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Mudroom Insulation

Post in 'DIY and General non-hearth advice' started by Vic99, Feb 8, 2013.

  1. Vic99

    Vic99 Minister of Fire

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    I have a roughly 5x8 ft mudroom. Walls and ceiling have 3 inches closed cell spray foam (~R 21). Has a weather striped steel door to outdoors and a new solid pine door to the kitchen. That pine door has a cat door. No baseboard hot water/gas heat in that room, but woodstove heats house 95% of season.

    The floor is the problem. All I've got are original planks (1920) with gaps, then particle board (I think) with linoleum stick tiles that I put on 2 years ago. I know it is not a heated space, but the floor cold is killing me. I'd like more of a buffer zone between the elements and the kitchen. I seem to lose a lot of heat through that cat door.

    There is space to add a couple of inches to the floor without affecting door swing. I'd rather not tear up the floor, but add to it's height. If I could get a good air seal and R 4-5, do you think that would make a difference?

    Research led me to a few options that leaves the linoleum and lets me build on top of it. Material cost is not much of an issue since it is such a small space.

    a) Rosin paper, then cork flooring (~R2), then carpet underlayment (~R1), with short carpet on top (~R1).

    b) Dricore subfloor, then carpet underlayment, then carpet.

    Other suggestions are welcome. Thanks.

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  2. ironpony

    ironpony Minister of Fire

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    I have heard cork is great, I am going to install over concrete one of these days
    it feels warm when you touch it
    so maybe Dricore then cork plank flooring?
  3. Jack Straw

    Jack Straw Minister of Fire

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    What is under this mudroom? Basement, crawl space or is it on posts?
  4. semipro

    semipro Minister of Fire

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    I've used 1" XPS (i.e., Foamular) foam under laminate planks with great success.
    Waterproof laminate (e.g., Allure) is available and may work well in a mudroom.
    midwestcoast likes this.
  5. midwestcoast

    midwestcoast Minister of Fire

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    I reno'd a covered porch into a mud-room/sunroom/wifes massage room & did 2" XPS on the slab followed by OSB an laminate. It worked well to hold the heat BUT if you're not gonna heat the room the most important thing for a warmer feel will be the thermal mass of the flooring, so carpet will be good for that.
    Carpet and Mudroom don't seem to go together for me so I'd be doing XPS (as thick as you can) then subfloor or direct to laminate with some rugs near doors...
    mikefrommaine likes this.
  6. woodsman23

    woodsman23 Minister of Fire

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  7. I'd agree with the foam/subfloor/finished floor on top of what you have. Personally I'd go with tile on top. But it will feel cold unless you do underfloor heat of some kind.

    Doesn't matter how much insulation you put in the mudroom it's always gonna feel cold without a heat source.
  8. woodgeek

    woodgeek Minister of Fire

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    Insulating an unconditioned space is usually not that helpful. Is this a comfort issue in the kitchen.....or when you are in the mudroom.

    If in the mudroom, how about an IR space heater hooked up to a motion sensor??
  9. Vic99

    Vic99 Minister of Fire

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    Jack: Effectively a leaky basement space. To store pottery, previous home owner built a greenhouse-like space (large glass windows) with a shingled roof. To get under the space from the green house would be tearing out a plywood ceiling covered in flourescent lights. More than I want.

    Enclosed photo: snow covers the greenhouse roof and most of side windows. Door on left is mudroom exterior door. Photo taken through the kitchen window.

    Semi & midwestcoast: Polystyrene under the floor? Do you have to use some kind of spacer so it is not compressed? Does OSB take care of it and is this what you mean by OSB?: http://en.wikipedia.org/wiki/Oriented_strand_board

    Woodgeek et. al.: Not looking to heat the mudroom. Want the kitchen to be more comfortable and part of that is cold spilling in through the mudroom door. Cat door is part of problem. Best I can do so cat will still use it is cover it with towel giving a curtain effect. Anything more, nervous kitty will vomit.

