Insulation help in attic/half story

Discussion in 'Insulation and Radiant Barriers' started by swindmill, Apr 14, 2010.

  1. Apr 14, 2010 #1

    swindmill

    swindmill

    swindmill

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    I purchased a 100 year old, recently remodeled home several months ago. It's a 1.5 story shotgun style house. The second story has a bedroom and a full bathroom. It has a relatively small unfinished attic space, where I am in the process of adding a walk in closet. I have read many threads on insulation and followed links to outside sources and read those, so I'm in the process of learning what I can about proper insulation, but I still have quite a few questions.

    The entire house appears to have been insulated using rolls of fiberglass R-13 and R-19. As far as I can tell, the exterior walls were done with R13, but there is R19 in random places. I can't discern if there is a method to where the R-19 is vs. the R-13, but the house is built with a mix of original studs (2x5??) and newer 2x4s. I get the feeling that the insulation job done by the remodelers wasn't stellar, but the half story/attic space is really bad.

    I've gutted the bathroom upstairs and it appears as though the ceiling in the side attic is insulated w/ R-13, and the knee walls aren't insulated at all. The 'ceiling' upstairs is a strip that's about 1 foot across ( /-\ ). There is recessed lighting there, and the remodelers simply did not insulate at all in the top attic, leaving a large amount of space uninsulated. A side note - there is a large faux vent on one wall that simply leads to the side attic...maybe someone can explain that, or tell me it needs to be filled. Another observation I had is that there is no insulation on the "floor" of the side attic, above the downstairs ceiling.

    The unfinished area in the attic has loose insulation between the floor joists, but it can't be much more than 5" deep. There is no insulation between the ceiling joists. It doesn't appear as though the soffits are vented. There is one gable vent. I am in the process of adding a ~4x8 closet in this space, leaving side attic space on either side and about 3 ft. between the back wall of the closet and the front of the house (where the gable vent is).

    After all that description, my question is what steps do I need to take in order to correct the existing insulation and how do I best insulate the unfinished space as I build the closet? It gets very hot upstairs while the downstairs stays very comfortable. Money is an issue, so if I can do this myself it would be preferable. The biggest issues I see are insulating the top attic without tearing down drywall and without getting near the recessed fixtures. I hope my description makes sense and thanks for reading through all of this. Any thoughts or advice concerning how to go about this and what type(s) of insulation to use are greatly appreciated.
     
    Last edited: Apr 14, 2010
  2. Apr 15, 2010 #2

    AU_Prospector

    AU_Prospector

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    Hey it looks like u have some work to do. My limited knowledge says three things from your post.
    1) All your attic space, that is your interior ceilings (ALL) should be insulated to R38. Two layers of R19 will do it. First layer faced on the bottom, second layer unfaced. I think thats around 18 inches minimum if you use blown in fiberglass.
    2) You cant have enough ventilation in your attic. You need to add some. Soffits are a must, Gable is good, the more the better. Maybe add an attic/roof fan to pull air up through your soffits and out your roof or they make them for gables too.
    3) Dont block any flow of ventilation. If your closet project cuts your attic in half and blocks the flow of air, you should vent both halves adequately. Dont leave the other half unvented.

    Personally I dont have enough insulation either so I have work as well. But my vents are good. I have a weird roofline with vents at each gable (5 vents). I also have two electric roof fans that click on at higher temps. I have ridge vents cut into the tops of my rooflines. Also my soffits are vinyl and perforated for ventilation. I am also careful not to block airflow from the soffits up to the crest of my attic. If I stand in my attic with all the lights off, I can see light all around me from the gables to the soffits. On a windy day its breezy in my attic. I think that is good.
     
  3. Apr 15, 2010 #3

    swindmill

    swindmill

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    If I already have fiberglass rolls between the the roof and the drywall, is it possible to have more insulation blown in without tearing down all the drywall?
    Also, I'm not mistaken in thinking that I'm limited in R value by the space available between the roof and drywall? Because ceiling height is obviously an issue in a finished attic, I can't feasibly lower the ceiling even if I went to the length of tearing out the drywall.

    I have to look closer at my soffits to see why they aren't vented, or what's in the way. The outside of the house is newer vinyl siding over the old wood. I know the soffits are perforated on the outside, but something must be blocking them on the other side.
     
