Lightweight cementitious roofing, tapered and recessed

A roof shake having an elongated body with top and bottom surfaces that extend lengthwise of the body, the body having laterally spaced, elongated edges, and opposite ends. The body bottom surfaces have a taper angled to flatly engage the roof near an upper end of the shake, whereby the shake may be nailed to the roof in spaced relation to the end so that the taper engagement with the roof provides leverage resisting wind up-lift forces exerted on the shake near a lower end of the shake installed in spaced relation to the roof. The bottom surface has hollow shallow cavities to reduce weight. The length and width are such as to reduce number of shakes in installation.

BACKGROUND OF THE INVENTION 
This invention relates generally to the provision of lightweight, fireproof 
roofing shakes, capable of withstanding installation and foot traffic, and 
without breakage, as well as wind up-lift forces, and more particularly 
concerns cementitious admixtures from which such roofing pieces are 
formed. 
There is continuous need for improvements in lightweight cementitious 
shakes, and their installation, for example to prevent breakage during 
such installation, and thereafter, and to prevent up-lift due to wind. 
Current lightweight concrete and fiber cement roof shakes and shingles are 
produced in flat sheets or continuous taper shapes. These shapes do not 
lay flat when installed and must flex when installed or walked upon. 
Necessary flexural strength is obtained using high density and therefore 
heavy materials in a thin (1/4 to 3/8 inch thickness) section or low 
density lighter materials in a thicker (approximately 3/4 inch thickness) 
section. The thin section materials suffer from low market appeal and the 
thicker section materials are not thick enough and suffer also from 
excessive breakage during application and underfoot traffic. 
Existing alternate material shakes used to replace traditional wood shakes 
to provide fire safety, are made in 22 inch long by 12 inch maximum width 
shapes. These shakes are installed with a 10 inch exposure often over 
spaced sheathing boards which are on 11 inch centers making adjustment of 
the nailing point necessary. Additionally, from 120 to 150 shakes must be 
installed to cover 100 square feet of roof surface (1 roofing square). 
It is the object of this invention to create a new shape which, when 
installed in a full double overlap shingled method, lays flat and can, 
therefore, be made very thick (up to 11/2 inches) using a very lightweight 
cementitious material (or other suitable material) which can be formed by 
standard extrusion or pressure/vibration tile, paver or block forming 
machines. Additionally, nail points are pre-marked in two, separate 
locations to provide for normal wind up-lift forces and for very high wind 
up-lift forces. 
It is yet another object to produce shakes of minimum 23 inches long and 
minimum 121/2 inches wide size to allow for 11 inch exposure installation 
and 11 inch on center nailing points and 100 or less shakes per roofing 
square. 
Prior roofing shakes or shingles and methods of production are disclosed, 
for example, in Jakel U.S. Pat. No. 3,841,885, Jakel U.S. Pat. No. 
3,870,777, Kirkhuff U.S. Pat. No. 3,852,934 and Murdock U.S. Pat. No. 
4,288,959, and Wood U.S. Pat. No. 4,673,659 describing problems 
encountered in lightweight extruded tile production. 
SUMMARY OF THE INVENTION 
It is a major object of the invention to provide improvements in the 
structure of, as well as the installation of, lightweight, roofing shakes 
or shingles made of cementitious or other materials. 
Basically, and in accordance with one aspect of the invention, the improved 
roof shake has 
a) an elongated body with top and bottom surfaces that extend lengthwise of 
the body, the body having laterally spaced, elongated edges, and opposite 
ends, 
b) the body bottom surface having a taper angled to flatly engage the roof 
near an upper end of the shake, whereby the shake may be nailed to the 
roof in spaced relation to that end so that the taper engagement with the 
roof provides leverage resisting wind up-lift forces exerted on the shake 
near a lower end of the shake installed in upwardly spaced relation to the 
roof. 
