Our home is about 30 years old and has Masonite siding on it that is in bad condition. There are several rotted areas in the siding in different areas of the house. There are nails pulling through but I think the framing is solid. We have talked with a contractor about having vinyl siding installed. He wants to install the new vinyl over the existing Masonite and says that the new vinyl siding will work fine going on this way. Is it alright to install vinyl over the old siding even if it is in poor condition?
The old siding you are referring to is probably Louisiana Pacific siding commonly called LP siding and was sold under several different trade names. It had some inherent problems that include water penetration causing the siding to turn to mush and actually fall out in areas if it was not maintained extremely well. These types of composite sidings were manufactured from different combinations of wood fibers and chips bound together with glues and resins. The failure of these siding can be blamed on several factors but a huge class action law suit was filed and literally millions of dollars was paid out to home owners. To my knowledge the class action law suits are all closed, but I have heard that some home owners are trying to reopen some of the litigation.
Now to your question, it is generally acceptable to put vinyl over the siding, I have inspected several homes that have had vinyl installed over old wood siding and the masonite type sidings and have not found a problem just because of the installation. Good workmanship is very important; there are a few guidelines you need to adhere to. The flashing must be installed around windows and doors correctly. Any structural damage caused by water penetration will need to be repaired prior to covering the siding. If the siding is in too poor of condition to hold the siding nails this will need to be addressed before installing siding over it. Neither the old siding nor the new siding can be in contact with soil or covered with mulch, this allows termites and other insects to invade the home. If your home has a chimney with siding on it, it is critical that it is properly flashed to keep any water from entering. If the work is not done correctly and water is allowed to get behind the vinyl and wet the old siding it will deteriorate and rot very fast and can create mold conditions, so be sure the installer flashes the intersections properly to keep out any water.
Many of the installation techniques involves nailing a thin layer of foam board insulation over the old siding then put the vinyl on top of the foam. This accomplishes several goals, it gives the installer a smooth backing for the vinyl to lay on which makes a much better looking home when everything is even. It cuts down on air infiltration and a small factor of insulation. Most of the foam manufacturers use foam that has some small perforations to allow for some vapor movement, it is important not to seal the old siding too tightly.
Good luck, just be sure to keep out any moisture and your face lift on your home will look and perform for many years
This article was written by Donnie Bentley, primary owner and operator for Bentley & Associates Home Inspection Services. He is a home inspector working in East TN inspecting homes in Knoxville, Lenoir City, Maryville, Greeneville, and Morristown TN. We have a group of 5 home inspectors that service the area with professional home inspections.