Q: I live in the upper unit of a Victorian duplex. It’s a rental unit and I assist the landlord in upkeep. From time to time, I suggest maintenance items to him.

I would like to know how difficult and effective it is to put roof insulation in a unit like this. During the winter, it is difficult to keep heat in. During the summer, the heat builds up in the afternoon and remains into the evening. There is no insulation in the attic.

It was my thought to have rolled fiberglass installed. I know the landlord won’t go for the expense of blown-in insulation. Can you tell me if I need to do anything other than just lay down the insulation between the studs? And will it assist me in keeping the summer heat out of my unit?

A: This one’s a no-brainer: Don’t hesitate, insulate.

But insulation is only part of the solution. The landlord should also think seriously about ventilating the attic. To do a Cadillac job, weather-stripping the exterior doors and windows and insulating the exterior walls also should be included in the project.

The doors are easy and inexpensive to do. On the other hand, weather-stripping the windows and insulating the walls is more complicated and probably requires more expense than the owner wants to get into.

If the house doesn’t have attic ventilation, consider suggesting that the owner install some. Gable vents, ridge vents and soffit vents allow the warm air to move out of the attic in the summer and help prevent condensation in the winter.

High school taught us that hot air rises. This is called convection. So a good bit of the heat you’re feeling on the second floor is generated from below. That’s good in the winter but can be uncomfortable in the summer.

Heat is also conducted from one space to another by radiation. The hot air in the uninsulated attic warms the plaster ceiling of the second floor and creates an ovenlike environment in your apartment. By the same token, when you have the heat on in winter, it warms the plaster ceiling and radiates out to the cold attic air. This increases the workload on your heater and adds to your energy bill.

To inhibit this radiation, installation of a material with thermal resistance is a must. Fiberglass insulation is one such material. A 12-inch layer of R-38 rolled or batt fiberglass insulation will significantly reduce the amount of heat conducted between the attic and the living space. The result will be a cooler summer and a warmer winter.

Installation is an easy do-it-yourself job, requiring only a couple of simple tools and some protective clothing. It’s also inexpensive. Make sure to buy either craft-faced or foil-faced insulation to provide a vapor barrier between the conditioned living space and the unconditioned attic. The vapor barrier blocks any condensation that may develop in the insulation because of the difference in temperature. The vapor barrier should be placed face down, toward the conditioned space.

Fiberglass is sold in rolls or batts, and is available at home centers and lumberyards. We’ve worked with both and prefer batts for attic retrofits. Insulation is available in 15 3/4-inch and 23 3/4-inch widths to fit snuggly between 16- and 24-inch ceiling joists.

Protective clothing is a must when installing insulation. Long pants, a long-sleeved shirt, a neck scarf, a hat, gloves, eye protection and a dust mask will prevent most of the stray fibers from the insulation from getting on your skin or in your lungs. Without this protection you risk damaging the mucous membranes of the eyes and nose, irritating the lungs and getting an insufferable itch from skin irritation.

To install the insulation in the attic, simply remove the insulation from its packaging and lay it between the joists with the vapor barrier facing down. If the ceiling joists are more or less than 16 or 24 inches, you may have to cut pieces so that the insulation covers the entire area between the joists. If the house has soffit vents (which we doubt), make sure not to cover them.

Use a utility knife with a sharp blade to make any cuts that might be necessary. That’s all there is to it.

Another good option is to rent a hopper and blow in loose insulation. The material and machine are often available at home centers. To learn more about insulation, including a tool for calculating the amount needed for this job, go to www.jmhomeinsulation.com/basics/why_insulate.php.

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