Need some help with an addition attachment HAVE PICTURE UPLOADED - Contractor Talk - Professional Construction and Remodeling Forum

TurnkeyConst · 03-04-2007, 09:39 AM

Hi,
Appreciate you taking a look at this. I have not done any additions yet which require this. thus asking for advice. The house is on a slab so therefore putting addition on a slab. Can you just butt the 2 slabs against each other to pass code? I am in NC and understand you may not be. But looking for what you might do where you live. Also in the picture you see the red ridge board or whatever you might call it. We plan on using 16" I joists I know for a 12-14' span its overkill but hoping to get all the ductwork and electrical through it. Will be spacing them 16" on center. How would I go about attaching the ridge board to the house? Will it require posts from the ground up? Or is there a feasible way to attach it to the upstairs walls? Havent run into this before. IF you have any other questions please post and will try to answer them ASAP. They had other contractors tell them that they couldnt do vaulted ceilings in the addition. Trying hard to get them what they want. Hope picture helps sorry made it in MPaint.
Thanks Houston

CheckmateOhio · 03-04-2007, 11:05 AM

Pull the siding off and nail the ridge to the studs. Just like new construction.
Not sure bout slab since you are in another state, but your drawing shows a monolithic pour.

woodmagman · 03-04-2007, 02:01 PM

Quote:

Originally Posted by TurnkeyConst

Hi,
Appreciate you taking a look at this. I have not done any additions yet which require this. thus asking for advice. The house is on a slab so therefore putting addition on a slab. Can you just butt the 2 slabs against each other to pass code? I am in NC and understand you may not be. But looking for what you might do where you live. Also in the picture you see the red ridge board or whatever you might call it. We plan on using 16" I joists I know for a 12-14' span its overkill but hoping to get all the ductwork and electrical through it. Will be spacing them 16" on center. How would I go about attaching the ridge board to the house? Will it require posts from the ground up? Or is there a feasible way to attach it to the upstairs walls? Havent run into this before. IF you have any other questions please post and will try to answer them ASAP. They had other contractors tell them that they couldnt do vaulted ceilings in the addition. Trying hard to get them what they want. Hope picture helps sorry made it in MPaint.
Thanks Houston

If you are unsure, take the sketch to your local building inspector and ask their advice. They are the ones who will pass or fail the application.

Bone Saw · 03-04-2007, 02:19 PM

You should be fine assuming the existing slab in on footings, If it is monolithic as you stated without footings you should run a purlin at the top spanning the addition with ample post, collums or point loading in the end walls and ample footings as well

TurnkeyConst · 03-05-2007, 07:50 AM

The slab in the picture is the one we are going pour and it will be poured monolithically. Thats the only logical thing that I can think to do with 12"x16" footers. Would nailing the ridge board to the wall studs be an acceptable building practice? Has anyone ever heard of running ductwork through ceiling joists? First time dealing with a slab house normally everything is on a foundation and adding on to the gable end.

pn70 · 03-05-2007, 08:32 AM

Houston,

Will you be tapping off the existing heating system or will you be installing a seperate unit for the addition? I have run 6" round duct through wooden IJoists before but if I remeber correctly I had to follow the engineers specs on where to run within the span. My concern would be that you still need to run a trunk line which is usually rectangular duct and then tap off that with 6" round runs. You should get together with your HVAC guy and also talk to the engineer about your IJoists in regards to the duct work. You might be better off to go with mono scissor truss's and have them designed/engineered to accept a rectangular duct run or a Spiral main duct run.

CheckmateOhio · 03-05-2007, 11:34 AM

What about insulation in the bays with the heat ?

TurnkeyConst · 03-05-2007, 03:11 PM

Planning on installing a new unit, was going to use batten insulation between the joists because of no attic will contact the supplier of the joist. maybe they will let me get by running the duct through the joists which they will cut for me but since im in such a short span for the 16" i joists. havent ever had to deal with running hvac through the ceiling but first for everything. Dont know what i would do about insulation in the bays with heat. What I could do is build the flanges up with 2x4s to drop the ceiling a little bit maybe to allow some room

karma_carpentry · 03-06-2007, 06:49 AM

Check out this page from Boise Cascade for guidelines on cutting holes in their I-joists. (Download the guidelines in PDF format there, check out Table 3.) You may not need to use 16" - maybe 14". The guideline even lets you cut 6" holes in the 9-1/2" joists on a 14' span although I don't know if I'd feel comfortable doing that.

