STRUCTURAL PERFORMANCE 

OF COP+-PLY STUDS MADE 

kWTH -iaWBRB5@OOD VENEERS 

COOPERATIVE RESEARCH 
June 1979 

Satrlheasterrs Forest Experi~nent Station 

Asi~euiile, Ner tb~ Carolina 
STRUCTURAL PERFORMANCE OF COM-PLY STUDS MADE WITH 

HARDWOOD VENEERS 

Robert H. McAlister, Principal Wood Scientist 

Forestry Sciences Laboratory 

Athens, Georgia 

Cooperative Research by 

U.S. Department of Agriculture, Forest Service 

Southeastern Forest Experiment Station 

and 

U.S. Department of Housing and Urban Development 

Division of Energy, Building Technology 

and Standards 
PREFACE 

This report is one of a series on the possibilities of producing house framing and structural panels with 

particleboard cores and veneer facings. These COM-PLY or composite materials were designed to be used 

interchangeably with conventional lumber and plywood in homes. Research on structural framing was 

initially limited to COM-PLY studs but has now been extended to include larger members such as floor 

joists. 

In 1973, the home-building industry faced a shortage of lumber and plywood and consequent rising 

prices. Both industry and government recognized that this situation was not a temporary problem, and that 

long-range plans for better using the Nation's available forest resources would be necessary. 

The Forest Service of the U.S. Department of Agriculture and the U.S. Department of Housing and 

Urban Development accelerated cooperative research on ways to utilize the whole tree. They concentrated 

on composite wood products made with particleboard and veneer as a way of using not only more of the tree 

stem, but also using less desirable trees and a greater variety of tree species than would conventional wood 

products. The particleboard which comprises a large portion of COM-PLY studs and joists is made from 

chipped-up wood that comes from forest residues, mill residues, or low-quality timber. Thus, such 

composites could greatly increase the amount of lumber and plywood available for residential construction, 

our major use of wood, without eroding the Nation's timber supply. 

Research on composite wall and floor framing was performed by the Wood Products Research Unit, 

Southeastern Forest Experiment Station, Athens, Georgia. The American Plywood Association cooperated 

in these studies by designing and testing composite panel products that are interchangeable with plywood. 

Both types of products have been incorporated in demonstration houses. 

Included in this series will be reports on structural properties, durability, dimensional stability, 

strength, and stiffness of composite studs and joists. Other reports will describe the overall project, 

compare the strength of composite and solid wood lumber, suggest performance standards for composite 

lumber, and provide construction details on houses incorporating such lumber. Still others will explore the 

economic feasibility of manufacturing composite lumber and panels and estimate the amount and quality of 

veneer available from southern pines. These reports, called the COM-PLY series, will be available from the 

Southeastern Forest Experiment Station and the U.S. Department of Housing and Urban Development. 
CONTENTS 

Page 

MATERIALS .................................................................................................................... 2 

PERFORMANCE TESTS ..................................................................................................... 3 

METHODS ................................................................................................................ 3 

RESULTS .................................................................................................................. 3 

STATIC BENDING ............................................................................................................ 3 

METHODS ................................................................................................................. 3 

RESULTS .................................................................................................................. 3 

TEST OF COMPRESSION PARALLEL TO GRAIN ................................................................. 8 

METHODS ................................................................................................................. 8 

RESULTS .................................................................................................................. 9 

TESTS OF COMPRESSION PERPENDICULAR TO GRAIN ..................................................... 11 

METHODS ............................................................................................................... 11 

RESULTS .................................................................................................................. 11 

NAILING TESTS OF COM-PLY STUDS ................................................................................ 14 

METHODS ................................................................................................................ 14 

RESULTS ............................................................................................................... 14 

CONCLUSIONS ............................................................................................................... 14 

LITERATURE CITED ........................................................................................................ 15 
ACKNOWLEDGMENT 

The Forestry Sciences Laboratory, Wood Products Research Unit, acknowledges the valuable 

assistance and guidance of: 

Orville G. Lee, AIA 

Howard C. Hilbrand, PE 

U.S. Department of Housing and Urban Development 

Charles R. Morschauser, Technical Director 

National Particleboard Association 
STRUCTURAL PERFORMANCE OF COM-PLY STUDS 

MADE WITH HARDWOOD VENEERS 

ABSTRACT.--€OM-PLY 2 x 4 studs made with veneers of yellow-poplar, sweetgum, and white oak 

were tested for strength and stiffness, nail-holding properties, modulus of elasticity of component 

parts, static bending, and compression parallel and perpendicular to the grain. All tests were 

conducted according to performance standards for composite studs used in exterior walls or ASTM 

standards. Results indicated that the tested properties of COM-PLY 2 x 4's with any of the three 

hardwood veneers are comparable to those of COM-PLY 2 x 4's with southern pine veneers and to 

2 x 4's of solid wood. 

