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Ask Mr. Tight-Watt: Insulating an attic  Smart Choices Archive

Ask Mr. Tight-Watt: Insulating an attic

Foam insulation is a good choice for insulating the attic in an older home.

Ask Mr. Tight-Watt

Mr. Tight-Watt is always happy to answer our readers’ questions about home energy efficiency. Today’s questions relate to remodeling an older Victorian-style home and how to best insulate the attic.

Q: Is foam insulation the best choice for an attic that has complicated roof angles and crevices as in my Victorian home? If so, should the area where the eaves and floor joists meet behind existing 16-inch knee walls be insulated? –Annette, a Smart Choices reader

Mr. Tight-Watt called on Bill McAnally, energy-efficient home building expert, to answer Annette’s question.

A: Yes, foam insulation is an excellent choice for insulating the attic of an older home, even one with a complex structure of angles and crevices. The steps to take are:
1. Insulate the floor
2. Insulate the knee wall
3. Insulate the attic roof if you plan to use the space for storage or living

However, there is one caveat: If your home has old knob-and-tube wiring, you can’t insulate over it. You must box it in and keep it separated from the insulation or you’ll have a definite fire hazard. Foam insulation cannot come in contact with that old wiring.

Another critical factor in insulating – whatever type you choose – is to be sure to hire a knowledgeable and reputable installer. Be sure to find out:
1. How long the company has been in business. If it has a history, chances are good that the company has done a good job over the long haul.
2. The amount and type of training the installers have. Look for industry-standard training not just company-specific training. The better the training, the more the installer will know about codes, standards, and new installation methods.
3. Ask how the installer would handle a situation such as the knob-and-tube wiring. If the installer would foam over it, you know the installer is not well trained. Many installers are not aware of this problem, and if they don’t handle it correctly, your home and the lives of your family members are at risk.

Do you have a question for Mr. Tight-Watt? Ask your question and view answers he has provided to other questions here.

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