(At least as far as I know). They are much stronger. Hope this helps. We have found that the I joists can be installed much easier than the 2x10. You may have to order early, but with the way lumber is today, I can't recommend soild lumber for floor joist.Not like it used to be.Ed. If you are truly looking to stabilize the floor, an additional layer of sub-floor will offer the most stability and strength. Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features. and had very few culls. Williams, *Thanks for the info Joe. The few floors I "test drove" with TJI's seemed bouncy to me. I chose 2x10 doug fir and have no complaints. Podcast 301: Stick vs. Post Frame, Upside-Down Clapboards, and Caulking Cedar Shingles, Builder’s Advocate: An Interview With Viewrail, Plus, get an extra 20% off with code GIFT20, Simple Way to Make Old Walls Straight and Plumb, Expert insights on techniques and principles. That was definitely a concern of mine when choosing my floor, but cost was still the big factor. Una_Persson July 30, 2010, 11:33pm #1. They also typically require a few days of lead time to get in. I'm kind of curious what brand they were, and what part of the country you're in. simple span joists and rafters with uniform load. About three times the price for I joists in my case. It may be legal but not too comfortable to walk on. I had a chance to get free I-joists for a 12x20 addition but the rim was more than new 2x10's for the entire floor. I chose 2×10 doug fir and have no complaints. I have no bounce in any floors built with EFJ's, and I never will. Additionally, the load that the floor needs to support is also a consideration. They are strong, they don't bounce if engineered right, and the electricians and plumbers love to run wires and pipes through them.That's what I think,Ed. A common problem is using the span tables too literally. If the span is 6 feet or less, use 2X6’s, if the span is 8 feet or less, use 2X8’s, less than 10 feet, 2X10’s, etc. As far as bounciness (deflection) is concerned, that too is a matter of design. Once you start to work with them, you will really like them. In all the houses that we build now, we are using floor trusses. *I think you've hit it on the design thing. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. Deflection Limit: 0.003 x engineering span or 12mm whichever is lesser. Required fields are marked *. Your email address will not be published. It is assumed that for "Built-In" joists that the masonry is 100mm wide and for joists "On Hangers" the hanger has a 75mm bottom plate. ), The Secret Science of Solving Crossword Puzzles, Racist Phrases to Remove From Your Mental Lexicon. You didn't mention wood web floor trusses, but what the heck - I'm on a roll.Floor trusses are generally the most expensive to buy, but take the least labor. A Douglas Fir typically has the ability to span a larger distance than a Spruce Pine or Southern Pine. *Geoff is right. Two 2x10s would give 2x(2.7777) = 5.55 times as strong as a 2x6. Hope this helps. Any of the 3 can give you a good floor, if you follow written guidelines. (Ductwork requires quite a bit of pre-planning, though) Trusses require the longest lead time to order - often 2 to 4 weeks. Same type of math says that a 3x10 would be a reasonable substitute for a 2x12. My supplier of engineered joists keeps consistant pricing. Until you got to the part about "closing up the spacing". for 11-7/8". (owner-builder) With my spans I could have used 7 1/2″ TJI’s, but no room for plumbing. Structural Engineering Quesiton - sistering joists. © 2020 The Taunton Press, Inc. All rights reserved. In situations calling for a greater amount of pounds per square foot capability, the span length will decrease. For floor joist, I wouldn't use anything except #1 Southern Yellow Pine. "I have learned so much thanks to the searchable articles on the FHB website. In new home construction, what is the best way to go for the joists, including the issues of initial cost, installiation time and quality of finished floor? 3/4 T&G OSB over 2×10’s on 16″ ctrs seems plenty stiff, but my longest span is 16 feet. The few floors I “test drove” with TJI’s seemed bouncy to me. One "big" one is length, I just ordered a load of 11-7/8" SP 55 40ft's and 9-1/4" SP 55 36ft's. spanning 8′ on a single story home 32′ wide, be an overkill? hope this helps, Geoff. *Lew, all the above is good advice, but one drawback to I joists is their short burn time if there is a fire, talk to some local firefighters and get their opinion, this is what I have heard "over the fence". If you have to use a non-dimentional lumber floor system, I vote for floor trusses. 2 X 8 joists spanning only 8 feet is more than enough. Decreasing the spacing has very little effect. As a professional firefighter who is stumbling through the construction of his own home, I an tell you that at least out here on the west coast lightweight construction is a concern anytime we get a house fire with heavy involvement. *Lew:Just went throught the same dilemma with the two story I'm building. As to cost, I've found that the market price of 2x joist material too changeable, usually up, just after I present my bid. Some situations require time-consuming blocking, mostly in multi-story applications. Question: I was wondering would 2×10 floor joists 16 o.c. A first floor joist also typically requires a higher psf rating than a second story or attic. I never thought about it being a higher series of I-joists. Part is a 15' span which is on 12" centers, 3/4" t&g plywood, constuction adhesive, I don't think I'll get any bounce. Before jumping into the span tables, let's first consider wood species and wood grades. *Designed properly, engineered joists will make for a stiffer floor. *Conventional joists are the cheapest choice, if you consider materials only. This assembly will provide a stable floor that will not flex, squeak or move. L/360 over a long span will give you a fair amount of movement. You will however, need to become familiar with reading your local floor joist span tables for floor beams, floor joists, window and door lintels, ceiling joists, roof joists, roof rafters, and roof ridge beams, as well as the sizing and spacing of wood studs tables. Will 5G Impact Our Cell Phone Plans (or Our Health?! For longer spans, engineereed joists are most likely the way to go. and the 9-1/4" were $1.66 pf. I got quality lumber from my local yard,( not H.D.) If a joist's "Max. Get used to engineered joists. Some of those were done with engineered joists and some with 2x10s. It's 1.6666 times the depth of a 2x6 and hence is (1.66666)^2 = 2.7777 times as strong in bending strength. (owner-builder) With my spans I could have used 7 1/2" TJI's, but no room for plumbing. General Questions. I'm using 2x10 Southern Yellow Pine in my personal house. Truss Joist brand isn't used a lot in central Illinois due to their higher cost, and lack of availability. They are almost perfectly straight, and will probably give you the flattest floor. How Far Can You Span a 2 X 10 Floor Joist. Just as most builders would not try and use the minimum size allowed 2x joist to acheive a stiff floor, you should not push the limits of engineered joists. Their primary disadvantages are that they take more labor than any other framing system, and they aren't very straight.I-joists are virtually always more expensive as far as material costs, but take a bit less labor. Commercially we also use a product known as gyp-crete which is a gypsum product that is actually poured over the sub-floor to soundproof, fireproof and provide additional density to the floor assembly. I would recommend the I joists.Eric. The "spring" or "feel" of a floor isn't considered when making up span charts. *Joe - $2.10 sounds pretty high for 11 7/8" I-joists. Bearing Length, in. They are flimsy, and I have had them fall apart on me. The listingis the maximum allowable spans. "Max. The span table dictated 2x12 is only 4x as strong, so two 2x10s are considerably stronger than a 2x12. Williams, *I have capped many a foundation for Habitat for Humanity. *Dear Lew,You might not even be reading this strain any more, but I thought that I'd throw in my two cents. We got a callback on a commercial job when the file cabinets looked as if they might topple when someone walked by. You are definitely right in saying that it isn't a good idea to push the limits on span tables. Having the luxury of being able to compare, the first 8 or 9 years in the trade, to the last 6 years I'd say the I'm now a fan of engineered wood products. Learn more about affordable, modern floating stairs, from design to manufacturing to installation.