Manufactured home belly insulation
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| Posted in Energy Efficiency and Durability on
Spray foam insulation, open-cell. 1983 double-wide manufactured home.
Job was to remove belly paper and old insulation and spray foam new insulation in cavities, with special attention to seal / insulate all ductwork.
Thermal imaging prior to job showed significant heat loss. After the job, no difference was noted.
Foam was chosen to stop air infiltration and insulate. My instructions were to fill the cavity, no wood exposed (2 x 6 floor joists), The crew was verbal about 3.5 in in the cavity. They were used to doing walls.
What would be your suggestion to decrease the heat loss, now? Thank you for your input.
Dianna
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Replies
Do the interior walls have drywall or paneling on them?
What access to the floor joists?
More importantly, what's in the ceiling- roof?
Dianna,
If what you're saying is that the foam contractor was supposed to fill the 2x6 floor joist cavities and cover all exposed framing, and they instead installed only 3.5" of foam between the joists, then you need to have them come back and finish the job according to specifications or refuse to pay them and have someone else complete the job.
The roof is certified cool, standing seam metal roof over silver/foam/silver insulation over previous shingled roof.
I physically cannot go under the house to visually check all the cavities. It appears there are high and low depths to the spray foam. I can only use my thermal camera to shoot the skirting, which shows just as much heat loss as before the project was done. The contractor was paid when the job was completed. I had first asked for closed cell but their sales manager said open cell would better for this application. I wonder.
Interior paneled walls.Floor joists access only from below.
Dianna - a thermal camera does not really measure air infiltration. If you had a poorly insulated floor to begin with and your entire floor showed blue on the camera (assuming it is cold wherever you are) installing 3.5" of spray foam is not going to improve things much. It may help with the air infiltration but with 3.5: of open cell foam - you only have about an R-10.5 - R12 which is not a lot in a cold climate especially with an open area below. You are still losing plenty of heat through the floor which is why it still appears blue in the thermal camera. Need to add more insulation.
We are losing air in the summer (blue) and heat in the winter (red). I hope more sprayed foam will stick to foam. Will be having an intense conversation with contractor soon. Thank you, all.
Just re-read your post. I was assuming you were observing your floor with your camera which is why I thought you were seeing blue. Sounds like you are looking from the outdoors at the skirting/underpinning/foundation and seeing the hot air. A lot of that hot air may be coming from your ducts - if that is the case, adding insulation may not result in a visual "improvement" through the eyes of the camera. Have your ductwork measured for leaks and see if the ducts are insulated. A combination of duct sealing and insulating the ducts may give you better results. To get true results from the insulation, I would compare before and after the temperature of the floor from the inside though. Good luck arguing with your foam contractor.
Dianna, where are you located? how cold is it? And is there a lot of moisture in the ground under your building?
We are south of Dallas Tx. Mixed Humid climate. The home is sitting east-west.We have rain gutters draining at least 5 ft away from the house, but we have relatively high water table and black gumbo soil. I am sure there is moisture migration, but only wet around the edges sometimes.
As suspected and then confirmed, the ductwork is suspended from the 2x6 floor joists. Contract specifically addressed to heavily cover the ductwork completely on all four sides This, the crew understood. I truly believe the company and the crew had never worked on a mfg home.I had invited the sales mgr to come and see before he took the job but he didn't and has not called to see how we liked it. I have never heard or read of anyone doing this type of job to a mfg home, but I was sure it was a good idea.A lot of contractors assume there is not any difference between a mfg home and a stick built home crawlspace. Now What ;-(
Dianna,
So the guys had to remove a section of the skirt,(what type of skirt?) and then craw into the space, lay presumably on their back, or side and pump the foam between the floor joists to fully fill the cavities. The only thnig that you can do at this point is to find someone that can craw into the space to inspect and document the quality of the installation. If you are not satisfied with the job, get the contractor back to make it right. How high is the craw space?
There is a link in the GBA PRO section called Crawspace Insulation that may give you some insight.
Crawl space is SW corner 18-20 inches. NE corner is 4 Ft. S & W side metal. E & N is vinyl underpinning.
I cannot access GBA PRO as I am not a pro. Thought I was, some formal education, an educated consumer with a Flir thermal camera. Got the camera prior to failing the RESNET exxam and re-evaluating my goals.
Having retrofitted many mobile homes, I would like to suggest that spray foam underfloor is an impractical solution.
1. It is difficult to move under a mobile home, so it is difficult to keep the foam gun moving for good production.
2. There are many obstructions under these homes, which makes it difficult to get a proper seal.
3. Plumbing could be isolated from the tempered space above. This puts these runs at risk for freezing, even in Dallas.
4. Depending on the furnace install, an unaware foam sprayer may cut off the combustion air supply from the belly, which may lead to backdrafting concerns.
For most mobile homes, when treating the belly, I like to:
1. Stretch 6 mil poly in as continuous a layer as is possible under the entire home, inside the skirt (unless on a slab).
2. Foam all penetrations in the floor with single part, closed cell.
3. Replace any damaged sections of belly with Typar and strapping.
4. Duct sealing with mastic, or two part foam. Seal base of furnace to trunk as well.
5. Blow the perimeter of the belly with chopped fiberglass (lighter, not hygroscopic) to a fairly tight pack.
6. Blow the main portion of the belly with fiberglass to a lighter density than that of the perimeter (remember those pipes).
7. Foam all belly penetrations.
8. Make 2 insulated and weatherstripped hatches for the skirt.
9. Spray foam the entire skirt perimeter with two part closed cell, from the belly to the poly over the ground/ or slab.
I realize this is a “belt and suspenders” approach to improving mobile homes, but it does work very well. Obviously, the ceiling, walls and windows almost always need some help too.
John,
Thanks for sharing your experience.