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TJI vs 2x12 rafters

the cm's picture

To All,


In a couple of weeks, I'm going to have to make a decision on our current project (new construction) to possibly substitute the specified 2x12 rafters with 12" 560 series TJI rafters. Since the rest of the house (floor frames, girders, etc), except for the 2x6 and 2x4 fir stud walls (interior and exterior), is made up of structural lumber, I was thinking of switching to the TJI's. Cost is not an issue, as they are actually close in price.


I would appreciate any feedback from the braintrust called breaktime.


 


 


The CM


 

 

The CM

 

(post #69925, reply #1 of 62)

Well not a framer by trade, but have helped build a few here & there.


One thing I always liked about engineered lumber vs dimensional lumber is I never have to look for the crown or a twist in the board.

 

(post #69925, reply #2 of 62)

As a framer, I'd rather look for a crown than install all that additional hardware any day.  I can deal with I-joists for floor framing, but think they're a royal PIA for roof framing.  Just my opinion.


I'd also charge more for a roof framed with I-joists over conventional lumber because of the additional labor involved.  Don't know if that matters to you or not either.


(post #69925, reply #3 of 62)

I wouldn't think twice if I could use the 2x12s. I certainly wouldn't pay more to torture myself with the Ijoists.


blue


 

"...

keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #69925, reply #4 of 62)

I've done it both ways and completely agree with Dieslepig and Blue.


I was extremely pleased with the outcome using TJI's ( straight, strong, etc. ) but it was alot of extra screwing around.


Remodeling Contractor just on the other side of the Glass City

Remodeling Contractor just on the other side of the Glass City

(post #69925, reply #5 of 62)

There's definitely a lot more work and hardware in putting up I-joists as rafters. I think it gives a better roof, but is more expensive and labor intensive.

You might be able to offset some of the added cost by spacing the I-joists farther apart. Like using 24" O.C. I-joists vs. 16" O.C. 2X rafters.

I assume you know that I-joists require a ridge BEAM, not just a ridge BOARD. That can be a deal killer in some cases.

I'm not a happy camper. It's not because I'm unhappy. It's because I'm not a camper.

(post #69925, reply #6 of 62)

Bosshog,


This job is already under contract. Cost is not too much of an issue as long as I keep within the set budget and I have allowed enough room to compensate for some add ons. The greater concern I have is that it is a 24 foot rafter length with a 9 pitch and I can't stand looking at humps in the roof plane. 2x12 DF stock at that length tends to develop nasty crowns (even when you cull out initially) that show through the roofing.


I always use LVL stock for the ridge, valleys and hips. Maybe I should go with LVL rafters instead of TJI's just on the main box and eliminate the hardware along with the reinforced web at the birdsmouth cuts.


 


The CM


 

 

The CM

 

(post #69925, reply #7 of 62)

I saw a big frame-up this past summer in which TrusJoist's LSL (laminated strand lumber) members were used for rafters.


LSL is sold in a light thickness, I believe 1-1/8", for rimboard.  I think they make it in 1-1/2" thickness, and that is what I saw used.


Probably higher cost than your other two alternatives, but dead straight, and no hardware requirements at connections.

(post #69925, reply #8 of 62)

Stinger,


The LSL used for rims is like a chip board composite in the lighter thickness and can't take a nail from the side (like in a birdsmouth cut or toe nailing into the ridge). Is the thicker version the same composition? If it is, how did they get away without using hardware at the cuts?


 


 


The CM


 

 

The CM

 

(post #69925, reply #9 of 62)

Try this link.

http://www.trusjoist.com/PDFFiles/2080.pdf

Joe Carola
Joe Carola

(post #69925, reply #11 of 62)

Joe,


Perfect. Thank you. I deal with a large lumber yard who has been carrying TJ products for years and they did not have a clue that this rafter system existed. I am amazed. I must have asked my salesman (who I've been with since 1986) a dozen times over the past year and got nowhere. Their online system doesn't even have the product listed and its brand new. Looks like this product has been around for about a year. Guess who's going to catch a little sh#t on monday morning.


Thanks.


 


 


The CM


 

 

The CM

 

(post #69925, reply #12 of 62)

Stinger,


Thanks. Nice call.


 


 


The CM


 

 

The CM

 

(post #69925, reply #13 of 62)

Very good call.  That stuff is killer and this sounds a perfect application.

(post #69925, reply #16 of 62)

"I always use LVL stock for the ridge, valleys and hips."

Using LVLs doesn't mean it's a ridge BEAM.

Do you know the difference?

If there were any justice in the world, barking dogs would get sore throats.

