Underbelly

[Etana]

I am currently redoing the underbelly of a doublewide. I'm in the tearout phase now, and I have a curiosity question:

What would happen if I just left the underbelly open and didn't reinstall bellywrap? (Besides the obvious energy loss - this home does have central heat & air with ductwork running under the floor. It will be skirted, and a vapor barrier will be installed over the dirt floor.)

[JD]

I can think of a couple of major concerns off the top of my head. First would be bugs and other pests. While underbelly is not total protection, without the underbelly pests would find it much easier to recognize and use the new direct routes to your home. Furry pests in particular would sense the the cool or warm air escaping through the floor much easier and would create tiny "game trails" towards this comfort.

Second would also be associated to the heat and cooling loss. Air flows like water, taking the path of least resistance. Without an insulation and vapor resistant barrier, this flow would be magnified. As air moves like streams towards these openings, it will be carrying the humidity in the inside or outside air with it. This will concentrate the moisture into smaller areas creating all of the associated moisture problems.

I would never say that a mobile home does not need floor insulation and a vapor barrier or even say that it might not be such a bad thing. It is an important component to the entire home. Installing the vapor barrier is a lot of dirty work, but as cost per square foot in materials go, it is pretty cheap. Probably around 50 cents a foot. I hope you decide to install it.

JMO
JD

[CraigE]

I had a bathtub leak several years ago and had to cut out a 10X6 section of underbelly and insulation. Repaired leak and left underbelly open for about a month to air out. This was during the winter and there was a tremendous difference on how cold the floor was after cutting that section out. I am not really in a cold region. I do have masonite skirting but not insulated.
Craig