United States

Department of

Agriculture

Forest Service

Forest

Products

Laboratory

Research

Paper

FPLRP578

Ten-Year Performance

of Treated Northeastern

Softwoods in Aboveground

and Ground-Contact

Exposures

Douglas M. Crawford

Rodney C. DeGroot

Lee R. Gjovik

★
Abstract 

The commercial value of several softwood species of the 

northeastern United States could be increased if these woods 

could be treated to meet existing American Wood Preservers’ 

Association (AWPA) Standards and used in durable structures. We evaluated the long-term durability of incised and 

unincised white pine, red pine, eastern spruce, balsam fir, and 

eastern hemlock treated with ammoniacal copper arsenate 

(ACA) and chromated copper arsenate (CCA–Type C). The 

treated wood was exposed above ground and in ground 

contact in the southern and northeastern United States. 

Simulated decks were tested above ground in Cumberland, 

Maine, and Amherst, Massachusetts. Stakes were tested in 

ground contact in Saucier, Mississippi, and Cumberland, 

Maine. Replicates of all test species and conditions, including untreated controls, were represented in the test plots and 

decks. Both the stakes and deck material were monitored 

annually for structural condition and appearance. After 

10 years of aboveground exposure, all untreated decks (controls) failed as a result of decay. Wood treated with CCA 

showed somewhat better durability than did wood treated 

with ACA. Except for white pine, treated incised wood species showed no evidence of decay. Incised white pine treated 

with ACA failed by excessive checking. Unincised white 

pine treated with CCA also failed, as a result of transverse 

scaling and radial checking. In ground-contact field trials, 

failure patterns of untreated stakes showed more differences 

than did performance patterns of treated stakes at different 

exposure sites. Overall, these results suggest that treated 

northeastern softwood species could be used for durable 

construction. 

Keywords: CCA, ACA, deck, softwoods, incised 

November 1999 

Crawford, Douglas M.; DeGroot, Rodney C.; Gjovik, Lee R. 1999. 

Ten-year performance of treated northeastern softwoods in aboveground 

and ground-contact exposures Res. Pap. FPL–RP–578. Madison, WI: U.S. 

Department of Agriculture, Forest Service, Forest Products Laboratory. 9 p. 

A limited number of free copies of this publication are available to the 

public from the Forest Products Laboratory, One Gifford Pinchot Drive, 

Madison, WI 53705–2398. Laboratory publications are sent to hundreds 

of libraries in the United States and elsewhere. 

The Forest Products Laboratory is maintained in cooperation with the 

University of Wisconsin. 

The United States Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national 

origin, gender, religion, age, disability, political beliefs, sexual orientation, 

or marital or familial status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (braille, large print, audiotape, etc.) should 

contact the USDA’s TARGET Center at (202) 720–2600 (voice and TDD). 

To file a complaint of discrimination, write USDA, Director, Office of Civil 

Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, 

SW, Washington, DC 20250–9410, or call (202) 720–5964 (voice and 

TDD). USDA is an equal opportunity provider and employer. 

Acknowledgments 

The authors thank the following persons for their contributions in helping with the inspection, evaluation, and compiled 

data for this report: Bessie M. Woodward, for inspection and 

evaluation; Apolonia Bocanegra–Severson, for compiling 

the data; Jack Dwyer, Vermont Department of Forest Parks 

and Recreation for assistance; and Northeastern Lumber 

Manufacturers Association, for funding. 