(post #69925, reply #20 of 62)

Bosshog,


A ridge is supported by the rafters, a ridge beam is a structural member supported by bearing point loads carried down through the building, calculated and dependent on its length, the weight of the roof frame and based on the required load capacity.


Thank you for asking.


 


 


The CM


 

 

The CM

 

(post #69925, reply #22 of 62)

We stick frame almost everytime we frame a house.  We regularly use 24' 2x12 without humps in the roof.  There are some tricks.  We cut our roofs in racks http://pic9.picturetrail.com/VOL293/2163851/4215122/53031627.jpg The majority of the time.  For straight gables, you can rack and cut in less than an hour.  This house http://pic9.picturetrail.com/VOL293/2163851/6440753/82815157.jpg was all 2x12 24'ers.  As you can see none of the difference between rafters is more than 1/4" or so.  We frame 24" oc here with 7/16" OSB (I know we are hacks) without problems.  Our lumber is kiln dried hem fir too.


Here are a few more pics http://pic9.picturetrail.com/VOL293/2163851/6440753/82815148.jpg


http://pic9.picturetrail.com/VOL293/2163851/6440753/82815135.jpg


http://pic9.picturetrail.com/VOL293/2163851/6440753/82815112.jpg


Me in orange http://pic9.picturetrail.com/VOL293/2163851/6440753/82815128.jpg


I didn't see what your specs are.  I read halfway down the thread before posting.  I would rather upgrade to 5/8" OSB before switching to I-joists.  We've got a plan being looked over by TrusJoist right now where we may use thier engineered roof system, LSL for rafters, but that is 31' long :-)


I wouldn't worry about the humps telegraphing through the roofing.  What kind of roofing are you going to use?  If it's shake, you won't see it.  If it's tile like this house http://pic9.picturetrail.com/VOL293/2163851/7273486/108749466.jpg which was all 2x10, you'll have to be a little more careful.  If it's a thicker comp like an architectural comp, you can get away with a lot.


I would avoid going the I-joist route if you can.  It isn't worth the extra labor.  I'm not sure where you are from, but get KD lumber, order a few extra (that can be cut into jacks or used inside in a trey ceiling) and you'll be fine.


Edit:


I read the rest of the posts.  The Trusjoist system isn't widely available yet.  We'll probably use it an a couple of months.  Just checking the price vs. trusses right now.  Its up to you whether you want to use it vs. 2x12.  Save money if you can, try a new product if they'll let you :-)  Post pics if you get to use it.  I really don't think the crowns in the 2x12s are going to be a big deal.  Where are you from by the way?


Edited 1/15/2006 10:50 pm ET by Timuhler

www.pioneerbuildersonline.com From Lot 30 Muirkirk

http://picasaweb.google.com/TimothyUhler                                     

(post #69925, reply #23 of 62)

Tim,


For 30 years we have always used 2x12 hem fir. We also use racks to cut rafters in bulk. (its nice to see we all think the same way, 3000 miles apart). Either you get better lumber out there or by the time it gets across country to Connecticut it goes to hell. On a rack the size of the one you have pictured, we would probably cull out around twenty percent. A lot of the guys out here are switching to spruce because of the price and the weight is a lot less. The problem is that the spruce crowns later, after the building is up.


The last three we did showed crowns through the timberline architectural comp and didn't leave a good impression for the clients.


Specs are for 2x12 hem fir. TJI's are too involved and problematic. I'll end up going with the LSL roof system. I'm looking forward to using the new product. I'll post some pics when we get there. We start framing next week.


Thank you for the info, I really enjoyed the pics.


 


The CM


 

 

The CM

 

(post #69925, reply #28 of 62)

Sweet.  I can't wait to see the pics.  I just found out last night that we'll do the house with the LSL rafters sooner rather than later, maybe 2 months or less, but that might change.


Can you order Doug Fir?  Just curious.

www.pioneerbuildersonline.com From Lot 30 Muirkirk

http://picasaweb.google.com/TimothyUhler                                     

(post #69925, reply #32 of 62)

Tim,


Yes, we can order doug fir but it comes in as hem fir, not pure doug fir. I am guessing that it is reserved for you lucky guys on the west coast.


I made the call to my lumber salesman this morning inquiring as to why the LSL rafter system is not up on their site yet, or even in their inventory. We start framing next week if the weather clears up, we got smacked with a nor-easter yesterday and temps went from 45 to minus 20 overnight.


 


The CM


 

 

The CM

 

(post #69925, reply #24 of 62)

Yes, Tim, but what species are you typically using for rafter stock?  In the NE, it is mostly spruce we are using, and you wouldn't like framing with our spruce at all.

(post #69925, reply #25 of 62)

Stinger, I'm in NE too (MA).  We get hem-fir regularly for any stock over 20'.  The rest is SPF.  Amazing how things differ just a relatively short distance away.

