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Old 03-26-2019, 11:04 PM   #1
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Enclosed Porch: Insulation between rafters?


I have an old enclosed back porch that acts as an entry way to my two story house. It's roughly 12' by 12 ' with a new shed roof that has a ledger board attached to the 2nd level of the back of my house. The eaves do have soffit vents but the roof itself has no vent on top. The top plate of the front wall is roughly 7' and the back the room is up to 11' or so. The 2x8 rafters are exposed. There's no HVAC that runs to this room. There are windows on 2 of the 4 walls that let plenty of cool air in during the winter. I keep them open in the summer for a breeze. My summers can be in the 80s and the winters can get single digits. We treat this as a mudroom for coats, shoes, etc. The only time we'd hang out in there is when the outside temperature is 60-80 or so. There's a tiny table to have lunch and what not.

Anyways, we are hoping to finish the underside of this roof. Still looking for ideas. Someone recommended putting R-19 fiberglass batts between the rafters and nailing bead board (or similar) to the rafters for a nice ceiling finish. His reasoning is it'd keep the ceiling from getting so warm in the summer. I get it, but I always thought there should be air flow, right? I'd rather not cut a cut in the roof for a vent. Will this insulation really make a difference? Is it necessary? If so, any other ways to create air flow without cutting a hole in the roof? Thanks!

I've read lots of good threads on venting roofs and insulation, but I couldn't find one that really matched my situation with my enclosed porch. Sorry if it's repetitive.
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Old 03-27-2019, 08:07 AM   #2
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Re: Enclosed Porch: Insulation between rafters?


Tough project. Insulation suggests people and their activities and the moisture they bring along. Add any conditioning and the air inside can hold even more moisture. When that moist air leaks into the ceiling and finds a cold surface it will deposit that moisture, thus the needed ventilation to remove that humid air before condensation occurs.

Pictures would help but a note, there are usually building codes in place that will override your plans and our suggestions. In fact a porch like that may not have been an approved addition in the first place. In any case it is always good to check to be sure your plans meet local requirements.

Bud
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Old 03-27-2019, 08:16 AM   #3
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Re: Enclosed Porch: Insulation between rafters?


Got a picture so we can see what your seeing and a location?
The best way would be to build a flat ceiling and insulate that instead of the roof.
Soffit vents with no roof or sidewall vents are useless.
There should have been a vent like this if your not going to build a ceiling.
https://dciproducts.com/shed-roof-roof-to-wall/
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Old 03-27-2019, 10:55 AM   #4
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@joecaption Here are some pictures. Originally, there was a porch (or 3 seasons room) roof that was added onto the roof of that 1st floor bump out. It’s pitch created a low ceiling on the porch. We build a shed roof on top so that we could vault the ceiling and make that room seem a little bigger. Plus, it straighted out the roof line too. The old ceiling joists are now useless and will be removed.
Attached Thumbnails
Enclosed Porch: Insulation between rafters?-b7837b43-bfb8-4fee-b868-f48d3e2bb046_1553702048814.jpeg   Enclosed Porch: Insulation between rafters?-9a7a1810-98bc-48df-bbc5-8dedda5b7669_1553702064133.jpeg   Enclosed Porch: Insulation between rafters?-879debf6-f402-4c21-b012-622da40e3084_1553702079963.jpeg   Enclosed Porch: Insulation between rafters?-5ad3912f-5dba-4cc1-9a7c-1dd8067f5c00_1553702101316.jpeg   Enclosed Porch: Insulation between rafters?-824f2953-f2a1-4824-8c91-1aafa70777aa_1553702118724.jpeg  

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Old 03-27-2019, 12:14 PM   #5
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Quote:
Originally Posted by Bud9051 View Post
Tough project. Insulation suggests people and their activities and the moisture they bring along. Add any conditioning and the air inside can hold even more moisture. When that moist air leaks into the ceiling and finds a cold surface it will deposit that moisture, thus the needed ventilation to remove that humid air before condensation occurs.

Pictures would help but a note, there are usually building codes in place that will override your plans and our suggestions. In fact a porch like that may not have been an approved addition in the first place. In any case it is always good to check to be sure your plans meet local requirements.

Bud
There won’t be any conditioning to this room. It’s really just an enclosed porch with a door and several windows that I keep open when it’s warm outside.

As far as codes go, I’m not really sure what rules this room is or isn’t breaking. All I really want to do is just attach some paneling or boards onto the rafters to create a finished slanted ceiling. I don’t know if I should add in insulation first or not. I added some pictures. Maybe that’d help clear some things up? Thanks for the input.
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Old 03-27-2019, 12:27 PM   #6
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Quote:
Originally Posted by joecaption View Post
Got a picture so we can see what your seeing and a location?
The best way would be to build a flat ceiling and insulate that instead of the roof.
Soffit vents with no roof or sidewall vents are useless.
There should have been a vent like this if your not going to build a ceiling.
https://dciproducts.com/shed-roof-roof-to-wall/
I added some pictures for you that may help.

This room actually had a flat ceiling that we removed. It created a 7ft high ceiling and made the room feel tight. I just have to get rid of the old ceiling joists and some old eaves that overhang into that room.

I know the soffits are useless if we don’t a have vent at the top. We kept those because they were doing no harm.

I guess I have two options/questions:

1) Do you think even adding R19 fiberglass insulation between the rafters add any benefit for keeping this room from baking in the summer months? I’ve only insulated conditioned spaces...never something like this.

2) If I did add the R19 batts, what would be the side effect of NOT venting at the top? Remember, not a conditioned space, but it is enclosed.

Thanks for the feedback.
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Old 03-27-2019, 12:55 PM   #7
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Re: Enclosed Porch: Insulation between rafters?


