Math

Question 1

How many board feet are there in two boards that are 2” x 12” x 20’?

Answer 1

2 x (2 x 12 x 20) / 12 = 80 BF

Question 2

A room is 12’ x 16 ‘ with an 8’ ceiling. What is the square footage of gypsum boards needed?

Answer 2

12x16=192 (ceiling)
16x8x2=256 (2 walls)
12x8x2=192 (2 walls)
640 SF total

Question 3

A room is 14 x 24’. How many LF of 4 1/2” baseboards is required?

Answer 3

14+14+24+24=
76 LF

Question 4

A supplier has given a quote of $0.42 per board foot for boards over 12’ long. What is the cost of a 2” x 10” that is 20’ long?

Answer 4

(2x10x20)/12 = 33.3333 BF
33.3333 x .42 = $14

Question 5

How many 4’ x 12’ x 2” styrofoam sheets are required to protect the waterproofing membranes on a foundation 32’ x 60’ with waterproofed height of 8’?

Answer 5

32x8x2=512 SF
60x8x2=960 SF
1472 SF to cover
1472 / (4x12 SF) = 30.666 sheets
31 sheets

Question 6

How many square yards (SY) of carpet are required for an area 12’ x 36’?

Answer 6

(12 x 36) / 9 = 48 SY

Question 7

The basement is 1440 square feet. This equals how many square yards?

Answer 7

1440 / 9 = 160 SY

Question 8

Excavation of a ditch 24’ long by 2’ wide and 18” deep, how many cubic yards of dirt would have to be removed?

Answer 8

24x2x1.5 = 72 CF
72/27 = 2.6667 CY

Question 9

A building has a foundation footing 85 feet long, 16 inches wide, and 8 inches deep. How many yards of concrete is needed?

Answer 9

85 x 1.333 x .66667 = 75.556 CF
75.556 / 27 = 2.798 CY

Question 10

What is the diagonal measurement of a rectangular foundation that is 27’ x 36’?

Answer 10

square root of [(27 x 27) + (36 x 36)]
729 + 1296 = 2025
45 FT

Question 11

A building has a foundation wall that is 125 feet long and 4’ high. How many brick will this foundation require?

Answer 11

125 x 4 = 500 SF
500 x 7 (bricks/SF) = 3500

Question 12

A building has a foundation wall that is 125 feet long and 4’ high. How many block will this foundation require?

Answer 12

125 x 4 = 500 SF
500 x 1.125 (blocks/SF) = 562.5

Question 13

What is the difference in an elevation of 2% grade over a horizontal distance of 75’?

Answer 13

75 x .02 = 1.5 FT

Question 14

What is the slope factor of a 6:12 roof slope?

Answer 14

square root of [(6 x 6) + (12 x 12)] / 12
1.118

Question 15

What is the total length of a rafter where the roof span is 24’ with a 2’ overhang, and a roof slope of 4/12?

Answer 15

Run + overhang = 12+2 = 14
Slope factor = square root [(4x4)+(12x12)]/12 = 1.054
14 x 1.054 = 14.757

Question 16

How many LF of wire reinforcement are needed without overlapping: A mason is building a wall 60’ long and 12 courses high. The top course will be bond-beam blocks, reinforced with #4 rebar and poured solid. Plans call for wire reinforcement in bed joints of every course.

Answer 16

60 x 12 = 720

Key: “EVERY course”, though typically would not use rebar in the bed joint of the bottom course.