How To Measure a Backyard : Professional Methods of Site Measurement
Methods of Measuring Property / Boundary Lines
How To Find the Square Footage of your Yard
There are many reasons why you would want to measure your backyard, or for that matter your side yard or front yard. Before we delve into various methods of measuring your yard, we should look at situations and projects that require or necessitate yard measurements on your residential lot.
Backyard Extensions and Additions:
When you are planning on extending your existing house with extra rooms or building new detached outbuildings such as a studio, garage, guest house, tuck shop and servants living quarters, you will need to measure the size of your rear yard. This includes determining the location of building lines (setback lines) on your property. The architect needs site measurements to plan the design and produce accurate drawings. The quantity surveyor (construction estimator) needs site measurements to prepare bills of quantities and make accurate cost estimates. The building contractor also needs site measurements. Basically, before any type of construction begins, the owner must produce a site plan. Producing a site plan is the responsibility of the engineer, and this plan includes a lot of important detail such as the position of underground utility services, nature of terrain, adjacent buildings, structures, streets and access which may affect the design.
Landscaping and Gardening:
Before you build a backyard garden or any landscaping features and improvements, you must take measurements of the yard and reproduce them on a site plan that an architect or landscape designer will make. This allows the landscape designer to find the right spots for physical features such as pathways, koi ponds, sculptures, pergolas, flower beds, shrubs, hedges, trees and lawn. The site measurements will determine the size of these physical features and their position with respect to other features and/or the site.
While house extensions and structural additions are going to have their location and span limited by setback distance codes, landscaping features are usually not affected by setback rules, but this is something that you have to check with your city zoning department.
When you are selling your house, one of the things that you have to do is getting property and real estate valuers to inspect your house and yard. This includes taking measurements of your lot and yard to determine the real square footage. Property valuers will also take notice of all improvements on your yard and take measurements. They will inspect the conditions of the buildings and additions, measuring the size and estimating the value. Property valuation is also known as real estate appraisal.
Tools and Methods of Measuring Property / Boundary Lines
The following are methods used to measure a backyard or any type of site.
Tape Measure Method:
The tape measure is one of the most common and important tools that are traditionally used to take site measurements by construction estimators, quantity surveyors, builders, engineers and architects. You cannot go out to the site or in the field without a measuring tape. This is a handy surveyor’s tool that fits in your pocket. In order to take measurements on your private property, you will need a notebook and pencil for taking down measurements, a piece of white chalk to mark positions as well as an assistant to help you. Measuring the size of your backyard is easy. You simply need to align the tape along the boundary lines, and progressively take measurements of the whole backyard perimeter. Retractable measuring tapes come in different lengths of 5, 8 and 10 metres. If the ground distance is too long, get an assistant to hold the other end of the tape, but you will always need an assistant to hold the tape on point, even for short and medium distances. A metal tape measure will be suitable for construction site measurements. The diagram below illustrates how to take measurements of a lot or yard.
Laser Measure Method:
Instead of taking site measurements using a measuring tape, you can use a laser measure also known as a laser distance measurer. With this digital measuring tool, you can take measurements much more quickly and easier than a tape. You won’t need an assistant to help you on the site with this tool, meaning you can take measurements alone. To take measurements in your backyard with this tool, you will need to reset the button to zero, then point your laser to a point or obstruction along the boundary line. The instrument will measure and record the distance as the laser beam is reflected back and detected by the device. The device automatically calculates the distance travelled by the laser beam using the formula D=CT/2, where C is the speed of light and T is the time it takes for the laser beam to travel to and from the obstruction (the reflector).
Laser measuring tools have much longer ranges. As an example, Bosch is a brand name in digital measuring tools, producing 18 laser models with a measuring range of 35 to 825 feet (11 to 252 metres). As you can see, a site surveyor can quickly take measurements of big yards with this device. Whereas the longest tape measure is about 10 metres long, a laser measure can take single measurements up to 252 metres.
When taking yard measurements with a laser device, you will need a travelling board that blocks and reflects the laser beam. Place the travelling board at a point connecting a straight boundary line, then send a laser beam to hit the board. Take down the measured distance on your notebook. Alternatively, depending on your measuring device, there are devices which can save the dimensions, so you won’t need to write down the measurements. A travelling board or reflector will only be used where distances are too long to get a high degree of accuracy or where there is no physical reflector such as a wall or post at the end. If there is a permanent physical reflector or obstruction on the end point, it’s much better to make use of it rather than using a travelling board.
