Old home’s insulation hard to check

Hey there, time traveller!
This article was published 22/12/2002 (8417 days ago), so information in it may no longer be current.

Question — We have a one-and-a-half storey home, built in 1950, that has old wooden frame windows. We moved into the house in 2001. The train and traffic noise is terrible and we suspect that there is no insulation in the outer walls. How can we check? We have plaster and lath walls.

Also, we have tried to hang a mirror and pictures on the inside walls with 3M hooks, and you guessed it, they fell off the walls. What would you suggest for hanging these items on the old plaster walls?

I hope you can solve at least the problem with the hangers. The walls look so bare!

Thank you kindly.

— Dorothy Cherepak, Winnipeg

Answer — Checking for wall insulation may be very difficult in an older home without doing a fair amount of destruction on the interior or exterior of the walls. The easiest way to attempt this is to remove a section of the plaster and lath on the inside or alternatively, the siding and sheathing from the outside. The inside removal method is often much easier.

The removal of the plaster and lath may be attempted in an inconspicuous area, like a closet or other easily repairable area. This is not always practical, but may be a good idea if the plaster is in poor condition and needs repairs. The wall covering could be completely or partially removed from a section of exterior wall and later covered with new drywall. Once the wall is opened substantially, it will be easy to see if insulation is present. The insulation may be minimal, settled or not present at all. Opening a large section between two joists may be the only way to fully determine the amount and type of insulation, but this may not be a desirable method.

One other alternative is to drill or cut smaller holes and try to look inside the wall cavity to determine insulation levels. In older homes of this era, large baseboards may be installed that are 4 to 5 inches high. These boards may be carefully removed in a small area and the plaster and lath may be cut away behind the baseboards, enough to see the contents of the wall cavity. It may not be a full indicator of the true insulation level if there are older wood shavings, or other loose fill insulation. The insulation may have settled and be filling the wall cavity at the bottom, but not higher up.

Drilling small holes in a closet and probing with a screwdriver or other long object may give some indication of insulation level or type, but may be difficult to evaluate. I have seen magnifying scopes with a light on the end of a thin flexible rod used for this purpose, similar to medical scopes, but these are not readily available to the average homeowner. A small inspection mirror and flashlight is a better alternative, but a larger hole will have to be opened to accommodate the mirror.

Hanging pictures and other heavier objects on plaster walls may be accomplished with a variety of wall plugs or anchors. There are many types designed for use on hollow or partially hollow walls that differ in their weight bearing capacity. The standard plastic wall anchor is very inexpensive and easily installed. A small hole, appropriately sized for the anchor may be drilled, then the anchor tapped in gently with a hammer until flush. A screw is inserted into the anchor, which causes a slight expansion, holding the anchor and screw in place. These anchors work well with most pictures and all but the heaviest wall hangings.

For the mirror, or other heavy object, a spring loaded wall anchor may be preferable. These are metal anchors that have integral bolts and are installed by drilling a larger hole that for the plastic unit. After the hole is drilled, the anchor can be pushed through in the folded position. Once the anchor is past the inner face of the plaster and lath, inside the wall cavity, it spring open, to provide a larger surface to prevent the anchor from pulling through the smaller hole. The age of the home in question indicates that it likely has drywall lath behind the plaster rather than wooden lath. Drywall lath are long, narrow sheets of drywall installed horizontally on the studs and covered with plaster. This material holds most wall anchors well, but wooden lath and plaster may be more difficult to secure anchors to. Due to the age and dryness of the old wood lath, it may become damaged and cause the plaster to crack or fall off when drilled. Caution should be applied when drilling into this style of wall covering.

When in doubt, the best way to anchor a hook or fastener into a plaster wall is to secure it to the stud behind the wall covering. The studs can be located using an inexpensive electronic stud finder, available at home centres and department stores. Once the studs are located and the centres approximated, a small hole can be drilled through the plaster and a wood screw driven directly into the stud.

Ari Marantz is owner/inspector of Trained Eye Home Inspection Ltd. and is the P. R. Rep. for the Canadian Association of Home Inspectors- Manitoba (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.

trainedeye@iname.com