Real estate


Does vinyl siding need replacing?

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Is insulated siding worth the additional cost?

Q. Aside from the aesthetics, does vinyl siding ever need replacing? My siding is about 30 years old, according to my neighbor. Parts of it have cracked (I think a hailstorm was the culprit), sections are wavy, and some of it has buckled. I can see a gap between one piece of siding and the next.

If so, do you have any recommendations about insulation? Is insulated siding worth the additional cost? I have an old house (circa 1920) that probably has no insulation in the plaster-and-lath walls. I’ve heard blown-in insulation is great, but it can cause mold in this type of wall. I certainly don’t want mold, but it would be nice to have insulated walls.



A. Without seeing the siding, it’s tough to tell, but based on your description, it sure sounds like it needs to be replaced. I get a lot of questions about insulated vinyl siding, and I’ll be honest, I’m not a fan. Vinyl siding cracks, fades, melts, and can be leaky in windblown rain. The vinyl siding you mention has form-fitted expanded polystyrene (EPS) insulation built into the backside. The EPS provides an added R-value of R-2 to R-2.7 in some cases. This small improvement in thermal performance is less of a selling point than the stiffness the insulated siding offers. I think it makes more sense to consider an energy retrofit that would provide much greater R-value and airtightness than this product can offer.

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Cellulose insulation has been the favorite for retrofit projects for 50-plus years. It is no more likely to create moisture/mold problems than any other insulation. Blown-in cellulose insulation is not perfect, and when done as a retrofit, it will never give you 100 percent coverage, mostly because of human error and framing issues. It is effective as an insulator, however, and also helps deaden sound.

It’s a good idea to check the Material Safety Data Sheet to see exactly which chemicals are used in a particular brand of cellulose. Borate is typically added as a low-toxic alternative to other more chemically laden fire retardants, and it doubles as an insect preventive.

Once your house is insulated, it will be tighter, so make sure your exhaust systems (from cooking, showers, and humidifiers) vent to the outside. Tip: Use a bathroom fan with a timer to ensure you exhaust vapor during and after your shower.

Additionally, you will need to make sure your exterior siding, trim, and flashing are all intact and keep water from getting into your wall cavity. Your walls are currently an empty void, and if water does get in there, it dries out faster and probably doesn’t present mold issues. Adding insulation would change that.

Rob Robillard is a general contractor, carpenter, editor of, and principal of a carpentry and renovation business. Send your questions to or tweet them to @globeaddress or @robertrobillard.