Part 5
In enumerating the places where fire-stops should be built, the most important ones are the blocking of the space between the plaster and furred brick wall at each floor level and the closing of the air-space in exterior stud walls at each floor (Figs. 1, 2, 3). The filling in of the hollow space at the base of every interior stud partition is likewise necessary (Fig. 4). A wooden cornice banks up the heat from any neighboring fire, and it is advisable to fire-stop the space around the ends of the rafters where they join with the ceiling-joists over the plate (Fig. 5). Where the second floor of the house projects out over the porch, it should be filled with fire-stopping material, not only for safety against fire but also to keep out the cold in the winter (Fig. 6). The pockets into which sliding-doors roll should be lined with gypsum board, not only as a fire retardant but also to prevent cold drafts from coming out of these pockets (Fig. 7). The plaster should be carried down behind all wooden wainscots as a fire-stop (Fig. 8). The space between the stair carriage should also be closed at each story (Fig. 9), and all chases and ducts should be filled at each floor level. Wherever exposed pipes pass through horizontal parts of the house they should be run through sleeves. Wherever hot-air flues go from one floor to the next they should be packed around with incombustible material (Fig. 10), and all registers in floors should be insulated in the same way. The space between floor-joists and chimneys must also be filled in with fire-stopping materials.
_Materials to be Used_
It is not necessary to use expensive materials for fire-stops, but they should be carefully placed. Materials like mineral wool are the best, since they expand as the wood shrinks and fill up the space. Concrete which is held in position by strips of metal lath is also excellent. The concrete or mortar used can be made from refuse material, and need not have any great strength. Old bricks are satisfactory if they are slushed into position with mortar which fills all the crevices. Gypsum blocks are good except for damp location, where they absorb moisture easily and, holding it, induce dry rot in the surrounding timbers. Asbestos board, gypsum board, and metal lath and plaster are suitable for covering large areas, such as cellar ceilings, over the boiler. In fact, fire-stopping can be cheaply done with odd-and-end bits of material which usually go to waste around the building.
The details of constructing these fire-stops are best shown in the illustrations, and no further descriptions will be necessary.
_Chimney Construction_
In view of what was said in the first part of this chapter, the construction of a chimney by approved methods is also a safeguard against fire. It can be considered a rule that every chimney should be lined with a terra-cotta flue, that every chimney should be an independent structure of its own, with walls thick enough for stability, capable of standing upon their own foundations and not hung from any part of the structure, that all woodwork of the building should be framed far enough from the chimney to make no contact with it, and, finally, that all the smoke-pipes which enter into the flues should be proof against leakage of flames and heat of such intensity as to cause combustion.
In the past this need of lining the flues of a chimney with terra-cotta flue tiles was not considered important, but to-day it is a well recognized fact that no chimney is safe without this protective lining. There are many instances where chimneys are built without this lining and show no fire dangers, but the action of flue gases is slow and sure, and the mortar is attacked gradually, with the resulting disintegration of the brickwork, through which the flames eventually find their way to the surrounding wood timbers. It is found that even where terra-cotta flue linings are used the hot gases from the burning of natural gas as a fuel break down their resistance and they crumble, so that in such cases the flue linings should be made of fire-clays. From practical experience the minimum thickness allowable for any of these flue linings should be 1 inch, and the joints should not be made with collars.
When setting these linings they should be laid in cement mortar, not in lime mortar, for this disintegrates under the action of gases from burning wood. The joints should be struck smooth on the inside, and the space between the lining and the brickwork filled in solid with mortar. Wherever two flue linings are run within the same chimney space, the joints should be staggered or offset at least 6 inches. Two linings, however, in one chimney space should be the maximum number permitted. Where more are required, each group of two should be separated by brick walls of at least 4 inches, which are well bonded into the outside walls of the chimney. This is in order to give stability to the chimney and also prevent any fires in one flue spreading to others. The thickness of outside walls of the chimney around the flues should not be less than 4 inches if built of brick or reinforced concrete, but if built of stone they should be 8 inches. Wherever there is no flue lining of terra-cotta, such as in the smoke-chamber, the thickness of the masonry from the interior to the exterior should never be less than 8 inches.
If chimneys are built of reinforced concrete, the reinforcements should be run in both directions to prevent cracks during the setting of the cement or from temperature stresses. Where concrete blocks are used, reinforcements should run continuously around the blocks, and the shell of the blocks should not be less than 4 inches thick.