KEYWORDS: Modulus of elasticity, strength, stiffness, bending,compression, nail-holding ability, 

veneer, particleboard. 

The Forest Service, U.S. Department of Agriculture, the Department of Housing and Urban Development, and several manufacturers of forest products have cooperated in developing a new composite lumber 

product. This product, the COM-PLY stud, is a structural sandwich with a particleboard core placed 

between layers of solid wood veneer. 

The major use of forest products is in residential and commercial construction. Almost all of the wood 

products used in construction are softwoods. This dependence on softwoods is based on their availability, 

ease of drying and nailing, and generally lighter weight in comparison with hardwoods. Projections indicate 

that the future demand for softwood products will exceed supply. 

Forested land in the United States is predominantly in hardwoods. If future demands for forest products 

are to be satisfied, methods must be found to use more of our hardwood resource. Select hardwood lumber 

and veneer have always had a ready market for use in furniture, cabinets, and paneling. For centuries, the 

hardwood forests have been selectively cut-the high-value trees have been taken and the culls and less 

desirable species have been left. Consequently, the residual hardwood stands would require more money to 

harvest and prepare for restocking than would accrue from selling the harvested timber for conventional 

processing. 

The COM-PLY approach to manufacturing composite lumber and panels is ideally suited to the 

efficient use of hardwood stands. Composite products reduce or eliminate the major problems with 

hardwood utilization-long drying times, poor dimensional stability, and the difficulty of obtaining large 

sizes and long lengths of lumber. Since 60 to 80 percent of a COM-PLY product consists of the particleboard 

core, such products can utilize low-quality forest or manufacturing residues. 

There is an abundant supply of several species of hardwoods that are not being used. Consequently, 

potential manufacturers and users of COM-PLY studs need to know about the structural performance of 

COM-PLY studs made with hardwood veneers. COM-PLY studs might be used for blocking, posts, headers, 

beams, or plates. Engineers and building code officials need to know whether COM-PLY studs made from 

hardwood veneers have sufficient structural strength for these uses. 

The strength properties of greatest interest are (I) suitability for use as studs as measured by a 

performance test of strength and stiffness; (2) working stresses for extreme fiber in bending as measured by a 
static bending test; (3) axial load-bearing capacity, or strength in compression parallel to the grain; 

(4) bearing, or strength in compression perpendicular to the grain of the face plies; and (5) nail-holding 

ability. 

This report, directed principally to designers and engineers, describes how the above strength and 

mechanical properties were determined for COM-PLY studs made with three species of hardwood veneers. 

This report is closely related to COM-PLY Report 12, "Structural Properties of COM-PLY Studs," which 

discusses the characteristics of COM-PLY studs made with softwood veneers (McAlister 1978). 

MATERIALS 

Yellow-poplar (Liriodendron tulipifera L.), sweetgum (Liquidambar styraciflua L.), and white oak 

(Quercus alba L.) make up over 50 percent of the volume of hardwood stands in the Piedmont of the 

Southeastern United States. We selected these three species for testing as the veneer components of 

COM-PLY studs. 

The test studs were fabricated with 116-inch-thick veneers which were available from a veneer gradeyield study. Performance standards for composite studs (Blomquist and others 1976) specify that a sample of 

10 studs be used to test performance. We decided on the basis of previous tests that a sample of five studs 

would be sufficient to determine structural properties. Thus, for our series of tests, 15 COM-PLY studs were 

needed for each hardwood species, or 45 COM-PLY studs in all. 

