Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an exterior insulating
sheathing and more particularly to a composite product
having improved structural strength, and other improved
properties o~er the present existing insulating sheathings
as will be discussed hereinafter.
BACKGROUND OF THE INVENTIGN
There are several kinds of exterior insulating sheath-
ings existing: Polystyrene, polyurethane, polyisocyanurate,
glass fiber, and phenolic sheathings are known and used.
These are normally 4 feet wide by 8 feet long or 4 x 9, and
occasionally 2 feet by 8 feet. However, these do not
possess the rigidity one would wish them to have. --
In house construction, generally walls are built on the
floor: The beams are laid down and khe sheathing fixed to
them, after which the wall is lifted to an upright
position: In Canada, walls that are constructed on the
floor and then upxaised, is termed platform construction.
~he insulating sheathings are normally 4 feet by 8 ~eet. In
order to fix the insulating sheathing one has to walk on the
2" x 6" or 2" x 4" beams, or beams having other size,
sometimes walking on the sheathing itself. Such walking on
the sheathing often results in its perforation due to its
weakness. Another problem associated with some sheathings
is their tendency to warp, yielding a surface which is not
flat, in particular the glass fiber one. In such cases, new
sheathing must replace the old one. Because sheathings of
glass fiber and foam have low strength, braces have also to
be put; this is an additional expense and adds to costs.
Also, there is no composite materials having exterior
insulating sheathing that exist. The composite materials
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that are known, are generally spot glued.
THE INVENTION
Applicant is now providing a sheathing which overcomes
part of, or all of the above mentioned drawbac~s. Broadly
stated, the invention is directed to an exterior insulating
sheathing comprising a foam polystyrene ply and a second ply
which is preferably a fiberboard ply or may also be a wafer
board, said second ply being glued to said polystyrene ply
throughout with a continuous layer of glue, so that said
continuous layer of glue is sandwiched between said foam
polystyrene ply and said second ply has to continuously
fasten said polystyrene ply to said second ply, to form a
unitary product defining a sheathing, said sheathing having
the exposed side of said second ply board water resistant,
said sheathing being nailable and having a racking minimum
load according to the ASTM E~72 of 1900 to 3700 lbs, a
minimum tensile strength of 65 + 14 kPa, a linear expansion
at 97~ relative humidity (RH) and 23C, of less than 0.40%
+ .02, and a minimum water vapour transmission of 96 at
least nonagram per second per meter s~uare (ng/Pa.s.m2)
and a modulus of rupture of 0.5 to 17.2 megaPascal (mPa).
BRIEF DESCRIPTION OF THE DRAWINGS
Further features, objects and advantages will be
evident following detailed description of the preferred
embodiments of the present invention taken in conjunction
with the accompanying drawings, in which:
Figure l is an exploded view illustrating one form of a
sheathing as obtained in a particular embodiment of the
present invention and position in a wall for better under-
30 standing.
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Figure 2 is a top view along line 2-2 of Figure 1.
Figure 3 is a segmented view illustrating another
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in Figures 1 and 2, the sheating 10, comprises
a ply of polystyrene foam 12, and a ply of fibre board 14,
glued throughout onto said polystyrene foam 12. Preferably,
the polystyrene foam 12 i5 good quality of expanded and
extruded polystyrene (such expanded polystyrene for instance
is obtained by steam expansion of polystyrene marbles). ~or
example, such a polystyrene may have a density of: 0.6 to
1.5 lb/ft3, and has a thickness of normally 1.5 inch
although it may vary within a thickness of 1.5 ~ 1 inch,
with the foam density according to the intended use.
The fiberboard ply 14 is normally in the order of about
half an inch or 7/16 of an inch, it is generally a
fiberboard which is asphalt coated on one side, as shown at
14a, said coated side to be the exterior side of the
sheathing 10. If desired, in order to obtain water
resistance of the exposed side of the second ply of the
sheathing, instead of a fiberboard which is asphalt coated,
an asphalt impregnated flberboard may be used.