Wherever the walls of dwellings are of brick and 12 or more inches thick, they may be used to contain chimney flues. If it is necessary to corbel out the flues from the wall, they should not extend farther than 4 inches from the face of the wall, and the corbelling should not be done with less than five courses of bricks.
Next in importance to the correct lining of flues is the proper construction of the foundation under chimneys. There are often cases where it is necessary to cut off the chimneys below in part or in whole to supply room on the first floor. This should be avoided as much as possible, but if it cannot be done it should be supported by steelwork from the ground up.
Another mistake that is continually made is to cut off the chimney at too low a level and cap it with only a plastering of mortar. All chimneys should be carried at least 3 feet above flat roofs and 2 feet above the ridge of a peak roof and properly capped with stone, terra-cotta, or concrete. If they are not capped, and the bricks improperly tied, the mortar joints will be loosened by the action of the weather and the heat issuing from the chimney, and eventually the bricks will be moved from their position, leaving the top in a dilapidated condition.
This extension of the chimney through the roof leaves a joint which must be covered with flashing to prevent leaking. The usual method of building a tin-covered cricket behind the chimney, and protecting the other sides with tin flashing counter-flashed is very satisfactory; but the practice of corbelling the brickwork out over the roof, in order to cover over the joint, is extremely bad. When a chimney built in this way settles, the corbelled-out parts catch on the roof, and the whole top of the chimney is lifted off, leaving a crack through which the hot gases pass to the wooden rafters. See illustrations on pages 145 and 170.
If there are any fireplaces to be built in the chimney the walls should never be less than 8 inches thick around them. It is best to line them with fire-brick of at least 2 inches in thickness. Hearths should extend in front of the fireplace at least 20 inches to prevent sparks from falling on the wooden floors. These hearths should be supported upon trimmer arches or be constructed of reinforced concrete. It is important to keep the woodwork of any mantel away from the opening at the top at least 12 inches and at the sides at least 8 inches.
In fact, no woodwork should be permitted to come in contact with any part of the chimney. Wooden beams and joists should be kept at least 2 inches from the chimney and at least 4 inches from the back of any fireplace. This space, as was previously stated, should be filled in with fire-stopping material. Where a chimney is on the line with a wooden stud partition, it is better to plaster directly over the brickwork of the chimney than to carry studs over it on which lath and plaster is constructed. By using metal lath over the brickwork the danger of cracks can be eliminated. Where a base-board must be carried along this wall in which such a chimney occurs, the plaster should be carried down behind it and then asbestos board should be placed behind the base-board to prevent too much heat coming in contact with it.
If these precautions are taken in the construction of the chimney and the correct methods of fire-stopping employed, the house of wood can be made less of a fire-trap than it is to-day. None of these devices require much additional expense, and should, on this basis, have a broad appeal.
VII POOR METHODS OF CONSTRUCTION EMPLOYED BY UNSCRUPULOUS BUILDERS
It would be an endless task to list and describe all of the possible faults of construction which an unscrupulous builder might use in the erection of a small house, and, indeed, it would result largely in rehearsing all of the details of good construction, and then reversing them, showing that instead of doing the correct thing it was done quite the opposite way. But there are certain obvious and glaring faults of construction which are employed by speculative builders with one purpose in mind, namely, to reduce the cost but maintain a good appearance.
An intentional and clever disguise of poor construction is, at heart, the dishonest thing against which this is written. The defects of construction which are either the result of ignorance or unskilled labor, while they are bad enough, are not malicious, but those defects which are intentionally planned are simply systems of stealing, and they are usually found in the so-called speculative house, which the unwary public buys in preference to securing an honest house, designed by an architect. And it is this system of dishonest construction that makes the speculative house seem, on the face, cheaper than the honest house.
Indeed, it is the whole intention of such dishonest methods of building to make the house seem, on the face of it, substantial, good-looking, and honest, but to hide, beneath the glamour of its exterior, weaknesses of structure which will cause all kinds of failures after a few years of standing. So long as the house stands together until the builder has sold it to some unsuspecting buyer, that is all that interests him.
In observing some of these dishonest methods of construction it is well to keep in mind that they will appear on the exterior well done, but that their faults are hidden, and intentionally planned to reduce the cost for the builder.
In order to systematize our observations along these lines let us imagine a house which we will inspect in an orderly fashion. We will begin with the cellar and proceed upward to the roof. This house is an ordinary frame dwelling upon a stone foundation.
