A Hundred Years of Roofing Experience (1958)

Johns-Manville Corporation made this film in 1958, its centennial, about its asbestos built-up roofs; the title card adds "The Story of Johns-Manville Asbestos Built-Up Roofs". It opens with H. W. Johns making roofing felt in 1858, then the J-M mine and asbestos fibre, and explains why J-M said asbestos felts outlast felts made of organic fibre. Most of the film is laboratory tests of Aquadam, J-M's bitumen for dead-level roofs, at the J-M Research Center. It ends with roof insulation, the Asbestile flashing system, and crews of J-M approved roofers at work.

What it says about asbestos and health

Nothing about dust or disease. It calls asbestos "a mineral fiber which cannot rot, decay or burn" and "as permanent as stone".

About this copy

Our copy is a transfer of a print from Johns-Manville's own film archive (box 04-03391), shown in full, 19:56 long.

Transcript

A machine transcript of the soundtrack, not yet checked against the film; names and technical words may be wrong.

A century ago, in 1858 to be exact, the company we now know as Johns-Manville was founded by H.W. Johns in a small basement room in lower New York. One of the first products turned out by Mr. Johns was an improved roofing felt. In fact, tradition has it that Mr. Johns helped remove the excess bitumen from the first batch of felt by running it through an old-fashioned clothes wringer, turning the handle himself.

These early roofings, with their successors, have set a standard of quality which has won the approval of architects, building owners, and roofing contractors for generation after generation. Today, a hundred years later, Johns-Manville continues to manufacture quality roofings, but the small basement room has grown into huge manufacturing plants located strategically in the United States and Canada. Canada. One of its greatest contributions to the roofing industry has been the introduction of asbestos felts into roof construction. Today, from great mines located in Canada and other parts of the world, Johns-Manville mines and processes its own asbestos fiber. The employment of asbestos fiber instead of organic fibers in roofing felts gives many advantages asbestos is a mineral fiber which cannot rot decay or burn it is as permanent as stone ordinary roofing felts are made of organic fibers which are actually tiny hollow tubes filled and coated with bitumen on the other hand asbestos fibers are inorganic they are small solid rods which being solid are not filled with bitumen, but are coated only in the manufacturing process.

With ordinary roofing felts, the organic tubular fibers act as wicks and allow the sun to draw off both the bituminous saturant in the felt and the cementing agent used between the plies of felt. This destructive oxidation process greatly shortens the life of the roof. Asbestos roofing felts guard against this damage through oxidation. Because asbestos fibers are solid, they cannot act as wicks through which the asphalt may be drawn off by the sun. They form a network in each ply which protects the impregnated bitumen within the felt and the layers of bitumen between the felts. When an asbestos felt roof bleaches in the sun, the action is only skin deep.

Wherever you scrape the gray weathering of a smooth surfaced asbestos roof, you will find black asphalt underneath. This test can be repeated a dozen times in the same spot with the same results. Because of the protection of the bitumen by the asbestos fibers roofs built with asbestos felts do not require a protective slag or gravel surfacing smooth surfaced roofs offer many other advantages damage is easy to locate and repair thorough roof drainage is assured and the roof deck is not subjected to the excess weight of slag or gravel john's manville has two basic asbestos roofing specifications. First, for decks with pitches from one-half inch and over, there is the well-known Flexstone built-up roof, which has been protecting commercial and industrial buildings for scores of years. Second is an asbestos roof specifically designed for slopes of less than one-half inch and for dead level decks. It is the Aquadam built-up roof.

The Aquadam built-up roof is the result of a number of years of experimentation and testing in the laboratory and in the field. Before Aquadam was publicly announced, test installations were made on buildings all over the country and under varied climatic conditions. Today, after 10 to 20 years of actual field tests, they are in perfect condition. These asbestos roofs owe their superiority to Aquadam, the cementing agent which is used between the plies of felt and on the surface. Aquadam contains all the valuable qualities necessary for the construction of a superior dead-level built-up roof. Qualities not found combined in any other one bitumen.