    Goal is to reduce cold loss in kitchen. I realize unheated space next to kitchen is not ideal, but would like to do better. Kitchen 6 ft long R3 bay window doesn't help, but great views. It's covered with thermal curtain at night. Got all other issues in kitchen that I could think of short of tearing off walls and updating insulation.

    Hoping for a semi-quick fix, <$300. That's why adding on top of what is there is appealing and a job that I could handle, I think.

    Attached Files:

  10. woodgeek

    woodgeek Minister of Fire

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    Is there another cat door in the mudroom for the cat to get outside, or do you have the box out there??

    So, I agree this must all be an infiltration issue....the heat loss through a cat sized door (unless its a tiger) has to be pretty small.

    Air sealing the whole room and exterior door to a much smaller free area than a cat door sounds like a PITA for an unconditioned space.

    If it is just infiltration, put a mechanical vent to depressurize the mudroom slightly, maybe blowing the semi-conditioned air into the crawl underneath. You can buy a small Soler-Palau ducted blower, rated for 100 cfm, and put a speed control on it to get it to 20 cfm nominal, which should be more than enough to reverse the flow through the cat door. As for the energy cost....20 cfm is prob ~15 gallons of oil/season in your climate (with a kitchen ventilation and warmer mudroom 'benefit'), blower is 11W, so that is 4 kWh/year. If you wanted to reduce the energy loss you could try dampering it down to lower flow.

    http://www.amazon.com/Soler-Palau-TD-100-In-line-Exhaust/dp/B0027E3Q4Y/ref=sr_1_1?ie=UTF8&qid=1360599869&sr=8-1&keywords=soler palau
    http://www.amazon.com/Soler-Palau-CVC-100-Continuous-Ventilation/dp/B0051HEL2A

    'bout $100 total.

    IF the cold is coming through the pine door (not infiltration), this will likely help some, not clear how much.

    (I've got the same rig negative pressure venting my attached garage 365 days a year, been running for 4 years 24/7 without a problem)
  11. midwestcoast

    midwestcoast Minister of Fire

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    Yes, Extruded Polystyrene (XPS) the blue or pink stuff. It has much more compressive strength than Expanded Poly Styrene (EPS), the stuff made of little foam balls.
    Yes that's OSB. The stuff used to sheath houses. It's cheaper than plywood. I used 5/8" tongue & groove OSB glued together & floating over the XPS (also floating, glued & seam taped) as a base for laminate flooring. The OSB is also to spread any point loads & prevent denting the XPS. The laminate itself may have been enough to do that, but didn't want to risk it. The floor will have to be level or you'll feel hollow spots underfoot.
    Honestly I dont see how insulating this floor is going to warm the adjacent kitchen.
    There are weather-proof cat doors available from simple clear flaps with magnetic closures, to automatic ones using Radio-Frequency I.D. tags. If the cat will go through a towel, maybe one of these would work.
  12. begreen

    begreen Mooderator Staff Member

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    Does this mudroom have a door isolating that space from the kitchen or is it just an extension room that is open at all times to the kitchen. If it is always open, can you add a doorway to this area (with a second cat door)? If not, insulate the floor and consider adding a second magnetic cat door on the interior so that you have a double-cat door. I did this for our north facing cat door and it really helps keep out cold air when the wind is out of the north. Our very nervous cat handles it fine.
  13. semipro

    semipro Minister of Fire

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    I don't use a spacer or anything on top the foam unless I need a nailing surface. I'm currently sitting in a room with nothing but XPS with an inexpensive laminate floating over it. Despite the presence of a rolling office chair, upright filing cabinet, and big dogs, the floor has held up perfectly for over five years. XPS is quite strong in compression.
  14. G-rott

    G-rott Member

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    I agree with all the post about using XPS foam and a floating floor, with all the other insulation in that small a room I would thing the heat loss through the pine door will actually warm the room some. Adding a magnetic sealed cat door will help too, rather than just the flapper type.

    If your on a fixed schedule radiant floor heaters might be worth looking into, with the programmable timed thermostats they don't need to run much to increase comfort when you need it. I put some under tile and I recommend them highly. Did a large system in a bath and the electric bill was similar to prior years in usage.

    Warm feet are nice.

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