312. Actual Weight of Fireproof Floors

In the spring of 1895 a series of fireproofing tests was made in the basement and first story of a building then being erected in Boston, a full description of which may be found in the American Architect of September 7, 1895.

The question of the comparative weights of the different floor construction having been raised, it was decided to weigh a section of each.

The debris from the fires was removed from the houses, the floors broken down, care being taken to preserve all the material that had entered into their construction, and it was then weighed on platform scales. The data thus gathered are tabulated below :

TEST NO.

CONSTRUCTION.

AREA OF SECTION.

TOTAL WEIGHT.

WEIGHT PER SQ. FT.

I.

18 sq. ft.

1,295

lbs.

72

lbs.

2.

Metropolitan System, panel construction ........

18

"

427

44

23.7

"

3.

Expanded Metal Co.'s System .................

22.5

44

1,697

"

75.4

"

3a

Same as No. 3, with additional flat ceiling .........

22.5

4 4

1,814

"

80.6

"

4.

Eureka System .............

20.25

44

1,648

4<

81.3

"

5.

12-inch porous hollow tile arch blocks covered with concrete 2 inches thick..

20.25

44

1,781

44

87.95

"

In considering this table it should be noted that all of the floors, with the exception of No. 2, were plastered on the under side, and were concreted on top, ready to receive the wood floors. The plastering on No. 5 fell during the fire test and was removed with the debris, and, consequently, not weighed with the other material; the weight of the 12-inch floor beams is not included in the weight given above.

313. Selection of a System

Where there are so many styles of fireproof floors, each claiming to be superior to the others, it is difficult for the architect to decide on a particular construction. The choice of a system of fireproofing is more apt to be decided by the question of cost than by other considerations. The relative cost of different systems will also vary somewhat with the locality and distance from the manufacturing centres. It should be ascertained, before fully deciding on the system to be used, by obtaining approximate bids from the different fireproofing companies, most of whom are always ready to submit such bids.

The author believes that either of the floor systems described herein, if properly constructed with materials of good quality, will make a thoroughly fireproof floor, although where the danger from a severe conflagration is especially imminent, porous tiling is generally considered as the superior non-conducting material.

The question of strength hardly needs to be considered except for floors for warehouses and heavy storage buildings, as either of the systems possess sufficient strength for other buildings if the sections are not made too light or the spans too great.

Where heavy loads are to be carried, however, those systems which have uniformly developed the greatest strength should be selected. The question of lightness is often one of considerable importance, especially in dwellings, apartment houses, hotels and office buildings. Very often the considerations of speed in erection and quickness in drying out, the adaptability to putting in place in cold weather, etc., are sufficient to decide in favor of a particular system.

Many engineers still favor the use of dense or porous tiles for fireproofing, and these materials are undoubtedly of great value, and possibly the best for certain conditions, but the combinations of iron with Portland cement concrete are rapidly gaining in favor, and the author believes that concrete, when properly combined with the metal, makes a very strong and thoroughly fireproof construction, and that it has now been used for a sufficient length of time to fully demonstrate its adaptability to floor construction.

With nearly all systems of fireproofing the efficiency of the construction depends very largely upon the character of the workmanship and the quality of the materials used. When it is desirable to use as much unskilled labor as possible, the Fawcett, Roebling or Columbian floors can be used to advantage, an intelligent and honest foreman being the only skilled person required.