Question,
I just took delivery of my floor joists and trusses. The wall in question is 18′ outside to outside.
The floor joists span is 17′ 10 3/4″ (stamped on the joists and the delivery plans is 17 10 8)
What is this missing 1 1/4″ on the floor joists?
Thanks for the input.
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WWPD
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Replies
Could be your rim joist (timberstrand). Who created the floor layout? Who signed the shop drawings?
Around here I carefully inspect the cad drawings from the joist supplier to confirm that it matches what is shown on my approved (by building dept.) structural drawings. I check spans, number of joists, size of joists, load bearing beams and if they placed beams under all of my parallel walls. Some of this is shown on the structural drawings and some is called out in the notes.
By the time I have ordered my lumber material I have developed a complete understanding of the structure. I work on large projects and typically am reviewing these drawings during excavation. I feel that it is imperative to understand the structural details before concrete begins, this is when some of the hold downs and bearing paths need to be thought out. For, example how far back from the concrete corner do you place your shear wall hold downs.
Forgive me for I have begun to ramble.
Wood is Good
Adam Greisz
I checked all prints, talked with truss plant lead engineer in person, went over my plans, his plans and all were 18'
THese are 2nd floor joists on framed walls-----------------------------------------------------------------------------
WWPD
Did not mean to preach. Are the joists long enough? Is your concern that they are not sized properly for an 18' span?
Wood is Good
Adam Greisz<!----><!---->
<!---->
yes.
And how am I to make up the 1 1/4"
I don't understand the previous response. How would thos floor joists sit atop the wall if they are 11" short?????-----------------------------------------------------------------------------
WWPD
I am guessing here, or maybe not. You need a rim joist. Your joist are 17-10-8, that is 0-1-8 short of 18-0-0. 3/4 inch plywood (timberstand) on each end makes the rim board. NOW, normally the rim board I get is 1 1/8 so you may want to check with supplier as to where the rim board is since it should be part of the package. If you use 1/18 rim board then you will also need a saw. I have never seen these joist come out square on both ends, luck to get one, so you may need a saw anyway.An inch to short. That's the story of my life !
bstcrpntr --- I hope to grow into this name.
Thanks bstcrpntr!!!!
I thought that may be the case. But like i said I have limited experience.
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WWPD
Here's what I have, just wondering are they supposed to end up short like that? If so, what do I do to get them out flush with the wall? Rip down some 5/8 ply?
In my limited experience I don't recall having to do that.
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WWPD
>> I don't understand the previous response. How would thos floor joists sit atop the wall if they are 11" short????? <<
There is some confusion of terminology here. Clear span is the distance between the inside faces of bearing walls, beams, posts, etc. So, In the previous example where the house is 18' wide with 2x6 walls, the floor system would be ~18' wide but since the inside faces of the walls are ~17'1" apart the Clear span span is ~17'1". Here are some definitions I ripped from this web page (first thing I found on a quick Google): http://www.nautilusrealestate.com/glossary/construction/index.html
SPAN:The nominal distance measured across structural supports such as posts, columns, walls or openings.
CLEAR SPAN:The actual unsupported span between two support points.
Those definitions probably just confused it more... but note the word nominal. The thing is that often the word span is used interchangeable with clear span, the word clear being inferred or insinuated. Obviously, the truss company is using the word span to mean the entire length, not the unsupported clear span.
Now - to the meat of your question: your building is 18' wide. Normally, the foundation would be built to exactly 18' wide, and the framing would be set in the thickness of your sheathing. Is it common to use 5/8" sheathing in your area? If so, the building would be framed at 17'10 3/4" - outside to outside of the walls - not including the sheathing. Then, once the sheathing is applied the overall width of the house is 18' - even.
Here is another example: I'm building a house right now that is 30' wide. Since we use 1/2 " sheathing, the open web floor trusses for the 2nd floor and the roof are 29'11", total length. Actually we use 7/16" sheathing, but the discrepancy is negligible.
