. Nowadays the 2x12 you commonly see at the yards is suspect at best. Not to mention the weight of marying 2 2x12s. We use BCI i joist all the time. They are light, strong and easy to install. They do cost more and with the additional cost of the brackets its a hard not to consider the options, but when your done you will have a perfectly flat floor, and ceiling and for running wiring or plumbing you only need to knock out the pre stamped holes. Drilling through 2 2x12s with all the nails is a real pain in the rear.