To relate modulus of elasticity (MOE) of the stud components to the physical properties of the 

assembled COM-PLY studs, we had to determine the MOE of the components before the studs were 

fabricated. We randomly selected 64 strips of veneer of each species to represent all veneer cut from tree 

diameter classes of 12 to 20 inches. All strips were 1.5 inches wide, 96 inches long, and nominally 116 inch 

thick. All of the veneer had been conditioned to equilibrium moisture content at 70°F and 40 percent 

relative humidity. 

We used the stress-wave method of determining dynamic modulus of elasticity (MOEd) for each strip. 

This method has been described by Koch and Woodson (1968). 

The veneer strips were then laminated together into pairs with a phenol-resorcinol adhesive according 

to the procedures of Vick (1977). The strips were laminated together in predetermined order (strip 1 to strip 2, 

. . . strip 63 to strip 64) so that the MOE of each component strip was known. After laminating, the MOEd of 

each laminate was determined by the stress-wave technique. 

The core material used in this study was a phenolic-bonded particleboard 1% inches thick. The 

particleboard had an average density of 40 Iblft3, an internal bond of 75 lblinz, an MOE (in plane of panel) of 

300,000 Ib/in2, and contained 8 percent phenolic resin binder throughout the three layers. 

Cores for COM-PLY studs were ripped to a width of 2.83 inches. We determined the MOE of the core as 

a beam 1.5 inches wide and 2.83 inches deep by center-loading as a simple beam over a span of 90 inches. 

Deflections at midspan were measured to the nearest 0.001 inch for loads of 10,20, and 30 pounds. We used a 

dial gage mounted on a yoke to measure the deflections. To calculate the MOE in bending (MOE,,), we 

subtracted the deflection at 10 pounds of load from the deflection at 30 pounds of load and determined the 

slope of the loadldeflection curve for this 20-pound increment. The MOEd of the veneer strips and the MOEb 

of the particleboard core were used in all calculations. 

The two-ply strips were laminated to the cores with the odd-numbered strips to the outside of the 

assembled stud. Thus, the position of each ply in each stud was known. The gluing procedures used in 

fabricating the COM-PLY studs had proved satisfactory in previous studies (Vick 1977). 

After fabrication, 10 studs from each species group were selected at random for the performance 

testing. The remaining five studs were cut into segments for the strength tests, as shown in figure I. 

Figure I.-Location of stud segments for the three strength tests: A, static bending; B. compression 

parallel to the grain; C, not used; D, compression perpendicular to the grain. 
Properties of transformed sections were calculated for all studs according to the method found 

satisfactory in a previous study (McAlister 1978). Transformed sections were used to calculate all allowable 

strength properties except static bending. 

PERFORMANCE TESTS 

METHODS 

We conducted the performance tests according to the procedures outlined in "Performance Standards 

for Composite Studs Used in Exterior Walls" (Blomquist and others 1976). In addition to the combined axial 

and transverse loading specified, all studs were first tested on edge in static bending under limited load. We 

used quarler-point loading over a %-inch span to a maximum load of 250 pounds to determine the bending 

stiffness factor or EI. To calculate the EI of the COM-PLY studs, we subtracted the deflection under 100 

pounds of load from the deflection at 200 pounds of load and calculated the slope of the loadldeflection curve 

for the resulting 100-pound load increment. 

RESULTS 

The results of the performance tests and the static bending tests under limited load for COM-PLY studs 

made from yellow-poplar, sweetgum, and white oak veneer are shown in table 1. 

The predicted EI was higher than the actual EI for the yellow-poplar and sweetgum studs and lower than 

the actual EI for the white oak studs. The predicted EI values averaged within 7 percent of the actual EI 

values. Somewhat closer predictions could be made if the dynamic MOE of the veneers were corrected to 

tensile MOE. Note that the transformed moment of inertia, It, is a little more than half the geometric I of a 

1.5-inch-wide by 3.5-inch-deep beam section. 

The performance standards for composite studs (Blomquist and others 1976) specify test methods and 

the methods of calculating allowable loads and allowable deflection. Applying these procedures to the 

average deflections and maximum loads given in table 1 yields the results shown in table 2. COM-PLY studs 

with veneers of yellow-poplar, sweetgum, and white oak met the performance criteria. The values are 

comparable to the performance values of COM-PLY studs made with southern pine veneers. 

We plotted loadldeflection curves for each of the studs for the static bending and the combined loading 

tests (axial load of 1,190 pounds plus bending load). A typical plot of the two curves is shown in figure 2. Note 

that axial loading increases the stiffness of the COM-PLY studs because of the reaction moment at the fixed 

reaction block in this test. 