Qs: is this a 2 story structure with the first floor system being a slab or a dimensional lumber frame, and then the 2nd floor system being a trussed floor system? Are the walls already framed? If so, what is the distance from the outside of the studs in one wall to the outside of the studs in the opposing wall?
Edited 8/14/2005 11:08 am ET by Matt
Looking at your drawing,are they web-truss joists?
If they're typical I-joists[plywood-web],I don't understand your problem.In your drawing it shows each side 5/8in short.
I-joists are never installed flush with framing.....not around here anyway.
Have you mentioned what rim board is to be used?If they are wood-web trusses, I believe they should be flush but it's been years since I've messed with those.
If it were easy....a caveman could do it.
1)They are web truss joists not I.
2)The first floor is framed and 18' outside to outside.
3)There is not a 5/8 requirement for sheathing.
As suggested, it may be that the truss plant factored in sheathing and we should have built the walls set in to accomodate, however the standard sheathing around here is 7/16th
What I guess I should do is call tomorrow and find out for sure what/why they did what they did
If its not a structural issue, we can use 5/8 as a rim joists
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WWPD
"2x6 walls, the floor system would be ~18' wide but since the inside faces of the walls are ~17'1" apart the Clear span span is ~17'1"."
That's true with I-joists, bot NOT with wood webbed floor trusses.
The span is still figured on the ovcerall length of the truss, since they're designed more as a "pin joint model". The forces start where the first diagonal web meets the verticals at the end of the truss.
A minor point, maybe. But worth noting.
Nothing risqué, nothing gained. [Alexander Woolcott]
Before you make any decisions, check to make sure the ends of the joists are square. If you have to square the ends, you may loose precious inches
A joist's clear span is the distance from inside of bearing to the opposite one.
Thus, a joist bearing on 2x6 wallframes with an outside wall width of 18'-0", will have a clear span 11 inches less than 18 feet, or 17'-1".
Your joists may be stamped with their max span at some load condition or another.
Like bstcrpntr said, they may have assumed you wanted to use 3/4" ply on both ends for boxing. But that seems unlikely. I don't think I've ever seen anyone use 3/4" for boxing.
.
But my guess would be that someone screwed up. The guys in the typical truss plant aren't exactly brain surgeons.
I'd call the truss plant and ask for an explanation. If you have to use the 3/4" ply to fir them out, and they screwed up, they should pay you to do that.
Or at least they can explain why they did what they did.
BTW - What kind of trusses are these? Wood webbed floors, trimmable end, metal webs, or what?
The span is based on the INSIDE span. Unless your walls are very very THIN, you have no problem.
One other thought... You used the term "engineered floor joists" in both your thread title and your first post.
To me, that could mean at least 2 things.... 1) I-joists or 2) open web truss joists joists. Both are engineered floor systems. I think that most people here were assuming the 2nd definition since you said the truss company sent out blah blah blah. It wasn't so clear to me since the truss companies I deal with sell both trusses and I-joists. Once I saw your drawing I was sure you were using the second definition of the 2.
On the other and I think BestCarpenter was assuming the first definition since he is talking about rim board.
Edited 8/14/2005 10:35 am ET by Matt
OK, here is a Q for myself so that everyone won't think I'm a f-ing know it all...
Sailfish said: >> The floor joists span is 17' 10 3/4" (stamped on the joists and the delivery plans is 17 10 8) <<
Exactly how does the 17 10 8 translate to 17' 10 3/4" and more precisely what does the '8' stand for in 17 10 8?
Edited 8/14/2005 11:11 am ET by Matt
"...what does the '8' stand for in 17 10 8?"
That's one of the more annoying things about the truss industry - Everything is done in feet, inches, and sixteenths. So in this example, it means 17 feet, 10 inches, and 8/16. (8/16 is obviously 1/2")
Why the software can't be changed to print it out in normal fractions I don't know. But it's annoying. I have to explain this at least once a week.