Measuring Wheel Method:
Although it’s not as accurate as the tape measure or laser measure method, this is one of the easiest ways of taking rough measurements on a site or yard. Keep in mind that you have to use this method only when you need quick and rough measurements. A measuring wheel also known as a rodometer or trundle wheel is a tool for measuring distance on the ground using a wheel. By pushing the wheel along the boundary line, it will automatically register the distance travelled using the car odometer analogy. The circumference of the wheel is known, and this is used to calculate the distance travelled or the number of cycles that the wheel has turned.
The problem with a rodometer is that it won’t give you an accurate linear measurement between two points, due to the fact that the wheel follows the ground terrain, and not the horizontal line between the points. So if you have a rectangular backyard, the two opposites sides which are supposed to be equal in length will have discrepancies. The sides won’t have the same lengths as expected because what was measured is the ground terrain or topography. One side of the yard might be rough or sandy ground and the other side might be a fairly flat surface with lawn or pavers.
When measuring each side of the backyard with a measuring wheel, you should always reset the counter or meter to take new measurements. The measuring wheel is useful for measuring large yards, roads and fields.
How To Find the Square Footage of your Yard
Methods of Calculating Backyard Area From Site Measurements
After taking yard measurements, you will need to calculate the area of the backyard or any portion of the yard that you are interested in.
Calculating the area of a rectangular site is easy. You simply need to multiply the length by the width. As an example, if side A is 40 feet and side side B is 25 feet, your area will be:
Area = Length x Width
Area = 40 x 25 feet
Area = 1000 square feet.
Calculating the Area of Irregular or Polygonal Shapes:
Backyards are not always rectangular in shape. Some residential lots are irregular in shape, and in this case you have to use a particular method.
A parallelogram is a quadrilateral (four side shape) with two parallel sides. If you have a residential lot or yard with this shape, you should use the area of a parallelogram to find the square footage:
Area of Parallelogram, A = Base x Height.
A = B x H
If your residential lot is polygonal, with more than 4 sides, i.e. 7 or 10 sides, then you have to divide the yard into triangles and rectangles. You should then find the area of each of these subdivisions and add them up to get the total area of the yard.
After measuring the sides of the yard with a measuring tool, draw the lines on a sketch pad and mark the dimensions. Draw the building line on the sketch pad and mark the dimension. In this case, you should take backyard (rear yard) wall of your house as the building line or reference point. Measure the length of this rear wall elevation and mark the dimension on your drawing. The good thing about this rear wall is that it is usually a straight line. Draw straight virtual projecting lines from both ends of the rear wall. These straight lines should project from the wall to the boundary line (fence) on both sides of the house. Now, at the point of intersection of the projecting line and boundary line, you should draw a line that is perpendicular to the projecting line. This perpendicular line should be drawn as far as the furthest point on your backyard. To clarify, if the rear wall of your house is facing North, the perpendicular line should also face North and it should project as far as the furthest point on your backyard fence or boundary wall. So now, you will have two perpendicular lines emanating from the building line. Your next step is joining the ends of these perpendicular lines with a parallel line (line parallel to the building line), to form a rectangle.
At this point, on your sketch pad, you should have a rectangular section that encloses the irregular outlines of your existing yard.
You have to transfer these site measurements and sketch drawings on your computer or laptop. Let’s hope you have construction drawing software such as AutoCAD or Google Sketchup installed on your computer. Google Sketchup is free and it does the job well for both 2D and 3D drawing. However, we are only interested in 2D Plan Drawing here.
Open the CAD program, and choose an appropriate scale for your sketch drawing. A scale of 1:500mm, 1:200mm or 1:1000mm is suitable for a site plan. Draw the sketch plans from your field sketch book, and when you are done, a program like Google Sketchup can automatically calculate the area of surfaces enclosed by perimeters. To do this, click the Text tool on Google Sketchup and then touch or highlight the enclosed surface that you want to calculate. You will see the surface area in real life scale marked in square millimetres or inches, which can be converted to square metres or square footage.
Alternatively, if you don’t have a computer or CAD software, you can transfer your site measurements and sketch drawings on a grid paper, but make sure that you draw the lines to an appropriate scale. After drawing the yard sketch on grid paper, count the number of full squares or grids covering the yard, and add up the totals to find the area. This will give you an approximate size of the backyard.