These and other objects and advantages of the invention, as well as the 
details of an illustrative embodiment, will be more fully understood from 
the following specification and drawings, in which:

DETAILED DESCRIPTION 
In FIGS. 1 and 2, the shake 50 has a bottom side 51, top side 52, forward 
or lower edge 53, rearward or upper edge 54, and right and left edges at 
55 and 56. A beveled or tapered portion 51a of the shake bottom side 51 
nearest edge 54, and extending between edges 55 and 56 is parallel to and 
flatly engages the roof. The front portion 50b of the shake is spaced from 
the roof 62a and directly and flatly supported on the rear extent of the 
top side 52 of the next lower shake 50 on the roof, as seen in FIG. 1. 
Each tile then has extensive bottom side planar support, at regions 65 and 
66. Top surface 52 extends at angle .alpha. relative to 51a and 62a. The 
length of the tapered portion 51a from edge 54 is between 1/5 and 1/3 the 
tile length. 
Note that the only unsupported extents of the shakes are at recess portions 
57 between taper edge 51a edge 58, and lower shake upper edge 54. Edges 54 
may be squared off, as shown. 
The shake bottom side seen in FIG. 2 is also provided with hollow shallow 
recesses or cavities 76-80 of elongated and selected generally rectangular 
shape, to reduce the mass of the shake, thereby reducing load on the roof. 
Elongated ribs 81-86 extend at opposite sides of the recesses and are load 
bearing as during walking of workmen on the roof. The bottoms of the ribs 
extend to the plane of shake bottom side 51. Both the recesses and the 
ribs intercept the tapered surface 51a, but are spaced from lower edge 53, 
as by a lateral ridge 87. 
Pre-drilled or marked points for nailing the shakes are seen at 110. Wind 
up-lift forces tending to rotate the shakes clockwise about nail fulcrum 
points, at 110, are resisted by shake taper at 51a flatly engaging roofing 
62a, between points 110 and edge 54. 
Pre-drilled or marked points for nailing the shakes, as at 111, are located 
under overlapping extents of the next above shake. Wind up-lift forces 
tending to rotate the tiles clockwise are resisted by a very long fulcrum 
between points 111 and 54. 
It is another object of the invention to provide a formulation of 
lightweight aggregates which have been graded and prepared in a very 
specific manner, and which, when mixed with Portland Cement in prescribed 
sequence, and specified mixer speeds, will produce a "dry" mix which can 
be easily extruded using existing extruding machines designed for standard 
concrete mixes, and which will extrude at very high speed on these 
machines without modification to the machine. The object is to make 
production of such lightweight shake products, as disclosed above, very 
efficient and therefore relatively inexpensive, compared to the slower 
"wet" processes being used currently. 
It is yet another object to provide an aqueous, yet "dry" admixture that is 
extrudible to produce lightweight cementitious roofing shakes and 
shingles, that consist essentially of the components: 
a) expanded perlite in particulate form 
b) an ingredient or ingredients selected from the group consisting of 
pumice and expanded shale, and expanded clay, that ingredient or those 
ingredients being in particulate form, and 
c) Portland Cement in particulate form. 
Such an admixture also typically contains a small amount, by weight, of 
cellulose and/or polyester fiber. More specifically, the mix typically 
contains such components in relative weight amounts: 
about 1 part of the above b) ingredient or ingredients 
about 1 part Portland Cement, 
about 1/2 part expanded perlite. 
A further object is to provide an improved method of processing, including 
pre-screening of the aggregate, in order to produce a superior product. 
Thus, by grading standard sources of pumice, expanded shale or clay and 
expanded perlite into specific particle sizes and then re-combining them 
in a prescribed manner and sequence, a mix is created which can be bound 
together using common Portland Cement giving superior physical strength 
and maintaining a compacted weight only slightly heavier by volume than 
the aggregates themselves. The two grades, when recombined create an 
optimum range of particle sizes to be coated by the cement. Prior 
lightweight mixes using these aggregates (and other similar) did not 
remove the high quantities of fines (smaller than 50 mesh) in pumice, 
(pumicite) expanded shale or clay and perlite. These fines have enormous 
surface area and use up large quantities of cement to bind them, which 
results only in increased weight, thus defeating the reason for using 
lightweight aggregates. Additionally, such prior mixes using too many 
fines are difficult to extrude or press into shapes, since they resist 
flow and tend to "spring back" after the pressure is removed. The 
resulting product, if it can be formed at all, is generally very low in 
strength due to the low compaction resulting from improper aggregate 
particle size distribution. 