Once you get used to thinking in sixteenths, it quickly becomes second nature. But for anyone outside the industry (like all our customers) it's a pain in the neck.
So I appologize on behalf of the stubborn and slow to change truss industry.
We all have problems. Mine are just more important than yours.
>> That's one of the more annoying things about the truss industry - Everything is done in feet, inches, and sixteenths. So in this example, it means 17 feet, 10 inches, and 8/16. (8/16 is obviously 1/2") << Yea I know that - but he said 17'10 3/4"...
Interesting point about the span thing though... I wonder if he has actually put a tape measure on the floor trusses - I thought he had.
Also, you said: >> The span is still figured on the overall length of the truss, since they're designed more as a "pin joint model". The forces start where the first diagonal web meets the verticals at the end of the truss. << OK, but isn't there a double 2x4 at the end of most floor trusses? ... which would mean that the diagonal meets the vertical 3" in from the end of the truss? Another example - If you have a floor truss that is suspended from the end of the top cord/flange, say 18' wide building, 2x4 walls, what is the clear span of the truss? Really I think that we are on the same page, and it's just a mater of semantics of how the word span (vs. clear span) is used... Can't we say span = entire length, whereas clear span = unsupported length?
Edited 8/14/2005 1:04 pm ET by Matt
I put a tape on them 17 10 3/4"
I measured my girders 17 10 3/4"
Either case, whether it should be 17 10 3/4 or 17 10 8/16, why?-----------------------------------------------------------------------------
WWPD
They allowed something for the sheathing thickness. How they came up with 5/8" I don't have any idea. Really though, if the un-sheathed frame had have been built to 17' 11" the 1/4" discreency wouldn't mean squat.
Bottom line is though is as you said, after checking with the truss company, just pack out the outside of the floor system band so that your sidewall sheathing will all come out pertty flush. OSB will work fiine. Might even end up with a stronger house ;-)
I'd be as diplomatic as possible though when calling the truss company - you don't want to put them on the defensive. This is a small problem and I'm sure they will just give you the green light unless the word "liability" comes up.
I'm assuming these same issues apply to your roof trusses too?
You have a set of plans? Maybe drawings that came with the trusses? What do they say?If I remember right, wood-web joists have a 'notch'for a 2x4 to hold them straight....no rim joist required. Maybe it's different nowadays.Anyway,that's small potatoes....just rip some plywood.The problem will be your roof trusses, as someone mentioned.Well not really a problem, it'll effect your soffit overhang though.
If it were easy....a caveman could do it.
Thanks Matt.
I'll give a call anyways, pack out the difference.
Oh yeah, the roof trusses........18 0 0 ..go figure
Thanks all-----------------------------------------------------------------------------
WWPD
>> Oh yeah, the roof trusses........18 0 0 ..go figure <<
Ron (BH) - correct me if I'm wrong, but I believe they only allow for sheathing on roof trusses for raised heel trusses where the sheathing may/will run up above the wall cap plate. I've been asking for raised heel trusses lately so have gotten used to seeing the -1".
Sail: You probably don't see many raised heel trusses in FLA - it's for more energy conscious areas - what it does is allows a full 13" or so of insulation to extend out onto the wall top plates.
Edited 8/14/2005 4:04 pm ET by Matt
"Ron (BH) - correct me if I'm wrong, but I believe they only allow for sheathing on roof trusses for raised heel trusses where the sheathing may/will run up above the wall cap plate."
Everyone does it differently. Some want an 18' truss for an 18' wide building. (As in this case)
Others want a 17' 11" truss so it's 18' to the outside of the plywood.
That's one of the first things I ask people when they order floor trusses. I want to make sure guys get what they want.
I can't understand why the guy wasn't asked what he wanted in this case.
The important thing in acting is to be able to laugh and cry. If I have to cry, I think of my sex life.