STATIC BENDING 

METHODS 

We performed structural static bending tests according to the methods outlined in ASTM D 198-76 

(ASTM 197%). The test span was 69 inches with loads applied at one-third points by a universal testing 

machine. Head speed was maintained at 0.25 inch per minute. Height and width of the test segments were 

recorded to the nearest 0.001 inch. Deflections under load were determined by using a dial gage mounted on 

a yoke, and readings were taken to the nearest 0.001 inch at 100-pound load increments until the deflection 

was at least 0.500 inch. The gage and yoke were removed and the test was continued until failure. We 

recorded the time required to load the specimen to failure, the method of failure, and the maximum load. 

We calculated the bending stiffness, Elb, of the COM-PLY studs by subtracting the deflection at 100 

pounds of load from the deflection at 300 pounds of load and determining the slope of the loadldeflection 

curve for the resulting 200-pound increment. 

RESULTS 

The results of the structural static bending tests for the COM-PLY studs made with the three species of 

hardwood veneers are shown in table 3. The transformed moment of inertia (I,) for the COM-PLY studs 
Table 1 .--Component MOE values, stiffness factors, and performance test results for COM-PLY studs made with three species of hardwood veneers 

White oak 

Million lb/in2 . . . . . . 

1.82 1.84 

1.82 1.84 

1.98 2.09 

2.01 1.95 

2.26 2.28 

2.16 2.14 

2.1 0 2.1 1 

2.30 2.20 

2.07 2.16 

2.51 2.49 

Million lh/in2 

5.41 5.71 

5.41 6.74 

5.80 5.93 

5.89 6.37 

6.44 6.74 

6.22 5.93 

6.1 1 6.41 

6.65 6.96 

6.02 6.61 

7.13 7.91 

Avg. 

SD 

Avg. 

SD 
Table 1 .-Component MOE values, stiffness factors, and performance test results for COM-PLY studs made with three species of hardwood veneers-continued 

. . . . . illi ion lb/inZ . . . . . . rn4 Million lb/in In Lb Lb/fl 

ul Sweetgum 

Avg. 

SD 

Transformed 

moment 

of inertia 

(It) 

Bending stiffness 

(El) 

Perfarmance values 

Veneer 

species 

Stud 

No. 

Ultimate 

load per foot 

of span 

(w) 

Component MOE 

Ultimate 

load 

Deflection 

at 225 Ib 

Predicted 

- 

Average 

laminate 

MOEd 

Core 

MOEb 

Actual 

static 

bending 

Average 

strip 

MOEd 
Table 2.-Summary of performance values for 

COM-PLY studs made with three species of 

hardwood veneers 

Yellow-poplar 

Sweetgum 

White oak 

Veneer 

species 

*W must be greater than 40 to pass performance standard. 

**D must be less than 0.412 to pass performance 

standard. 

- 

@ COMBINED AXIAL AND BENDING LOADS 

Adjusted 

load 

(W*) 

0.1 0.2 0.3 04 0.5 0.6 0.7 0.8 0.9 1.0 

DEFLECTION (INCHES) 

Adjusted 

midspan 

deflection 

(D**) 

Figure 2.-Typical loadldeflection curves for two methods of loading COM-PLY studs. 
Table 3.-Results of structural static bending tests on COM-PLY studs made with three species of hardwood veneer as based on transformed section analysis 

Million lb/in fn4 

White oak 1 2.02 0.280 3.33 

2 2.19 .3 1 1 3.48 

5 2.65 .30 1 3.30 

13 2.27 .283 3.38 

15 2.04 .237 3.20 

Avg . 2.23 .282 3.34 

S D .255 .028 .I01 

Avg . 1.96 .289 3.28 I .48 1.74 5.57 6.44 1,243 14,295 4,45 2 

SD .I75 .018 .I13 ,046 .05 7 .489 .599 266 3,056 950 

Maxinlum 

fiber 

stress 

(MOW 

Sweetgum 

Veneer 

species 

Avg . 1.82 .29 1 3.22 1.47 1.76 4.90 5.85 1,097 12,615 3,971 

SD .I29 .033 .09 1 .059 .118 .249 .266 158 1,823 59 1 

*Transformed to average veneer MOEd base. 

