Weatherization for Your Old House
A part of what we mean by our word “home” is a shelter that to some extent protects us from the elements and provides the kind of environment we need or desire on the inside. Keeping the outdoors out-of-doors without sacrificing the beauty of your old house presents special challenges. This section has to do with the insulation and the exterior of your house, the only things between you and the weather.
It is very rare that you will find an old house that does not need a great deal of attention to insulation and other energy conservation measures. A first step may be merely to keep the wind from roaring through the various cracks and holes so much that the curtains blow in the breeze. All old houses need to be better insulated than they were designed to be, but there’s no truth to the myth that this lack of insulation means that one can’t live comfortably and economically in an old house and that they are all doomed to be torn down. Granting that there are many heat-loss features in an old house that you can do little about, you must be very serious about the kinds of things you can do something about.
The main reason buildings from the last century were not insulated is that few good insulating materials were available. But over time, other problems may have exacerbated this lack of thermal integrity, even in the best of old houses:
• Building may have been constructed carelessly.
• Old-style windows run well but seal poorly.
• Warping has caused cracks in the exterior.
• Interior plaster, which was the major sealing material, has cracked.
• Rot, termites, or squirrels have made holes.
• A careless remodeling effort was undertaken.
How Our Ancestors Coped with Cold Weather
For homemade insulation, the old-timers sometimes used crunched up newspapers, dirt, corn cobs, or aged manure, all of which had decided disadvantages. Layers of wood and plaster were better, but of minimal insulating value. Sawdust, although effective, encouraged rodents, snakes, and rot. The best ways of dealing with the cold were to add more wood or coal to the fire, put on more clothes, and simply huddle around the heat source and pray for an early spring. and in some cases, insulation just wasn’t considered worth much trouble, because most people had cheap heat.
Special Cooling Features in Old Houses
Our ancestors’ dwellings dealt somewhat more effectively with hot summers. The following typical features, in fact, are some of the real assets of an older home:
• Double-hung windows that open top and bottom
• Shutters that let the air in but keep the sun out
• High ceilings
• Central halls with doors front and back
• Houses built on piers (in the South)
• Houses built in groves of trees (especially in the South)
• Detached kitchens (especially in the South)
Modern Weatherization Materials
Some modern methods have proved to have problems of their own. Asbestos, which was poured or blown into the walls, and a foam containing formaldehyde have both been found to be carcinogenic. There are some relatively inexpensive and simple insulation techniques, however, that work quite well. Small areas or cracks may be insulated or plugged with an aerosol urethane foam or with latex or, better still, silicone caulking material. Temporary, inexpensive sealing can be accomplished with polyethylene sheeting. Serious consideration should be given to those projects and methods that offer the most gain.
Degrees of Gain in Weatherization:
Methods of Insulating Ceilings:
Methods of Insulating Walls:
An excellent option for a major renovation effort is to tear out all the plaster and lath on outside walls, apply rigid foam sheathing or fiberglass bats between studs, and cover insulation with wallboard—two thicknesses, if necessary, to build the wall out to its original thickness so that the old woodwork will show properly. If you decide on this course, you can also take the opportunity, while the walls are open, to upgrade wiring and to remove window casings and make any necessary repairs to decaying sash cords.
The much easier way is to add rigid foam insulation right over the existing plaster, then a layer of wallboard over that for a fresh wall surface. Window casings have to be made even deeper. New baseboards must be used.
Measurement of Insulation
The government-set standard of measurement for all insulation is the “R-value,” invariably marked right on the insulation.
Insulation Efficiency Ratings
Adequately Insulated Home
Walls: 3 1/2-inch, fiberglass between the studs, R-16
Ceilings: 5 1/2-inch, fiberglass over the ceiling, R-16
Walls: 3 1/2-inch fiberglass between the studs , R-11
Ceilings: 11-inch fiberglass over the ceiling, R-32
Highly Energy-Efficient Home
Walls 3 1/2-inch fiberglass between studs
+ 1-inch rigid foam sheathing, R-11 + R-7.2 = R-18.2
5 1/2-inch fiberglass between studs, R-16
Ceilings: 11-inch fiberglass or more over ceiling, R-32+
Tips on Insulation
• There are diminishing returns on thicknesses in insulation: The difference in comfort and savings between R-16 and R-32 is very small compared to the difference between 0 and R-16.
• No fair squashing 5 1/2-inch insulation into a 3 1/2-inch area. Although it will have a higher insulating value than 3 1/2-inch insulation in a 3 1/2-inch cavity, its R-value will be less than it would be in a 5 1/2-inch cavity because part of the insulating quality comes from air trapped in the loose fibers.
• Place the paper or aluminum side of insulation, which serves as a vapor barrier to keep moisture away from the insulation material, toward the warm side of the house. In other words:
• Toward the room for wall insulation
• Down toward the ceiling below for attic insulation
• Up toward the floor above for basement or crawl space insulation
• You may add a layer of insulation on top of existing insulation that contains a vapor barrier (typically done in the attic); the added insulation shouldn't have a vapor barrier.
How to Use a Cellulose-Insulation-Blowing Machine
Cellulose insulation must be blown in, rather than poured, because the air that's incorporated during the process fluffs the material up, resulting in greater insulating value. This method works only in buildings that have air spaces between interior walls and exterior siding. An early form of house construction known as the plank house used no such air space; therefore, in these houses rigid foam sheets should be used. The procedure for blown-in insulation is as follows:
• Machines are available at tool rental stores and sometimes at places that sell the insulation. A 50- or 70-foot hose allows you to reach as high as your attic.
• Drill 1- to 1 1/4-inch holes (depending on equipment) between each wall stud both at the top of the wall and just above the foundation, and above and below all windows.
• Blow insulation into upper holes; lower holes both allow air to escape during the insulating process so that no air pockets form, as well as allow you to see whether or not the insulation is filling right to the bottom rather than being blocked by some structural obstruction.
• Examine bottom holes in corners to be certain that insulation fills corners well; sometimes bracing on the interior of the wall blocks the flow at these points.
• Drive plugs cut from wooden dowels and covered with water proof glue into the holes, and sand surface with disk sander.
Insulation, Moisture, and Proper Ventilation
Peeling paint usually signifies a moisture problem in the present design of the house. Moisture comes from a variety of sources present in any house, not the least of which is condensation formed when the heated air from inside the house meets cold exterior wall surfaces. The places where this meeting occurs, of course, aren't only exterior walls, but also ceilings where the area above is unheated and floors where the area below is unheated. Moisture also builds up due to:
• Humans (and plants) breathing
• Unvented clothes dryers
• Damp or wet basements or crawl spaces
• Frequent showers
• Roof and gutter leaks
Moisture may build up in one area or in all areas of the house. if it forces its way out through the walls, the exterior paint will mildew and peel. Usually, most is trapped in the attic, where it can run down walls or rot out roof sheathing. Here are some solutions to the problem, in order of their likelihood and importance:
• Cut unnecessary moisture by venting dryer to the outside and placing exhaust fans in bathrooms and kitchen.
• Dry out the basement by improving drainage around the foundation.
• Provide attic ventilation by opening windows, installing turbines on roof, and placing vents in peaks and soffits.
• In bathrooms and kitchens, where a great deal of moisture is generated, apply oil paint or vinyl wallpaper, which will act as an additional vapor barrier.
Plain Talk About Storm Windows and Doors
Storm windows and doors are optional in warm climates, but they become increasingly necessary the farther north and the colder the winter. A good option for old houses, in particular, is to install new double-glazed, small-pane windows. Probably less expensive are aluminum storm windows, but they have disadvantages as well as benefits.