If I have to laugh, I think of my sex life. [Glenda Jackson]
Around here I am spoiled, the truss company will call me up before production and ask if I need to change anything, or ask if they need to confirm measuremnts before building,
they will come out, free of charge and measuere the floor and assume that the walls and top plates will match the floor.
in your case maybe this happened and your first floor aint exact
I(he) was. Three times. The last time I spoke directly with the plant engineer. With his design plans in front of us and we agreed and I signed them in front of him. Not much more this retentive guy coulda done other than cut, and lay the boards out for them LOL
I'm hoping that structurally, it's not an issue.
Once again thanks for all the help/advice on this one.
I promise to all, that if you make it down here, I'll take ya offshore on a fishing trip! Weather providing of course.-----------------------------------------------------------------------------
WWPD
>> I promise to all, that if you make it down here, I'll take ya offshore on a fishing trip! << OK - I'm there... BTW- time for a good high jack... :-)
Check out the below pics
12 - me with a rooster23 - rush hour @ Boca Grande31 - 2 hrs after the traffic jam - he dragged us about 5 miles...40 - Wife's first fishing trim - "It's Sooooooo big!!!!!!!!"41 - John with a bull42 - Joe with a yellowfin
Those are some great fish.
Almost looks like light day in the Boca Grane pic. That place is a zoo. I've seen it where you could walk from boat to boat to boat to boat, and someone have a 150# fish on...........and no one moves. We even had one jump accross our stern one time!
Thanks for the photo's-----------------------------------------------------------------------------
WWPD
>> We even had one jump accross our stern one time! << What... he didn't jump into the boat... the nerve of him.... That tarpin I had on for what seemed like hours - 22' boat with medium light tackle... That was the "captain" who pulled him in the boat for a photo oportunity before the release. No way I could lift him after that fight... what a rush!!!
My favorite pic is the one of my wife - the expression on her face says it all :-)
"Can't we say span = entire length, whereas clear span = unsupported length? "
Not on a wood webbed floor truss - That was my point.
Even if you have a 2' wide bearing, it doesn't make any difference. The forces in the chords and webs are the same.
DW always laughs during sex - no matter what she's reading.
The plant goofed
The dude laying it out assumed it was the first floor. he gave the extra 1.5 " for plywood/siding to end up flush with the block stem wall.
Our joists were 2nd floor on wood frame.
they said 3/4" ply would be ok to bring it out
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WWPD
Edited 8/15/2005 9:36 am ET by Sailfish
Thanks for letting us know how it turned out. I was kinda curious about what the heck they had done and why...
A bird in the hand is safer than one overhead.
Not to be negitive here, but I still think you framed in a non-conventional way...
Unless four foundation is actually 18'1".
Edited 8/16/2005 7:49 am ET by Matt
Your not negative. In fact I appreciate any and all criticism/errors (how else will I learn, right?).
Could you elaborate for me?-----------------------------------------------------------------------------
WWPD
If the building width is to be 18', everyplace I have ever worked, the floor frame, walls, etc would be framed to 17'11" giving 18' once the sheathing was installed.
That's one of the more annoying things about the truss industry - Everything is done in feet, inches, and sixteenths. So in this example, it means 17 feet, 10 inches, and 8/16. (8/16 is obviously 1/2")
But what happened to 18'? Thats an odd miscalculation/fat finger typo.
Hypothetically speaking of course.
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WWPD
Edited 8/14/2005 1:22 pm ET by Sailfish
"But what happened to 18'? Thats an odd miscalculation/fat finger typo."
I agree that it's odd. But stranger things have happened.
It could be that the truss drawing called for one thing, and the boards got cut to the wrong length. Then the guys who assembled them just threw the pieces in, clamped it and stuck the plates on.
Like I said, truss assemblers aren't brain surgeons.
But just about anything is possible. They could just tell you "That's just the way we've always done it". No way you'kll know until you talk to 'em.
A lady is one who never shows her underwear unintentionally. [Lillian Day]