TM 10-14(draft)
Screw Holding Capacity
Test Method for
Determining the Screw
Holding Capacity of Wood
Doors
WINDOW & DOOR MANUFACTURERS ASSOCIATON
WDMA T.M. 10-2014(draft)
TEST METHOD
FOR DETERMINING THE SCREWHOLDING
CAPACITY OF WOOD DOORS
Published By
Window and Door Manufacturers Association
330 N. Wabash Avenue, Suite 2000, Chicago, IL 60611
2025 M Street NW, Suite 800, Washington, DC 20036
® Copyright 2014
No part of this publication shall be reproduced in any form, in an electronic retrieval system or
otherwise, without the prior written permission of the publisher.
1.
SCOPE
This test method determines the ability of a wood door (vertical edge, horizontal edge and face) to
resist the withdrawal of a screw perpendicular to the surface.
2.
3.
APPLICABLE DOCUMENTS
2.1.
ASTM D1761-12, Standard Test Methods for Mechanical Fasteners in Wood
2.2.
ANSI B18.6.4-1998(R2005), Thread Forming and Thread Cutting Tapping Screws and
Metallic Drive Screws.
SIGNIFICANCE AND USE
This test method will provide useful data for designers, specifiers, and manufacturers in making
judgements on the ability of the door assembly to maintain serviceability under operating
conditions.
4.
APPARATUS
Any testing machine (Instron or equivalent) capable of applying a load at a uniform rate motion at a
rate of 0.10 inches [2.5mm] per minute. The equipment must be capable of recording the load
required to withdraw the screw. The assembly shall be similar to Figure 2.
5.
TEST SPECIMEN
5.1.
A complete test series shall consist of ten (10) specimens, selected at random,
representative of actual pre-fit door construction. Specimens are referenced in Figure 1
for Sections 5.2, 5.3 and 5.4, and shall not be beveled.
WDMA TM 10-14(draft)
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Vertical Edge Samples: Cut no more than one (1) 3” [76 mm] specimen from each 30”
[762 mm] of door hinge stile edge for each test series, and selected from random
locations. No specimen shall include portions of end rails or optional blocking. The
width (Dimension “A”) of the individual stile component shall be measured and
recorded in the test results. The specimen shall be prepared for testing as follows:
5.2.
5.2.1. Cut and remove 0.134” ± 0.005” [3.4 mm ± 0.1 mm] for 1-3/4” [44.5 mm] pre-fit
doors or 0.105” ± 0.005” [2.7 mm ± 0.1 mm] for 1-3/8” [34.9 mm] pre-fit doors,
from the exterior surface of the vertical edge to simulate the removal of material in
preparing for the hinge leaf.
5.2.2. Where remaining stile or stile/core material is greater than 1”, cut and remove
enough material from the interior surface to yield a specimen width of 1"
(Dimension “A”). Where stile edge is less than 1”, no additional trimming is
required.
5.2.3. The screws shall be appropriate for the size of the test specimen in accordance with
the following:
Specimen Thickness
Screw Size
1-3/8” [34.9 mm]
#10 Type AB (Section 2.2)
1-3/4” [44.5 mm]
#12 Type AB (Section 2.2)
The length of the screws shall be adequate to insure a constant diameter is engaged
throughout the full sample. See Figure 2.
5.2.4. Lead holes shall be pre-drilled, through the full sample depth, using 90% of the root
diameter of the screw.
Screw Size
Root Diameter
90%
Drill Bit
#10
0.135” - 0.141”
[3.4 mm – 3.6 mm}
0.122” - 0.127”
[3.1 mm – 3.2 mm]
1/8”
#12
0.157” - 0.164”
[4.0 mm – 4.2 mm]
0.141” - 0.148”
[3.6 mm – 3.8 mm]
#27
Specific Materials may require different pilot holes. Record any variations from this
test method in the test report.
5.2.5. A 10 gauge plate (approximately a 0.134” [3.4 mm] hinge) with a 0.330” [8.4 mm]
diameter hole shall be used for 1-3/4” [44.5 mm] door specimens. A 12 gauge plate
(approximately a 0.105” [2.7 mm] hinge) with a 0.260” [6.6 mm] diameter hole
shall be used for 1-3/8” [34.9 mm] door specimens.
5.2.6. Position the plate on top of the specimen as shown in Figure 2. Insert the screw
through the plate hole and into the lead hole, deep enough to engage the entire
sample with the constant diameter portion of the threads. Insert the screw with a
turning motion so as not to reduce the thread engagement strength of the specimen.
5.3.
Horizontal Edge Samples: Cut no more than one (1) 3” [76 mm] specimen from each
15” [381 mm] of pre-fit door rail edge for each test series, and selected from random
WDMA TM 10-14(draft)
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locations. No specimen shall include portions of stile or optional blocking. The width
(Dimension “B”) of the individual rail component shall be measured and recorded in the
test results. The specimen shall be prepared for testing as follows:
5.3.1. Where remaining rail or rail/core material is greater than 1”, cut and remove enough
material from the interior surface to yield a specimen width of 1" (Dimension “B”).
Where rail edge is less than 1”, no additional trimming is required.
5.3.2. #12 Type AB (Section 2.2) shall be used for the test specimen. The length of the
screws shall be adequate to insure a constant diameter is engaged throughout the full
sample (see Figure 2).
5.3.3.
Lead holes shall be pre-drilled, through the full sample depth, using 90% of the root
diameter of the screw.
Screw Size
#12
Root Diameter
90%
Drill Bit
0.157” - 0.164”
[4.0 mm – 4.2 mm]
0.141” - 0.148”
[3.6 mm – 3.8 mm]
#27
Specific Materials may require different pilot holes. Record any variations from this
test method in the test report.
