Insulated wall construction

A wall construction comprising a plurality of horizontally spaced vertically extending studs, an insulation board mounted on an outer side of the studs, a scrim adhered to an outer side of the board, fastening means mechanically securing the board and scrim to the studs, and a coat of cementitious material covering the board, scrim, and fastening means, at least one of the studs being disposed between opposite vertical edge portions of the board, and the scrim having a greater number of vertically extending strands per inch of width in the vicinity of said at least one stud than in areas between the studs.

TECHNICAL FIELD 
This invention relates generally to insulation of outside walls of 
buildings, and more particularly to wall constructions wherein fibrous 
insulation boards are secured to wood studs, the boards having a 
factory-applied scrim adhered thereto for reinforcing a field-applied 
cementitious coating. 
BACKGROUND ART 
U.S. Pat. No. 4,522,004 discloses a wall construction of the 
above-described type wherein the scrim has about six by six strands per 
square inch (column 2, lines 16-19). When staples with leg portions spaced 
on three-eighths-inch centers are used to secure the insulation boards, 
only two strands are held by a staple. 
DISCLOSURE OF INVENTION 
In accordance with the invention, the scrim adhered to the insulation board 
in the factory is non-uniform, having five by five strands per square inch 
in areas falling between studs when the boards are installed, and twelve 
by five strands per square inch in two spaced areas of the board aligned 
with studs when the boards are installed. Each staple holds four strands 
of the denser scrim in the stud area of the board. Negative wind load 
resistance is increased over that of the former construction, and less 
yarn is required in the scrim, while the cement coat is still adequately 
reinforced.

BEST MODE OF CARRYING OUT THE INVENTION 
With reference to the drawings, FIG. 1 shows an insulation board 10 
constructed in accordance with the invention and including a glass fiber 
board 11 having a density of about four pounds per cubic foot, preferably 
having a thickness of at least one inch, and consisting essentially of 
glass fibers impregnated with about thirteen percent by weight of a binder 
such as phenol-urea-formaldehyde resin. The insulation board 10 also 
includes a scrim 12, preferably woven alkali-resistant or plastic-coated 
glass fiber, adhered to an outer side of the glass fiber board 11. 
Opposite, normally vertical edges of the glass fiber board 11 are rabbeted 
to provide shiplap-type joints between adjacent mounted boards. The 
full-thickness portion of the board 11 may be forty-six inches wide, and 
each of the rabbeted portions may project two inches. Preferably the board 
11 is eight feet high. The scrim 12 may be fifty inches wide, including a 
loose flap 12a at one rabbeted edge. 
In accordance with the invention, the scrim 12 is provided with five by 
five strands per square inch in areas labelled "A", "B" and "C", but with 
twelve by five strands per square inch in areas labelled "D" and "E", the 
twelve strands running vertically on a mounted board. The areas D and E 
are preferably four inches wide and disposed on sixteen-inch centers to 
match normal spacing of wood studs such as studs 14 shown in FIGS. 2 and 
3. The boards 10 may be stapled to the studs 14 by staples 16 and covered 
with a rough cementitious coat 18 and a finish coat 20. 
While the additional vertical strands in the stud area are preferably built 
into a non-uniform scrim, it is within the scope of the invention to use 
uniform scrim all across the board and place additional scrim strips 
vertically along the stud areas. 
With twelve vertical strands per inch of width in areas D and E, a staple 
16 will enclose twice as many strands, namely four, than with six vertical 
strands per inch, as in the prior uniform scrim having six by six strands 
per square inch all the way across an insulation board. Wind load tests 
show that this results in a stronger wall, even with using less glass yarn 
in the scrim overall. 
The six by six scrim has twelve inches of yarn (6 +6) in a square inch. The 
scrim of this invention has ten inches of yarn (5+5) per square inch in 
areas A, B, and C, and seventeen inches of yarn (12+5) per square inch in 
areas D and E. This averages out to 11.12 inches of yarn per square inch 
when the eight-inches total width of areas D and E and the forty-two 
inches total width of areas A, B, and C are taken into consideration, or 
92.66% as much yarn as in the six by six scrim. 
In negative wind load tests, the former panel failed at 57 pounds per 
square foot, while the panel of this invention did not fail at 14.6 inches 
of water, the maximum vacuum available with the equipment, or 76 pounds 
per square foot. 
Various modifications may be made in the structure shown and described 
without departing from the spirit and scope of the invention as set forth 
in the appended claims.