**(EItdp = (Average veneer MOEd) x (It). 

tMOR calculated by using section modulus for 1.5-inch x 3.5-inch section. 

Stud 

No. 

Bending stiffness 

(EI) 

Ultimate 

Actual load 

(EIb) 

Maximum 

moment 

t 

Average 

veneer 

MOEd Predicted** 

(EIblp 

Core 

MoEb 

Properties of 

transformed sections 

Area 

(4) 

Moment of 

inertia* 

(It) I 

Section 

modulus 

(St) 
averaged between 3.22 in4 and 3.43 in4. These values are somewhat greater than the 2.75 in4 value found for 

COM-PLY studs made from slash pine veneer. Part of the difference is due to the generally lower MOEd of 

the hardwood veneers in comparison with that of slash pine and also to the slightly greater depth (0.067 inch) 

of the studs made with the hardwood veneers. 

The best predictor of actual bending stiffness (EIb) for the COM-PLY studs was the average MOEd of 

the four plies of veneer. There were species differences in the linear regression equations, as follows (all 

moduli in million 1blin2): 

Veneer Coefficient of 

species Regression determination 

rZ 

Yellow-poplar EIb = 1.299 + 2.175 x (average veneer MOEd) 0.6 1 

Sweetgum EIb = 2.135 + 1.516 x (average veneer MOEd) .62 

White oak EIb = 7.330 - 0.447 x (average veneer MOEd) .08 

Slash pine EIb = 2.43 + 1.53 x (average veneer MOEd) .74 

The regressions for yellow-poplar and sweetgum are quite similar, but there appears to be no linear 

relationship for the studs made from white oak veneers. The significant result is that the bending stiffness of 

COM-PLY studs made from yellow-poplar and sweetgum can be predicted with a good degree of accuracy. 

There was little linear correlation between modulus of rupture (MOR) and average veneer MOEd for 

COM-PLY studs made from hardwood veneers. This lack of correlation was surprising because there was a 

close correlation (r2 = 0.73) found for this relationship in GOM-PLY studs made from slash pine veneer. 

The allowable bending stress based on rectangular section modulus and safe resisting moment in 

bending were calculated by a formula proposed in ASTM D 245-74 (ASTM 1978a): 

Allowable Average ultimate strength - to.os (SD, standard deviation) 

strength = 

property 2.1 

where to.o5 = 2.132 for 4 degrees of freedom. A more conservative approach to establishing allowable 

stresses can be foudd in ASTM D 2915-74 (ASTM 1978b). The allowable stresses presented below apply only 

to COM-PLY studs made from materials with properties similar to those used in this study: 

Veneer All'owable fiber Safe resisting 

species Average EI stress moment 

............ Lb/ine ............ Znllb 

Yellow-poplar 5.57 x lo6 1,156 3,704 

Sweetgum 4.90 x lo6 1,291 4,156 

White oak 6.33 x lo6 2,086 6,804 

A larger sample would tend to increase these allowable design values for COM-PLY studs made with 

hardwood veneers by decreasing the value and standard deviation. 

The COM-PLY studs made from yellow-poplar and sweetgum have about half the allowable fiber stress 

value found for COM-PLY studs made from slash pine veneer. However, the values for studs made from 

yellow-poplar and sweetgum are higher than the 850 lblin2 allowable for stud-grade, kiln-dried studs of 

southern pine (NFPA 1977a). 

TESTS OF COMPRESSION PARALLEL TO GRAIN 

METHODS 

A strength property of interest to engineers and designers is compression strength parallel to the long 

axis of the stud. Axial loading simulates the use of the stud as a column carrying compressive loads. 

The procedure we used to test compression parallel to the veneer grain was based on the recommenda- 
tion in ASTM D 198-76 (ASW 1978~). Load was applied through a spherical loading head on a universal 

testing machine. We recorded deflections over a &inch gage length (to the nearest 0.0001 inch) for each 

1,000-pound load increment until the COM-PLY column failed. 

The loadldeflection curve for each COM-PLY column was plotted so that the load at the proportional 

limit could be determined. A typical loadldeflection curve is shown in figure 3. For each column we recorded 

ultimate load, the time needed to apply that load, and the weight of the section. All dimensions were 

measured and recorded to the nearest 0.00 1 inch. 

