I’m working up a materials list for my next home and I’d like to look at options and their prices, for the floor system. Biggest span is twenty feet.
What floor system do you recommend and what’s the current price, per lineal foot?
I looked at GP’s web site. It said their 11 7/8″ LVL I-joist would be good up to twenty-one feet on 24″ centers. How does that fit with your experience? Got a perference?
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Replies
I like the 11 7/8 depth, but I like them on 16 centers. Stiffens the floor up.
I knew I was going to get that comment. <G> I'm sold on 16" centers too but I might go with 24" as an economy measure. Depends on the price.
So how much, per lineal foot, does a large order of 11 7/8 go for these daze?
Edited 10/13/2009 5:56 pm by Hudson Valley Carpenter
Can't tell you.
what's the desired floor covering?
I'm doing a new build right now and I had to span 19'10" in one room and 21' in another. I used 11 7/8" I-joists with 3.5" flanges and T&G Advantech subflooring. Owner wanted to feel as little vibration as possible. I set on 12" centers. That floor is rock solid, very little vibration. We drop lumber on it (by accident) and the vibration is very minimal. Price here was $2.06/lf.
Price here was $2.06/lf.
There we go...thanks. Not so bad, difference of about $1200 between 24" centers and 16" for the duplex I'm planning. Shouldn't break the bank, not that item anyway.
I know I've beat this subject to death here, but have you read the thread on floor vibration?
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=21010.1
Personally, I don't like to see 11 7/8" I-joists spanning over about 18'. But I'm pretty conservative.
The ones you saw on their website that will span 21' on 2' centers might be a special order wide flange I-joist that will cost twice what a typical I-joist will. You would be better off checking to see what brand and series is available locally.
Prices vary a lot. It depends on the series of I-joists, the supplier, and the distributor. About all you can do is price a system out and see what it comes to.
If you're thinking about 2' centers, wood webbed floor trusses might be a good choice.
If you're looking at tile anywhere, I think they strongly recommend 16" centers.
BTW - I like to avoid calling them "I-beams". It seems to give people the idea that they're a heck of a lot stronger than they really are.
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have you read the thread on floor vibration?
Ron, thanks for the link to that excellent post. I hadn't read it before but it doesn't surprise me to hear that depth is more important that spacing, for stiffness. It's very helpful to have you confirm that, both scientifically and from experience.
Having framed a few cheap vacation homes and quite a few well engineered primary residences, the difference in vibration and deflection is pretty obvious when a few men are walking around on them at once.
Our "Mr. Whipple" engineering test was to drop a 50lb box of nails in the middle to the span, see if that made the saw horses jump off the floor. Good for a laugh when the joists were a minimum depth.
What happened to the 19.2" spacing that most I joists used when they first came out? You never seem to see it anymore.
I never used 19.2" centers on I-joists - Just floor trusses. Maybe that varies by region?
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20' span? Open web floor trusses. Makes plumb/hvac/elect a heck of a lot easier too.
Open web floor trusses never caught on in the NE. Can't really explain why, but they haven't.
Here is part of the reason. They are great for slab houses since you can't have many of the utilities under the main floor, so you are dependant on a large percentage HVAC & electrical being in the floor system between the 1st and 2nd floor. Plumbing has to be were it has to be, but it always sucks having people drilling on your solid wood joists. Slab houses aren't common where you are because of the cold. I'll be the first one to say slab houses aren't my favorite, but they do work better in warm climates.