attn: question for maggot builders

[gimpy]

hoping any of you nail pounding fools can help me answer a question i've got. i have a 26' subfloor span w/ a girder at the halfway pt (13') and i have some shorter length bci's that i'd like to use up. the engineer said it was ok to use them breaking on the girder and sistered appropriately. what is the appropriate way to sister bci joists?? i've read the installation guide and googled it but i've found nothing. i'm guessing that 4' of the joist should be sistered/scabbed togther w/ a 16 d nail every 12" but that is just an educated guess. so, i'm thinking that 2 17' joists sistered together w/ 4' overlap centered over the midspan girder should work. can anyone help me here?????


and i would ask th engineer but he only takes 1 call per week from contractors and i've already used that up.

[splat]

hoping any of you nail pounding fools can help me answer a question i've got. i have a 26' subfloor span w/ a girder at the halfway pt (13') and i have some shorter length bci's that i'd like to use up. the engineer said it was ok to use them breaking on the girder and sistered appropriately. what is the appropriate way to sister bci joists?? i've read the installation guide and googled it but i've found nothing. i'm guessing that 4' of the joist should be sistered/scabbed togther w/ a 16 d nail every 12" but that is just an educated guess. so, i'm thinking that 2 17' joists sistered together w/ 4' overlap centered over the midspan girder should work. can anyone help me here?????


and i would ask th engineer but he only takes 1 call per week from contractors and i've already used that up.

You answered you own question. 4' typically always flies on the lap for the scab. I assume the girder falls under anything bearing load. bci's? I'm out of the lingo loop but assume they're some sort of thin vertical lam. Wider at the top and bottom so you need to slide something solid inbetween? Or do you just nail the tops and bottoms? 16d on 12" centers should be plenty, depending on the joist dimensions and engineering. If they're like 12+" high, there's prolly a three in the field rule or something.

[train07]

I never use these, so take what I say with a grain of salt. You're landing over a girder right? You could probably just butt these things and scab the sides. Your deck sheathing is going to tie everything together after that. Short of butting, which could be a pain due to measuring vs the overlap, I have similar loose thoughts about just going with two 14'rs with only a one foot overlap. You're over the girder, deck sheathing tying it together, and I'm assuming a deck band joist secured to the sills locking these things in again.

Disclaimer: I don't do this type of work.

edit. However, be a man and butt the fuckers.

[Dam Skier]

If you have a mid span beam you can break them on it, no overlap needed. The minimum you need is two inches bearing. Butt them, if your center beam is wide enough, and be sure to roll block them.

[gimpy]

cool, thanx folks. local consensus here was to butt and gusset so i did that to keep layout from changing w/ the sistering. hopefully the hardass county inspector agrees. that guy is a pain the arse and it looks like our fire scene is keeping him from losing his job which was sposed to happen before the fire happened.

and ya i know this is a skiing board but i seem to get better info here on everything under the sun then from most places.

[2FUNKY]

gimpy:It has been awhile since I have pounded nails but in your situation we were advised to do the following. Span sister 2' with each I-Joist. Sandwich 1/2" material in webbing with PL4000. Nail vertically, 3 nails spaced appropriately in webbing then every 8"oc. DO NOT nail top or bottom cord, Doing so degrades the structural integrity of I-Joists.Nailing to beam is only exception.You must also Squash Block them.This was per our engineer. Glue and nail Sheeting.Oh yeah use ring shanks.

[CaddyDaddy77]

2 Funky is on the money, use ply or osb to fur out to the flange of the BCI ( Depending on your size it may not be 1/2") and nail accordingly. Block with BCI between Joists, and your good to go.

PL4000 is key, no squeeks, but nasty shit, it repairs shoes, holes in hoses, ets..

Look at the link below for additional info, I can't get my adobe to upload to give you the right guide but look under Western Install Framers Guide, if memory serves, there's an example there.

http://www.bc.com/wood/ewp/guides.jsp

[G]

I'd use duct tape.

[splat]

Tahoe carpenters....

[gimpy]

nice splat.

thanx again all. its a done deal for now until the inspector tells me to change it. unfortunately he won't tell me how to change it so hopefully i can get my engineer on board w/ how i did it. farking inspector wants me to get a note from him okaying the bci split even though its only 2 out of 20. i'm wishing i'd just kicked down for the 2 additional full length joists at this point but i'm committed now.

[Split-It]

just a tip (im an engineer in the 'ho too, or was pre-Argentina). next time you do a change like that, you should always take pics to prove what you did to the engineer. if he's going to sign off on something, he definately wants to know it was done right. and butting and gussetting is fine, as long as both have enough bearing.

[danhikeski]

I used to do CS for a company that distributed BCI's (you do mean a Boise product, or are you using someone elses I-joist and throwing their name at it?) If they are, call 1-800-341-9612, during the week, east coast company called Wood Structures, Inc.. Anyone in customer service will tell you if the BCI's will work for your span and how to make the connection over girder. The concensus of the board, butting together is correct, I will not say yes or no without knowing if the I's you have will work for the span (but you didn't ask that question).

