Wall Insulation and Caulking

[Fiat]

I am rehabbing a 1969 Skyline Buddy. It has aluminum siding, 2x4 studs, R5.6 fiberglass insulation and wood paneling. I want to increase the insulation and install drywall, but I have a couple of concerns. Where the siding meets the sill plate the corrugations allow air gaps. I am wondering if this is intentional to allow for dissipation of the moisture that may accumulate on the back side of the aluminum. My initial thought was to caulk all of these gaps but now I’m not sure that is a good idea. The wind blows throught these gaps like a hurricane.

If I install a vapor barrier behind the drywall and caulk the gaps, what is the potential for moisture to get trapped in the wall, run down the aluminum and rot the sill plate? My second option is to spray foam the wall cavity but the expense seems excessive. I would like to end up with a much more energy efficient home but I don’t want to introduce a new problem.

Also, if I go with the foam, any idea on how thick it should be?

Thanks

[David Oxhandler]

Your home was built prior to the HUD code. In 1969 manufactured homes were build to a patchwork of building codes and non codes, depending on where they were built. So... it is difficult to say with certainty why thing were done the way they were or waht would happen if you try to over-seal the home.

That said, I can tell you that I live in a mid 80's Fleetwood that I purchased in the early 90's. It had the original corrugated siding. We wrapped the home in sheets of foam and installed stucco over the foam. It has been about 18 years. We live in Florida - the humidity and mold capital of the western hemisphere, but have yet to have any problems. We did add perimeter foundation blocking every 4 feet under the home to support the additional weight.

If I was renovating your home I would max out the insulation through out the home. The most effective and economical way to do that would be with blown insulation. See the three videos in our archives from the U.S. Department of Energy titled Adding Insulation To Your Manufactured Home If you purchase the insulation from Lowe's or some other building suppliers, they will loan you the machine you need to blow-install the insulation.

Once the home is fully insulated I would install drywall directly over the paneling. That old paneling will not easily pop off the wall. Leaving the old paneling in place will save you quiet a bit of time and money, you would have spent removing the old panels, removing all of the nails or staples that have been in the studs for years along with the hassles and expenses of clean up, hauling and dump charges.

I have overlaid drywall in about 2 dozen manufactured homes with great results. I use 3/8 inch dry wall sheets. You save a few bucks, over the cost of the half inch, and wont add quiet as much weight to the walls. The insulation differential is insignificant, especially with the paneling still in place.


Read our free article Weatherize Your Home for Energy Savings for additional tips on controlling energy costs.

Come back and let us know how your projectg progresses.

[trmimo]

It depends on where you live. Florida is humid, but it is a hot climate. In a cold climate where the temperature gradient between inside and outside is greatest during the winter months, a vapor barrier under the drywall is essential. (In Florida the vapor barrier goes on the siding side of the wall.) In a Skyline home of this age, I would strongly urge perimeter blocking under the home to support the extra weight of the drywall because the floor joists run length-wise. You would be Ok caulking the siding if you install a vapor barrier. Without a vapor barrier you need that ventilation to keep the wall dry.

[David Oxhandler]

Thanks trimimo -


My renovation experience is Florida centered. It is great to have your experience and input here.