Contents 

 Page 

Introduction ...........................................................................1 

Experimental Design .............................................................1 

Materials and Methods ..........................................................1 

Treatment Procedures........................................................1 

Rating Criteria ...................................................................2 

Results ...................................................................................4 

Aboveground Field Trials..................................................4 

Ground-Contact Field Trials..............................................4 

Conclusions ...........................................................................5 

References .............................................................................5 
Ten-Year Performance of Treated 

Northeastern Softwoods 

in Aboveground and 

Ground-Contact Exposures 

Douglas M. Crawford, Forest Products Technologist

Rodney C. De Groot (retired) 

Lee R. Gjovik (retired)

Forest Products Laboratory, Madison, Wisconsin 

Introduction 

A number of softwoods in the northeastern United States 

would have greater commercial value if they could be successfully treated with preservatives. Balsam fir, eastern 

spruce (red, white, and black), and eastern hemlock are 

particularly susceptible to budworm attack. If these woods 

could be treated, opportunities for addition utilization are 

plentiful. From 1984 to 1996, the market for treated wood 

grew at an annual rate of 12% nationally. During this same 

period, the northeastern market for pressure-treated lumber 

and timber grew 20%/year. In all probability, this market has 

grown even more since 1996. The northeast is home to 67 

treatment plants, which treated approximately 3.5 billion 

board feet of lumber and timber and 2.5 billion board feet of 

plywood in 1996. (Note: 1 board foot = 0.00236 m3

; 

billion = 109

.) Lumber accounted for 49.8% of total 1996 

production. An estimated 71.4% of the treated stock was 

southern yellow pine (AWPI 1996). 

Experimental Design 

This paper reports the results of phase 2 of a two-part study. 

In phase 1, effective levels of preservative penetration were 

determined for various combinations of wood species and 

preservatives using conventional preservatives and treating 

procedures in the laboratory (Gjovik and others 1992). In 

phase 2, selected species–preservative combinations were 

tested in the field for 10 years. Wood decks were exposed 

above ground and wood stakes were exposed in ground 

contact. 

For the aboveground field trials, test decks were installed at 

exposure sites in Amherst, Massachusetts, and Cumberland, 

Maine. A single retention was used for these trials. Five 

replicates were used for each treatment combination and 

control. For the ground-contact field trials, wood stakes were 

installed at exposure sites in Saucier, Mississippi (Harrison 

Experimental Forest), and Cumberland, Maine. The stake 

tests involved a minimum of four preservative retentions for 

each preservative–species–site combination. Ten replicates 

were used for each variable. 

Materials and Methods 

For aboveground field trials, simulated decks were constructed of treated 50- by 150- by 750-mm (2- by 6- by 

30-in.) members (Fig. 1). Variables for these field trials are 

shown in Table 1. 

For the ground-contact field trials, 10 replicate 50- by 100- 

by 450-mm (2- by 4- by 18-in.) stakes were used for each 

treatment combination and control (Fig. 2). Variables for 

these trials are shown in Table 2. Stakes were tested using 

standard methodology for evaluating wood preservatives. 

The stakes were inserted into the soil to a depth of half their 

length and monitored periodically. The durability of the 

wood was determined by monitoring how effectively it resisted attack of naturally occurring microflora and fauna over 

time. The exposure sites represent severe and mild climates 

in terms of wood deterioration (Table 3). Plots were established in a randomized block design consistent with AWPA 

Standard E7 (AWPA 1997). 

Treatment Procedures 

All specimens were treated by full-cell process, using the 

schedules shown in Table 4. The lower pressure, 861 kPa 

(125 lb/in2

), was used for the treatment of eastern spruce and 

balsam fir to avoid cell-wall collapse. The other species (red 

pine, eastern white pine, and eastern hemlock) were treated 

using the higher pressure, 1,034 kPa (150 lb/in2

). 

All specimens were precisely molded to 36.58 by 87.38 mm 

(1.44 by 3.44 in.) and precision end-trimmed to 457 mm 

(18 in.). This procedure allowed a single preservative volume 

for each specimen. Thus, the preservative retentions obtained 

during weighing of the specimens were very accurate. 
2 

Each specimen was weighed before and after treatment to 

determine the preservative or chemical oxide retention. The 

treating solution concentrations were analyzed and calculated 

in accordance with AWPA Standard A–11 (1997) and held 

constant at 2.5% oxide basis. 

Rating Criteria 

Rating criteria for decks and stakes are shown in Tables 5 

and 6, respectively. 

