the walls of the average house are double walls. In other words there is an exterior wall which is supposed to protect the house from all outside influences such as rain, snow, wind and weather; and an interior wall which is supposed to add decorative effect to the interior of the house and also aid in conserving heat and repelling the cold. If your house has solid brick or stone walls, the exterior wall also bears the weight of the roof; but the average house relies on the frame, which is in between the exterior and interior walls, for strength and for carrying the roof.
When the exterior or outside walls of a house are kept in good repair they will protect the house as long as it stands. You hear a lot about houses being built of unseasoned lumber, and you hear predictions that they will fall apart in a few years, but even green lumber seasons in time, and when it is taken care of properly it will eventually shape up and become sound enough. Of course, if you neglect the exterior walls there will be rapid disintegration, and once they are thoroughly bad the interior walls will be unprotected and the house will be done for.
The correct manner in which to treat exterior walls is to keep them solid. If the walls are wood they should be kept well painted. When a board or plank springs out of place, even a fraction of an inch, it should be renailed back in place. All joints where boards meet, should be kept caulked tight with caulking compound or with white lead, before painting. If the walls are shingled, the shingles should be painted, oiled or treated, according to their composition. If a shingle warps, it must be nailed flat again. If the walls are of flat wood siding, called flush siding, they should be watched for splits or cracks, and as soon as they appear they should be carefully filled.
Most house walls are composed of an exterior and an interior wall with open spaces between them. This is where insulation goes.
Exterior walls bear the brunt of all weather. They are attacked by rain, snow, cold, heat and dampness. They must be kept in shape.
According to statistics, more than ninety percent of the homes throughout this country have wood exterior walls, and as a result, a great deal of research has been done by the U. S. Government and the producers of lumber, with a view to educating the public on the proper treatment of the material. There is no doubt about the fact that wood is the ideal building material, because it offers great strength combined with light weight and enduring qualities. Most of the research has proved that wood will last as long as other building materials which are exposed to the weather providing that it is treated properly. Exactly what we want to stress is probably best explained in this manner - If you take a piece of good wood of any kind whatever, and hang it up outdoors where it is exposed, it will be wet by rains and snows, but in between the storms it will have a chance to dry out. Ten years from now it will probably be as good as the day you hung it up; simply because it had a chance to dry. Take the same piece of wood and paint it, and put it in a damp spot where sun and wind never reach it, and in three years it will be quite rotted. Now - when you nail boards to the frame of a house to make the walls, the underside of those boards never sees the sun and never has a chance to dry. If the weather-side of the boards is painted, and the cracks and joints all filled so that moisture cannot get at the back of the boards, all will be well with the wall. If there are openings through which water can penetrate and soak the back of the boards all will not be well, and rot will set up. You must protect the exposed surface of good walls if you want them to last.
Many times you will see an old house with rotted boards covering the walls. Every time, if you look carefully, you will see that the rotting had started and is the worst at the ends of the boards where there was a crack for the moisture to get in and go to work. Other times you will see where nail-heads are rusted and the wood immediately around them has become spongy. The same thing applies here, moisture got in through the hole made by the nail, and started the decay. This points up the absolute necessity of keeping wood walls tight.
Invariably, decay will start where boards meet or where there is a joint in the exterior covering of the house. In spite of the best paint, wood walls will deteriorate unless the joints are full.
In many of our New England towns and in some southern cities, you will find wood houses that have stood up for centuries and which are still as solid as a rock. In every instance you will find that they have been given attention at regular intervals. They have been caulked and puttied and painted, and every time a piece of wood showed signs of decay, it was cut out and replaced with a sound board. In some of the countries of the east, there are houses made of wood which have stood for thousands of years instead of centuries, simply because they have been rubbed with oil continuously until the wood has taken on the properties of stone, and because the joining in the first place was so perfect that it can hardly be seen. The climate naturally has a lot to do with the length of time wood will last, but you know all about the weather you should normally expect and can be guided accordingly.