Would it be ok to use EPS rigid insulation instead of spray foam to avoid tearing out the inside or outride? I could put in 2-3 inches and leave an air gap?
If there is no insulation on the sloped side of the interior, this becomes the place on the roof where the snow melts and then refreezes below it in the soffit area. The area of the conditioned space needs a 1 1/2"-2" space for continuous ventilation from the soffit to the ridge. That leaves only 1 1/2"- 2" of remaining space for insulation within the 2x4 rafter. Adding insulation on the conditioned side of the rafter with 4x8 sheets of 2" ridged insulation panels or possibly adding additional 2x4's on the conditioned side to increase insulation R value. I can't think of any other way around it. Interior space on the sloped area will be less because of the added insulation. In my 1 1/2 story house, the sloped area in our bedrooms are closets.
Well that helped immensely! Thank you for that video Mr. Bluin. I have a knee wall space with no soffit ventilation or any ventilation for that matter. I was hoping I could open up a cold air return in there and possibly a fan on the other end if needs be (moisture detector will help with that). I have very little experience insulating but I understand the concept of humidity and airflow. Here comes a trial and error!! Thank you again!! P.S. I would hire you but budget is on the lower end right now.
How did it work out? The slopes are sealed only house so I'm installing 2 gable vents on each end of the house in the kneewall and throwing powered gable vent fans on the other, my knee walls get so hot I can feel heat radiating off them right now. Probably gonna glue rigid foam to the back of the drywall as well.
@@Bigshoots86 Hello! Well this house is giving me many learning opportunities. I had to shift my focus on sealing my foundation as it was drawing in way too much air! Once I got that tied up (for the most part), and insulated the attic it really helped the house hold it's temps. I am now thinking of spray foaming the back of the roof deck in hopes of bringing the kneewall spaces to storage temps. They are still closer to outside temps even with fiberglass insulation. Which doesn't really surprise me. This framing is tough to insulate when this is not your profession! 😁 Adding a vent fan on one end of my gable is a good idea I think. Hope your adventure in insulation treats you well!!
I have ridge vent and soffit vents with the holes every 3 feet or so, will replacing the soffit with the kind that has the holes with no gaps make a difference, I still get ice dams in winter, cape cod hose so no attic to get into to add insulation in roof, man I wish I had a company like yours near me so I could get the foam in during my next roof replacement
Let's also emphasize blocking air flow between the floor joists under the conditioned air space. My upstairs is half over a 2-car garage and half over a 1st floor room. I hope to address the knee wall insulation/ventilation this fall provided I can subjugate my procrastination demon... I wonder if there would be any benefit to putting in some vents (seasonably adjustable) in the garage ceiling to the unconditioned air space...
hi cant you just fill the floor joists above that area with cellouse to eliminate warm air from rising thru that bypass area to the upper attic/ roof sheathing??
Why spray foam on the back of the knee wall and not simply continue down the entire roof (add come backing material in the area behind the knee wall). This way the space behind the knee wall will become part of the thermal envelope of the home and will be more useful as there won't be extreme temperature swings in there. Also, if there is any plumbing running through that space, you can't completely isolate it the way you describe because pipes will freeze (they don't currently freeze because enough heat escapes into the unconditioned space).
id argue spray foam is the worst choice, if you ever plan on doing anything in them areas for renovating later in the future. But if ur gonna do it for a one timer and not touch it agian till you sell, sure you can leave mess for the next guy to work around it.
Yeah that spray foam sounds great until you want to remodel the interior and it's stuck to the drywall like shit to a blanket... terrible idea unless you first install some type of barrier such as house wrap.
We have an asphalt shingle roof with the exact house your drawing, what are your thoughts on ridge vent compared to the max vents? Thanks for your video & time
Same. I'd like to know as well. I have a cape style roof and it's get hot in the summer and cold as hell in the winter. I thought about upgrading to a ridge vent style
Not sure if you are still wondering about this, you would have to talk to a structural engineer. Usually those short walls would be providing structural strength to the roof of the home as they are built into the truss system. Spray foam on the roof deck works if you want to condition that space but removing the knee walls is usually a much bigger project.
@@Tin5674 I don't think he was recommending removing the joists of the wall, just the drywall or paneling of both the wall and ceiling to access the insulation from the interior.
you drew a one story house with a finished attic. My house is a true one and a half stories. You didn't address the venting correctly, how does the air enter the soffit? My house is 110 years old with no venting at all in the attic.
It has been proven and is actually written in building codes that while ventilation is important it is not a solution nor a prevention method for ice dams. I’m not saying what you do doesn’t work but it can discredit you when you mention vent and ice dam prevention in the same sentence as any seasoned roofer knows it’s not about venting.
Before The Mandalorian, Pedro Pascal was an insulation expert.
Would it be ok to use EPS rigid insulation instead of spray foam to avoid tearing out the inside or outride? I could put in 2-3 inches and leave an air gap?
