Insulation paralysis......

[jpcjguy]

Hi all,

So am close to doing insulation. My final for plumbing and electrical is tomorrow and then I just need to do some final framing for the drywall. My contractor did not leave the building in a good state for insulation and I am stuck on my options.
I have attic trusses over 2/3 (32 of 48 feet wide) and I had them scab in a extra 2x6 on the "slope" of the room. I am also on 19.2" centers.

My initial plan was to insulation the entire envelope by building 1" air gap channels in each bay and sealing them with construction sealant and then using pink or rock wool on top of that.
Now looking at the scope of that work - ripping 2x4s to 1 x 0.75" strips and nailing them to the trusses, finding a thin plywood or other air impermeable to cut and nail in each chase and then sealing the "chase" - I might have underestimated the work/ROI because I am looking at 50+ chases.....

Then looking at the lift bay area with a 4/12 interior pitch (exterior is 8/12), I wonder how that would work - especially with the extra bracing the contractor put in. Also, on the gable wall of the lift bay side, I have to rip 2x6s down to 3 7/8" to continue the wall up the end truss - Sigh....
I also have to figure out the end bays and close them off from the soffitt up the peak - as you can see in the below pic (last bay before soffit) they are wide open. (In that pic you an see the bracing that goes between the trusses that I have to drill holes in if I want airflow in the chase from soffit to ridge)

Maybe as an alternative do a flash and batt - do 2-3" of closed cell and then batts to not have to build 50+ chases....

I feel like my initial plan is disintegrating in front of me...
I do plan on 1-2 mini-splits down the road - who knows when because I just found out today my downstairs HVAC in my house is done and it is the old R22 so there is 6K gone....

 

[nadogail]

Good Luck in finding a solution to your dilemma.

 

[MrSurly]

Hire a pro.
Walk away
Come back when it's finished.
.

This sounds like the right way forward in this situation. When you find yourself outrunning your plan because you’ve hit a large unknown and then suddenly trying re-invent the wheel to fix it, you are at the point where (it seems to me) that *you need help* and an experienced pro will likely save you money AND time over fluid re-scoping
during the build.


Sent from my iPhone using Tapatalk

 

[zanexx]

i have made my living insulating stuctures for over 20+ years, its what I do, its what I know. if u want my opinion shoot me a message and we can discuss it further. I'll make it as simple as I can and give u the options u have and what I would do if it were mine.

 

[mike93lx]

i have made my living insulating stuctures for over 20+ years, its what I do, its what I know. if u want my opinion shoot me a message and we can discuss it further. I'll make it as simple as I can and give u the options u have and what I would do if it were mine.

Why not post here so everyone can benefit?

 

[Leaflessshadetree]

Not sure I understand the issue. Sounds like common baffles in each chase would be an easy and inexpensive solution to the ventilation concern.

 

[CJ7VFR]

What are you going to put in the attic/upper part of the building? Is that just for extra storage?

Jim

 

[NUTTSGT]

It's sort of hard to tell in the pictures, are your trusses open to the soffits ? Some pics, I can see light and other not.

In the scissor trusses, I'd put baffles in to ventilate, add metal siding and fill them full of blown insulation (even though I hate the stuff). The regular trusses, probably the same way. Is fiberglass batts available for 19.5 centers ?

 

[spudley]

I don't see any stairs so I'm guessing you're leaving the vaulted area open to the upper area for access? If so, you'll be insulating the roof area which means Leafless has the answer. Baffles followed by batts, covered with drywall.

If you're going to make your own baffles, why rip 2x4's to 1" x .75 when material already comes in 3/4" (.75) wide?

The gable ends don't need additional structure so one could use 2X4's on the wall plate, no need to rip down 2x6's to match the remaining space.

If you close off the upstairs...I'd put air baffles in the angled roof section upstairs with batts under, batts in the vertical "knee walls". Blown in in the floor area from knee walls to side walls. Batts under the upper floor area.

Or open the check book and spray foam everywhere.

I'm diy all the way but you may be money ahead by hiring a pro.

 

[matt_i]

I might be wrong about your intentions but I don't think you have to create the entire plane, the insulation baffles/channels already exist as a molded product. Just one example.

https://www.sprayfoamsys.com/produc...Dps0EMKatJiKd5NDL5LatvKOBVR2n6GoaAr9cEALw_wcB

Make sure you plan & install your wiring before you get to insulating and drywalling! No drilling or notching of trusses is acceptable.

 

[jpcjguy]

NUTTSGT - yes, trusses are open to the soffit. the attic trusses have a 2' raised heel to match the 12' exterior/bay wall height.

spudley - there is not a walk up stairs inside, but a pull down access using a Louisville "Big Boy" ladder - which is awesome! I also have a man door upstairs on the gable end that will have an outside stairs built. The space between the attic and the lift bay will be walled in.

As for the baffles that are available like the AccuVent, they don't come in 19.2 width. Also from what I hear, that they are not a good air seal and if using fiberglass insulation it will "air wash" as the air from the soffit goes up to the ridge. From what I learned on greenbuildingadvisor.com, if you are going to do baffles, make sure you seal them tight!

The reason for doing the entire envelope and not insulation just behind the knee wall is to make it easier for any future electrical needs. Easy to run wire to the other side of the building through the "floor" of the attic truss if there is no insulation there.