The fiberboard ply 14 and the polystyrene foam ply 12 -~
have a continuous layer of glue 16 sandwiched in between, to
form a good unitary product. Although the layer 16 may be
hot melt glue, it is preferable to use a glue such as vinyl
acetate glue or other like glue compatible with the foam
layer 12 and the fiberboard layer 14. The glue 16 has to be
spread throughout the common surface adjacent the poly-
styrene foam ply 12 and the fiberboard ply 14. It is
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preferable to lay the fiberboard ply 14 in stagger
relationship on the polystyrene ply 12 as to obtain a ship
lap and thereby preventing a thermal bridge as shown at 18
and 20.
In accordance with my invention, it is also preferable
to produce these sheathing 10 in size 2" x 4' x 9'. In mak-
ing a wall, for instance, the exterior insulating sheathing
10 is nailed to the beams with polystyrene ply 12 facing the
beams (such as 2" x 6" or 2" x 4") which are laid on a
floor. During this operation, a person of normal weight can
walk over the sheathing 10 without occurance of breaking the
polystyrene ply 12: the fiberboard 14 enabling a greater
weight distribution over the polystyrene layer 12. Also,
generally it has been found that the present insulating
sheathing 10 when affixed to the beams eliminates need for
bracing, said sheathing 10 having sufficient structural
stren~th to hold the beams. Yet sheathing 10 is very easily
cuttable, and it was found to have excellent dimensional
stability aside from having good insulating
characteristics. Once fixed on the 2" x 6" or 2" x 4", the
wall is put on its upward position, the exterior o~ the
sheathing 10 which is the fiberboard ply 14 coated with
asphalt 14a is able to receive on it a finish 30, for
instance clad boards such as vinyl or aluminum type which
may be nailed through the sheathing 10 onto the beams.
From the interior in succession are added, for
instance, the glass fibre 40 in between the spacing created
by the beams 42, a air/vapor barrier 44 held in place by
strapping 46, and then the gypsum wall panel as shown in
Figures 1 and 2 next to strapping 46.
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Since the wall panels are generally 4' x 8', the 4' x
9' sheathing panels allow an overhand beyond the wall to
cover the floor spacing 50-52. Also, as is easily seen the
present invention allows for a gain 54 in the floor surface
area over the prior art that requires the insulating shea-
thing 10 to rest on the floor instead in accordance with
present invention said sheathing 10 is secured on beam 42.
As seen in Figure 3, the polystyrene foam ply 12 is fastened
by glue 16 to a waferboard 14b which is generally self-
1~ containing a wax coating as is illustrated by means of 14a.
Such a sheathing has generally a minimum tensile
strength of about 65 ~ 14 kPa, a linear expansion at 97% RH
and 23C of less than 0.40% + .02, and a minumum ~ater
vapour transmission of 96 nonagrams per second per meter
s~uare (ng/Pa.S.m2) a modulus of rupture of 0.5 to 17.2
megaPascal tmPa). When fiberboard is used, the minimum
rac~ing load is of the order of 2100 ~ 200 lbs and the
modulus of rupture is of the order of 0.6 + .1 megaPascal.
When a wafer board is used, the minimum racking load is more
of the order of 2300 + 300 lbs for a ply having a thickness
of 3/8" to 1/4" and 3500 ~ 200 for a ply of o.5 inch in
thickness and the modulus of rupture is 16.2 + 1 megaPascal.
The following will serve onl~ to illustrate particular
embodiments of the invention and to compare some of these
embodiments over the prior art.
EXAMPLE 1
An insulating sheathing was made using a 0.5 inch fiber-
board asphalt coated on one side, glued to a polystyrene
foam having a density of 1 lb/ft3 and a thickness of 1.5":
the R value was determined and found to be 6.85. This was
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compared against the following existing insulating sheathing
where R is shown:
Applicant's product - 1.5" 6.7
EscladTM Phenolic foam - 1.1" 6.0
GlascladTM glass fibre 1" 4.4
GlascladT~ glass fibre 1~" 6.7
EXAMPLE 2
Six insulating sheathing panels were made as in Example
1. The sheathing panels were a composite board of fiber-
board 7/16'i thick and expanded polystyrene 1-7/16" thick,
measuring nominally 4' x 9'. A racking load evaluation of
the six (6) sheathing panels was made.