Let us take you to the largest research center in the world devoted to building materials and show you actual tests which prove that Aquadam possesses the qualities the architect or engineer considers most desirable for the construction of a superior built-up roof. The first quality demanded of a roof is that it must withstand the weather. Aquadam fully meets this qualification, as you will see. In this modern machine, accelerated weathering tests can be made. Films of Aquadam and other bitumens are exposed to ultraviolet light, water sprays, heat, cold, and thermal shocks under controlled conditions. After being subjected to those conditions for many cycles representing years of exposure, Aquadam showed less deterioration than other bitumens tested.

Another important quality an architect or engineer might demand in a roofing bitumen is its ability to heal itself if for some reason cracks or imperfections have previously formed in the bitumen layer. This test is designed to measure the degree to which a bitumen will heal itself under sun temperatures. Films of Aquadam and other dead level asphalt are placed on aluminum panels and scribed with cracks. These panels are then placed in an oven heated to 135 degrees Fahrenheit. After a period of time the amounts of of rehealing of the scribed lines is noted. Ordinary dead level asphalts, as you can see, show an almost complete absence of self-healing qualities.

Aquadam, on the other hand, resealed itself 100%. The third quality demanded of a good bitumen is that it have a high degree of ductility. By ductility, we mean the ability of the bitumen film film to be distorted without breaking. This distortion might be due either to expansion and contraction of the roof deck or to building movement. On this test machine, specifically designed to test the ductility of various bitumens, we see an ordinary dead level asphalt being tested. The break occurs when the bitumen is stretched from seven to eight centimeters. bitumens such as these would soon crack and break when subjected to sudden temperature changes or movement of the roof deck let us see what happens to Aquadam in the same test because Aquadam is truly ductile it can be stretched to the absolute limit of the machine without breaking here is the proof that this improved bitumen will most effectively resist distortion and breakage under actual service conditions.

As everyone knows, the bitumen used in a built-up roof comes to the job in solid form. It must then be reduced to a viscous state before applying it on a roof. In many cases, through heating the bitumen in the kettle, many of the virtues built into it by the manufacturer are destroyed. Therefore, the bitumen that changes the least when heated will be the one to reach the roof in the nearest to its original and desired characteristics. This is the kettle stability test designed to measure the ability of a bitumen to retain its original composition under the normal and abnormal temperatures to which it may be subjected in the kettle. In this test the samples of various bitumens are first weighed in standard containers and placed on a shelf in the oven.

In the oven they are subjected to a temperature of 500 degrees Fahrenheit for five hours. At the end of the five-hour period the samples are removed and reweighed for volatile loss and measured for softening point increase. The results of the kettle stability test are shown on these charts. Note how the weight loss of Aquadam compares favorably with that of the dead level asphalts and is infinitely less than the weight loss sustained by coal tar pitch. Notice too that while all bitumens are susceptible to a softening point increase to some degree, the softening point increase of dead level asphalts was twice that of Aquadam and the softening point increase of coal tar pitch was many times that of of Aquadam. Another quality that an architect or engineer would look for is the degree of adhesiveness of a bitumen.

High adhesive properties result in more effective brooming in of the felts, less chance of air pockets and potential blisters. Mineral surfacing is held and kept in its proper place. The adhesion test is made by warming films of two ordinary bitumens and a film of Aquadam. They are raised to specific temperatures and then roofing felts are brought into contact with the warm bitumens. Notice that with only brief contact the other samples do not hold while Aquadam bonds readily to the felt. It is important too that a bitumen provide good adhesion to gravel when used.

Here is a gravel adhesion test being performed on Aquadam and other dead level bitumens. As before, films of the various bitumens are warmed to specific temperatures. Gravel is then sprinkled over the films. After a period of 30 seconds, the containers are turned upside down. When the containers are turned right side up, the amount of gravel loss is evident. The first two samples show little, if any, adhesion to the gravel.

Aquadam shows excellent adhesion and that is most important to guard against gravel erosion on a dead level roof. The next quality, which a superior roofing bitumen should possess, is an ability to withstand water immersion. Parts of some dead level roofs, for one reason or another may be under water for long periods at a time and it is important to the architect and the engineer to select a bitumen that is not affected or changed by standing water here samples of the various bitumens are first weighed and then covered with one inch of distilled water at weekly intervals the water is poured from the surface and the bitumen blotted dry. Then the quantity of water absorbed by the bitumen is determined by reweighing the sample. The samples are also examined at the same time to see what effect immersion in water may have caused, such as swelling, discoloring, or breaking down of the bitumen. In this test, definite conclusions were not arrived at until after one year's immersion of all samples.