RESULTS 

The results of the compressive-load tests are shown in table 4. The average compressive strength 

(ultimate stress) for the short columns made from COM-PLY studs varied according to wood species, with 

1 I I I I I i I I I 

0.002 0.004 0.006 0,008 0.010 0.012 0.014 0.016 0.018 0.020 

DEFLECTION ( INCHES) 

Figure 3.-Typical loadfdeflection curve for compression parallel to grain of COM-PLY studs made 

with hardwood veneers. 
Table 4.-Values of compressive-load strength and stiffness for COMPLY studs made with hardwood veneers as based on transformed areas 

...... Lb ........ . . . . . Lb/in2 . . . . . In Million lb/in 

White oak 

Avg . 

SD 

Transformed 

area 

(At) 

Ultimate 

stress 

Veneer 

species 

Avg. 

SD 

Compressive 

MOE 

Sweetgum 

Stud 

No. 

38 7,000 1 1,300 4,299 6,932 1.63 3.68 

40 7,000 1 1,520 4,217 6,940 1.66 2.41 

4 1 8,000 12,560 4,252 6,681 1.88 2.28 

42 8,000 12,860 4,261 6,840 1.88 2.66 

44 8,000 12,120 4,511 6,847 1.77 3.08 

Avg . 7,600 12,072 4,308 6,848 1.76 2.82 

SD 548 664 117 104 .I 18 .570 

Stress at 

proportional 

limit 

Load to 

proportional 

limit 

'Itimate 

load 
white oak being the strongest and sweetgum the weakest. 

The allowable compressive stresses (f,) based on transformed section area for COM-PLY studs made 

with the three species of hardwood veneer, as calculated by the same basic formula (ASTM 19784 used for 

bending stresses, were as follows: 

Veneer Average compressive Allowable compressive 

species ultimate stress stress 

..... ..... . . .. Lblin2 .. . ... . ... . .. . . 

Yellow-poplar 7,382 2,999 

Sweetgum 6,848 3,155 

White oak 7,750 3,094 

The fc values for COM-PLY studs made with the three species of hardwood veneer compare favorably with 

the allowable f, of 3,432 1b/in2 found for COM-PLY studs made with slash pine veneers and with the 

allowable f, of 675 Ib/in2 for stud-grade, kiln-dried 2 x 4's of southern pine (NFPA 1977a). 

The compressive MOE's based on transformed section areas of the COM-PLY studs made with 

hardwood veneers were quite high, with yellow-poplar and white oak studs averaging over 3.5 million lb/in2 

and sweetgum studs averaging over 2.8 million lb/in2 (table 4). 

Surprisingly, there was no correlation found between the compressive MOE and the bending stiffness 

and modulus of rupture for COM-PLY studs made with hardwood veneers. Reasonably good correlations 

for these relationships were found for COM-PLY studs made with slash pine veneers. 

TESTS OF COMPRESSION PERPENDICULAR TO GRAIN 

METHODS 

The test for compression perpendicular to the veneer grain measures a stud's ability to resist crushing 

or bearing loads. Our test of this property was based on the procedures outlined in ASTM D 143-52 (ASTM 

1978d). Only the 1%-inch-wide veneer edge was tested because the veneer plies in the 3%-inch face were not 

perfectly aligned with the core. Removing enough core and veneer material to provide flat, parallel surfaces 

would have caused erroneous test results. 

The tests were made on a universal testing machine with a capacity of 10,000 pounds. Head speed was 

0.01 inch per minute. We measured the deflection of the 2-inch-wide loading block (to the nearest 0.0001 

inch) for each 200-pound load increment until the total deflection reached 0.10 inch. We considered that the 

0.10-inch deflection constituted failure. This load was recorded as the maximum load. 

The loadldeflection curve was plotted so that the load at the proportional limit could be determined. A 

typical load/deflection curve is shown in figure 4. For each test segment we recorded the weight, all 

dimensions to the nearest 0.001 inch, the identification number of the outer veneer ply under the loading 

block, and the time required to reach a deflection of 0.10 inch. 

