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posted: 7/18/2014 12:01 AM

How to best insulate walls of an old house

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Q. We have an 80-year-old home with lathe and plaster on the inside walls. The house is hard to heat in the winter and becomes very hot in the summer, so we want to add insulation. One contractor recommended injecting insulation into all of the outside walls, but another contractor says this is not as good as removing the plaster and installing fiberglass and drywall. The second method is much more expensive, so we're not sure what to do. What do you recommend?

A. Injected insulation is a popular method for upgrading the energy efficiency of older homes. This type of insulation comes in two forms: expanding plastic foam or particles of cellulose, usually consisting of pulverized newspaper. Injection is definitely the less costly method, but there is one drawback. The wall cavities are not always completely filled when insulation is injected. Spaces between the studs can be missed because of wood blocks, bracing, and electrical wiring. Some insulation companies try to overcome this problem by injecting insulation through holes along the top and bottom of each wall, but even this approach does not guarantee that all of the wall spaces will be totally filled. However, some contractors follow up with infrared cameras to detect places that were missed when the insulation was installed.

The alternative method is much more costly but leaves no doubt that the walls have been thoroughly insulated. By removing the interior lathe and plaster, all wall spaces are fully exposed. This enables total insulation of the wall cavities and also provides an opportunity to inspect for defects inside the old exterior walls. Wiring can be upgraded, additional outlets can be installed, and evidence of termite damage and dry rot can be addressed. Once the work is completed, the old walls are refinished with new drywall.

If you can afford it, opening the walls and replacing the lathe and plaster will more effectively accomplish your objective to upgrade the quality of your home.

Q. My cat and I have become ill from the arsenic that is in our well water. We bought the property five years ago, and our home inspector did not recommend having the water tested for contaminants. Worse still, he said it was not necessary to test water from a community system because testing was required by the state. Do you think we have a legal case against our home inspector?

A. Water quality is not within the scope of a home inspection, and it is not the responsibility of a home inspector to advise clients to have their water tested. On the other hand, it was a violation of common sense for your home inspector to discourage you from having the water tested and to advise you regarding the likelihood of contaminated water. What he should have said was something like, "I have no knowledge of water quality issues, but if you have concerns of that kind, I recommend you have the water tested." That answer would have acknowledged the fact that water quality is not a home inspection issue while protecting you from the current consequences of not testing the water.

By the way, is your cat really the co-owner of the property?

• To write to Barry Stone, visit him on the web at, or write AMG, 1776 Jami Lee Court, Suite 218, San Luis Obispo, CA 94301.

© 2014, Action Coast Publishing

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