Q: Our 1920s bungalow has a small front closet that is punched out from the wall of the house so that the box of the closet extends past the exterior walls. This leaves the three walls and floor in direct contact with the outside damp air. We use this as a coat closet, but because of the outside dampness and lack of insulation in the lath-and-plaster walls, clothes get musty.
The closet is very small, so simply adding a layer of insulation on top of the walls would make the closet prohibitively small. I was thinking of removing the lath and plaster, adding insulation between the studs, then putting up drywall with a vapor barrier. If I get particularly inspired, I may add cedar paneling. What would you suggest?
A: Your instincts are right on. Insulating the walls will go a long way toward warming up your closet and eliminating the musty smell. But since you’ve started, and you’re going to make a mess anyway, why not go for the whole enchilada and insulate the floors and the ceilings, too? It’s not that much more work and the job will be done right.
The first step is to strip all the lath and plaster off the interior walls and ceiling. A claw hammer and a flat bar are the only tools you’ll need for this part of the job.
We suggest you leave the baseboards and door casing in place. Ripping off the case and base adds unnecessary work. Leaving it maintains the original character of this part of the house.
To demo lath-and-plaster walls and ceilings, it’s easiest to crack the plaster with the hammer and scrape it off the lath with a flat bar. Wear a mask and go easy when near interior walls. You don’t want to put cracks in your entryway, meaning more patching and painting.
Once all of the plaster is off the walls and ceiling, shovel it into a garbage can and send it off to the landfill. Next, use the flat bar to carefully remove the lath, exposing the stud bays. If a piece of lath is buried halfway behind the baseboard, leave it alone. Score the lath that extends behind the door casing with a utility knife and break it off. This is the perfect time to add or update any electrical wiring that may be in the closet.
With the ceiling joists and the stud bays open, install the insulation. Use a paper- or foil-faced insulation and place the vapor barrier toward the inside of the closet. Conventional practice is to apply vapor barriers toward the warmer air of conditioned spaces. We assume the wall studs are about 3 1/2 inches thick, so R-11 batts are what’s needed. For the ceiling joists you probably can go a little heavier, depending on the space available. R-19 batt insulation with a thickness of 6 inches should do the job. At any rate, the batts should fill the stud and joist bays and should not be compressed.
We’ve found that interior plaster is generally 3/8 inch thick and applied over 3/8-inch wooden lath for a total thickness of 3/4 inches. Although using 1/2-inch drywall for the ceiling is perfectly acceptable, it won’t work on the walls. To reproduce the 3/4-inch wall thickness, nail pieces of lath vertically to the studs and apply 3/8-inch drywall to finish the walls.
Tape, texture and paint the walls, and you’re done, unless you decide to face the closet with cedar. In that case, tape and one coat of mud will do as a base for the cedar paneling.
Because the bottom of the closet is cantilevered out the side of the house, we suggest you also consider insulating between the floor joists.
From underneath the house, install batt insulation with the vapor barrier toward the conditioned air of the closet. Nail or screw a piece of plywood to the floor joists to cover the insulation. Before you install the plywood, drill two 1-inch holes in the plywood at each joist bay to allow for ventilation and cover the holes on the inside of the plywood with screen mesh. That will keep critters from taking up residence in the insulation.
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