Table 1—Variables for aboveground field trials 

Species eastern spruce: red (Picea rubens Sarg.), white (P. glauca (Moench) Voss), 

and black (P. mariana (Mill.) B.S.P.) 

 balsam fir (Abies balsamea (L.) Mill.) 

 red pine (Pinus resinosa Ait.) 

 white pine (Pinus strobus L.) 

 eastern hemlock (Tsuga canadensis (L.) Carr.) 

Pretreatment conditions unincised and incised 

Preservatives chromated copper arsenate (CCA–Type C), ammoniacal copper 

arsenate (ACA) 

Exposure sites Amherst, MA; Cumberland, ME 

Controls five unincised and untreated specimens per species 

Figure 1—Aboveground field trials: (a) view of entire test 

deck; (b) close-up of portion of deck. 

Figure 2—Ground-contact field trials: (a) exposure site; 

(b) test stakes. 
3 

Table 2—Variables for ground-contact field trials 

Species eastern spruce: red (Picea rubens Sarg.), white (P. glauca (Moench) Voss), 

and black (P. mariana (Mill.) B.S.P.) 

 balsam fir (Abies balsamea (L.) Mill.) 

 red pine (Pinus resinosa Ait.) 

 white pine (Pinus strobus L.) 

 eastern hemlock (Tsuga canadensis (L.) Carr.) 

Pretreatment conditions unincised and incised 

Preservatives CCA–Type C, ACA 

Exposure sites Saucier, MS; Cumberland, ME 

Controls 10 unincised and untreated specimens per species 

Table 3—Environmental conditions at field plots for ground-contact trials 

Location Environment 

Harrison Experiment Forest, Saucier, MS 

2 km (1.2 mi) from Gulf of Mexico 

Mean annual precipitation, 1,580 mm (62.2 in.); average annual 

temperature, 19.6°C (67.3°F); soil type, coarse fine sandy loam 

Cumberland, ME Mean annual precipitation, 1,135 mm (44.7 in.); average annual 

temperature, 7.5°C (45.5°F); soil type, Buxon silt loam 

Table 4—Preservative treatments 

 Vacuum Pressure Solution temperature 

Preservativea (inHg (kPa)) 

Time 

 (min) (lb/in2

 (kPa)) (°F (°C)) 

Final 

vacuum 

ACA 28 (95) 30 125 (861) 135 (57) None 

 150 (1,034) 

CCA–Type C 28 (95) 30 125 (861) Ambient (Ambient) None 

 150 (1,034) 

a

ACA is ammoniacal copper arsenate; CCA–Type C is chromated copper arsenate. 

Table 5—Rating criteria for decks in aboveground trials 

Level Twist Cup Bow Crook Splitting Graina Stain Checking 

1 None None None Absent None Smooth None None 

2 1/16–2/16 rise 1/16-rise 1/16-rise Present 0–10% <10% <10% 0–10% 

3 3/16–4/16 rise 2/16 rise 2/16 rise 10%–50% 10%–50% 10%–50% 10%-50% 

4 5/16–6/16 rise 3/16 rise 3/16 rise 50%–80% >50% >50% 50%–80% 

5 Failure 4/16 rise 4/16 rise Failure Surface broken 100% Failure 

a

Percentages pertain to amount of grain (surface texture) affected. 
4 

The aboveground decks at the Amherst and Cumberland field 

sites were constructed in 1985 with five replicates of each 

wood species/unincised or incised/preservative combination. 

Durability and physical appearance were evaluated according 

to the extent of defects and other considerations (Table 5). 

Defects included warp (twist, cup, bow, and crook), splitting, 

and checking. Other considerations were surface texture 

(grain) and discoloration from stain. 

Warp refers to distortions in wood caused by variation from a 

true or plane surface. It includes twist, cup, bow, and crook, 

or any combination of these. Twist is caused by the turning 

or winding of the edges of a board so that the four corners of 

any face are no longer in the same plane. Cup is deviation 

flatwise from a straight line across the width of the board. 

