I just did a deck with a 16 foot span with 2x10 joists 16 on center and im lookin at it, and the joists sag. 16 foot is ok with local code but the thing sags like 1/2 inch in the center. I did not install bridging blocks because I wanted to eliminate the sqeak factor. Do you think thats why it sagged or do you always have to oversize preasure treated lumber because it is so wet and floppy?
floor joist sizing
bluebird5
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I like the morning Wood thing :shifty:
The span charts are rated right next to falure -.2 percent.
I am not understanding " I did not install bridging blocking because I wanted to eliminate the sqeak factor " If anything the close cut blocking would have helped.
A 16 ' span with 2x 10s installed outside exposed to the weather on a deck is going to bounse and fail. Your project is ill fated.
JonMon www.deckmastersllc.com
The span charts are rated right next to falure -.2 percent.
I am not understanding " I did not install bridging blocking because I wanted to eliminate the sqeak factor " If anything the close cut blocking would have helped.
A 16 ' span with 2x 10s installed outside exposed to the weather on a deck is going to bounse and fail. Your project is ill fated.
JonMon www.deckmastersllc.com
Well I checked the span table for local code. I guess that is what I am getting at because it said 16' max span was allowable. I will just never trust it again. The American wood council calculator I checked after the fact and it allows 2x10 pine to span 16'1'' but that is a 360. All in all it is very nice, and the homeowner is thrilled. Next time I make sure I get a 480 which I thought I was getting when I followed the table. It is not really bouncy I just noticed a bit of a sag which got me to wondering if preasure treated lumber was more deflective than kiln dried. Also I put a roof over it so it is not exposed to the elements. Anyways, I am done rambling and will post some pics maybe thursday when I go back to finish. Thanks to all for their input!:clap:
We use pressure treated douglas fir here.
I'm very conservative with my spans and I have a easy rule that I follow for deck joists. This actually is from back when I framed a 24" on center, so I allow a little bit longer when I frame at 16" O.C.
6" joists span 6'
8" joists span 8'
10" joists span 10'
12" joists span 12'
These numbers always give me a little wiggle room.
I'm very conservative with my spans and I have a easy rule that I follow for deck joists. This actually is from back when I framed a 24" on center, so I allow a little bit longer when I frame at 16" O.C.
6" joists span 6'
8" joists span 8'
10" joists span 10'
12" joists span 12'
These numbers always give me a little wiggle room.
I'm with you on that. I will sometimes give a bit more but not much. Passing code sometimes just isn't enough.
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What span tables is the local building department using? 1933 version?
http://www.awc.org/calculators/span/calc/timbercalcstyle.asp
You can get this in a Iphone app too.
14' 4" is the typical span for a 2x10 span of most common lumber. That will give L/360
Unless you used Select Structural lumber. Which is what is required to allow 16' span 16' 5" to be exact. Or No.1 You may have failed with your structural calculation. No.2 or better is not a option at this span.
http://www.awc.org/calculators/span/calc/timbercalcstyle.asp
You can get this in a Iphone app too.
14' 4" is the typical span for a 2x10 span of most common lumber. That will give L/360
Unless you used Select Structural lumber. Which is what is required to allow 16' span 16' 5" to be exact. Or No.1 You may have failed with your structural calculation. No.2 or better is not a option at this span.
The thing that you guys need to understand is that the span table give you the maximum allowable span for a given load. That does not mean that the joist will not sag or flex, it will.
Be conservative or expect it to move, sag or flex. If you want a stiff floor, do not max out your spans.
Be conservative or expect it to move, sag or flex. If you want a stiff floor, do not max out your spans.
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Yes this is true. But I don't think bluebird read the tables right or at all and was basing in second hand knowledge with. The calculation of the dead load is what is screwing him along with not using the right grade of lumber. Also incised lumber has a lower span.
I have a feeling this is a combination of several factors than just maxing out a span table with proper procedures and material.
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As stupid as this sounds...
If you can't put a beam down the center, fasten 2x4's with 6" screws to the underside of your framing. You'll be surprised how much this works.
