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How can I upgrade the insulation in my walls?

sephiro499 | Posted in Energy Efficiency and Durability on

Walls in my mobile home only have R-10
All values:
walls U .097 R-10.3
ceiling U .038 R-26.3
Floor U .048 R-20.8

I live in a mobile home designed for New Orleans (Katrina, FEMA trailer) yet I live in northeast Maryland (Elkton, MD). The minimum for new construction (based on my zip code) is R-13 and EnergyStar dictates R-20 (15 cavity + 5 sheathing).

The front room of the trailer, that exposed on three sides, is unbearably hot or cold 4 months out of the year. The heat isn’t so bad in the rest of the place, but in that room it’s terrible. The cold is terrible no matter what room I’m in.

According to this:

“”Blowing loose-fill insulation into an existing manufactured home is difficult because of the narrowness of the wall and roof cavities.””

It appears the only two options I have are to either remove the siding or remove the wood panels, replace the insulation, then put new panels on. I’ve tried to remove a panel but even after taking all the nails out it wont move. I suspect it may be glued as well? I’d have to destroy the existing stuff and buy new.

Short of major renovations I was thinking of 2in R10 rigid foam insulation finished with 3/8 sheetrock. I’ll work around windows and electrical outlets. I live on a fixed income and suspect getting it done the ‘right way’ would be at least a few thousand dollars. My solution, although not elegant, seems it would be effective.

I have no ‘building’ experience and the foam with sheetrock sounds like the more realistic option. To give you an idea last winter, after getting an electric bill over 200 dollars – for a 700sq foot trailer – I put the heat on 55 and just wore my winter coat. Especially when it comes to the cold, it just doesn’t matter what you do, you WILL be cold.

The walls themselves, especially the closer you got to the bottom, are cold (in the winter). I know if the walls are cold there is a problem. Whether that is from inferior insulation or air infiltration is another issue.

My goal is to take steps now, while it’s warm, to mitigate the cold weather. Last winter was my first winter in the place and it was quite difficult.

I’ve also read that insulation types and techniques have a baring on the climate. The example used was an insulation blanket and how that is ineffective in cold climates but works in warm climates.

Anyway I don’t know much about mobile homes and short of ripping a wall off to see what is going on in there I don’t really know.

Any suggestions, web resources, or books would be most appreciated. I do have “Foremost mobile home fix-it guide” but it doesn’t address this issue directly.

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  1. GBA Editor
    Martin Holladay | | #1

    Yes, you can install a layer of rigid insulation on the interior of your walls, followed by a layer of 1/2-inch gypsum drywall. Here is a link to an article that discusses your suggested approach: Walls With Interior Rigid Foam.

  2. georgejfrick | | #2

    Are you sure you don't just have a lot of significant air infiltration or leaks? You might find a significant improvement with as little as a temperature gun and a can of spray foam. If you HVAC runs 'under' the unit, make sure it is sealed/etc.

    From the description of it being colder lower on the walls, you might research insulating the bottom of the trailer from underneath?

  3. user-1085194 | | #3

    I saw a series of videos from a weatherization company that was working on older manufactured homes. For the walls they would loosen the skin at the bottom and slide batts up into the wall cavities. For the ceiling they had a few options. Either loosen the skin at the roof edge and add insulation or drill holes thru the roof or ceiling and use blown-in product. The floor is pretty easy, just cut the belly wrap to inspect/ repair the ducts and insulation and then seal it back up. I have also seen manufactured homes retrofitted with conventional roofing and siding.

  4. sephiro499 | | #4

    2. I do not know. I purchaed a 10 heat gun but didn't find it very helpful. Insulated skirting is at least 2,000 to install. An energy audit costs 500 dollars. I just don't see the point in someone coming over when I already know the insulation is woefully inadequate.
    3. If you are referring to the WxTV videos, my mobile home is newer and has vinyl siding. Taking off the siding is a herculian task. My trailer does not have 'skin'.

  5. user-4524083 | | #5

    Vincent - Insulated skirting is probably not worth it, but tightening the skirting probably is. What is the skirting now? Why is that front room so cold? Was it added on? Is there a tight skirt around it? How large is the trailer? What do you pay for heat now for the winter season?Is the $200. for one month? Are the windows reasonably tight, or are they drafty? I doubt that any serious insulating, like adding foam and drywall would be worthwhile. I lived in a 25 year old mobile home in Maine for 12 years while we built our house. The pipes would freeze until we figured out a good system. We put bags of dry leaves around the skirting in the winter which was cheap and seemed to help. We also made sure the skirting had no major drafts blowing through it. The windows were just storm windows with added on interior storms for the winter. But the volume of the house was so small that we used only one tank of oil a year to heat it. A different heat source may be more cost effective than insulating,a concept that irks me but may be true. Minisplit?That would cost at least $3000, but may be worthwhile. I'm sure that there are things you could do to improve the situation short of what you are proposing. Best of luck with this project.