I would remove the ceiling and that portion of skirt roof but I would go up higher and put a small level ceiling so you have a common air space so 2 box vents would work.
I would also add to the depth of the rafters so you have close to 10 inches. so you have room for air chutes from the soffit to the common space at the top. And sealing between living space and insulation is really important.
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Old 03-27-2019, 02:17 PM   #8
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Re: Enclosed Porch: Insulation between rafters?


Like this
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Old 03-27-2019, 03:07 PM   #9
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Quote:
Originally Posted by Nealtw View Post
I would remove the ceiling and that portion of skirt roof but I would go up higher and put a small level ceiling so you have a common air space so 2 box vents would work.
I would also add to the depth of the rafters so you have close to 10 inches. so you have room for air chutes from the soffit to the common space at the top. And sealing between living space and insulation is really important.
Those old ceiling joists and skirts will definitely be removed. I understand your suggestion for adding a new level ceiling a higher...maybe about 9ft. The bottom of the rafter go as high as 11’. We’d lose a bit of that vault feel and still have to add those box vents. I’m trying to avoid cutting into the roof because I have no experience with that.

I came across a project here which was similar to mine but his porch is open: https://www.younghouselove.com/well-...eiling-please/

Towards the bottom of the article, he explains how he put a long vent which seems to run parallel with and right underneath his ledger board, but it vents downwards into the room. It seems backwards to me, but I’m no expert. Could this have any benefit?

I’m tempted to just leave it all exposed, install a pendant style lantern light, and call it a day. Haha.
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Old 03-27-2019, 03:28 PM   #10
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Quote:
Originally Posted by Nealtw View Post
Like this
Yes I believe this is the best route. I was reponding to your other post and didn’t see the image, but your explanation made perfect sense. I just want to keep the project simple. Throw some bead board up there, or other paneling, with some simple trim and be done. Adding more to the to-do list (although a better idea) doesn’t come as easy/quick to me. The previous set up had no insulation or roof vents and really caused no issues (that I know of at least).
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Old 03-27-2019, 03:33 PM   #11
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Re: Enclosed Porch: Insulation between rafters?


Quote:
Originally Posted by TimRemo View Post
Those old ceiling joists and skirts will definitely be removed. I understand your suggestion for adding a new level ceiling a higher...maybe about 9ft. The bottom of the rafter go as high as 11í. Weíd lose a bit of that vault feel and still have to add those box vents. Iím trying to avoid cutting into the roof because I have no experience with that.

I came across a project here which was similar to mine but his porch is open: https://www.younghouselove.com/well-...eiling-please/

Towards the bottom of the article, he explains how he put a long vent which seems to run parallel with and right underneath his ledger board, but it vents downwards into the room. It seems backwards to me, but Iím no expert. Could this have any benefit?

Iím tempted to just leave it all exposed, install a pendant style lantern light, and call it a day. Haha.
It always amazes me how people who know nothing proudly post there work on the net. Don't look at that article any more, there is nothing there there you need.



So you would be happy but for the box vents, watch some videos for that, it not all that scary . Besides that then from that attic space you could cut a vent in the side wall and into the other roof where you do have a box vent.
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Old 03-27-2019, 03:47 PM   #12
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Re: Enclosed Porch: Insulation between rafters?


Quote:
Originally Posted by TimRemo View Post
Yes I believe this is the best route. I was reponding to your other post and didnít see the image, but your explanation made perfect sense. I just want to keep the project simple. Throw some bead board up there, or other paneling, with some simple trim and be done. Adding more to the to-do list (although a better idea) doesnít come as easy/quick to me. The previous set up had no insulation or roof vents and really caused no issues (that I know of at least).

You are changing everything from an unheated box with an attic where the attic gets to disperse heat or cold to a closed tight space with insulation, you can not compare one to the other. We can likely find others with problems caused by taking short cuts.
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Old 03-27-2019, 05:26 PM   #13
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Re: Enclosed Porch: Insulation between rafters?


Quote:
Originally Posted by Nealtw View Post
You are changing everything from an unheated box with an attic where the attic gets to disperse heat or cold to a closed tight space with insulation, you can not compare one to the other. We can likely find others with problems caused by taking short cuts.
It's actually a pretty similar set up. I have the benefit of seeing everything in person. I'm sure some info is lost over the internet.

The original setup with the short 7' ceiling didn't really have an attic space. The largest gap between the bottom of the rafters and ceiling joist had to be a matter of inches, just barely enough for a pitch. It had little to no insulation and no venting. I'll attach 2 pictures so you get an idea. There were no issues. The new set up would be similar, just with or without insulation. Actually, the 2nd story addition provides a lot of coverage from the sun, so the roof is exposed to the sun for much less time. It's probably be slightly better.

I know you disagreed with that article. I questioned the venting method too, but maybe it works for their situation. There's a lot to factor into every job. If I left my setup as is, there's not much of a downside.
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Enclosed Porch: Insulation between rafters?-11.png   Enclosed Porch: Insulation between rafters?-22.png  
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Old 03-27-2019, 05:41 PM   #14
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Re: Enclosed Porch: Insulation between rafters?


@ TimRemo


Yes I understand but in this wall you can put a vent in the wall just below the rafter






In this picture we can see a box fent for the other roof

In this picture we can see the two roofs are common and a hole could be cut there to allow venting


Continued.
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Old 03-27-2019, 05:50 PM   #15
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Re: Enclosed Porch: Insulation between rafters?


@ TimRemo


If you remove the ceiling some of the roof sheeting should be removes so the wall can be continued up the roof, unless that is done already.




Building a ceiling is placing a 2x8 directly below the ledger that is holding the rafters
Add short 2x4 level with the bottom of that 2x8 out level and nailed to the rafters.
Then add blocks between the 2x4 at the 2x8.

The ceiling would be an hour or two.
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