  4. Apr 15, 2010 #4

    Perry525

    Perry525

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    A bathroom needs to be comfortable not too hot or too cold and as a bathroom creates a lot of water vapour it need to be ventilated.
    I recommend that you do this job properly as water vapour can lead to wood rot.
    You need to tear down the drywall.
    And fit polystyrene or Blue Board between the framing, pack in at least four inches thick, and it needs to be a tight fit, between the rafters. No gaps or cracks.
    Cutting it with a knife works OK, a saw makes even more mess.
    Then fit a plastic water proof sheet over the framing taking care to overlap the joints and seal them.
    This is to ensure that none of the water vapour gets into the wall/wood and starts rot.

    Then fix another two inch thick layer of polystyrene over the plastic and finish with drywall. This last layer is to prevent the heat from the bathroom escaping by conduction through the wood, and it stops the heat from the sun coming in.

    A temperature of 51C/124f on one side of a two inch thick piece of polystyrene will often result on a temperature of 38C/102f on the other, so you can see six inches of polystyrene should meet your requirements, with a drop to about 22C/70f.

    It makes sense to do the whole attic to the same standard.

    Then fit an extractor fan, one with an automatic shutter to keep out the wind and a built in humidistat that will turn it on as required.

    PICT0967 amended.JPG
     
  5. Apr 15, 2010 #5

    swindmill

    swindmill

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    Tearing down the drywall in the bathroom wouldn't be a huge job, and I think I probably should. The Blue Board idea is a good one, although I'm not sure I'll have two inches to spare outside the rafters. Maybe five inches would be enough. What about spray foam? I understand that it has a pretty high R value per inch. There is a fan above where the shower will be that vents directly into a roof vent above the bathroom. Perhaps that helps with the rotting concern.

    As far as the rest of the attic, it is quite a large space and replacing all of the drywall would be a big job for me, and certainly put me past the time period in which I was planning to finish the upstairs. If there is no good alternative, then I have to do what I have to do, I suppose. I will probably live in this house for 4-5 years, so not too long relatively speaking.

    The part that I am finishing will obviously be done correctly from the start, but I need to figure out what correct, or even perfect, is for this situation.
     
  6. Apr 15, 2010 #6

    AU_Prospector

    AU_Prospector

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    can you add pictures? That would help
     
  7. Apr 15, 2010 #7

    swindmill

    swindmill

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    Here's one of the bedroom and unfinished portion of the attic where the closet will be. I'll add better pictures, including the bathroom, later on today. Thanks for the help.

    [​IMG] [​IMG]
    [​IMG]

    The wall between the unfinished and finished space (not pictured from unfinished side) is not insulated. There was an old chimney there, which I removed in order to put a closet entry way in. I'm hoping that correcting that will make a big difference.
     
    Last edited: Apr 15, 2010
  8. Apr 15, 2010 #8

    Perry525

    Perry525

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    I accept that space upstairs is always tight.
    I am sure that except on the hottest days and coldest nights 5 inches will be fine.

    Spray foam is the best insulation (available) as it fits into every space and leaves no cracks for the air to be pulled through.
    However, while it is quick and easy to apply, if you are on a budget you will find it very expensive.

    The fan above the shower, venting into a roof vent is fine, if you can buy a humidistat to fit on to it....that's good enough.

    The thing with fans is they need to pull the air from somewhere, so they can blow out the steam. Is there an vent for the air to come in?

    Sorting a home and making it air tight and bringing the insulation up to date, when you are working, does take a long time. Best to do a bit when ever you feel like it.

    Do keep in mind that there are millions of homes that are poorly insulated, badly ventilated and suffering damp and mould in twelve or so different States.
     
  9. Apr 15, 2010 #9

    swindmill

    swindmill

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    Bathroom:
    [​IMG]
    [​IMG]

    You can see how the upstairs is likely insulated throughout from these pictures of the bathroom. The knee walls are not insulated, but the roof is, at least until it gets near the top attic space where it stops.
     
  10. Apr 16, 2010 #10

    Perry525

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    I afraid the pictures say it all, the insulation is just not good enough by today's standards.
    Where we are all trying to keep our heating and cooling costs down.
    One really needs a bathroom to be comfortable, not too hot, not too cold, and cheap to run.
    And R13 just doesn't do it.
    Not only is the insulation poor, it totally ignores the heat loss/gain through the framing.
    With six inches of polystyrene or Styrofoam, you have a situation where for most of the year the bathroom will be comfortable without adding extra heat or using the air conditioning.
    Done once and done right, it will continue saving money for a lifetime, for you and subsequent owners.
     