Also, do you need to be putting 16" I-joists 16" OC? why not 24", what sheathing are you using?

I don't see what's the question about attaching a ledger - plenty of lag screws into the studs as long as that wall can bear the load, right?

karma_carpentry · 03-06-2007, 07:19 AM

Oh, maybe the 16" OC was for your ceiling or for the insulation. If I was doing this job, I'd consider spacing the rafters 24" or at least 19.2" OC, sheathing and roofing then running ductwork, then spraying in Icynene to a certain depth - leaving some space below the insulation for running the electrical. Then rock with 5/8" board.

TurnkeyConst · 03-06-2007, 12:36 PM

Well reason was going 16 oc was for sheetrock mainly but also to avoid any questions about spacing. have thought about going to 24 to bring price down and maybe win the job. what would you sheet with if you went to 24" I understand 5/8" sheetrock. what is icynene? also will not have no access after sheetrock is up by doing a vaulted ceiling. Ill download that pdf though thanks

karma_carpentry · 03-06-2007, 05:23 PM

Icynene is a sprayed foam insulation, it's a brand name, so basically I meant to say use a sprayed foam insulation. You get a contractor to do it, they come with the truck with the blower and run a long hose in the addition and spray the stuff in. Normally they fill the bays and cut off the excess with what looks like a 3 foot long brad knife on a sawzall, but I was thinking if you're going 16" depth they only need to fill around 8 inches or so, maybe 10 - you're in NC so it's not all that cold anyway and Icynene is 3.6 R per inch. The stuff is good in cathedral ceilings because there's no need to vent the bays like you normally should do if you use fiberglass, and I also thought it would be easier than stuffing batting especially if you went wider than 16". It does have a price tag, though - but then you don't have to stuff fiberglass over your head on ladders, so it's a tradeoff. If you're curious, the thing to do is find a spray foam contractor in your area and ask them for a quote. Anyone want to guess? I'd ballpark $500 to $1000 as a price.

karma_carpentry · 03-06-2007, 05:24 PM

By the way, if you have everything roughed in the wall, you can get them to include that in the insulation job.

TurnkeyConst · 03-06-2007, 08:29 PM

I really appreciate the advice will check into it. hey since i am doing vaulted ceilings how would I go about ventilating it? roof vent between each space and soffit vents or what? have just thought about it today. because I cant put in ridge vents like normal any suggestions would help but if not ill figure it out. thanks for all your help karma!! definately sound like you know what your doing!!

obxwood.com · 03-07-2007, 01:42 AM

Here is what i am doing attaching a deck to simular app. I know the load is going to be differently but this is a stronger way of doing your attachment! I am going inbetween each stud spacing and putting a header with jacks on each side and then lagging my band to house,you might want to consider running your main trunkline for hvac along the top and flatten off a small portion of ceiling to box it in and then run flexduct! Just a thought!

karma_carpentry · 03-07-2007, 10:07 PM

Turnkey,

According to the Icynene company, roof venting is not necessary because the Icynene is an effective and tight vapor barrier. However, my feeling is still that roof venting is a good idea, especially in hotter climates. I've only installed Icynene on additions without roof ventilation, but I am in Boston, so heat gain is not much of an issue.

If you wanted to provide roof ventilation, you could tape in a layer of pink foam across the flanges of the I-joists and tape the joints, leaving the 1-1/2" of air space above it. Still, the top vents are difficult in the shed addition.

If you're roofing with rubber, you could also choose a white EPDM - this is EPDM but the solar heat gain is much lower than black. Costs more though, and you may have to order a roll if no yard carries it in your area.

But on the Icynene website, they cite a This Old House project that insulated a vaulted ceiling addition with Icynene, with no roof venting. But like I said, it's in Boston.

TurnkeyConst · 03-08-2007, 06:32 AM

Appreciate it Karma I knew it was going to be complicated with the ventilation. Will check with inspection department to see if they will require it. Thanks