Yet another object is to provide a formula of lightweight aggregates, fiber 
and Portland Cement, which, when graded, prepared and mixed as described 
produces a lightweight, fire and thermal resistive concrete which can be 
successfully and easily extruded into shapes for use in construction, 
principally, roofing tiles, shingle and shakes as described above. This 
mix can also be pressed into the same shapes and brick and block shapes 
using pressure and vibration as in a paver or block production machine. 
The resultant compressed product is homogeneous and uniform thus creating 
superior strength characteristics compared to present lightweight fiber 
cement mixes. This "concrete" is approximately half the weight of 
traditional concrete (specific weight is 0.85 to 1.0, or expressed in 
metric, 0.85 gr. per cc.) and is half as strong and absorbs the same 
amount of water. 
The admixture formula to produce the described shingles and tiles is as 
follows, with parts listed by relative weight: 
FORMULA: by weight 
1 part Portland Cement 
0.8 to 1.2 part Pumice (or expanded shale or clay) 
0.3 to 0.4 part expanded Perlite 
0.015 to 0.025 part treated cellulose fiber (optional) 
0.005 to 0.015 part Polyester fiber (optional) 
0.2 to 0.3 part water (portion 1) 
0.4 to 0.6 part water (portion 2) 
GRADES 
Where: The Portland Cement is Type II Common or Type III High Early or Type 
C Plastic. 
Where: The Pumice or expanded shale or clay as received is dried to less 
than 1% moisture content and then screened to create a material having the 
following sieve analysis expressed in % by weight retained on screen: 
______________________________________ 
4 mesh 0-5 
8 mesh 10-20 
16 mesh 20-30 
30 mesh 30-50 
50 mesh 5-15 
Pan 5 max. 
______________________________________ 
This material has a specific weight of 0.80-0.90 weighing 40 to 60 
lbs/ft.sup.3. 
Where: The expanded Perlite is screened (before or after expansion) to 
create a material having the following sieve analysis expressed in % by 
weight retained on screen: 
______________________________________ 
8 mesh 0-7 
16 mesh 30-40 
30 mesh 25-35 
50 mesh 15-25 
80 mesh 0-6 
Pan 2 max. 
______________________________________ 
This material has a specific weight of 0.13-0.17 weighing 7 to 11 
lbs/ft.sup.3. 
Where: The Polyester fiber is of 1.5 to 6.0 straight drawn and cut to 0.25 
inch to 0.5. 
Where: The cellulose fiber is typically obtained from newsprint or kraft, 
opened fully by processing and moisture resistance treated. 
PREATION 
The Pumice, shale or clay preparation and handling prior to mixing must 
insure that the material does not segregate into concentrations of 
particle sizes within the grade. Anti-segregation methods of these 
aggregates must be employed in the transport and measuring systems. 
The Pumice and/or shale must then be completely saturated with water 
(exposed to water until it stops increasing in weight) prior to mix start. 
Portion 1 of water is used for this purpose. 
The Perlite must be handled (mixed for example) before and after expansion 
to insure that the particles do not segregate into concentrations of 
particle sizes within the grade. The Perlite may be either expanded "on 
demand" or handled insuring that the particles do not segregate prior to 
measuring and mixing. 
MIXING 
The sequence of the introduction of materials to the rotary mixer and the 
mixer rotor speeds and configuration are important: 
1. The fiber, if used, is introduced into a rotating pan-high speed rotary 
mixer that has tip speeds in excess of 60 feet per second. Mix time 
continues until the fiber is completely opened. 
2. Portland Cement is introduced into the fiber in the mixer and mixed at 
the same speeds until the fiber is fully dispersed into the cement. 