5.3.4. A 10 gauge plate (approximately 0.134” [3.4 mm]) with a 0.33” [8.4 mm] diameter
hole shall be used.
5.3.5. Position the plate on top of the specimen as shown in Figure 2. Insert the screw
through the plate hole and into the lead hole, deep enough to engage the entire
sample with the constant diameter portion of the threads. Insert the screw with a
turning motion so as not to reduce the thread engagement strength of the specimen.
5.4.
Face Samples: Cut no more than one (1) 3” [76.2 mm] specimen from each door face
maintaining at least 15” [381 mm] between samples for each test series, and selected
from random locations. The thickness (Dimension “C”) of the individual face sample
shall be measured and recorded in the test results. The specimen shall be prepared for
testing as follows:
5.4.1. Cut and remove enough material from the interior surface to yield a specimen
thickness of 1" (Dimension “C”).
5.4.2. Final specimen size to be 3” [76.2 mm] in length x 1.5” [38.1 mm] in width x 1”
[25.4 mm] in thickness for both 1-3/4” [44.5 mm] thick doors and 1-3/8” [34.9 mm]
thick doors.
5.4.3. #12 Type AB (Section 2.2) shall be used for the test specimen. The length of the
screws shall be adequate to insure a constant diameter is engaged throughout the full
sample (see Figure 2).
5.4.4. Lead holes shall be pre-drilled, through the full sample depth, using 90% of the root
diameter of the screw.
WDMA TM 10-14(draft)
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Screw Size
#12
Root Diameter
90%
Drill Bit
0.157” - 0.164”
[4.0 mm – 4.2 mm]
0.141” - 0.148”
[3.6 mm – 3.8 mm]
#27
Specific Materials may require different pilot holes. Record any variations from this
test method in the test report.
5.4.5. A 10 gauge plate (approximately a 0.134” [3.4 mm] hinge) with a 0.330” [8.4 mm]
diameter hole shall be used.
5.4.6. Position the plate on top of the specimen as shown in Figure 2. Insert the screw
through the plate hole and into the lead hole, deep enough to engage the entire
sample with the constant diameter portion of the threads. Insert the screw with a
turning motion so as not to reduce the thread engagement strength of the specimen.
6.
CONDITIONING
The test specimen shall be conditioned to an equilibrium moisture content at 75 degrees ± 10
degrees F [24 degrees ± 6 degrees C] and 50% ± 5% RH.
7.
8.
PROCEDURE
7.1.
Insert the specimen in the holding fixture of the test apparatus (as shown in Figure 2).
Engage the screw head in the load-applying fixture.
7.2.
Apply the load to the specimen, throughout the test, at a uniform motion rate of 0.10
inches [2.5mm] per minute.
REPORT
Report results on test report attached. The report shall include the following:




The average and individual loads required to withdraw the screws from the specimens. (Note:
If the screw is broken rather than withdrawn, it shall be noted and the test value shall not be
included in the average value reported.)
A complete description of the sample specimens tested as well as the composition of all
components.
Details of any deviations from the materials and/or methods outlined in this procedure.
Screw holding capacity for the test series shall be the average of the tested specimens.
WDMA TM 10-14(draft)
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1.75"
[44.4mm]
FACE SAMPLE
Extract Sample from area
of concern or where screw
attachment is planned.
Dimension C
1.00"±0.01" [25.4mm±0.3mm]
3.00"
[76.2mm]
INTERIOR SURFACE
CORE OR BLOCKING
DOOR CUT-AWAY
FOR SAMPLE
EXTRACTION
INTERIOR SURFACE
RAIL COMPONENT
PREFIT
AFTER TRIM
EXTERIOR
SURFACE
VERTICAL
EDGE SAMPLE
HORIZONTAL
EDGE SAMPLE
3.00"
[76.2mm]
Full Door
Thickness
1.75" [44.5mm]
Max.
Trim 0.134" [3.4mm] for
1.75" [44.5mm] doors
or 0.105" [2.7mm] for
1.38" [34.9mm] doors to
Simulate the Hinge Pocket
Full Door
Thickness
1.75" [44.5mm]
Max.
Dimension B
PREFIT
AFTER TRIM
EXTERIOR
SURFACE
Dimension A
1.00"±0.01" [25.4±0.3mm]
3.00"
[76.2mm]
1.00"±0.01" [25.4mm±0.3mm]
STILE
COMPONENT
FIGURE 1: SAMPLE EXTRACTION & SIZING OF SAMPLES
LOAD APPLYING FIXTURE
1.00"
[25.4mm]
(Typ.)
STEEL PLATE
HOLDING
FIXTURE
3.00" [76.2mm]
Dimension
"A", "B" or "C"
FIGURE 2: DIAGRAM FOR SCREW WITHDRAWAL
WDMA TM 10-14(draft)
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WDMA TM-10 SCREW HOLDING CAPACITY TEST REPORT
Name and identification of testing organization
Vertical Screw Holding Capacity (lbs)
Horizontal Screw Holding Capacity (lbs)
Face Screw Holding Capacity (lbs)
Test date
Tested by
Reported by
Vertical edge samples
Specimen #
Failure load
MC (%)
(lbs)
Description of
Failure
Sample description
Composition of all
components
Description of
Failure
Sample description
Composition of all
components
1
2
3
4
5
6
7
8
9
10
Average
Horizontal edge samples
Specimen #
Failure load
MC (%)
(lbs)
1
2
3
4
5
6
7
8
9
10
Average
WDMA TM 10-14(draft)
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Face samples
Specimen #
Failure load
MC (%)
(lbs)
Description of
Failure
Sample description
Composition of all
components
1
2
3
4
5
6
7
8
9
10
Average
WDMA TM 10-14(draft)
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WDMA TM 10-14(draft)
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