  11. Apr 16, 2010 #11

    swindmill

    swindmill

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    Bathroom: You've definitely talked me into tearing out the rest of the drywall and starting over with insulation. I'm guessing I'll need to put some sort of stop (drywall, plywood) behind the framing of the knee wall so that I can put polystyrene there as well. I'll do at least 5 inches, 6 if feasible, along the knee wall, sloped ceiling, and top attic so the room is completely incased in it. I'll have to work around the recessed lighting and fan of course.

    Closet: Should I do the same thing with the closet? Incase the room in 6 inches of polystyrene? I could then just add lose insulation to the area of the attic that remains unfinished and vent it properly.

    Bedroom: While I'm a big fan of doing things right, I just can't tear down all that drywall and have to rehang, refinish, and repaint that entire space. I'm thinking about having an insulation company come out and look into blowing additional insulation in behind those walls and into the top attic. Doing that (if it's possible?) along with properly insulating the closet and unfinished attic space would be a big improvement, I would think.


    If I'm going to do the foam board in the bathroom and closet, would it make sense to have a spray foam contractor come out and spray foam those two rooms, or would that be a lot more expensive than doing the boards myself? Thanks for the help.
     
  12. Apr 17, 2010 #12

    Perry525

    Perry525

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    If you cut the foam as a push tight fit, then it will stay in place without any backing.

    Yes the idea is to have a complete polystyrene box, that is both air and water vapour tight.

    With the lights and fan, use some cans of spray, to keep the total integrity.

    Keep in mind, for the fan to do its job it needs to pull air from somewhere, so that it is pushed outside with the water vapour.
    If there is no air supply the fan will struggle to clear the room. I normally suggest that an extractor fan with a heat exchanger be used as you get a balanced flow, with the incoming air being warmed by the extracted air.....but, in your case venting through the roof...it may not be possible.

    Yes. The problem with water vapour (that which is not expelled by the fan) is that it always makes for the coldest spot to condense, these spots are the toilet cistern, the windows and any spots like the closet, where there is no warm air circulating. Result, damp, mould, wood rot, smells. Not good.

    Finish the bathroom and closet, see how it goes through the summer, then think about the rest of the job and decide when you are sure.

    The spray foam, you can do it yourself, and will probably take more care and do a better job.(and it will be cheaper) Ask around you may find a good price, watch out for a cheap price and someone who doesn't do the job properly.
    If you do get someone in, stand there and watch them do the job, do not go away and leave them to it. After all its your money and you have to live with the result.
     
  13. Apr 19, 2010 #13

    swindmill

    swindmill

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    Thanks for the advice. I'm going to look into the spray foam option and weigh it against the Polystyrene option. I'll do one of the two in the next month or so. Waiting on the bedroom is a good idea. Hopefully it will feel better with the closet and bathroom done.
     
  14. Apr 20, 2010 #14

    Perry525

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    May I add one more recommendation.
    Buy an infrared temperature gauge.
    With this you can hold the trigger and scan anything and it will tell you its surface temperature.
    Use it to measure the temperature of the walls in the bathroom and closet after you have finished.
    Then read the temperatures of the rest of the attic that are "as now."
    This will show you what you have achieved and what remains to be done.
     
  15. May 25, 2010 #15

    swindmill

    swindmill

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    The closet mentioned above is framed in and ready for insulation. I'm still debating on what exactly to do to keep it cooler up there. The roof joists are about 5" deep and 24" apart. From reading up on this issue, I'm led to believe that I really need a radiant barrier against the actual roof, before putting in insulation. Is this true?

    If so, based on cost and limited space, I'm thinking about doing the ceiling of the closet in this order: roof|radiant barrier|R-19|3/4" polystyrene board over the joists|drywall

    That'll give me R-23 plus the radiant barrier, which isn't great but unless I give up ceiling height it seems to be about the best I can do, taking cost into account.

    My main objective is to combat the extreme heat upstairs. Since knocking the wall out for the closet, it's so incredibly hot up there that I literally start sweating within 30 seconds of walking up the stairs.
     
  16. May 26, 2010 #16

    Perry525

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    Fix two layers of 2 inch thick polystyrene between the rafters. With staggered close fitting joints. Cut them to a push tight fit.
    Two inch thick is easy to cut with a knife.
    If you go for one four inch thick layer cutting with and old saw will be easier, but more messy.
    Stick a radiant barrier on the top sheets, carefully leaving a one inch gap between the top of the polystyrene/radiant barrier and the underneath of the roof, this will enable the radiant barrier to reflect the suns radiation back up through the roof.
    The polystyrene between the rafters, will stop the hot convection currents transmitting the heat from the roof through to the drywall.
    Then fix another layer of polystyrene across the rafters, this will stop the conducted heat that arrives in the room via the, roof and the wooden rafters.
    Then fix the drywall screwing through the drywall/polystyrene into the rafters.
    The result, a one inch gap, a reflective layer, five inches of polystyrene, one layer of drywall.
     