RESULTS 

Results of these tests are shown in table 5. The average fiber stress at proportional limit for all species 

was considerably higher than for COM-PLY studs made from slash pine veneer. The allowable bearing 

stresses calculated by the same basic formula (ASTM 1978a) would be: 

Allowable Average stress at proportional limit - (SD) 

bearing = 

stress 1.5 

Such calculations would yield the following results for COM-PLY studs made with the three species of 

hardwood veneer: 
Veneer Allowable bearing 

species stress 

Lblin' 

Y ellow-poplar 432 

Sweetgum 547 

White oak 60 1 

These allowable stresses in bearing are greater than the 405 lb/in~llowable (NFPA 19774 for 

stud-grade, kiln-dried 2 x 4's of southern pine and the 227 Iblin%llowable for COM-PLY studs made with 

slash pine veneers (McAlister 1978). 

DEFLECTION ( INCHES) 

Figure 4.-Typical load/deflection curve for compression perpendicular tograin ofCOM-PLY studs made with 

hardwood veneers. 
Table 5.---Values of compression perpendicular to the veneer face for COM-PLY studs made with three species of hardwood veneers 

White oak 

Veneer 

species 

Million Eblin ...... Lb ....... . . . . . I, b/in2 . . . . . 

1 0.280 2.02 3,000 5,480 1,003 1,832 

2 .3 1 1 2.19 3,400 7,100 1,130 2,359 

5 .301 2.65 3,600 6,330 1,200 2,110 

13 .283 2.27 3,400 5,580 1,127 1,850 

15 .237 2.04 3,000 5,320 995 1,765 

Avg. .282 2.23 3,280 5,962 1,09 1 1,983 

SD .028 .255 268 745 89 248 

Stud 

No. 

24 .285 2.03 2,400 5,450 805 1,829 

27 .274 1.74 2,400 5,380 797 1,786 

28 .285 2.17 2,400 4,670 803 1,563 

29 .319 2.05 3,000 6,000 1,000 2,000 

3 0 .276 1.83 3,000 5,640 1,000 1,880 

---- 

Avg . .289 1.96 2,640 5,428 88 1 1,812 

SD .018 .I75 329 487 109 160 

Sweetgum 

Core 

MOEb 

Avg . SD 

Average 

veneer 

Load at 

0.10-inch 

Load at 

proportional 

t MOEd limit compression 

Stress at 

proportional 

-- 

Stress at 

maximum 

limit load 
NAILING TESTS OF COM-PLY STUDS 

METHODS 

Nailing tests were performed on the unbroken sections of COM-PLY studs used for performance 

testing. We tested lateral load on joints between plywood wall facings and the veneer faces of studs and 

direct nail withdrawal from the narrow faces of studs according to procedures described by Walker (1977). 

We did not perform tests involving the stud-to-plate joint because these values are primarily a function of the 

nailing characteristics of the particleboard core. The results for COM-PLY stud-to-plate joints with this core 

material have been published (Walker 1977). 

RESULTS 

The results of the lateral load tests of plywood-to-stud joints are shown in table 6. Specifications issued 

by the National Forest Products Association (NFPA 1977b) set the allowable lateral design load for this type 

of joint at 5 1 pounds when spruce studs are used. COM-PLY studs made with yellow-poplar, sweetgum, and 

white oak exceeded this minimum requirement. The same specifications give the allowable lateral design 

loads for Group I woods (ash, beech, maple, and oak) at 78 pounds for the kind of joints used in this test. 

Both sweetgum and white oak COM-PLY studs exceeded this value, and the yellow-poplar studs almost 

equaled it. 

The results of the direct nail withdrawal tests are shown in table 7. There are no specifications for this 

type of test. However, the resistance to direct withdrawal of all nail types tested with COM-PLY studs made 

with hardwood veneers equaled or exceeded the comparable values for spruce studs in previous tests 

(Walker 1977). 

CONCLUSIONS 

COM-PLY studs made with yellow-poplar, sweetgum, and white oak veneers met the performance 

criteria for composite studs used in exterior walls. Thus, potential manufacturers of COM-PLY studs can 

use these readily available hardwood veneers to produce studs. 

The engineering properties of COM-PLY studs made with yellow-poplar, sweetgum, and white oak 

veneers are comparable to the values for kiln-dried, stud-grade lumber of southern pine and compare 

favorably with COM-PLY studs made with high-quality veneer of slash pine. 