  6. sephiro499 | | #6

    The trailer has vinyl skirting, brand new. It's a fema mobile home and my dad bought it. I don't think that room was added on but unsure. Trailer is 14x60 something I do believe.

    Windows are storm windows. 200 was the price for one month of heat. Even paying 200 the trailer is very drafty and uncomfortable.

    All I know about the trailer is it is from FEMA and that the ceiling cracked in two places while they moved it. I was told this is 'normal'. I had no control over this purchase and just live here.

    There are nice 1/4 - 1/2 gaps from the ceiling to the drywall? that was hidden by trim pieces along the top. I'm going to remove the trim and fill it wiht great stuff.

    The floors are just linoleuim and have no idea if that contributes to the cold or not.

  7. slopecarver | | #7

    If the trailer won't be moved in the future you can attempt adding exterior insulation with taped seams to the entire trailer 2" under the floor, 2" on the walls, 4" on the ceiling would likely make a huge difference. You would have problems with securing the insulation to existing studs which may be difficult to find, the added expense of re-siding/roofing the trailer to cover and protect the foam, and trimming out the windows.

  8. sephiro499 | | #8

    You mean exterior insulation in the interior? I got frustrated and just demo'd the one room. If I'm going to do it I'm going to do it right. The insulation was installed completely wrong. Two cavities had no insulation at all. Ripping the drywall down wasn't all that difficult but cleaning the adhesive off the studs is going to be a job.

  9. GBA Editor
    Martin Holladay | | #9

    The suggestion made by Joseph Malovich isn't very practical -- especially if you have already begun ripping open your walls from the interior.

    Good luck with your work. I'm sure it's frustrating, but the work you are doing will make your home more comfortable and will lower your energy bills.

  10. srenia | | #10

    Having done the interior foam. It's a lot of work. lol.

    -Fiberglass tape and mastic joints.
    -Caulk electrical openings, bottom and top of foam boards.
    -Stagger Drywall over Foam

    1" Foam you can place drywall directly on drywall. Above 1" you'll need to strap the foam so you have something to attach the drywall to. A 2" you might as well put a double wall in and call in good. Cheaper and better. The 1" foam works with eletrical extensions as well. The 2" is the wrong size for extension so new boxes will be needed. Since new boxes will be needed it is illegal and dangerous to pig tail the existing electrical boxes. So above 1" foam interior you will need to run new electrical lines to new boxes on the outside walls.

    R-5 continous insulation will block 80% of heat transfer alone. With probably real life r10 of the walls (just a guess, another expert probably has the exact figure) that remaining insulation should get you in the 90 percent heat blockage U-Value Range. Think the greater thing you will notice is going to be from air sealing above everything else. You can use a fireblock caulk on the back of the eletric boxes to seal the electric wire opening and outside air openings. If the wall is already off then you could install a baffle behind the electrical boxes.

  11. sephiro499 | | #11

    I decided to rip all the drywall down. The plan at first was rigid foam over drywall then more drywall. Now that the walls are exposed I have a new question. Some of the wall cavities, have upwards of 20+ nails that did not hit the stud. This is all over the room. You can see in this HQ pic, attached is an image with lower color depth

    My new concern is air infiltration cause by all of these small holes from the nail that 'didn't hit their mark'. Just moving my hand near the nails I can feel the heat. Whether that is due to the nails conducting heat from the outside or air I don't know.

    I want to know if I should rigid foam to create as much of an airtight seal as I can. Is there any other way I could/should address this issue? Is it not a big deal? Currently I'm caulking the heck out of it with dynaflex caulk. I can't really caulk the nails nor can I tape it.

  12. GBA Editor
    Martin Holladay | | #12

    If you want to seal around the nails, you can use the "cut-and-cobble" method if you want. Leave a wide gap near the nails, and seal the space between the rigid foam and the studs (over the nails) with canned spray foam.

    For more on the cut-and-cobble method, see Cut-and-Cobble Insulation.

  13. sephiro499 | | #13

    Thank you for that link. I've already purchased roxul rock wood insulation for the wall cavities. I thought about cutting rigid foam for the wall but figured it was too expensive for the R value. So now it's just a question if I'm going to get the rigid foam after the roxul or not. This room faces the road so I thought the sound suppression was a good idea.

  14. jshima | | #14

    You could cut all the nails off with a metal cut-off wheel on a grinder and then put tape over the spot where the nails were. Just be aware of the potential to start a fire with the sparks from the grinder.

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