Timber Design Solution

Chapter 2 Solutions
Page 1 of 19

Problem 2.1
a) See Appendix A and Appendix B for weights of roofing, sheathing, framing, insulation, and gypsum wallboard.
Asphalt shingles
3/8 in. plywood sheathing
(3/8 in.) (3.0 psf/in)
2x6 @ 16 in. o.c.
Fiberglass loose insulation
(5.5 in.) (0.5 psf/in)
Gypsum wallboard
(1/2 in.) (5.0 psf/in)
Roof Dead Load (D) along roof slope
Convert D to load on a horizontal plane:

= 2.0 psf
= 1.1 psf
= 1.4 psf
= 2.75 psf
= 2.5 psf
= 9.75 psf

Roof slope = 3:12
Hypotenuse = (9 + 144)½ = 12.37
Don horizontal plane = (9.75 psf) (12.37/12) = 10.1 psf

[NOTE that this does not include an allowance for weight of re-roofing over existing roof. For each additional layer of shingles add 2.0 psf along roof slope, or (2.0 psf)(12.37/12)=2.1 psf on horizontal plane.]
b) Wall Dead Load: Stucco (7/8 in.)
2x4 @ 16 in. o.c.
Gypsum wallboard (½ in.)
Wall Dead Load (D)

= 10.0
= 0.9
= 2.5
= 13.4

psf psf psf psf c) Wall Dead Load: wall height = 8 ft
D = (13.4 psf) (8 ft) = 107.2 lb/ft
d) R1 = 1.0 since not considering tributary area
R2 = 1.0 for slope less than 4:12
Basic Roof Live Load: Lr = 20 R1 R2 = 20 psf
e) R1 = 1.0 since not considering tributary area
R2 = 1.0 for slope of 4:12
Basic Roof Live Load: Lr = 20 R1 R2 = 20 psf
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Chapter 2 Solutions
Page 2 of 19

Problem 2.2
a) See Appendix A and Appendix B for weights of concrete roof tiles, lumber sheathing, and framing. Concrete tile
(950 lb / 100 ft2) = 9.5
15/32 in. structural panel (plywood) sheathing (15/32) (3.0 psf/in.) = 1.4
2x8 @ 16 in. o.c.
= 1.9
Roof Dead Load (D) along roof slope
= 12.8
Convert D to load on a horizontal plane:

psf psf psf psf Roof slope = 6:12
Hypotenuse = (36 + 144)½ = 13.42
Don horizontal plane = (12.8 psf) (13.42/12) = 14.3 psf

b) See Appendix A and Appendix B for weights of framing, insulation, gypsum lath and plaster.