(post #69925, reply #26 of 62)

Actually, the long stock available isn't too bad.  Depends on the yard.  A couple of them stock framing lumber that ships in from Austria on containers, and it is very good.  Pricey, though.


We prefer trussframed roofs to stickframed.  The truss drawings for this one, including the details, consisted of over 100 pages.

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(post #69925, reply #27 of 62)

Wow, very cool looking.  Those trusses on the far right of the building.... looks like it's over an entryway.  Very nice detail.  Would that be an eyebrow or a barrel vault?

(post #69925, reply #30 of 62)

That looks like a cool house. 


I have to tell you though, I hate dealing with trusses.  I know they work for most people, but I don't like them.  Especially when we get really cut up houses (where you have to fill in all over anyway and piggy back. 

www.pioneerbuildersonline.com From Lot 30 Muirkirk

http://picasaweb.google.com/TimothyUhler                                     

(post #69925, reply #31 of 62)

"I hate dealing with trusses....Especially when we get really cut up houses where you have to fill in all over anyway and piggy back."

Believe it or not, so do I.

Seems to me that many houses like that should be simplified or stick framed.

The more difficult the house, the greater the likelyhood that the trusses won't fit. Then nobody wins.

With setups of lower quantities, it's harder to make money on the trusses.

It harder to load the trucks and ship the trusses in one piece.

All in all, it's a pain for everybody.

But it seems like once guys get used to trusses they don't want to go back. I catch all kinds of hell if guys have to stick frame parts of a house, even if it makes more sense to do so.

You can no more win a war than you can win an earthquake [Jeannette Rankin]

(post #69925, reply #36 of 62)

Boss,


Trusses are a great concept.  However, I can only assume that the guys putting them together necessarily the guys you or I would want doing it. 


I just really like stick framing :-)

www.pioneerbuildersonline.com From Lot 30 Muirkirk

http://picasaweb.google.com/TimothyUhler                                     

(post #69925, reply #41 of 62)

"I have to tell you though, I hate dealing with trusses. I know they work for most people, but I don't like them."

I don't use trusses but one thing I can think of where an existing house that is trussed where it would be way more expensive to build on would be on a ranch house that’s going to have to an add-a-level put on.

You would have to remove the whole entire truss which means that the whole ceiling, sheetrock, wires.....etc, has to be removed. Where as a house that's stick framed just the rafters come off and you don't have to remove any ceilings at all depending on the complexity of the job but I'm talking about you would have to remove the whole truss. That adds a big expense to an add-a-level or any other addition that has to tie into the existing roof like the one I'm on now, there's now way I would've been able to frame this if the existing rafters were trusses.

Joe Carola
Joe Carola

(post #69925, reply #43 of 62)

I don't see that as a valid reason NOT to use trusses.

How many houses get a second level added on them down the road? Around here it's maybe one in 5,000.

It's like they always say, if you're rich and white, you can get away with anything. [Jimmy Kimmel, on the Michael Jackson verdict]

(post #69925, reply #44 of 62)

"I don't see that as a valid reason NOT to use trusses."

I didn't say that is was a valid reason NOT to use trusses. I wasn't saying anything about not using trusses at all. I was just thinking about working on houses that have trusses because I do many additions all year and add-a-levels and the thought crossed my mind about how much more it would cost to work on a house with trusses.

"How many houses get a second level added on them down the road? Around here it's maybe one in 5,000."

Maybe so from where you’re from but around here there's add-a-levels going on every day. So far I haven't done one with a truss roof before. I'm sure from where your from people put additions on there houses though where you have to cut into the trusses, right? If that's the case I'm sure you have to rebuild the truss where you cut the trusses so that would make it a lot more work involved on existing homes.

Sometimes I have to cut right down the middle of the existing roof to install a valley to make a cathedral ceiling, so all I do is cut back on the existing rafters and nail them into the new valley. If I had to do that with a trussed roof what would I do with those trusses?

Joe Carola
Joe Carola

(post #69925, reply #45 of 62)

Maybe it's just a regional difference, then.

I only remember one add-a-level around here in the past 10 years.

It's kind of ironic when you think about it. The only Jackson you can accuse of committing a lewd act is Janet at the Super Bowl. The one we wanted to see. [Jay Leno]

(post #69925, reply #55 of 62)

Framer, when you do a second story over a trussed ranch, you cut out the webs and top chords and then hang the leftover ceiling members (the bottom chord) and drywall from the newly installed floor joists.


This new connection can be accomplished in many differnt ways. It does take a little more time but it's not an insurmountable obstacle.


blue


 

"...

keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.