Bow is deviation, in a direction perpendicular to the flat face, 

from a straight line from end to end of the piece. Crook is 

deviation, in a direction perpendicular to the edge, from a 

straight line from end to end of the piece. 

Splitting refers to damage to the end grain all the way 

through the piece, measured as a percentage of the piece. 

Grain refers to the direction, size, arrangement, appearance, 

or quality of the fibers in the wood. Grain was evaluated in 

terms of surface texture (smooth to broken).

In this study, stain refers to discoloration caused by fungi. 

The best rating indicates no or little discoloration (clear or 

gray wood) and the worst, extensive discoloration (wood 

covered with stain fungi). Checks are lengthwise separation 

of the wood that usually extends across the rings of annual 

growth and commonly results from stresses set up in the 

wood during seasoning. 

For decks, a pass/fail system was used to simplify the 

evaluation process. A treatment–wood combination was 

given a “pass” rating if the average rating of the five 

replicates was between levels 1 and 2. A treatment–wood 

combination failed if the average rating was higher than 

level 2. 

Stakes were evaluated according to the extent of decay, using 

the criteria shown in Table 6. 

Results 

Aboveground Field Trials 

Results of aboveground trials of decks at the Amherst and 

Cumberland exposure sites are shown in Tables 7 and 8, 

respectively. After 10 years of exposure, untreated controls 

of all species failed at both locations as a result of decay. 

None of the treated materials failed as a result of decay. 

Failure of treated materials was attributed to physical condition or appearance of the wood. 

Unincised white pine was the only deck treated with chromated copper arsenate (CCA–Type C) that failed. Failure 

was caused by transverse checks and splits around knots. 

However, the structural members appeared to be sound, with 

solid ends. 

Several decks treated with ammoniacal copper arsenate 

(ACA) failed on the basis of surface characteristics. Incised 

white pine at the Amherst site failed as a result of transverse 

scaling, which resembled shelling. Unincised red pine at the 

Amherst site and incised Eastern hemlock at the Cumberland 

site failed as a result of a tendency to check and split, which 

marred the appearance of the wood. 

Ground-Contact Field Trials 

Results of ground-contact field trials of stakes at the Saucier 

and Cumberland exposure sites are shown in Tables 9 and 

10, respectively. Overall, differences in performance were 

greater between control specimens than between treated 

stakes. At both exposure sites, stakes treated with ACA and 

CCA had acceptable (average < 7.0) ratings in general, but 

stakes treated to low retentions had low ratings. Relative to 

the performance patterns observed at both sites, preservative 

retention level was apparently more important than incising 

for eastern white pine and balsam fir. For these species, 

incising improved performance of wood treated at the lowest 

retention, but had little apparent impact at higher retentions. 

For red pine, eastern hemlock, and eastern spruce, incising 

apparently improved performance at all retentions. The 

relative contribution of incising as opposed to preservative 

retention was not evident for eastern larch. With eastern 

spruce, average ratings for each retention level were more 

indicative of good long-term performance than were the 

rating patterns at each exposure site. 

Table 6—Rating criteria for stakes in ground-contact 

trials 

Decay gradea

 Description of condition 

10 Sound—suspicion of decay permitted 

9 Trace decay—to 3% of cross section 

8 Decay from 3% to 10% of cross section 

7 Decay from 10% to 30% of cross section 

6 Decay from 30% to 50% of cross section 

4 Decay from 50% to 75% of cross section 

0 Failure 

a

AWPA E7–93. Methods of evaluating preservatives by 

 field tests with stakes (AWPA 1997). 
5 

Table 7—Condition of decks after 10 years of exposure at Amherst sitea

 Treatment 

Wood species Surface 

Preservative Rating Comment 

White pine Unincised ACAa

 Pass Ends solid 

 CCAb Fail Transverse checks, structurally sound; major splits around knots; 