Entering the cellar-door, the first thing we notice is that at the base of the stairs leading to this door is a puddle of water left from the last rain-storm. Upon inquiring concerning it we learn that in every rain-storm, and especially during the winter when the ground is frozen, the surface water flows down the steps, collects in the areaway in front of the cellar-door, and overflows the sill into the cellar itself—all because the builder had omitted a drain-pipe in the centre of this area to save money. Becoming interested in this matter of drainage, we look around at the areas under each of the cellar-windows and find that the drains have been omitted from these, and that a few broken pebbles were thrown into the bottom to give the impression that the water could drain off into the soil, and all this to save money and deceive the buyer. Inspecting the ground around the foundation-wall we notice that about each leader the earth has been worn down by dripping water, as though the leader had backed up and the gutter had overflowed. Inquiry shows that such is the case in every rain-storm. Apparently the outlet for the leader has been stopped up, so, in order to find out whether this is true, we need to remove the lower section of the leader from the terra-cotta pipe to look into it, for often it becomes clogged at this point with leaves and dirt. Breaking away the cement joint and pulling gently upon the sheet-metal leader, we suddenly find that it crumbles in our hands, and that the leader consists of a coat of paint holding a few particles of rust together. Yes, cheap, thin, so-called galvanized-iron leaders to save money and deceive the buyer! But continuing our search for the stoppage we poke our cane into the section of terra-cotta pipe projecting above the ground which received the leader, and find that it stops short. Twisting it around to remove the material which seems to block the pipe we find, much to our surprise, that the entire section of terra-cotta pipe breaks off, and then, looking closer, we find that this pipe does not connect with a cast-iron drainage-pipe leading to the plumbing system or to a dry well, but had merely been stuck into the ground to give this appearance and to save money and deceive the buyer. No wonder the leader backed up and the gutters overflowed in a rain-storm!
By this time we have become very suspicious of the house, so that when we finally go down into the cellar our attention is attracted to a section of the cement floor near the furnace where the large ash-cans are standing. The top surface has cracked under the weight of the cans, and it appears to be in thin slivers of cement. Leaning down and prying under one of these cracked pieces with a knife, a thin slab of concrete, about a quarter of an inch thick, is lifted up from the floor, and beneath this slab we find about 2 or 3 inches of tamped ashes, and then dirt. We marvel that this floor has lasted even as long as it has with so much water running into the cellar in damp weather. Think of it, 2 inches of ashes and a quarter of an inch of cement mortar on the top, when the correct method of building is to lay about 6 inches of cinders for a foundation, then 3 inches of concrete on top of this, and finally a top coat, 1 inch thick, of cement mortar over all.
Looking up from the floor we are rather impressed by the clean, whitewashed effect of the walls of the cellar, and one would hardly believe that it was a damp one, but around the windows and at certain points in the wall the whitewash is streaked with black, as though water had leaked in. Going over to these places in the wall it is quite evident that during the winter and damp season water has soaked through these crevices. Poking around with a penknife we are amazed at the ease with which the knife penetrates the mortar between the joints of the stones. Working at it a little harder with the knife soon shows that if the cellar were a prison it would not be very hard to scratch one’s way out through that wall. Suddenly, without warning, one of the stones in the wall drops out onto the floor, and we get a view of the construction within. For certain it is one of those stone walls built up with two faces, not bonded together, except by mortar which seems to be made up of mud and a small trace of lime, which lime has disintegrated with the constant dampness to which it has been subjected. A piece of the mortar we find can be crumbled easily in the hand. This is evidence of the employment of the cheapest kind of labor for the masonry work and the cutting down of expense in using poor materials. We only have to look closely to see that there is developing a long diagonal crack in the wall, and we can imagine that if the contractor built so poor a wall above the ground, the chances are that there is no footing beneath it. Near at hand a large bulge is noticeable, and when we hit it with a hammer the whole thing has a rotten sound, for the inside face is bulging inward from the load upon it and the uneven settling of the foundations.
Looking up now at the neatly whitewashed ceiling we cannot help but be suspicious of the plaster beneath the surface, so going over to that part of the ceiling above the smoke-pipe leading from the furnace to the chimney we jab our cane against it, and, as we expected, a big slab breaks off and crashes to the floor, revealing partly charred wooden lath beneath, which have been baking in the heat rising from the smoke-pipe, and which would eventually catch fire. Examining the plaster very closely we observe that in addition to being a very thin coat it has no hair in it to act as a reinforcement for the plaster key which held it to the lath base.