As you can see, Aquadam is stable in its reaction to water immersion and remains unchanged after a year's test. Commercial dead level asphalt show a distinct change in characteristics in the same time. Still another quality to look for in the ideal roofing bitumen is its ability to flow and thereby level and smooth itself at average sunroof temperatures. temperatures. Here is a test that scientifically measures the flow characteristics of different bitumens. Cubes of various samples are placed in V-shaped preheated metal troughs which have a 30-degree slope. The troughs are placed in an oven which is heated to sun temperature.

After six hours, the flow rates are recorded. The Aquadam sample in the middle shows a relatively uniform flow which averages midway between coal tar pitch at the left and dead level asphalt on the right. Aquadam's medium degree of flow is considered ideal. Coal tar pitch is recognized as having too great a flow with a tendency to leave bare spots at the high points of the roof. On the other hand the average asphalt usually possesses too little flow which is insufficient for good leveling and sealing characteristics which are so important to a well-built roof you have seen through these tests how Aquadam meets all of the requirements of a superior roofing bitumen for dead level or low pitched roofs it has a uniform rate of flow the ability to stand water immersion a high degree of adhesiveness the ability to retain its original characteristics characteristics when heated, high ductility, the ability to heal itself, and finally the ability to withstand weather while in service. Because it meets all of these important requirements for a long-lasting roofing bitumen, smooth surfaced Aquadam roofs built with asbestos felts are being specified and used more and more and when desired Aquadam roofs are also available in a slag or gravel surface specification a superior bitumen is of prime importance but there are other elements which are necessary to build a roof of quality proper insulation is one of those other elements and it is particularly significant when temperature conditions in the manufacturing process must be closely regulated roof and so provides such insulation it is made of wood fibers processed into a homogeneous board roof and so has great structural strength and resistance to compression yet it is light and weight it can be handled without distortion breaking or delamination it is sufficiently rigid to permit normal traffic during the installation of both the insulation and the roof above it and it has been designed to secure the lowest possible conductivity consistent with structural strength another important element is the flashing even the best of built-up roofs can fail if improperly flashed for this purpose the Asbestile system of flashing was developed to start the flashing installation the ends of the new roofing felts are turned up dry over the cant strip and on up the parapet wall a short distance.

Then the masonry wall is primed. Next a sheet of asbestos felt is mopped in place. This felt is covered by a sheet of base flashing, also mopped in place. Then along their upper edge the two felts are nailed into a brick joint. Now Now, over this base flashing, the cap flashing is placed using Asbestile, a heavy-bodied plastic cement specially developed to give thorough water tightness. The cap flashing consists of a troweling of Asbestile, a ply of felt, a second troweling of Asbestile, a second ply of felt, and a final troweling of Asbestile. tile.

This cap flashing extends under the coping and down the wall, overlapping the base felts. The last step is the stripping in of an asbestos felt laid in hot bitumen along the joint of the base flashing and the finished roof. Thus, a completely dependable built-up roof is produced. A roof that is backed by 100 years of experience in pioneering new materials and methods for the roofing industry. Among those accomplishments are asbestos felts, roof and so,l the asbestos system of flashing, Flexstone roofs for inclines of one-half inch to six inches, and now Aquadam roofs for low pitch and dead level roofs. But it is not enough that the built-up roofing products be manufactured to the highest standards of quality.

To ensure a roof of maximum wear and service, a built-up roof must also be properly applied by competent and reliable roofers. That is why Johns-Manville insists that its products be applied only by approved roofers who are selected for their experience, their know-how, and for their reputation in their business community. They are identified in your neighborhood by this heading in the yellow pages of the classified telephone directory and by this sign at their place of business 100 years have gone by since H.W. Johns developed his improved roofing felt today the company he founded is entering its second century of service to architects engineers contractors and and building owners. Utilizing its complete research facilities and vast experience, Johns- Manville will continue to lead in the development and perfection of new products to meet new construction concepts. Thus, materials offering the very best in protection and security will always be on hand for the buildings which will come into being as the future unfolds.