ends solid 

 Incised ACA Fail Transverse scaling, structurally sound; radial checks in ends 

 CCA Pass Ends solid 

 Control Fail Decay in ends 

Red pine Unincised ACA Fail Surface deterioration 

 CCA Pass Ends solid 

 Incised ACA Pass Splitting of ends on annual rings 

 CCA Pass Ends solid 

 Control Fail Decay 

Eastern spruce Unincised ACA Pass Ends solid overall 

 CCA Pass Ends solid overall 

 Incised ACA Pass Ends solid overall 

 CCA Pass Ends solid overall 

 Control Fail Decay in ends 

Balsam fir Unincised ACA Pass Beginning of radial damage in ends 

 CCA Pass Ends solid 

 Incised ACA Pass Ends solid 

 CCA Pass Ends solid 

 Control Fail Decay in ends 

Eastern hemlock Unincised ACA Pass Ends solid 

 CCA Pass Ends solid 

 Incised ACA Pass Ends solid 

 CCA Pass Ends solid 

 Control Fail Decay 

a

Summary of observations for five replicates. 

Conclusions 

Data from 10-year field exposure trials show that northeastern softwoods treated with appropriate concentrations of 

CCA or ACA, regardless of whether the wood is incised or 

unincised, can be used for both aboveground and groundcontact applications. In this study, the contribution of incising to durability varied with wood species. Incising exerted 

the greatest effect for the lowest preservative retention. 

In ground-contact field trials, failure patterns of untreated 

stakes showed more differences than did performance 

patterns of treated stakes at different exposure sites. 

References 

AWPA. 1997. Book of Standards. Granbury, TX: American 

Wood-Preservers’ Association. 

AWPI. 1996. The 1996 wood preserving industry production 

statistical report. Fairfax, VA: American Wood Preservers 

Institute. 

Gjovik, Lee R.; Schumann, David R. 1992. Treatability 

of native softwood species of the northeastern United States. 

Res. Pap. FPL–RP–508. Madison, WI: U.S. Department of 

Agriculture, Forest Service, Forest Product Products 

Laboratory. 20 p. 
6 

Table 8—Condition of decks after 10 years of exposure at Cumberland sitea

 Treatment 

Wood species Surface 

Preservative Rating Comment 

White pine Unincised ACA Pass Some warp, cup 

 CCA Pass Some stain 

 Incised ACA Pass Some warp, twist 

 CCA Pass Some crook 

 Control Fail Decay, stain 

Red pine Unincised ACA Pass Minor cup, checking 

 CCA Pass Good overall 

 Incised ACA Pass Checking 

 CCA Pass Good overall 

 Control Fail Decay, stain 

Eastern spruce Unincised ACA Pass Ends solid overall 

 CCA Pass Ends solid overall 

 Incised ACA Pass Ends solid overall 

 CCA Pass Ends solid 

 Control Fail Decay, checking, splitting 

Balsam fir Unincised ACA Pass Good overall 

 CCA Pass Solid overall 

 Incised ACA Pass Ends solid 

 CCA Pass Ends solid 

 Control Fail Decay, checking, stain 

Eastern hemlock Unincised ACA Pass Stain 

 CCA Pass Checking 

 Incised ACA Fail Surface deterioration 

 CCA Pass Ends solid 

 Control Fail Decay 

a

Summary of observations for five replicates. 
7 

Table 9—Incidence of decay in stakes after 10 years of ground-contact exposure at Saucier site

Treatment 

 Retention Number of stakes with various decay ratings after 10 years of exposurea

