Preventing Dampness in the Ground Floor: Methods and Materials

The Foundation of Houses

Man’s Ease Underground

It is a curious fact that Man, who is said to be descended from apes, has been at ease underground since his Pennpit Period. Ages and ages ago he built primitive Venices, showing great skill in the making of interlocked foundations with logs and brushwood held together by piles. Tunnels, pits, bridges, and foundations under water or in places insecure: these are among the jobs that men do best and with the greatest joy.

The Confidence of Human Nature

The earth-loving confidence of human nature is now so instinctive that even the most difficult and capricious persons in their dealings with architects rarely make ado about the foundations of houses, as if that one point would certainly be right; and in this they are not at fault. Only jerry-builders ever scamp a foundation.

The Trouble with Clay Foundations

Perhaps the most troublesome of natural foundations for building upon is clay because the moisture in it may be dried up by hot weather, lessening its volume and causing a house to give. Into mud it is easy to drive piles; or a great solid floor of concrete, two or three feet thick, can be floated over the mud so as to enclose it entirely; for, of course, the mud must not be squeezed out at the sides by the weight of a building.

The Use of Cement

A solid and continuous body of cement mixed with stones or broken bricks forms an excellent foundation on shifty or unstable sites; it holds together uniformly, sinking as a whole if it sinks at all. A minor poet says with common sense: “When houses ‘settle’ badly, here and there, Mild tenants growl and easy landlords swear.”

Ideal Natural Foundations

Two kinds of natural foundations deserve to be called ideal.

The Ideal Natural Foundations

Gravel and Rock

The first is gravel, for wet penetrates through gravel, filters through it, and so, as a weight-bearer, it remains unaffected alike by water and dryness. But rock is better still, solid rock such as old castle-builders preferred for their seaward fortresses. Not rock and clay or rock and pliant earth, this being a foundation that architects find troublesome.

The Widening of Walls

In modern buildings, as a rule, walls are not of the same bulk all the way up; they widen out at the bottom, gripping the foundation with extra courses of brick or with a thickened base of flat stones. This precaution is now thought necessary on all sites except those of solid rock; and no doubt by-laws cannot insist upon too much care in these days of “slim” business. Yet in some old castles, which have stood erect against the wind for six centuries, the walls are of the same thickness straight away from the ground!

The Lessons of Ancient Walls

Is not that a fact worth noting as an example to ourselves? How can we hope to build for the future in the quicksands of cheapness? Those ancient walls have several good lessons to enforce upon builders and architects. One is a question of cement.

The Mistake of Believing Our Forefathers Were Careful Workmen

There are many who believe that our forefathers were careful workmen from the first; but that is a mistake. Mediaeval historians, and particularly Matthew Paris, relate how towers fell, how steeples toppled down and bridges gave way and manor-villages were carried off by tempests and flooding rivers. It was owing to these accidents that thoroughness – the god-virtue of social life – became popularized by fear.

The Rise of Thoroughness

Carpenters then worked for the days to come; and masons had before them as rare models the brickwork and stonework surviving from Roman times. But unfortunately, the nearer we approach the modern period – the period introduced by steam labor and the factory system – the weaker the rule of thoroughness becomes in all forms of popular building giving rise to complaints about bad cement and slipshod methods.

The Importance of Good Cement

The Binding of Ingredients

Cement is a mixture of lime and sand or gravel, and it takes time to bind the ingredients together. Only, if sand and gravel mixed with lime are to be the strongest cement, much care must be taken in their use.

The Absorption of Carbonic Acid Gas

Limestone contains a good quantity of carbonic acid gas (fixed air) which is expelled by fire; but no sooner is quick-lime exposed to the air than carbonic acid gas is absorbed, and more readily after quick-lime has been mixed with water. Now, it is that absorption that causes lime to set hard; and that is why quick-lime gets slow and worthless when it is not kept away from atmospheric action. It ought never to be mixed with water until it is required for immediate work. “From a neglect of this consideration,” wrote Atkinson, “mortar is generally bad.” Will our own builders note this?

The Restoration of Outside Walls

Recently I watched some men at work restoring the outside walls of a suburban house. They dusted out the mortar as if it were chalk powder; next, they tinted the old brickwork, making it a pale, thin, yellowy red; and then refilled the brick joints, tuck-pointing them with white and using a board to guide their hands so that the lines of white rubbish were ruled hard and straight.

The Genius of Hocus-Pocus

And we come to that after a thousand years of reputable methods! Bad mortar applied not only in narrow strips and with a soulless uniformity but over an old wall colored to look like new bricks of a bad tint! Yet the “builders and decorators” advertised their names on a large panel. If their own joints were tuck-pointed they would be more entertaining than their botched workmanship.

In a London suburb, not very long ago, the genius of hocus-pocus ran wild in house-building; and report said that in many homes there were only thin tiles between the cellars and the bare ground which happened to be a wet slope; damp rose up into the rooms, of course, the very thing which all architects take the greatest care to guard against.

Preventing Dampness in the Ground Floor

The Use of Damp-Proof Materials

The lowest floors of houses should be covered with some damp-proof material such as slate or Caithness pavement or asphalt to prevent the damp rising in them from the ground. If the lowest floor is under the level of the ground outside, means must be taken to stop the damp from getting into the wall above the level of this damping course, as it is called, from the moist earth.

Various Methods to Stop Dampness

Sometimes the wall outside is covered with pitch; or loose stones are piled against it up to the ground level, with a drain at the bottom just under the floor-level, to carry off the surface water; or better, an area about six inches wide, with a drain at the bottom, is built all around the house, covered on top to allow the earth to come up to the walls; or the house may have a wide open area all around, standing in a sort of dry ditch, which is the system usual in townhouses. A house in the country looks better rising from the ground and can be kept perfectly dry even when its floor is under the surface level by making the floor and walls impervious to damp or by having cellars with openings to the air to keep them ventilated and therefore dry or by an open space a foot or two high under the floors through which air passes.

The Importance of Being Certain

Again, leave nothing to doubt; be quite certain that your ground floor will keep perfectly dry. So make it a rule to cover all foundations with asphalt or cement as a damp-proof bed under the lowest floors. When this work is well done, leaving neither crack nor crevice anywhere, black beetles and other vermin cannot enter a house.

The Use of Slate

Some architects are so particular in these matters that after building a snug bed of concrete for a house to rest upon they pave the lowest rooms with slate, a thorough method no doubt; but servants object so I am told saying that slates are unpleasant to walk upon and hurt their feet.

Leave a Comment