Three standard wood frames were built in accordance to
ASTM Standard ~-72, Section 14, each frame accomodating 2
sheathing panels. Stud grade spruce wood was used instead
o~ the southern pine or douglas fir required by the
Standard.
Sheathin~ panels were fastened with 3" spiral wood
nails having a square plastic "washer" measuring lxl". The
nails were located at 6" intervals along the perimeter of
the frame assembly and at 4 of the intermediate studs.
Inside corner studs were not used to fasten the panels.
The mix-stud where the sheathing panels butt joint with
approximately 1/2" fiberboard overlap on the polystyrene,
nails were placed on both sheathing panels at varying angles
between 15 to 30 degrees from ~he vertical at 6" intervals.
A hydraulic ~ack with a nominal capacity of lO,OO0 lb
was used to apply the load. A Moog 5ervo controller and
load cell feedback system controlled the applied load which
was read in a Daytronic Model 9005 Strain Gage Transducer
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Conditioner/Indicator with a resolution of 5 lb.
Racking loads were applied at intervals varying between
50 and 250 lbs. Readings were taken immediately after
reaching each load level. Dial Gages #1 and #2 were removed
when damage was possible. The test results are shown in
Tables 1, 2 and 3.
TABLE 1
Frame Nool Dial Gage Readiny Load, lbs.
Inches
#1 #2 #3
O O O O
.115 0 .20 50
.310 .002 .67 100
.420 .047 1.10 150
1.53 400
1.77 500
2.05 600
2.16 700
2.68 850
3.07 1000
3-50 1200
5.27 1800
(Maximum racking load recorded)2220
TABLE 2
Frame No:2 Dial Gage Reading Load, Lbs
Inches
#1 #2 #3
O O O O
.468 .028 .67 260
30.476 .038 1.10 500
.632 .051 2.36 860
.688 .058 3.03 1000
4.57 1500
6.14 1800
7.12 1940
(Maximum racking loard) 2100
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TABLE 3
Frame No:3 Dial Gage ReadingLoad, Lbs
Inches
#1 #2 #3
S O O o o
.130 .015 .27 100
.235 .058 .55 200
.360 .228 1.26 400
.408 .243 1.61 500
10.445 .253 2.00 600
.492 .263 2.44 700
.525 .268 2.71 800
.555 .273 3.11 900
.585 .277 3.38 1000
15.610 .279 3.70 1100
.631 .281 3.97 1200
.660 .284 4.33 1300
5.00 1550
5.31 1600
5.75 1700
6.22 1800
(Maximum racking load) 2000
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EX~MPLE 3
1. INTRODUCTION
A sample sheathing panel was made as in Example
1. The panel had a first ~12 mm (1/2") bitumen coated
fibre board ply and a ~37 mm (1-1/2") expanded polystyrene
insulation board, and nominal dimensions of 1220 x 2743 x
50 mm (48" x 108" x 2"). The following tests were made:
1) Weight per unit area
2) Tensile strength (ASTM D1623)
- perpendicular
3) Racking load (ASTM) E73 Sect. 14)
4) ~inear expan~ion (ASTM D1037)
5) Water vapour transmission (ASTM E96)
6) Water absorption (ASTM D2842)
- after 2 and 24 hrs under 50 mm of H2O
7) Flexural strength (ASTM c2~3)
- at 250, 406 and 610 mm spans
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The results as shown in Tables 4, 5 and 6.