Wood species Surface 

Preservative (lb/ft3

 (kg/m3)) 10 9 8 7 6 4 0 

Average 

rating 

White pine Unincised ACA 0.26 (4.16) 2 5 1 1 1 7.1 

 0.42 (6.72) 7 2 1 9.6 

 0.72 (11.52) 9 1 9.9 

 CCA 0.31 (4.96) 9 1 9.9 

 0.44 (7.04) 10 10.0 

 0.65 (10.40) 10 10.0 

 Incised ACA 0.26 (4.16) 8 1 1 9.7 

 0.42 (6.72) 10 10.0 

 0.73 (11.68) 10 10.0 

 CCA 0.33 (5.28) 9 1 9.9 

 0.52 (8.32) 10 10.0 

 0.74 (11.84) 9 1 9.9 

 Control 0 1 9 0.4 

Red pine Unincised ACA 0.29 (4.64) 2 3 3 1 1 8.4 

 0.30 (4.80) 6 2 1 1 8.6 

 0.44 (7.04) 10 10.0 

 CCA 0.23 (3.68) 9 1 9.9 

 0.32 (5.12) 8 1 1 9.6 

 0.46 (7.36) 9 1 9.9 

 Incised ACA 0.31 (4.96) 4 6 9.4 

 0.40 (6.40) 10 10.0 

 0.64 (10.24) 10 10.0 

 CCA 0.25 (4.00) 8 2 9.8 

 0.40 (6.40) 10 10.0 

 0.55 (8.80) 10 10.0 

 Control 0 10 0 

Eastern Unincised ACA 0.16 (2.56) 1 1 1 1 1 5 3.7 

 spruce 0.25 (4.00) 1 2 2 1 1 3 5.5 

 0.39 (6.24) 7 3 9.7 

 CCA 0.14 (2.24) 6 4 9.6 

 0.20 (3.20) 8 1 1 8.9 

 0.71 (11.36) 10 10.0 

 Incised ACA 0.24 (3.84) 7 2 1 8.8 

 0.28 (4.48) 6 2 1 1 9.1 

 0.48 (7.68) 9 1 9.9 

 CCA 0.25 (4.00) 9 1 9.9 

 0.35 (5.60) 9 1 9.9 

 0.78 (12.48) 9 1 9.9 

 Control 0 3 7 1.2 

Balsam fir Unincised ACA 0.26 (4.16) 1 1 6 1 1 7.3 

 0.32 (5.12) 6 4 9.6 

 0.59 (9.44) 10 10.0 

 Incised ACA 0.29 (4.64) 9 1 9.9 

 0.40 (6.40) 9 1 9.9 

 0.73 (11.68) 9 1 9.9 

 Control 0 10 0 

Eastern Unincised ACA 0.20 (3.20) 7 3 9.7 

 hemlock 0.32 (5.12) 4 5 1 9.3 

 0.37 (5.92) 10 10.0 

 Incised ACA 0.34 (5.44) 7 3 9.7 

 0.38 (6.08) 9 1 9.9 

 0.68 (10.88) 10 10.0 

Control 0 10 0 

Eastern larch Unincised ACA 0.18 (2.88) 1 4 4 1 8.2 

 0.23 (3.68) 6 2 1 1 8.6 

 0.41 (6.56) 10 10.0 

 Incised ACA 0.25 (4.00) 4 6 9.4 

 0.32 (5.12) 8 2 9.8 

 0.60 (9.60) 10 10.0 

 Control 0 1 9 0.4 

a

Total number of stakes, 10. 
8 

Table 10—Incidence of decay in stakes after 10 years of ground-contact exposure at Cumberland site