If there is no insulation on the sloped side of the interior, this becomes the place on the roof where the snow melts and then refreezes below it in the soffit area. The area of the conditioned space needs a 1 1/2"-2" space for continuous ventilation from the soffit to the ridge. That leaves only 1 1/2"- 2" of remaining space for insulation within the 2x4 rafter. Adding insulation on the conditioned side of the rafter with 4x8 sheets of 2" ridged insulation panels or possibly adding additional 2x4's on the conditioned side to increase insulation R value. I can't think of any other way around it. Interior space on the sloped area will be less because of the added insulation. In my 1 1/2 story house, the sloped area in our bedrooms are closets.
So modest. You draw well. Thx
Well that helped immensely! Thank you for that video Mr. Bluin. I have a knee wall space with no soffit ventilation or any ventilation for that matter. I was hoping I could open up a cold air return in there and possibly a fan on the other end if needs be (moisture detector will help with that). I have very little experience insulating but I understand the concept of humidity and airflow. Here comes a trial and error!! Thank you again!! P.S. I would hire you but budget is on the lower end right now.
Hi there,
We wish you best of luck and hope that what you learned through this video helps you with your particular project.
How did it work out? The slopes are sealed only house so I'm installing 2 gable vents on each end of the house in the kneewall and throwing powered gable vent fans on the other, my knee walls get so hot I can feel heat radiating off them right now. Probably gonna glue rigid foam to the back of the drywall as well.
@@Bigshoots86 Hello! Well this house is giving me many learning opportunities. I had to shift my focus on sealing my foundation as it was drawing in way too much air! Once I got that tied up (for the most part), and insulated the attic it really helped the house hold it's temps. I am now thinking of spray foaming the back of the roof deck in hopes of bringing the kneewall spaces to storage temps. They are still closer to outside temps even with fiberglass insulation. Which doesn't really surprise me. This framing is tough to insulate when this is not your profession! 😁 Adding a vent fan on one end of my gable is a good idea I think. Hope your adventure in insulation treats you well!!
I have ridge vent and soffit vents with the holes every 3 feet or so, will replacing the soffit with the kind that has the holes with no gaps make a difference, I still get ice dams in winter, cape cod hose so no attic to get into to add insulation in roof, man I wish I had a company like yours near me so I could get the foam in during my next roof replacement
Let's also emphasize blocking air flow between the floor joists under the conditioned air space.
My upstairs is half over a 2-car garage and half over a 1st floor room. I hope to address the knee wall insulation/ventilation this fall provided I can subjugate my procrastination demon... I wonder if there would be any benefit to putting in some vents (seasonably adjustable) in the garage ceiling to the unconditioned air space...
Can I do the same thing with rockwool the rafters and knee walls ... I have vent on both. Cables
hi cant you just fill the floor joists above that area with cellouse to eliminate warm air from rising thru that bypass area to the upper attic/ roof sheathing??
Why spray foam on the back of the knee wall and not simply continue down the entire roof (add come backing material in the area behind the knee wall). This way the space behind the knee wall will become part of the thermal envelope of the home and will be more useful as there won't be extreme temperature swings in there. Also, if there is any plumbing running through that space, you can't completely isolate it the way you describe because pipes will freeze (they don't currently freeze because enough heat escapes into the unconditioned space).
id argue spray foam is the worst choice, if you ever plan on doing anything in them areas for renovating later in the future. But if ur gonna do it for a one timer and not touch it agian till you sell, sure you can leave mess for the next guy to work around it.
Yeah that spray foam sounds great until you want to remodel the interior and it's stuck to the drywall like shit to a blanket... terrible idea unless you first install some type of barrier such as house wrap.
This was helpful. Thanks.
We have an asphalt shingle roof with the exact house your drawing, what are your thoughts on ridge vent compared to the max vents? Thanks for your video & time
Same. I'd like to know as well. I have a cape style roof and it's get hot in the summer and cold as hell in the winter. I thought about upgrading to a ridge vent style
What if you dont have soffits , and your roof is newer and you have a ridge vent ?
add soffit vents or a vent in the wall at each end of your attic. Its a simple in and out air system. idk im learning lol
Can you remove the knee walls and attic space to just open up the entire upstairs and then spray foam and sheet rock?
Not sure if you are still wondering about this, you would have to talk to a structural engineer. Usually those short walls would be providing structural strength to the roof of the home as they are built into the truss system. Spray foam on the roof deck works if you want to condition that space but removing the knee walls is usually a much bigger project.
@@Tin5674 I don't think he was recommending removing the joists of the wall, just the drywall or paneling of both the wall and ceiling to access the insulation from the interior.
So the upper attic at the peak will have no foam or moisture barrier of any kind? Is that for more venting from the room itself?
you drew a one story house with a finished attic. My house is a true one and a half stories. You didn't address the venting correctly, how does the air enter the soffit? My house is 110 years old with no venting at all in the attic.
It has been proven and is actually written in building codes that while ventilation is important it is not a solution nor a prevention method for ice dams. I’m not saying what you do doesn’t work but it can discredit you when you mention vent and ice dam prevention in the same sentence as any seasoned roofer knows it’s not about venting.