# Three season porch ceiling insulation



## Nellspayne (May 20, 2021)

Hi all, first post here. I've read lots of posts about insulation steps for a three season porch but thought I would ask a few questions based on my specs. I live in upstate NY and have a porch that was turned into a two season. I'm in the process of installing double hung windows now, I've already insulated the floor joists with rigid foam board and pink insulation, with a vapor barrier over it and a subfloor. It's about two feet off the ground, which I also laid a vapor barrier over the ground.
My main question is this - it only has 2x6 rafters but I want to insulate at least to close it up some. I don't plan on heating or cooling the space, I really just want it to be a three season porch with no intention on using it in the winter. If that's the case can I just insulate it and make it a "hot roof" rather than venting it with baffles and soffit vents? It has no ridge vent.
Second, do I need to add a vapor barrier to the ceiling/walls if I am choose to use Kraft backed insulation? I've heard so many yes and no'a, so not really certain at this point. 

thanks for the help!


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## Nellspayne (May 20, 2021)

Oh, sorry I meant to also include - the ceiling is a vaulted ceiling, not flat.


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## gthomas785 (Mar 22, 2021)

If you have a vaulted ceiling then it makes sense to insulate the roof directly. If you go that route you need a carefully detailed and taped vapor barrier below it. Even in an unheated porch, passive heating from the house would be enough to drive moisture up into the insulation and cause mildew without the barrier. An easy way to avoid those problems would be to insulate the roof with closed cell spray foam which acts as a vapor barrier (yes, more expensive..)


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## Nellspayne (May 20, 2021)

gthomas785 said:


> If you have a vaulted ceiling then it makes sense to insulate the roof directly. If you go that route you need a carefully detailed and taped vapor barrier below it. Even in an unheated porch, passive heating from the house would be enough to drive moisture up into the insulation and cause mildew without the barrier. An easy way to avoid those problems would be to insulate the roof with closed cell spray foam which acts as a vapor barrier (yes, more expensive..)


Thanks for the help. I'll add a 6mil vapor barrier once I insulate. I would love to do a spray foam but cant justify the cost just for a sunroom unfortunately. I'll probably use pink with Kraft paper to add a touch more protection in addition to the vapor barrier. Would adding soffit vents without baffles really make much of a difference? Would add baffles if there was more depth in the rafters.


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## gthomas785 (Mar 22, 2021)

I would skip the soffit vents if you're doing a hot roof. The whole point of soffit vents is to supply air that can flow up along the underside of the roof deck and out the ridge vent. Without that channel present, the soffit vents won't do anything.

In lieu of venting, you are relying on the vapor barrier to keep the rafter bays dry. Be really careful to tape all the seams, and I would even run a strip of tape along each rafter to cover the staple holes. This frost king tape is great, super sticky and stretchy, and will seal around whatever fasteners you use to put up your ceiling too.









Frost King T94H Plastic Weather-Seal Tape 2-Inch by 25-Feet, Clear, 2" X ft - Weather Stripping - Amazon.com


Frost King T94H Plastic Weather-Seal Tape 2-Inch by 25-Feet, Clear, 2" X ft - Weather Stripping - Amazon.com



www.amazon.com


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## Nellspayne (May 20, 2021)

gthomas785 said:


> I would skip the soffit vents if you're doing a hot roof. The whole point of soffit vents is to supply air that can flow up along the underside of the roof deck and out the ridge vent. Without that channel present, the soffit vents won't do anything.
> 
> In lieu of venting, you are relying on the vapor barrier to keep the rafter bays dry. Be really careful to tape all the seams, and I would even run a strip of tape along each rafter to cover the staple holes. This frost king tape is great, super sticky and stretchy, and will seal around whatever fasteners you use to put up your ceiling too.
> 
> ...


That makes sense, thanks. Not that we probably ever would, but if I wanted to add a small wood stove or something years down the road, I would need to revise the insulation set up in order to do so correct?


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## gthomas785 (Mar 22, 2021)

Nellspayne said:


> That makes sense, thanks. Not that we probably ever would, but if I wanted to add a small wood stove or something years down the road, I would need to revise the insulation set up in order to do so correct?


You shouldn't need to do that. Vented roofs tend to be more forgiving, but lots of people insulate their cathedral ceiling rooms with the hot roof method and heat the interior. It's just that it's easier for things to go wrong if you get a gap in the vapor barrier, because there's no ventilation to carry away moisture once it gets into the insulation. If you do as I suggested above, you should have no issues heating the space - with the caveat that it's still only 6" of insulation and you'll have some thermal bridging through the rafters.

This is another reason to take your time and do the vapor barrier properly - you don't know what the future use may be whether it's for yourself or a future owner.


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## gthomas785 (Mar 22, 2021)

Love the idea of a wood stove by the way... I installed two in my house and we keep them going most of the time from October to April. Nothing brightens my mood better than a cup of coffee by the fire on a Saturday morning.


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## Nellspayne (May 20, 2021)

gthomas785 said:


> Love the idea of a wood stove by the way... I installed two in my house and we keep them going most of the time from October to April. Nothing brightens my mood better than a cup of coffee by the fire on a Saturday morning.


I agree. Like I said, no plans on doing so anytime soon but if I could open it up in the winter as another useable space with a wood stove or pellet stove that would be great. Then again it would then tech become a four season and taxes would grow lol


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## Nellspayne (May 20, 2021)

gthomas785 said:


> Love the idea of a wood stove by the way... I installed two in my house and we keep them going most of the time from October to April. Nothing brightens my mood better than a cup of coffee by the fire on a Saturday morning.


Should I also be using a vapor barrier on the walls? Not too much to cover, Lower knee wall below windows and above the windows on the gable
End.


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## gthomas785 (Mar 22, 2021)

Nellspayne said:


> Should I also be using a vapor barrier on the walls? Not too much to cover, Lower knee wall below windows and above the windows on the gable
> End.


I would.


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## AleksShamles (Jun 2, 2021)

Good


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