Podcast
Questions and Answers
What is the approximate square footage of a 4in slab that can be covered with one yard of concrete?
What is the approximate square footage of a 4in slab that can be covered with one yard of concrete?
What is the purpose of multiplying the lineal feet of wall by 1.2 when estimating framing material?
What is the purpose of multiplying the lineal feet of wall by 1.2 when estimating framing material?
What is the formula used to calculate the length of a line or distance in a right triangle?
What is the formula used to calculate the length of a line or distance in a right triangle?
What is the percentage of waste that should be added to the calculation of roof sheeting due to cuts, overhangs, and other factors?
What is the percentage of waste that should be added to the calculation of roof sheeting due to cuts, overhangs, and other factors?
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What is the pitch over which the hip or valley rafter cut is always calculated?
What is the pitch over which the hip or valley rafter cut is always calculated?
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What is the approximate amount of roof sheeting needed to cover one foot of horizontal distance on a 4/12 pitch?
What is the approximate amount of roof sheeting needed to cover one foot of horizontal distance on a 4/12 pitch?
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Study Notes
Estimating Concrete Volume in Slabs
- A 4in slab gets 80 square feet out of one yard of concrete.
- A 6in slab gets 50 square feet out of one yard of concrete.
- Memorizing these numbers allows for quick estimation on the job site.
Estimating Framing Material
- Lineal feet of wall multiplied by 1.2 gets you close to the number of studs needed.
- Pre-cut studs are a little more expensive but are handier.
- For plate stock, multiply the lineal feet of wall by 5, and then divide by 16 (assuming 16ft boards).
Calculating Roof Sheeting (Plywood)
- The steeper the roof, the greater the amount of roof sheeting needed.
- Use the hypotenuse of a triangle to calculate layout: A² + B² = C².
- For an 8/12 pitch, it takes about 14 1/12 inches of roof sheeting to cover one foot of horizontal distance.
- For a 4/12 pitch, it takes about 12 3/4 inches of roof sheeting to cover one foot of horizontal distance.
- For a 12/12 pitch, it takes about 17 inches of roof sheeting to cover one foot of horizontal distance.
- Don't forget to add 10-15% for waste due to cuts, overhangs, and other factors.
Using the Pythagorean Theorem
- A² + B² = C² describes the relationship between the sides of a right triangle.
- This formula can be used to calculate the exact length of a line or distance.
- Practice using this formula to improve your estimation skills.
Cutting Hip and Valley Rafters
- Memorize that the hip or valley rafter cut is always the pitch over 17, not 12.
- For example, if the common pitch is 6/12, the valley or rafter cuts are 6/17.
- This is derived from the secant function in trigonometry.
Bonus: Accounting for Waste
- Always provide 10-15% extra material for waste due to cuts, overhangs, and other factors.
- Keep the material clean and in good condition to return it for credit if needed.
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Description
This quiz tests your knowledge of estimating concrete volume and framing materials in construction projects. It covers calculations for slab thickness and lineal feet of wall.
