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Sdot 03-17-2014 02:10 PM

Framing an addition
Hey all, i am putting an addition on the top of another wide open room, problem i face is that, i only want to do the shell this spring and take my time (money issues) completling the rest... I will have OW Floor joist spanning 23 feet, 14" depth 16" OC.. do not want to remove drywall below.. All of my HVAC and electrical will be ran through the joist, as we will also have cathedral ceilings... My question is, when i frame this bad boy up, do i need to deck the floor before i put my walls up? I really can't, i don't have the space to do all of the HVAC and electrical work with the current roof still on, and i won't have the time (weather) to do it with the roof off and new walls and roof not up... Every time i have framed something, joist, decking, walls.. never done it without decking the floor first... is this OK structurally (I'm 90% sure it is) but is it OK by code (generally) in most places (South Jersey)... Also, with open web joist, do i need to have cladding on the ends or can i sheath right over them?

Thank you in advance!


joecaption 03-17-2014 02:58 PM

You need to being doing a whole lot more research on that plan.
Not much of it is going to work out.
Yes there needs to be LVL rim joist made just for banding the engineered floor joist. Go on the wed side of the company making the joist for install info.
Decking needs to be glued and nailed in place with 8D ring shank nails before any walls go up.
Save up the money and do it right. That whole thing need to be at least dried in including shingles and siding,

Sdot 03-17-2014 03:11 PM

thanks Joe, yea i already had the joist engineered. I am lucky enough to have a truss company within walking distance.. They gave me the plans for the trusses and joist.. i didn't see anything on there about the rim joist.. i figured i would stop over there and ask for install info before i give them okay to build. Even with any amount of money i would still need to run all of my electrical and HVAC after i install joist, but before i put decking down... this could take days.. with the whole house being exposed to the elements.. This is why i posed that question.. it would be a lot easier to get the shell up, windows, tyvek, sided and shingled.. then go in, run my electrical and HVAC, then put my subfloor down.. (this was my plan)

joecaption 03-17-2014 03:24 PM

Electrical and HVAC is always done after the buildings dried in.
You are getting permits for all this right?
Subflooring is always done before walls go up, no exceptions.
Under lament can go in after if needed.
There is no way to get around having to remove the insulation and drywall in the ceiling below.
Those engineered joist need to be sitting on top of the old top plates not the old ceiling joist.
A job like this needs to be done by a full crew of people that know what there doing to closed it in ASAP.

Sdot 03-17-2014 03:32 PM

Thanks again joe, you are right.. i have 3 skilled and 2 laborers coming in to knock the framing out.. NO, i would not be sitting on top of the ceiling joist.. they are 24" OC we mapped it out, i would need to remove a couple, that would interfere with 16" oc.. it doesn't matter regardless, i would just seal her up and remove what i need to remove from below to access what i need to access.. It really isn't that big of a deal to do that, was just trying to see if that could be avoided... obviously your answer is it can't be done.. is there a structural reason behind this? i can't see adding 3/4 under the framing adding much support or tying much of it together.. just wondering why its done that way..

Thanks again for your quick replies, its much appreciated!

Sdot 03-17-2014 03:38 PM

ahhh that rim joist adds support to the floor... if you don't run it through the wall you have no support for the end of the subfloor in between joist... i got it... very dumb that i didn't think of that...

Sdot 03-17-2014 03:40 PM

yes I'm getting permits.. Btw... I'm not staring for another couple months.. I'm really still planning it all out, and getting my drawings together to get the permits... then decide on when to start... I'm sure i will have a lumber yard for a front yard for a couple weeks, until i see a full week without rain... lol

joecaption 03-17-2014 04:01 PM

Do not rush doing this, have plenty of tarps on hand to keep the lumber dry and some big enough to cover the whole addition if needed, weather man lie :).
Use Advantech for the subflooring.
Bet you find out leaving those old ceiling joist is a mistake.
There just going to be in the way, and may though off your subfloor spacing.

Sdot 03-17-2014 06:00 PM

WELLL... lol... in my original plan, they were going to be cut back of top plate during demo of old roof, then when i got the shell up (with no floor) was going to use a multi tool to cut screws and pull them out (after i screwed the old drywall underneath to new joist)... they will be in the way... you're right, best way is the right way, pull the ceiling out and go from there.. i didn't want to displace the family during this.. only for a week to break through and install the steps... but looks like a month or so at the in laws it is!

Do you know what it would cost (estimate) to get a crew to just do the framing in a day? just wondering.. all labor, i would supply all the materials..

Thanks again!

Sdot 03-17-2014 06:02 PM

i also wanted to save the insulation (loose) by keeping the drywall up, as a little sound barrier... again.. I'm causing more work for myself then i would if i just tore it all out... do i even need to insulate that area? or do you think 14" is enough space to dampen sounds... its a master bedroom... (kids on the other side of the house, lol) kitchen, dining room underneath..

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