LAYOUT OF BUILDING
A. Basic Understandings
1. When laying out a building, care should be taken to get the building laid out as
perfectly square as possible. If the building is not laid out square, compensation for
the error must be made throughout the entire construction of the building.
2. A building may be laid out square with a transit (or farm level) and measuring tape,
or with just a measuring tape. If only a tape is available, considerable time can be
saved if two tapes and a calculator with a square root key is used.
3. When laying out a rectangular or square building, all four corners must be 90o. To
check the building for squareness, measure both of the diagonals. If the two diagonals
are equal, the building is laid out square.
The diagonals are the The diagonals are not the
same measurement. The same measurement. The
building is laid out square. building is not laid out
square.
4. When checking a right angle (90o), two methods may be used to check the angle for
accuracy:
a. 3-4-5 method – If one leg of a right triangle is 3 and the other leg is 4, the
hypotenuse will be 5.
Hypotenuse = 5 (Any multiples of 3-4-5 may
Leg 1 = 3 be used, such as 6-8-10;
9-12-15, etc.)
Leg 2 =4
The basis of the 3-4-5 method is the Pythagorean Theorem, which states that in a right
triangle. The square of the hypotenuse equals the sum of the squares of the other two
sides. A right triangle is one in which one angle equals 90o. The hypotenuse is the side
opposite the right angle. The formula for the theorem is:
C2 = A2 + B2
Using the theorem to check the triangle is the example above:
52 = 32 + 42
OR 25 = 9 + 16
b. Another method of checking a right angle is to determine the hypotenuse of a
right triangle based on the total base and height of the triangle. The
hypotenuse of a right triangle will be the sum of the base of the triangle
squared (the number multiplied by itself) plus the height of the triangle
squared. When laying out a building, the hypotenuse will be diagonal for the
building.
Example:
10’ height Hypotenuse = 26.9’
102 (10 x 10) = 100
252 (25 x 25) = 625
725
√725 = 26.9’
Base = 25’
The Pythagorean Theorem is also the basis for this method of squaring a right triangle. If C2 = A2
+ B2, then C = √(A2 + B2).
By determining the hypotenuse (diagonal of the building) first, the building can be laid out using
two measuring tapes without using a trial and error method. If the 3-4-5 method is used, several
extra measurements must be made to lay out the building.
B. Laying Out a Building With Two Tapes and a Calculator
EXAMPLE: 8’ x 12’ Building
1. Establish one side of the building by measuring the desired length (or width) of the
building. This side can be made parallel to another building or can be simply determined
by the owner.
Corner A 12’ Corner B
Drive two stakes to mark the two corners of the building. Drive a nail in the top of the
stakes to more accurately locate the corners of the building.
2. Consider the building layout to be made up of two right triangles put together.
Corner A Corner B Corner A Corner B
Right triangle Right triangle
Right triangle
Right triangle
Corner C Corner D Corner C Corner D
The two right triangles will have the same hypotenuse. The hypotenuse will be the
diagonal for the building.
3. Determine the hypotenuse of the triangles. Again, the hypotenuse will be the diagonals
for the building layout.
a. On the calculator, multiply 12 x 12 (= 144) and press M+ on the calculator.
b. Multiply 8 x 8 (=64) and press M+ on the calculator.
c. Press Memory Recall (MR). The sum of 144 + 64 = 208
d. The hypotenuse (or diagonals) will be the square root of 208.
e. Press the square root key. The hypotenuse (diagonals) will be 14.42205 feet.
f. If you have a tape that is graduated in feet and tenths of a foot, the diagonals will
be 14.2’.
g. Since most tapes are graduated in feet, inches, and sixteenths of an inch, the
14.422205 feet must be converted to feet-inches and sixteenths of an inch.
1. The diagonals will be 14’ plus .422205’.
2. Convert.422205’ to inches by multiplying by 12. The diagonal will
be 14’5” plus .06646.
3. Convert .06646” to sixteenths of an inch by multiplying by 16. The
diagonals will be 14’5 – 1/16.
4. Establish Corner C.
a. Measure from Corner A toward Corner C a distance of 8’.
b. With the other tape, measure from Corner B toward Corner C a distance of 14’5-
1/16”.
c. The point at which these two measurements intersect is Corner C
Corner A Corner B
8’ 14’ 5-1/16”
Corner C
d. Drive a stake to mark Corner C. Drive a nail in the top of the stake to more
accurately locate the corner of the building.
5. Establish Corner D
a. Measure from Corner B toward Corner D a distance of 8’.
b. Measure from Corner C toward Corner D a distance of 12’.
c. The point at which these two measurements intersect is Corner D.
Corner A Corner B
8’
Corner C 12’ Corner D
d. Drive a stake to mark the corner of the building. Drive a nail in the top of the
stake to more accurately locate the corner of the building.
6. Check all measurements again. Measure both lengths, both widths and both diagonals.
Corner A 12’ Corner B
14’5-1/16”
8’ 8’
12’
Corner C Corner D
7. Make any adjustment necessary to square the building. Adjustments should be made at
Corner C and Corner D.
NOTE: ALL MEASUREMENTS SHOULD BE MADE WITH THE TAPE HELD LEVEL.
THEREFORE, ON SLOPING GROUND, IT MAY BE NECESSARY TO USE A PLUMB
BOB TO MARK THE LOCATION OF THE CORNERS OF THE BUILDING.
Setting Batter Boards
1. With all four corners of the building located, set batter boards beyond the corners. Place
the batter boards far enough away from the corners to allow the batter boards to remain in
place until the framing members of the wall are in place.
Corner A Corner B
Corner C Corner D
2. All batter boards should be set level and level with the batter boards on the other corners.
Use a spirit level and a string level to set them level.
3. The strings marking the location of the walls should pass directly over the nails marking
the location of the corners of the building. Mark the location of the strings on the batter
boards with a saw kerf.
4. After batter boards and strings are in place, the stakes marking the corners of the building
may be removed.