TABLE 4
(1) t2)* (3) (4)
Tensile Racking Linear
Weig~t Strength Load Expansion(%)
Specimen (kg/m-l (kPa) tlbs)max 97%RH. 23C
1 3.77 75.12,220 0.39
2 3.81 45.02,100 0.39
3 3.80 65.82,000 0.41
~ 3.80 74.2 0.42
0.41
6 0.38
Average 3.80 65.02,107 0.40
SD (n-l) 0.02 14.0110 0.02
(2)* Cohesive failure of the fiberboard
TABLE 5
Water vapour transmission Water absorption
Specimen (q/s.m2L (n /Pa.s.m2) (2 hrs) (24 hrs)
1 1.33x10-4 96.0 1.45 9.42
2 1.47x10-4 106.0 1.46 7.51
3 1.39x10-4 100.6 1.38 7.46
4 1.42 8.12
Average 1.40x10-4 100.9 1.43 8.13
25 SD (n-l) 7.0xlO 6 5.0 0-04 0.91
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TABLE 6
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Flexural Strength*
Specimen Modulus of Modulus of
Elasticity (MPA) Rupture (kPa)
250 406 610 250 406 610
1 17.8 26.7 28.1 584 542 572
2 16.8 27.8 29.8 613 601 567
3 17.0 27.6 29.6 591 535 587
4 17.6 24.5 29.4 610 543 529
10 5 18.1 27.4 30.3 562 594 598
Average 17.5 26.8 29.4 592 563 571
SD(n-l) 0.5 1.4 0.8 21 32 26
*With expanded polystyrene in tension
EXAMPLES 4 to 6
Four pieces of polystyrene foam composi~,e boards with
each board measuring approximately 1200 x 1200 x 48 mm (48"
x 48" x 1-7/8") were made with 38 mm thick polystyrene foam
and bonded with 10 mm thick compr~ssed wood fiberboard.
These insulation products were analyzed ~or thermal
conductivity and thermal resistance determination as
follows:
1) Equipment
The Dynatech R-Matic heat-flow meter having a test
accuracy of about + 2% was used to perform all tests. This
instrument has the established capabili~y of measuring test
sample with thickness up to 200 mm and it conforms to ASTM
C-518, Standard Test Method for Steady-State Transmission
Properties by Means of the Heat-Flow Meter.
2) Sample Preparation
Three boards were randomly selected for sample
preparation. (Examples 4 to 6). A test specimen measuring
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610 x 610 mm (24" x 24") was prepared from the central
portion of each board. The thickness of the test specimens
was measured accurately with a dial gauge in 12 points and
an average thickness value was determined. The total mass
of each specimen was weighed to an accuracy of + 0.01 kg.
The mass and thickness of the test specimens are given in
Table 7.
The prepared test specimens were conditioned at 25C
and 50% R.H. humidity for 48 hours prior to the test.
3) Test Procedure
Each of the test specimen was first placed in the test
chamber of the instrument and the chamber plate separation
was set at the exact thickness of the sample. The
instrument was then activated and equilibrated until a
steady-state condition was reached. For each test, the test
specimen has been kept in the instrument for a period
totalling about 4.5 hours to monitor the steady-state equi-
librium condition by a computer controlled data acquisition
system. The test was conducted at atmospheric pressure and
ambient room conditions, with room temperature in the range
of 22-24C and humidity in the range of 45-50% R.H. The
mean temperature of each test sample was about 24.5 +
0.1C and the temperature differential across the test
specimen was about 22.1 + 0.1C.
RESULTS
The thermal conductivity, K-factor, and thermal resis-
tance, R-value, of the test samples have been determined and
are given in the-following Table 7, in both metric SI units
and imperial units.
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TABLE 7
Thickness, Foam Mass and Foam Density of Test Samples
Test Specimen
Average
Thickness Foam Mass Foam ~ensity
Example (mm) (inch) (kq~(lbs) (Kg/m~)(lbs/ft3~
#4 48.60 1.91 1.41 3.10 77.79 4.08
#5 48.58 1.91 1.44 3.17 79.35 4.96
#6 48.58 1.91 1.39 3.06 76.40 4.79
10Average 48.59 1.91 1.41 3.11 77.94 4.61
Thermal Conductivity, Thermal Resistance
and K-Factor R/unit thickness
Imperial
Imperial Metric SI Unit
Metric SI Unit Un2it (ft ,hr
Unit (Btu/ft2 (m C/M) F/Btu)
Example (W/mC) hr,F/inL /m _ /in
#4 0.0425 0.2947 23.529 3.393
#5 0.0428 0.2970 23.364 3.367
#6 0.0414 0.2874 24.154 3.479
20Average 0.0422 0.2930 23.682 3.413
Thermal Resistance, R-Value, per Test Sample Thickness
Met~ic SI Unit Imp2erial Unit
Example _~ C/W) (ft ,h,F/Btu)
#4 1.143 6.493
25#5 1.134 6.438
#6 1.172 6.656
Average 1.149 6.529
Mod~fications may be made without departing from the
spirit of the invention as defined in the appended claims.
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