COM-PLY studs made with the three tested species of veneer can be used with standard fasteners in 

common applications. Allowable load values per nail equal or exceed values found for spruce studs. 

Table 6.-Values from lateral load test of 

plywood-to-stud joints for COM-PLY studs 

made with three species of hardwood veneers 

Average Veneer ultimate Standard Adjusted 

species load 

............... Lb ..... ..... . .... . 

Yellowpoplar 287 6 1 75 

Sweetgum 3 19 45 113 

White oak 269 34 10 1 
Table 7.-Loads resulting from testing direct withdrawal of nails fastened to the 

narrow faces of COM-PLY studs made with three species of hardwood veneers 

..................... Lb ..................... 

Yellow-poplar drywall 156 36 37 

8d common 258 42 84 

16d box 236 39 76 

Sweetgum drywall 177 11 8 1 

8d common 289 46 96 

16d box 29 1 34 112 

White oak drywall 180 25 64 

8d common 266 32 102 

16d box 2 14 29 77 

Veneer 

species 

LITERATURE CITED 

American Society for Testing and Materials 

1978a. Standard methods for establishing structural grades and related allowable properties for visually graded lumber. D 245-74. 

ASTM Stand., Part 22, p. 139-150. 

American Society for Testing and Materials 

1978b. Standard method for evaluating allowable properties for grades of structural lumber. D 2915-74. ASTM Stand., Part 22, 

p. 824-833. 

Nail 

type 

American Society for Testing and Materials 

1978~. Standard methods of static tests of timbers in structural sizes. D 198-76. ASTM Stand., Part 22, p. 113-138. 

American Society for Testing and Materials 

1978d. Standard methods for testing small clear specimens of timber. D 143-52(72). ASTM Stand., Part 22, p. 52-109. 

Blomquist, Richard F., John E. Duff, Gerald A. Koenigshof, Robert H. McAlister, and DickC. Wittenberg 

1976. Performance standards for composite studs used in exterior walls. U.S. Dep. Agric., For. Serv., Res. Pap. SE-155, 

COM-PLY Rep. 2,24 p. U.S. Dep. Agric., For. Serv., Southeast. For. Exp. Stn., Asheville, N.C. 

Koch, Peter, and G. E. Woodson 

1968. Laminating butt-jointed, long-run, southern pine veneers into long beams of uniform high strength. For. Prod. J. 

18( 10):45-5 1. 

McAlister, Robert H. 

1978. Structural properties of COM-PLY studs. U.S. Dep. Agric., For. Serv., Res. Pap. SE-180, COM-PLY Rep. 12, 15 p. U.S. 

Dep. Agric., For. Serv., Southeast. For. Exp. Stn., Asheville, N.C. 

National Forest Products Association 

1977a. Design values for wood construction. A supplement to the 1977 edition of National Design Specification for Wood 

Construction. Natl. For. Prod. Assoc., Washington, D.C. 20 p. 

National Forest Products Association 

1977b. Structural lumber, glued laminated timber, timber piling, fastenings. A supplement to the 1977 edition of National Design 

Specification for Wood Construction. Natl. For. Prod. Assoc., Washington, D.C. 78 p. 

Vick, Charles B. 

1977. Adhesives for COM-PLY studs. U.S. Dep. Agric., For. Serv., Res. Pap. SE-171, COM-PLY Rep. 6, 20p. U.S. Dep. 

Agric., For. Serv., Southeast. For. Exp. Stn., Asheville, N.C. 

Walker, Roy M. 

1977. Structural performance of nailed joints withCOM-PLY studs. U.S. Dep. Agric., For. Sew., Res. Pap. SE-175, COM-PLY 

Rep. 8, 18 p. U.S. Dep. Agric., For. Serv., Southeast. For. Exp. Stn., Asheville, N.C. 

b U.S. GOVERNMENT PRINTING OFFICE: 1979 - 644-148 

Average 

ultimate load 

Standard 

deviation 

Adjusted 

load 


The Forest Se:i;ice, U S, 

Department of Ag:;ctiitiii8,tS 

dedicated to :ha ~ri"iclp/e of 

muiinpis rr;a-;agemi.nt 9f the 

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fecreaton Through forestry 

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service to a growing Nation, 

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agatnst IP sni USDA-rnlaled activity sbc?u~@ write 

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Washington, 0 C 26%256