  17. May 26, 2010 #17

    swindmill

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    I noticed that Lowe's sells a polystyrene board with a radiant barrier affixed to each side of the foam. I think it's called "perma-R" or something similar. Could I use that in place of the radiant barrier and first polystyrene board?

    The old roof joists are all about 4 inches deep. They are not consistent in depth (and so not level), and 4 inches isn't deep enough, so I'll have to sister something to the inside of each joist. I imagine any gaps or cracks this creates can be addressed with a can foam insulation.

    Is there any need for a vapor barrier on the outside of all of this?

    One last question: Should I insulate the attic ceiling all the way down to where it meets the floor, and insulate the knee wall. Or, should I only insulate the knee wall? It is a 100 year old home and does not have soffit venting. It has only one gable vent, which really doesn't do much of anything. The space left unfinished is really just the side attic behind the knee walls. Should I just go ahead and insulate everything rather than worry about how to properly ventilate the little space that remains?
     
    Last edited: May 26, 2010
  18. May 27, 2010 #18

    Perry525

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    By all means use a board with a radiant barrier on both sides, only the side facing the sun will reflect the suns radiation.

    Five inches of polystyrene will reduce an outside temperature of 95f to about 74f on the inside.
    Yes blocking all gaps does make a difference. As I mentioned earlier once a convection current starts up it can move an incredible amount of heat from one side to the other. Foam is ideal for filling odd shaped holes.
    The purpose of an vapour barrier is to stop the water vapour created inside the home, by cooking, washing and breathing getting into the walls and rotting the wood. A vapour barrier is always positioned under the drywall.
    Polystyrene is windproof and waterproof (in as much as continuous immersion in water will result in a 3 to 4% take up of water) In your location, the fact that it is warm, makes polystyrene a useful vapour barrier. (Provided there are no holes)
    Yes, to get the maximum benefit of your work, the whole room should be protected by at least five inches of polystyrene.

    Keep in mind that the heat that will arrive inside the room, will mainly come by conduction via the roof, rafters and the small amount of polystyrene covering the rafters. If you measure the length of the framing to the room, the width and the total amount of square feet of wood covered by your proposed 3/4 inch polystyrene and divide that into the total square footage of the ceiling and walls, you will be surprised how large this weak area is, and what an impact it will have on the rooms temperature.

    One inch of polystyrene with a temperature on one side of 126f will show about 98f on the other, from this you can see that the wood of the rafters will end up being the weak link, two inches as a cover of polystyrene is better.

    The purpose of roof ventilation is based on an incorrect premiss.

    The theory is that the wind blowing over a home will create an area of low pressure to the lee of the home. This will then suck the air from the attic and remove any water vapour that has infiltrated from the home below.
    This will remove the likelihood of ice forming during the winter.
    The fact is there are many days/nights when there is no wind.

    During the summer, the theory is, the wind will remove the heat from the attic.
    When on many days there is no wind. And in any event the heat is transmitted via conduction through the framing and radiation.

    So yes! The more and thicker the insulation, the less heat will get through to the room.

    If you have south facing windows, then an outside shutter, will be a great benefit, shading the room and keeping the radiation out.
     
  19. May 27, 2010 #19

    swindmill

    swindmill

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    Then I'll plan on insulating the entire space, finished and unfinished, and then insulating the knee walls as well. I was going to change my plans a bit to include sistering 2x6's to the ceiling joists so that I have 5.5" of space for insulation. If I were to do that, I wouldn't have enough room to also put 2" of polystyrene on the outside of the 2x6's. 2x4's provide slightly less depth than the existing joists. So, I'd have to come up with some combination of material that puts the depth at 4.5". I'm thinking I could put a 1/2" polystyrene board with the radiant barrier in and then the 2x4 on top of that...but that just seems a bit unconventional. The bottom line is that 5.5" of insulation is about as much as I can do before putting up the drywall, otherwise I will be sacrificing too much head space, which is very limited as it is.
     
  20. May 28, 2010 #20

    Perry525

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    The only time you can get a job 100% right is with a new build.
    Renovation is always about compromise.
     

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