How To Install Ceiling Insulation And Ventilation For Shed Roof Framing

[@TexasBarnRats]

Good grief! Were you reading my mind? I was just contemplating this EXACT topic last night while planning a project. I didn't think of cutting a rectangular hole. Great idea!

[@valkasolidor6727]

Thanks for covering this topic. Although I don't have specific need for it like the guy that requested, it is good food for thought for considering roof insulation of a shop I built some years ago.

[@CivilianDan]

I never knew how to size the vent holes. Thank you so much.

[@gregvancom]

Happy to help!

[@f.p.4557]

It was me that ask for that video for so long :) thank you ! I would have like to see more components in the video, example, something goes over the batts.

[@Monkeyseemonkey79]

Thank you for producing this video! Much appreciated.

[@deantate6997]

Really appreciate this video!! Exactly what I needed. Can’t google this stuff…

[@gregvancom]

Great!!!

[@64CadFltwd]

We are planning to add a 36x30 garage. The doors would be on the 36’ wall. I’d love to see some ideas for this space with a loft about and gambrel trusses. Our zoning only allows 12’ side walls and I don’t want a HUGE peak. Would be curious to know your thoughts

[@G_Rapids]

So, if i am building an off grid 12x16 cabin, it seems that for my 24" OC 2x6 roof, i could use R13 insulation to provide a 1.75" air gap with bird blocking with vent holes on each side. (I do not need this to be terribly efficient, i just need it to not ruin my ceiling with moisture.

[@QuadTAZ]

Could one just screen the entire soffit area and run dimensional lumber one side down from the rafter and sub fascia? So 2 x 4 blocking for 2 x 6 rafters ect. Been brain storming best way to do this for a shed I'm building.

[@scotts2181]

My question would be why even vent the roof? I just installed roughly 1600sqft consisting of 3 - 2 inch layers to achieve an r-39.3 for a flat roof and finished attic in one of my apartments and just treated it like a spray foam installation making sure to seal everything air tight and right up against roof sheathing. Building inspector questioned it at first but after a closer look in the book it only states that rigid insulation shall be sealed off and sealed layer to layer.

[@towTruck42]

what kind of assembly? did you put rigid insulation between the rafters or outside the sheathing? I think one reason is the blanket insulation is so cheap to install, that leaving a 1" gap and installing soffit vents may save a bunch of time versus fitting rigid foam between rafters, or paying the premium for spray foam. Best is rigid foam outside the sheathing, layers staggered, but then you're looking at multiple layers of plywood so the costs are higher. For the impassioned owner-builder, the extra costs may seem justified, but for a spec build, the contractors I work with usually ask for the cheap-to-build route, not the cheap-to-own, so that keeps us returning to ventilated roofs.

[@scotts2181]

Yeah man, I put everything between the rafters. Outside would have been way easier ahah, but the roof was in good shape and at that point an even better option rigid on deck and batt in the bays. My original theory for this video is that this other viewer whom requested the video really doesn’t necessarily need to vent at all.

[@towTruck42]

@@scotts2181 nice. did you just stuff the rigid in there tight or do something to air seal around it like tape or spray foam? I had always thought detailing rigid between rafters would just be a pain to seal it up tight, whereas the batts kinda solve that in one go - neither needing to be sealed to be effective nor being difficult to get a good fit.

[@KatBradley-1968]

Where does/can the HVAC system go in a house with a shed roof?

[@AnthonyDibiaseIdeas]

EXCELLENT. THANK YOU.

[@gregvancom]

You are welcome!

[@Oldhogleg]

Yup, had insulation contractors cover every single vent without installing any vent baffles. Some inspectors will now ding you for compressing insulation where the rafters meet the wall plates and require you to use foam insulation for the first foot or two all long the wall to get the full R value. I don't know about the southern states but here in Northern California I've gotten in the habit of using 6mil clear plastic vapor barrier on the interior side of all insulation where ever it is to prevent mold from developing due to worm air from the inside condensing inside the walls during the winter months. Code doesn't require, but it saves your ass from lawsuits.

[@larrytheplumber9851]

How many suits 🤔

[@Oldhogleg]

@@larrytheplumber9851 why all of them.

[@gregvancom]

I've never understood using a water proof vapor barrier in walls of ceilings. Have you had any problems with using it and does the building code allow it.

[@Oldhogleg]

@@gregvancom Vapor barriers is allowed on the worm side of the insulation to prevent moisture condensation from the interior worm humid air during the winter season. But I do believe code dose not allow a vapor barrier on the cold side of insulation without ventilation because that'll cause moisture condensation of the warm humid interior air trapped in the wall cavity on the insulation cold side. That's why it's required that building wraps on the cold side of the wall has to be able to breath water vapor while repelling liquid water. Mold infestation was never an issue in the days before common use of insulation. It wasn't until common use of insulation that mold has become an epidemic. It's typically only those tentative to current building sciences that are familiar with the need of a vapor barrier on the interior side of insulation.

[@gregvancom]

@@Oldhogleg Okay and thanks. I'm not a big fan of water proof moisture barriers and need to do more research on the topic. Do you know of any building codes that allow or don't allow it, because I've seen crawlspaces sealed and am not a big fan of that process, because any water that leaks from above could be trapped in wood or metal floor framing.

[@blake343]

can you do one of these for the skillion double roof

[@gregvancom]

I think it's already on my list.

[@blake343]

@gregvancom great! Could you maybe show an example of the smaller side with an attic area for easy ventilation? I am thinking about doing that so I can put an air duct up there to heat and cool rooms on both sides

[@beanieweenie9543]

Just curious, obviously I know absolutely nothing about the subject but what exactly is the ventilation for or preventing?

[@gregvancom]

Believe it or not, it's for removing moisture, but it can also bring moisture in.

[@Alaska-Bush-Mom]

Was that batt insulation?

[@gregvancom]

Yes

[@Alaska-Bush-Mom]

@@gregvancom I am building a tiny cabin here in Alaska. It is 12x16 with 13’ wall on the high side and 11’ on the low side. With a loft and a half. It has a sloped/shed style/lean to style roof. I’m not sure what others call it. Do I need to cut the rafter tails before the fascia boards? Or can they stay as they are, as they came? I’m doing it myself and it’s very high off the ground (I’ll never build anything elevated this high ever again). Any advice?

[@tacosforus1688]

The squeaky wheel gets the grease