A house becomes a part of its world, but if it is to be an effective house, providing shelter on livable terms, then it has to be as much as possible sealed off from the world, especially from that part of the world that is wet.
The earliest houses in America were built on heavy logs that rested directly on the earth.
No doubt these logs served well enough for the immediate purpose of giving the builder a stable base upon which to construct the frame, but such buildings did not age well.
These sills soon rotted away, and then all sorts of terminal problems arose. The floorboards bent and warped, the sides buckled, the bugs and the wet got in and the house was done for.
You might think that this lesson, once learned, wouldn`t have to be learned again. But what often happens is that a porch or a deck gets added to a building sometime in its lifetime, and then a later owner needs the porch for year-round living space and quickly converts it by putting up walls without doing anything to improve the simple foundation.
So in time the new room settles, and when it does, it springs leaks, just like the early American house set on logs. With the leaks come water and the outside world, and soon the uphappy owner begins looking for another place to live.
Old problem returns
This should be an old-fashioned problem gradually fading away along with the older houses themselves, but the advent of so-called pressure-treated lumber has tended to encourage people to once again take a chance with building on a foundation of wood alone.
Pressure treatment essentially involves the use of high pressure to permeate a piece of lumber with water-repellent chemicals. The wood is thus protected against both rot and dry rot for 30 to 40 years.
This technique has provided an effective means of dealing with some basic problems in house carpentry, but it was never intended to eliminate the need for proper stone or concrete foundations. So be suspicious and cautious when you see a part of the house resting directly on the earth. It may not be a deal-breaker, but you had better count on correcting the condition sooner or later.
A lasting foundation
Today`s houses are usually built on reinforced concrete, one of the strongest and most stable materials known. If they are properly installed on the right kind of footings, concrete cellar walls will last forever.
You rarely saw this type of construction before 1950, however. Much more common in homes homes built in the first half of the century are concrete-block foundations. They`re not as strong as reinforced concrete and not nearly so impervious to water.
Furthermore, the joints between the blocks are made of mortar, a lime-based material that is prone to leaking. Because of this, a concrete-block wall needs good drainage on the outside of the building in order to carry away the groundwater. Otherwise, leaking cellar walls can become an insuperable problem.
Another common building material used for foundations in older homes is simple fieldstone set in mortar. ”Field” means just that, rocks collected from nearby fields or perhaps from the building excavation itself while the house was being built.
These stones were never meant to be quarried or cut into uniform building blocks. A mason simply laid the irregular shapes as best he could, filling the joints with gobs of lime mortar. Often such foundations, called rubblestone by some, age badly. They tend to leak and weep through the mortar and cannot be waterproofed. Even good ones will always be a little damp on the inside.
Additionally, stone foundations are prone to shifting and settling since there is so little ”glue” to hold the pile of rocks together. When water damage or structural failure has occurred, most contractors will simply remove the rubblestone walls altogether and replace them with concrete.
Wet basements are bad news and all too common. Home inspectors estimate that at least 70 percent of the homes they see have had water problems of some degree of severity at one time or another.
At any home show, you`ll see on display many products dedicated to the wet-basement problem, too many of them intended for application to the inside of the offending wall. Everyone I know who has worked with such product has wound up unhappy with them.
The laws of physics do not allow you to hold back hydrostatic pressure amounting to hundreds of pounds per square inch with something you apply with a brush to the inside of the walls or floor.
To make the water in a cellar go away, you must correct the basic problem. You must divert the water away from the foundation.
One way to do that-and it can seem the easiest-is simply to install a sump pump. You go ahead and let the water in, but then you pump it out. The basement might flood, but then it will dry out again.
The problem is that pumps run on electricity, and the same conditions that can flood your basement can also knock out your power supply.
Don`t fight water-drain it away. And if you don`t feel you have the heart or the resources to do it right the first time, go on to the next house.
Reading the cracks
Unsettling though they may look, cracks in the foundation are commonplace and need not indicate a serious problem or indeed any problem at all.
Vertical and diagonal cracks are generally innocuous. They are a natural and inevitable result of setting and of the shrinkage of concrete. Cracks of this kind that are no more than a quarter of an inch wide are probably nothing to worry about.
Bigger cracks, of course, may indicate a bigger problem, especially if the house is less than 10 years old. If you see such cracks in the foundation of a newer house, be sure to call them to the attention of the professional home inspector and ask if you have cause for concern.
Horizontal cracks indicate a potentially more serious problem. Regard them as a red flag. They could indicate negative grading (the ground slopes toward the house instead of away from it) or poor drainage. Horizontal cracking of the basement walls is something an inspector ought to notice and explain. In bad cases, problems of this kind can require substantial rebuilding of the whole foundation.
Built on a slab
Slab foundations are level pads of concrete that are poured on top of the ground as the base for the floor of the house. This construction method is seen from time to time in the Northeast, where it was favored in the post-World War II building boom because it was fast and cheap. It is more common in the South and California, and it is seen everywhere in Florida, where the groundwater is only a few inches below the grass.
If there`s no frost to worry about, why not use a slab? If there`s no need for oil storage, no need for a place to put the heater, and no need for occasional plumbing and wiring changes, a slab is all right.
I really wonder about slab foundations for principal homes, though. For one thing, they can crack. For another, many people find them cold and hard to walk on, even though judicious use of carpeting and tile can moderate the problem somewhat. If they`re not well insulated, they add to your heating costs and make plumbing additions very difficult.
Crawl spaces
Crawl space construction involves building on a concrete foundation that goes into the ground only slightly below the frost line-a point in the ground below which the ground never freezes.
As you might guess, the depth of the frost line depends on many variables besides degree of northern latitude, such as groundwater, shade conditions, and composition of the subsoil (sand never freezes).
The walls of a proper crawl space extend below the local frost line and protrude at least eight inches above the ground line (or mean grade) at its highest point. This is to insure that the wood of the frame and the siding never comes into contact with the ground.
The floor of the crawl space should be covered with a layer of sand for comfort and dryness. The space should be well ventilated; otherwise, airborne moisture from the crawl space will invade the living space above.
A polyethlene sheet should be laid across the entire earthen floor of the basement, to absolutely prevent groundwater from seeping in and, incidentally, to make the space bearable to crawl around in.