But being rather inquisitive about the construction hidden behind the plaster, and having broken some of it down, the removal of the few lath is worth the look behind them. And there we see the girder which supports the floor-joists resting upon the chimney instead of on a special pier or column. This saved the contractor the cost of the pier or the column, but the owner would probably lose his house some day by fire creeping through the joints of the brickwork of the chimney to the ends of this wooden girder, for it was quite evident that the mortar used in the chimney was not much better than that used in the wall, and it is well known that lime mortar disintegrates under the action of hot gases from burning wood.
Turning our attention now to other parts of the cellar, we notice that in the floor of the laundry a place had been broken into, and upon inquiry we find that this hole was dug by the plumber in repairing a stoppage of the system of drainage-pipes under the floor. It seems that the contractor had omitted placing any clean-outs in the pipes which he had laid under the cellar floor, and the owner’s wife, by accident, in pouring a pail of wash water down the water-closet in the cellar had allowed a rag to go down with it, which clogged up the system, so that the waste from the kitchen-sink began to back up into the laundry-tubs. As there was no way to get at the pipes, the plumber, in cleaning out the system, was obliged to break through the floor and cut out a hole in the pipe to run a wire through to the clean-out on the house-trap. The contractor who built the house had saved about fifteen dollars in omitting this clean-out, but the owner lost fifty dollars in plumbers’ bills before he repaired this defect.
Another defect was also found by the owner in the system of water-supply. There had been installed only one shut-off cock for the entire building, so that whenever a new washer had to be placed upon a faucet on any fixture the entire system had to be turned off. As most of the faucets throughout the house were of very cheap design, this had to be done very often, until one day the owner had turned the main shut-off cock once too often for its strength, and the handle broke off. He was obliged to call in the plumber to turn the water on again, as well as install a new shut-off cock.
Questioning the owner further, we learn that a disagreeable odor of sewage enters the dining-room windows during the summer months when all the sash are open, but as he admits he knows little about plumbing, he isn’t sure of its cause, but he thinks it comes from a pipe which opens directly beneath one of these windows. When we investigate we find that it is the fresh-air inlet of the plumbing system of the house. The contractor had saved money on piping by carrying this to the nearest outdoor point, which happened to be directly under the window of the dining-room, so that whenever any water-closet was flushed in the house a puff of foul air was blown out of this pipe in the most convenient place for it to enter the house if the windows were open. Instead of spending the extra money for piping to carry this fresh-air inlet well away from any windows, the contractor had put in the shortest length possible.
After looking at this pipe we glance at the porch near by and notice that it is beginning to sag. So, crawling under the porch, we find that instead of masonry piers under the porch columns, there are wooden posts driven into the ground, and that not only have these begun to settle under the weight but also have rotted away considerably near the ground, where they are subject to dampness. While we are under here we notice that the floor-joists are small, 2 by 4 inch timbers, and have sagged a great deal because of their extreme scantiness for the span over which they are placed.
In fact, as we walk up on the porch it vibrates under our weight, and when we enter the house we notice the same weakness, only to a slightly less degree. The owner says that in the beginning the floors were stiff enough, but that this weakness had been getting worse each year. It is evident that there is faulty bridging and too small timbers. Probably in the beginning the nails of the upper flooring helped to stiffen the beams, but as these became worn in their sockets the joists lost this additional strength. This lack of proper-size framing timbers saved the builder money but would cost the buyer a pretty penny some day.
But we are astonished at the excellent appearance of the floors, for by this time the things that are good are more surprising than the things that are bad. Then it occurs to us that of course the floor would be good, for this is part of the house which is visible and helps to catch the buyer’s eye. But later, when we go up-stairs, we notice that the floors are not so fine, but are the common flat-grained boards which sliver off and catch in your shoe if you scuffle. The owner also points out the kitchen as one of the biggest fakes he has seen. It has an oak floor, and when he had bought the house he had been deeply impressed with the luxury of having an oak floor not only in the dining-room but also in the kitchen. But he is not so keen now, for with constant scrubbing the cheap varnish and filler had come off and the pores of the oak have been exposed, so that now the floor is the greatest catch-dirt ever invented, and to make matters still worse the oak had been poorly seasoned, the boards had shrunk, the cracks opened, and there is no underflooring below to prevent the dust and dirt from sifting through these cracks from the hollow space between the floor-joists. The owner says he is about to install a new floor. He also admits that the varnish which gave such a fine surface to the dining-room and living-room floors when he first saw the house was so poor, and scratched so badly, that he had to have the floors completely done over.