I-Joist OR WW Floor Truss…which one?
Currently involved in a major house renovation. One of three additions is a 36′ x 46′ -16′ sidewall “Great Room” with a 10 foot basement. Final house SF will hit 7054.
In planning with the owner I sent a print to the truss company for the floor system. It came back with a Bid for I-joist and an option for Wood Web floor trusses.
The HVAC, Electrician & Plumber rejoiced at the WW trusses. The I-joist are 1/2 the price of the WW. The trusses run across the 36′ and the spans are 9′-18′-9′. The center span is to be used as a billards parlor with no stick hazards.
I see the advantages for the infrastructure folks, but the customer will see the $$$.
So, my question is………..
“What other merits do the WW trusses offer that make the price difference justifiable?”
…………..Iron Helix
Replies
Personally, I think walking across an I-joist floor is like walking across a drum head. Strong but kinda boomy and boingy (technical terms.) Although, I've never had the opportunity to do a direct comparison before the memory of what one feels like fades. I-joists cut off all perpendicular access without restricted holesaw sizes. All sizable HVAC lines will have to come from one end barring the availability of a crawl or attic (which I have run into.)
Maybe I just don't want to bother with cutting holes. I would think stiff for a pool table would be better. For that I would like to go walk a WW truss floor with comp. span and see for myself.
The more technicalterm for boingy would be vibration, but in a floor with same load design values, neither the Ijoist nor the open web wood truss floor would be better, IMO, IF they are both the same depth. The height of the system is more iindicative of the amt of vibnration that can be expected - so if the I-joists are 12" deep at 16oc but suppose the open weebs are 14" deep at 24" oc to make the same design load, then it would resist vibration better. Iron - pool table means you want less vibration and higher design loads because over time, deflection from any developing sag will cause the table to be misaligned.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
>walking across an I-joist floor is like walking across a drum headI definitely know examples that are NOT like that. I call them Chevrolet Floors--Solid as a Rock. OK, I just made that up. Seriously, if speced right, an I-joist floor, especially for those small spans, would be quite solid.
You are describing Caddy floors and constructionazii is remembering Ford floors
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
You oughta get back some of the extra cost of the web trusses in savings on HVAC, electrical and plumbing installation.
Remember also, in general, something doesn't cost half as much as something else without reason.
I have seen too much OSB flaking and degradation due to a variety of very common environmental factors to make me feel comfortable using anything made of it for structural purposes. I would pay the extra and go for the web trusses.
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
I'm surprised the WW floors came back at twice the price. Have you checked any other places? Pricing on WW floor trusses varies widely from one company to another.
The labor to install the floor trusses should be less than for I-joists, which would offset some of the cost difference.
If the electrician, HVAC guy, and plumber are happy about the floor trusses, I suppose you could ask them for a price difference between the 2 systems. If they want the WW floors they should be willing to cut a break to get them.
If the trussesa are only spanning 18', they most likely aren't very deep. That means there won't be a tremendous amount of room for mechanicals. Your electrical and plumbing supply lines will almost certainly fit. And maybe part of the HVAC supply lines will.
But the return air line most likely will NOT fit. And possibly not your plumbing drain lines. (Depends on where they run from/to.
As a rule of thumb, I tell people floor trusses need to be at least 18" deep before you can count on getting most everything in them.
WW floor trusses
I have to admit we've never used them. They aren't huge around here although we do see them occasionally.
What do you use for rim ?
Where does the big labor savings come from ? Eliminating all of the squash blocks ?
carpenter in transition
Instead of a rim board, most truss manufacturers leave a notch for a ribbon board. You can see the notch on the left end of the trusses in this picture:http://microtrus.com/images/ft06.jpgOn parallel walls, a "ladder" truss is used. You can see one on top of the pile and to the right in the picture.The labor savings is mainly because everything is cut to length. You just set it in place and nail it down. You have exactly what you need - No scrap to clean up afterwards, and no extra pieces. (Assuming everything goes right, of course)
There is only one way to find out if a man is honest ask him. If he says "yes," you know he is crooked.
thanks for the pic. must be nice walking on a 2x4 flat. the ribbon is an interesting concept.
what are the most commonly sold joist depths ?
carpenter in transition
"must be nice walking on a 2x4 flat. "
Yup - It is. The wide surface also gives you a lot of area for glue.
"the ribbon is an interesting concept."
Seems to me it makes good sense. You don't need a full depth bard to support the wall above.
"what are the most commonly sold joist depths ?"
We sell an awful lot of 12" floors. They easily span the typical 18' or so on most houses. We sell a fair amount in 14" through 18" depths.
Anything deeper is fairly rare - They're only done where someone wants long clear spans.
If you don’t think every day is a good day, just try missing one.
I'll chime in here and agree with most everything others have said.
You ought to get a second bid on floor trusses, and at the same time, ask all the mechanical subs to put, in writing, their bids with options shown for both floor system types. "Happiness" doesn't go in the account, at my bank.
Framing labor costs may vary with one system as compared to the other. If you are subbing the framing, get your framer to put, in writing also, the costs for each. If you're framing yourself, put pencil to paper, and figure your labor difference.
Additionally, make the subs fully aware of depths of one versus the other, webbing type and clear hole spacings in the trusses, and the allowable hole cutting standards from the I-joist folks.
Only then can you make the financial decision.
Edited 5/9/2005 8:10 am ET by Gene Davis
Met with the owner....surprised at how easily he went for the wood web!
Then he told me that the plumber and electrician had already knocked at his door to ask for the WW trusses. Less hours and problems on their parts...balances against the higher costs.
Trusses are not tall enough to benefit the HVAC duct people, their work will be in dropped soffits at the basement perimeter.
Actually did a second quote this AM and the found a reduced difference in $$ between WW & I joist through a different source.
Thanks to all for the input,info and opinions.................Iron Helix
The HVAC, Electrician & Plumber rejoiced at the WW trusses. The I-joist are 1/2 the price of the WW. The trusses run across the 36' and the spans are 9'-18'-9'. The center span is to be used as a billards parlor with no stick hazards.
I see the advantages for the infrastructure folks, but the customer will see the $$$.
So, my question is...........
"What other merits do the WW trusses offer that make the price difference justifiable?"
That's just it. The open web trusses are so much more easy to use, and the savings add up when there's a guy on a ladder drilling a dozen holes through each one just to run the utilities.
Look into Open Joist 2000 trusses. It's a finger jointed, no-metal-plates truss that can easily take the 18' span. I used them on my house to span 14', using a 12" depth (11-7/8", actually) and they are SOLID. If you want them stiffer you can get a 14" and 16" deep OJT. The price diff on mine VS. I-joists was only $500 (for a 1600 sf deck) and the labor savings will be a lot more than that.
Jon