Treatment 

 Retention 

Number of stakes with various decay ratings after 

10 years of exposurea

Wood species Surface 

Preservative (lb/ft3

 (kg/m3)) 10 9 8 7 6 4 0 

Average 

rating 

White pine Unincised ACA 0.32 (5.12) 2 7 1 1 9.1 

 0.38 (6.08) 9 1 8.9 

 0.71 (11.36) 9 1 9.9 

 CCA 0.30 (4.80) 8 2 9.8 

 0.46 (7.36) 10 10.0 

 0.66 (10.56) 10 10.0 

 Incised ACA 0.32 (5.12) 1 8 1 8.8 

 0.44 (7.04) 8 2 1 9.8 

 0.80 (12.80) 10 10.0 

 CCA 0.32 (5.12) 9 1 9.9 

 0.47 (7.52) 9 1 9.9 

 0.72 (11.52) 10 10.0 

 Control 0 1 1 4 4 4.2 

Red pine Unincised ACA 0.29 (4.64) 1 5 4 8.7 

 0.38 (6.08) 6 4 9.6 

 0.67 (10.72) 10 10.0 

 CCA 0.18 (2.88) 8 1 1 9.7 

 0.33 (5.28) 10 10.0 

 0.70 (11.20) 10 10.0 

 Incised ACA 0.26 (4.16) 1 6 3 8.8 

 0.45 (7.20) 5 5 9.5 

 0.53 (8.48) 10 10.0 

 CCA 0.23 (3.68) 7 3 9.7 

 0.45 (7.20) 10 10.0 

 0.78 (12.48) 10 10.0 

 Control 0 3 2 3 2 4.5 

Eastern Unincised ACA 0.13 (2.08) 3 3 4 7.9 

 spruce 0.21 (3.36) 1 1 3 5 7.8 

 0.26 (4.16) 5 5 8.5 

 CCA 0.10 (1.60) 5 3 2 9.3 

 0.13 (2.08) 6 3 1 9.5 

 0.53 (8.48) 10 10.0 

 Incised ACA 0.20 (3.20) 1 1 6 1 1 8.0 

 0.28 (4.48) 7 3 8.7 

 0.39 (6.24) 4 4 2 9.2 

 CCA 0.20 (3.20) 9 1 9.9 

 0.28 (4.48) 10 10.0 

 0.54 (8.64) 9 1 9.9 

 Control 0 2 2 6 2.6 
9 

Table 10—Incidence of decay in stakes after 10 years of ground-contact exposure at Cumberland site—con. 

Treatment 

 Retention 

Number of stakes with various decay ratings after 

10 years of exposurea

Wood species Surface 

Preservative (lb/ft3

 (kg/m3)) 10 9 8 7 6 4 0 

Average 

 rating 

Balsam fir Unincised ACA 0.20 (3.20) 5 5 8.5 

 0.25 (4.00) 2 5 2 1 8.8 

 0.42 (6.72) 5 5 9.5 

 CCA 0.19 (3.04) 9 1 9.9 

 0.40 (6.40) 10 10.0 

 0.59 (9.44) 10 10.0 

 Incised ACA 0.31 (4.96) 2 6 2 9.0 

 0.35 (5.60) 5 5 9.5 

 0.47 (7.52) 10 10.0 

 CCA 0.29 (4.64) 10 10.0 

 0.53 (8.48) 10 10.0 

 0.73 (11.68) 9 1 9.9 

 Control 0 5 1 4 3.4 

Eastern Unincised ACA 0.22 (3.52) 2 7 1 9.1 

 hemlock 0.36 (5.76) 7 3 9.7 

 0.38 (6.08) 6 2 2 9.4 

 CCA 0.20 (3.20) 10 10.0 

 0.30 (4.80) 9 1 9.9 

 0.41 (6.56) 10 10.0 

 Incised ACA 0.28 (4.48) 5 4 1 9.4 

 0.41 (6.56) 9 1 9.9 

 0.56 (8.96) 10 10.0 

 CCA 0.25 (4.00) 10 10.0 

 0.38 (6.08) 9 1 9.9 

 0.57 (9.12) 10 10.0 

 Control 0 1 2 1 1 5 3.5 

Eastern larch Unincised ACA 0.15 (2.40) 1 4 3 2 8.2 

 0.23 (3.68) 4 6 9.4 

 0.24 (3.84) 4 6 9.4 

 CCA 0.10 (1.60) 10 10.0 

 0.18 (2.88) 9 1 9.9 

 0.33 (5.28) 10 10.0 

 Incised ACA 0.16 (2.56) 5 4 1 9.4 

 0.25 (4.00) 6 3 1 9.5 

 0.32 (5.12) 10 10.0 

 CCA 0.14 (2.24) 10 10.0 

 0.28 (4.48) 10 10.0 

 0.49 (7.84) 10 10.0 

 Control 0 1 2 3 1 1 2 5.6 

a

Total number of stakes, 10.