It's not the best solution but hey it's something else to consider
If you can't put a beam down the center, fasten 2x4's with 6" screws to the underside of your framing. You'll be surprised how much this works.
It's not the best solution but hey it's something else to consider
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I haven't done a deck in probably a decade (no pun intended) but I thought decks were more strict then the house. I remember one that fell of just north of Barrie and it involved a kid and a senior citizen...two things you don't want but it changed the whole landscape on deckskatoman said:
Well here is what i used as my guide http://search.yahoo.com/search;_ylt...0aWQDTVNZMDE0?p=hendersonville+tn+deck+code&fr2=sb-top&fr=yfp-t-701&type_param=
Is is the 4th link. Or you can go to yahoo if that link does not work and type in hendersonville tn deck code and click the 4th link that says "doc city of hendersonville tn".
Also on the American wood council calcuator I keep coming up with 16-1 for the span for southern pine, number 2, 2x10, 360 deflection. The lumber is not incised and it is not a wet service condition because it is covered. I have 40 for the live load ands 10 for the dead load. You are saying the loads are wrong, What should they be? :whistling
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I believe you that you used the span table which are generic when it comes to printing them in a book or online. They usually only show a 30LL/10DL or 20DL or 40LL/10DL or 20DL.
So one other thing to factor in is what decking material did you use? This will change your loading. I believe that would be dead load. On the calc if you up the dead load to 15 or 20 the allowable span shortens to the typical 14'. If you up the live load to 50 it shortens also.
So since I am not a engineer. Whatever I say is speculation. But base on what you have said. You need to up the loads from what you used.
Deck collapses make the news. Don't make the news. You will lose your ass in the lawsuit.
It's not going to collapse. Come on man. 1 square foot of 5/4 or 2x6 does not weigh more than 10 lbs. Also 40 lbs. per square foot is standard live load unless you are hosting auditions for the biggest looser.
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My wife and her friends were victims of a deck collapse at a party. So you can make all the excuses you want. It happened about 3-4 years before we met. The story made it on the nightly news and in the local newspapers where I lived. It happened in some po dunk town across the puget sound on the peninsula that no one give two ****s about.
What kind of snow do you guys get in the winter?
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Dead load is the weight of the decking. Live load is the weight of furniture, people and what ever. So you claim that your deck is designed for 50 psf.
BTW is the SP you used No. 2 dense or non dense or just No. 2?
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Have to see what is the total load including the dead load and the live load on that deck.
Dead load is basically the load or the weight of the deck itself. In some cases its usually 10 DL. Then you got the live load which is created by all the extras you got on the deck, like furniture, flower pots, and people which is usually per code is about 40 LL so together the design load is 50 LB PSF. Now if you put a hot tub on the deck and in the winter you get 4' of wet snow, etc the load could increase to
60-80 LB PSF, so even the 2x10 which is being spanned to its max, the current load conditions on that deck could play a big part to cause the bounce, deflection, etc. So if the joists sag as you said they do, something is not right there and you should consider breaking that span up to reduce the span so it can support the load which is placed on the joist that is causing the sag... because if you leave it the way it is, and people will have more people then usual on the deck and they start to jump around, that deck could collapse.
Dead load is basically the load or the weight of the deck itself. In some cases its usually 10 DL. Then you got the live load which is created by all the extras you got on the deck, like furniture, flower pots, and people which is usually per code is about 40 LL so together the design load is 50 LB PSF. Now if you put a hot tub on the deck and in the winter you get 4' of wet snow, etc the load could increase to
60-80 LB PSF, so even the 2x10 which is being spanned to its max, the current load conditions on that deck could play a big part to cause the bounce, deflection, etc. So if the joists sag as you said they do, something is not right there and you should consider breaking that span up to reduce the span so it can support the load which is placed on the joist that is causing the sag... because if you leave it the way it is, and people will have more people then usual on the deck and they start to jump around, that deck could collapse.
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That sounds like a good idea
Also to bluebird- the original poster... if the sagging span is a concern, putting a temporary beam with a bottle jack to raise the sag back up and adding blocks in between the joists will add strength to the span... :thumbsup:
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