[Jim S]

I have nothing to add except that I'm impressed by the mags' breadth and wealth of knowledge.

[boarddad]

Hold on a minute...
The Engineer will only field 1 call a week? What kind of BS is that? I'd say get a new Engineer but it's probably out of your control. The engineer's communication with the contractor is more important than the Arch, Owner, Inspector, you name it IMHO. The projects I work on the contractor has my office phone, cell phone, fax number, e-mail address, heck, I'd take the info by carrier pigeon if that was the only way. If a 5-minute call with you saves you a day or more of re-doing the work that's a really good use of my 5 minutes. Don't be afraid to call the joist manufacturer or the applicable trade group (APWA?). They are always more than helpful in my experience.

As for your issue;
16d @ 12 doesn't seem like it's doing much of anything IMHO. Sounds like the BCI's were designed for a 2-span configuration. From what you describe deflection will control (L/240 max DL + LL or L/360 max for LL only). What you're essentially doing is breaking it into (2) single spans. In the (as designed) Double span configuration the max moment was over your middle support w/ max stress @ the top of the BCI. Now it's mid-span w/ max stress @ the bottom. What that means to you is that your finishes could take a beating (read; cracked tile if that's your finished floor) and your floor may be more "bouncy". If it's just 1 out of a dozen joists you're probably fine though - the joists either side of the "sistered" joist will help take the load. Alternate the sister's joists with the unaltered joists if you have more than one. Be sure you have adequate blocking over your support between the joists.

One last CYA thing - don't hide what you've done. Take pics and document it and be sure and take the engineer by the hand on his next field visit and make sure he sees it. BTW, your instincts are right. If the engineer isn't going to take an active role in the project don't deviate. You're the one who is ultimately responsible if you do.

[baseWeldr]

seems Ive been on both ends of this spectrum

in KC on the derelict framing crew we'd be using dimensional lumber 2x10s and just run 'em on either side of a layout line and nail off any overlap then block- making the layout for the floor jump 1.5" from front to back and in the middle of a sheet- sister a block on to catch an end if needed- (meaning the carpenter crackheads had to remember this, yeah, lotsa shiners)- but that was pretty blow'n go style... inspectors...?pffft....

when in FLA we used full width 3.5" floor trusses- deluxe to walk on and nailoff, butted 'em(mostly- quite a project if you have to cut them into their "web"- accurate ordering is key) on the girt/beams and still snapped lines to keep the floor nail-lines lookin all snazzy....

interesting the differences region to region and crew to crew- obviously FLA is hurricane driven code-wise and we strapped everything to everything else but even with KC in the heart of tornado country with cold winters and hot summers it was startling just how minimal and dicey the building was(is) even in the pretty decent neighborhoods we were in...
.02

[gimpy]

cali's got earthquake codes and tahoe has high snow loads so houses here are pretty bomber (i.e. over-engineered) w/ both. i wish i'd invested in simpson strong ties 10 yrs ago. lots of great info here but now all you suckas have got me 2nd guessing myself .

re: the engineer. i can se his point if i'm caling him every day w/ questions i should know but it's be nice to be able to have him call me back more then once a week. plus, the woman who is fronting us the lot for the house and permits was the one who paid him. for my next place i'll be using someone i know so this won't be an issue.

[Below Zero]

Who is the structural engineer's contract under?

[train07]

What you're essentially doing is breaking it into (2) single spans. In the (as designed) Double span configuration the max moment was over your middle support w/ max stress @ the top of the BCI. Now it's mid-span w/ max stress @ the bottom. What that means to you is that your finishes could take a beating (read; cracked tile if that's your finished floor) and your floor may be more "bouncy". If it's just 1 out of a dozen joists you're probably fine though - the joists either side of the "sistered" joist will help take the load. Alternate the sister's joists with the unaltered joists if you have more than one. Be sure you have adequate blocking over your support between the joists.

Say you're building a 13' long deck. You're going to span this with the 13' BCI joists supported on both ends. Where's the max stress?

[Below Zero]

Where's the max stress?

Shear or Bending?

[train07]

Whatever it takes to maximize my moment

[Below Zero]

Whatever it takes to maximize my moment

Huh?

[brice618]

That is a nerdy bunch of responses right there... sadly I understand them.

[Below Zero]

That is a nerdy bunch of responses right there... sadly I understand them.

Nerd Homework Review

Given:

-A wood beam spans 20'-0" with a 400#/ft uniformly distributed load for 10'-0" on the left side of the beam, and a 600#/ft uniformaly distributed load for 10'-0" on the right side of the beam.
-Allowable deflections: Total - L/240, Live Load - L/360

Find:

-Draw Shear and Moment Diagram
-Find Point of Inflection (point of maximum moment)
-Select most economical floor beam of douglas fir-larch No. 2

Formulas:

Fv = 3/2 x Vmax/A
Deflection = 5WL^4/384EI
S = M/Fb

OK........go!

[train07]

Huh?

Exactly.

[Below Zero]

Exactly.

Huh? Do you even know what the difference between bending stress and shear stress is? I was just messing around with you, since you didn't identify either bending stress or shear stress when you asked "Where's the max stress?"