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  1. #1
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    Default Porch converted to family room - insulation question

    Hi - the family room in my house was an add-on from what looks like an old porch. When you go to the basement, you can look out a couple of windows and see the ground below the family room and the bottom of the floor.
    The ground appears to have a clear piece of plastic covered with miscellaneous pieces of rock and other not so attractive debris. I'll assume that is supposed to be a vapor barrier and you want to have that in place?

    My bigger question is, a bunch of the insulation under the family room is falling out. It is R19 from what I could see but I noticed that it is all pink -i.e., no paper side. Assuming this needs to be fixed, is R19 what should go there (or should I use a higher rating?) and should there be any "cover" over it, like plywood? If not, shouldn't I use a paper sided type and have the paper facing the ground?

    Thanks.

    Steve

  2. #2
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    Aug 2007
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    Portland, Oregon, formerly of Chicago
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    Default Re: Porch converted to family room - insulation question

    Just curious:

    Is this area under the porch otherwise enclosed? Are the walls also insulated? If so, why not just open up that window into the area and let it become part of the house's envelope? At that point, the nature of that insulation under the porch is somewhat unimportant as the area is now somewhat heated. The floor would also then become more comfortable and foot warm.

    There is some thought now that crawl spaces would be better enclosed into the house envelope and become conditioned space. My house is on a crawl space and I am tempted to seal the area, make it vapor tight from the earth and connect the space to the home's furnace.

  3. #3
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    Default Re: Porch converted to family room - insulation question

    Hi - thanks for the reply. Let me do my best here - I may need to draw this out or take a picture to show you as I may not have explained this well:

    Is this area under the porch otherwise enclosed? No - part of it is the stone foundation and the other part is exposed (covered only with lattice)


    Are the walls also insulated? I can't tell - based on how cold the room was this morning, I would say no or it was done poorly. The walls sound rather hollow. I'm having Home Depot come over Saturday to go over insulation stuff - it is free. I have also scheduled for next week a full house energy audit.

    If so, why not just open up that window into the area and let it become part of the house's envelope? At that point, the nature of that insulation under the porch is somewhat unimportant as the area is now somewhat heated. The floor would also then become more comfortable and foot warm. - I think I get what you are saying but wouldn't work based on my response above.

    I'll try and snap a few pictures and post them in the next day or two.

    Many thanks.

    Steve

  4. #4
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    Portland, Oregon, formerly of Chicago
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    Default Re: Porch converted to family room - insulation question

    Steven,

    OK, the picture is a little clearer now. The underside of the room is basically open. My next question is what climate you are in, as it has a baring on how much insulation you need and where the vapor barrier should be located, if any.

    Generally, in a cold climate the vapor barrier goes to the heated side. If this a heated room in a cold climate, the vapor barrier will be immediately under the floor sheathing. However, in hot, humid climates, the barrier would go to the outside. In temperate climates, the barrier is often just omitted. Warm, humid air wants to move toward the cooler, less humid air, whether in Florida or Vermont! Before the advent of air-conditioning, the question of vapor barriers in Florida was not as important, as the great differential between inside and outside temps and humidity did not exist.

    If you are in a cold climate, R-19 sounds very minimal. In Florida, under the floor, out of the sun and close to the cool earth, it sounds reasonable. However, I would want the bottom of those joists enclosed, even if you don't increase the insulation. A sheathing of plywood would protect against mice,etc., it would decrease air infiltration, and of course, it would hold that insulation in place.

    Were I in a very cold climate, I would consider pulling out the old insulation and spraying in foam insulation. Foam would solve all the above concerns: air infiltration, vapor barrier, varmints and no need of supports for batt insulation. It will also have the highest per inch R-Value.

    Hope this has been helpful. I am a humble retired painting contractor, but have some knowledge of insulation. Perhaps some of the contributors here with carpentry backgrounds will also pipe up.

  5. #5
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    New Jersey
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    Default Re: Porch converted to family room - insulation question

    Hello - here are some more answers to your questions and then let me run by a scenario or two to make sure I'm 100% clear on how to proceed:

    1. located in NJ - about 12 miles west of NYC so in the winter, it can get cold and it can get into the 90's easily int he summer.
    2. Foam I will consider and even with my level of knowledge on this start beginning, I think as well that R19 is too little.

    So, does this sound like a feasible option without foam:

    1. remove and throw out the current R19 which looks to be in bad shape.
    2. put in its place UNFACED R38
    3. use some kind of wire or plywood underneath to lock the insulation in place
    4. Keep a plastic vapor barrier over the dirt

    I'm assuming because the temperatures swing so far that unfaced insulation in best as to not have any way to have moisture build-up int he wrong place?

    Thanks.

    Steve

  6. #6
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    Default Re: Porch converted to family room - insulation question

    Steven,

    Since this porch is open underneath, I would want as much insulation as I could get in the available space without compacting it. I don't know what size joists you have.

    Since this room is not subject to high humidity as would be a bath, laudry or kitchen, I does not bother me that there would be no vapor barrier. The average home in winter has too little moisture unless addtional is added via humidifiers. You don't state what is on the floor above. If it is tile, sheet goods or laminate, you already have a pretty good vapor barrier.

    Personally, I like the idea of covering the underside with thin plywood. This will slow air infiltration and keep little critters from nesting in there. I do think some ventilation would be a good idea with a small vent at either end of the joist and a small amount of air space left just below the insulation. There are spring like devices which will hold the insulation in place just above the sheathing.

    I don't think it much matters that there is a vapor barrier on the ground since you have so much air flow in the relatively open area. This is not an enclosed crawl space. It doesn't hurt to suppress weeds and critters, however.

  7. #7
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    Thumbs up Re: Porch converted to family room - insulation question

    I'm not sure what size joists there are either - I will have to measure that. The floor above is a faux-wooden type. In the summer, that room will have air-conditioning when needed.

    Thanks for your advice - I think I'm ready to go after a few measurements.

    On last question - does the plywood need to be any special type, i.e. - water resistant (if that exists)?

  8. #8
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    Portland, Oregon, formerly of Chicago
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    Default Re: Porch converted to family room - insulation question

    Steven,

    Since your plywood will never see rain nor sunshine, I don't think you have to be too particular about whether it is exterior grade. Were it mine, I would however prime both sides before installing it.

    Fiberglass batt insulation gives an R-Rating of about 3 per inch. Foam insulation gives anywhere from 4 to 7 per inch depending on the type of foam. I doubt that you will be able to significantly upgrade your insulation R Value in the space available with batts alone.

  9. #9
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    Thumbs up Re: Porch converted to family room - insulation question

    Thank you Ordjen - appreciate the help.

    Steve

  10. #10
    Join Date
    Mar 2009
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    240

    Smile Re: Porch converted to family room - insulation question

    Great discussion here. I just wanted to mention since the current is R19, I hope the space exists to upgrade to R38 without compressing it which is most important to make sure you actually get the true insulation value.

    If I were in your situation, I would forget the floor and make those walls surrounding the porch/room solid and insulated, thus adding the entire building envelope. Then opening/removing that window to create an overall internal balance between that room to the rest of the house. As a bonus, it might then be possible to use the newly conditioned crawl space as some kind of storage with some more work if desired. Just keep in mind that's only in my opinion and I usually go for overkill anyway
    My advice and opinions come from hands on knowledge...and This Old House Hidden Content

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