3. The prepared Pumice or Shale is put into the mixer and rotor tip speeds 
reduced to 40 feet per second. The first portion of water has now been 
added. Mixing continues until homogeneity is reached. 
4. Rotor tip speeds are further reduced to 10 to 12 feet per second prior 
to the introduction of Perlite. An alternate and preferred method is to 
transfer the mix from the rotating pan mixer to a folding paddle or screw 
type continuous mixer and to meter the Perlite into the mix. 
5. The final mix with the second portion of water added may be at the low 
tip speed for very short time (10-15 seconds). Folding paddle or 
continuous screw (with back paddles) mixing is the preferred method to 
insure that the Perlite is not degraded by the mixing action. 
Other common additives for concrete and lightweight cement or fiber cement 
products may be added at the appropriate places depending in the end use. 
These additives could include iron oxides for coloring, calcium chloride 
for curing acceleration, water repellant chemicals, etc. . . . 
CURING 
Product curing should begin immediately and in a controlled atmosphere. The 
humidity must be at least close to 80%. Temperatures can vary from 
100.degree. F. to as high as 170.degree. (170 should not be exceeded) 
depending upon need for early strength in the particular product being 
produced 
FORMING AND SHAPING 
By changing water content and making slight adjustments to fiber type and 
amount, the mix can be formed and shaped in a variety of ways. 
The principle method is extrusion where the forming pressure is 
approximately 200 lbs. per square inch and the typical extrusion method is 
as used to produce concrete roof shakes on a carrier pallet which creates 
the shape of the bottom of the shake and a roller and slipper shape the 
top surface, curing proceeding on the pallet or pallets, after which the 
shakes are removed. The lightweight mix does not have the strength of a 
typical concrete mix and therefore the shape of the shake and the 
thickness are modified in order that the resulting cured product can 
withstand foot traffic and pass the required "as installed"strength 
testing. The top surface of the shake which is shaped by the roller and 
slipper on the extrusion machine can be modified to produce any shape from 
a smooth European tile to a rough random shape of a cedar shake. The 
bottom surface is shaped by the pallet. 
The second method of forming and shaping employs a standard paver or block 
forming machine as this mix easily and consistently is handled by such a 
machine without modification. Thus, products currently produced using 
standard heavy concrete mixes can, by using the present mix, be also 
produced in a lightweight version. 
ADDITIONAL ADVANTAGES 
The formula of light and very light aggregates with Portland Cement and 
cellulose fibers produces a strong, flexible, fire resistive and 
insulative concrete. This formula, when properly prepared and mixed is 
easily shaped by extrusion an vibrative pressure by unmodified industry 
standard machines used in making standard machines used in making standard 
heavy traditional concrete. 
A combination of various grades of light and very light aggregates combined 
in described quantities as disclosed creates a balance and uniformity of 
particle sizes. This combination of particle sizes, when combined with 
Portland Cement, produces a uniformly graded and therefore strong concrete 
referred to as "Perlacem". 
The method of preparing very light aggregate as disclosed is such that the 
particle distribution will remain constant and not vary due to ore changes 
or by storage segregation. This eliminates the common problem of water 
"take-up" variation which creates forming and shaping problems. 
The formula of light and very light aggregates, graded and prepared as 
disclosed is such that maximum binding effect of the Portland Cement is 
achieved. Previous lightweight mixes using the same aggregates embodied 
too many of the naturally occurring fines (very small particles of the 
minus 50 mesh variety) and thus created an ineffective cement paste. 
The present shake configuration is such that the effective span of the 
installed tile is greatly reduced by using a tapered tail section; in 
addition, the tile or shake shingle can be hollowed out and made much 
thicker than those presently manufactured, and it employs a sharp taper to 
achieve a flat layup on the roof. 
It will be noted from the drawings that the shake has constant overall 
thickness from its lower end to its tapered end portion, and that as 
installed, the entire upper surfaces of the shakes are parallel. 
While the shakes can be made using composition methods other than as 
disclosed herein, such disclosed composition and methods are of unusual 
advantage as respects production of a markedly superior shake.