Wow! There is so much to say in regard to installing a fence in your yard! There’s a lot of preliminary stuff that you need to do and much to understand to make your project a success. But first, we want to say kudos to you for deciding to add beauty, architectural enhancement, and value to your outdoor living.
There are so many types of fences, and some of the materials needed to construct any of them may be more challenging to work with than others. Some fences may even require skilled labor such as those that use materials like masonry columns and cast aluminum fencing (posts, rails, pickets). Some materials for fences, such as wood, are easier to work with which lend them to being more of a do-it-yourself project. Installing a wood fence can be a time consuming commitment if you are planning on installing it yourself, but it is so very much worth the effort.
As with many outdoor projects, much preliminary work is needed before you even start to dig that first fence post hole. Whether you plan on installing the fence yourself or plan to hire a contractor, all this information is important to know for a successful project.
Things to Do Before You Dig
Before we get to how to calculate the number of fence sections and posts, the following things need to be taken care of:
• If any part of your fence will be installed near property lines, hire a professional surveyor to locate those property lines, any setbacks, any easements, and other things required by your local building department. If you will have a long run of fence, ask the surveyor to give you several pins along that property line – this comes in handy when measuring off of an invisible property line!
• Talk to your local building department for all the building code requirements that your fence design and installation must comply with; these may include, but are not limited to: height, footings (materials, widths, depth), frost line depth, setbacks, easements, permits. Some cities may even require you to submit some type of drawing showing the fence design and its proposed location on your property. Don’t be put off by having to submit a drawing. Building departments are typically helpful, and they will guide you through the process.
As for the permit(s), if you are having a contractor build and install your fence design, don’t assume they will obtain any required permit(s) – you need to make sure that you or your contractor has obtained all necessary permits!
• Before you dig, Call 8-1-1 to have all of your underground utilities located. This is a free service. Knowing where your underground utility lines are located can help you and your family be safe; and keep your utility services uninterrupted.
Correct Calculations Can Save the Project
Now that you have all the information you have collected from your survey and from your local building department you will have a better idea of where your fence can be located.
The next step is to calculate your fence length, the number of fence sections (which is the distance from center-of-post to the next center-of-post), and the number of posts. All this will give you your post locations so you can dig your post holes. Don’t dig your post holes for the line posts (meaning the posts between the end posts) just yet because you may be re-digging them! One easy way to calculate this is to install the end posts first, then it will be easier for you can make your calculations (we’ll go into this more in a moment).
For a basic fence design, having equal lengths of fence sections will create an attractive and beautiful fence for your yard. At this point though, it is difficult to know the exact length of the sections without the end posts located and installed. The end posts (and all later installed posts) should be located and installed as per your local building code. This code should also supply you with the required dimensions and depth that you need for your post footing, and the construction material(s) you would need to use to make the footing.
Also, the footing is part of the fence and it is wider then the fence post, so your fence will not be directly on top of your property line. The footings should be completely within your property line. Other constraints you may have to deal with include setbacks, easements, and utility lines.
In regard to the footing, we could give you the specific information we would use, but what we would use would not necessarily comply with other parts of the country/world (frost lines vary from region to region) or with other building departments. Regional conditions and local codes always take precedence.
Installing the End Posts First
Installing the end posts are key to arriving at your number for the total length of fence. After the end posts are installed, you will now be able to get the total length of your fence by measuring from the center of one end post to the center of the adjacent end post. With this measurement, you can now calculate the number of equal length fence sections and the number of posts you’ll need; and, where to dig the remaining line post holes.
An example calculation may help with this part. Everything is measured on center, which means center-of-post to center-of-post. In this example, a total length of 110.25 feet will be our measured distance from center of end post to the center of end post. The span between posts is a structural determination. For this reason, 8 feet (center-to-center) is the typical maximum span for fence posts (again, check with your local building department in case theirs is different). The spans can be less than 8 feet, but not greater than 8 feet.
So if we divide our length of 110.25 feet, in our example, by 8 feet to get our number of fence sections, we get 13.78 fence sections. We want our fence to be beautifully proportioned and have equal section lengths, so we go to the next whole number of 14. We now know we want 14 fence sections. To find the equal length for each fence section, divide 110.25 feet by 14 to get the length of 7.875 feet (110.25 / 14 = 7.875, which is equal to 7’-10 1/2” ).
Our example shows us that we have 14 fence sections and each section is 7’-10 1/2” in length (center to center). All the line posts will be at 7’-10 1/2” increments (center to center) and that’s where we would dig our post hole. ~ End of example.
After you do your own calculations for your own fence, start measuring to locate your fence posts from the center of one of the end posts and place a stake at each post location where the center of the post hole should be (which is also the core center of the post). Remember to keep the post hole within your property line, and out of setbacks and easements. Before you begin to dig, we recommend going right down the line locating the center of each post to make sure your calculations weren’t flawed. It is just a good thing to do – like the saying ‘measure twice, cut once’!
Now your have all your numbers and you can start building and installing your beautiful fence. And you already have a head start since you’ve already installed the end posts!
If you need an idea for a fence design, we have plans here for a beautiful Crossbuck fence.