How to Layout new fence posts.
Let's assume you have the old fence out of the way and now you are ready to start building your new fence. The first thing I always like to do, and need to do , is to look at how the land lies and see if there are any dips and troughs in the ground, and sharp inclines or obstacles we need to consider, basically anything which might interfere with the natural spacing and placing of our new fence and at this stage, the new fence posts.
In a perfect world, all the ground would be perfectly flat with nice soil, no drains, no gas pipes, no electricity cables or trees to get in the way, but that's a rare day lol, so what we tend to find is there's usually something to consider before we go ahead and mark out our post positions.
If you know for example, that a shared drain runs across the fence-line, you will have to mark that off and consider it when you come to mark out the post spacing to cross that point. If there's a big mature tree which the landowner wants preserved, or it might have a tree preservation order on it, you have to check, but let's assume it's staying. that will obviously affect where you can put fence posts.
The topography of the land itself also comes into play. What you have to decide here is how many times you are willing to have the incline of the fence change over the entire run. I always wanted to keep that to an absolute minimum, to try and achieve a pleasing to the eye aesthetic, if you know what I mean? Basically, one or two inclines across a 20m stretch is reasonable, but if you follow every slight dip and rise, the fence starts to look a bit higgledy-piggledy. (Showing my age now, but I'm not from the 1590's lol)
I better say at this point, some fencers don't care about aesthetics or dips and rises, they do what the farmers do and just go with the flow, and step, step, step from beginning to end, because it's easier. My issue with that approach is, it looks bad. (There was another word I was going to use there, but I can't lol)
This is also where I better say, this is why I always avoided panels. With fixed square panels, you really don't have a choice but to step each one in turn as you climb a hill. There is a place for panels, on flat and level ground, but as soon as you go from flat to an incline, the panels step in turn and if the incline isn't constant, your steps are all various sizes and that makes it look....what's the word lol...bad.
Each to their own though and if you like steps and you like panels, that's what you've decided so just be aware, there's not much you can do by way of adjustment, or spacing for that matter, so just be aware of that.
So, getting back to the lie of the land. Once you have checked and established where you can't put posts, now you're looking at the whole length and splitting it up into individual runs. If you're very lucky, the entire fence is on one constant level or one constant incline and there are no changes to be made anywhere on this fence. It's a good day when that happens. Alternatively, you have a slight slope developing somewhere on the line. Now, it might not be obvious, so what I like to do is to walk to the opposite side of the garden and crouch down for a better look, a bit like a golfer eyeing up a putt. You can tilt your head and shut one eye if you want lol, but it just helps you see better before you commit to digging any holes and get it wrong.
As my old boss used to say, "inspecting anything with the Mk1eyeball will only get you so far", so once you have a rough idea of how the land lies, now you have to actually do some measuring to get it absolutely right.
For me, my personal preference was to set my first and last fence posts in the ground at this stage, but without the concrete. As the saying goes, "nothing is set in stone" until it is lol. So dig the first two holes, stick the posts in and ram them down to finishing depth with the post rammer and then chuck a big stone or a brick down the fence-line side of the hole to hold the post steady, or steady enough to take a string line pulling on it.
Now set a string line along the front face of the fence line and pull it tighter than tight until it plays a nice high note, like a guitar string. It's got to be tight now so keep pulling, keep pulling. Is it going to snap? If it does snap then it's no use to man nor beast so bin it and buy a better string line. It's important that this line is ultra tight and perfectly straight. Any sagging and it's going to throw off all your measurements from the beginning and the fence will have that sag reflected in the finished look, and you definitely don't want that.
So now you have your string line up, it's time for Johnny Cash. I Walk the Line lol.
I'll have a wee bet with myself here that all my apprentices over the years still say that sometimes, having heard me say so many times lol. My "Young Jedi" or "Padawan Learners" as as used to call them have all gone on to be great tradesmen on their own, and it fair warms the heart when you see their work and know you had a hand in teaching them and passing on the trade. I look at their work and it's a carbon copy of what I taught and I couldn't be prouder. I don't tell them that, obviously lol.
Anyway, I digress, back to Johnny Cash. Get the measuring tape out now and lock it off a foot longer than the height of the new fence. Now "walk the line" and take a height measurement from the string line to the ground at 3ft intervals. You don't need to write the measurements down, just walk the line and see how the numbers change as you go. If all is good, the numbers will stay within a 3 inch range from one end of the fence line to the other, and that's another rare day, so typically, somewhere along the line, you'll see the numbers get higher and then lower again, or lower and then higher again. On the spot where the highest or lowest point is, mark that off. One of your posts has to go there. That's a change point. If you don't put a post here and set it to the desired fence height, and instead just go ahead and build to the line, the finished fence is going to have a big gap underneath at that point, and to correct that, you would have to order longer slats and trim each individual one to the changing height in order to blend it in, which is a complete pain in the...neck lol. Alternatively, if there's a low point there, and you haven't placed a post there, the fence slats are going to hit the ground there and you have to again, trim them off to fit, which looks...bad lol. So that's why we do that, walk the line, measure, measure again, be sure. "Measure twice, cut once." You've probably heard that said many times and it's always been good advice. Measure, measure and measure again, because once it's set in stone, there's no going back.
So now you have the start and end points and any change points established, it's time to join the dots and get the rest of the post positions marked out. the rule here is to keep every post at 1.8m spacing or less. There are two reasons for that. The first is to build in good strength, and at 1.8m spacing, the posts can cope with whatever wind is thrown at them. The 2nd reason is, most fence rail comes at 3.6m length, and if you go over 1.8m spacing, your rail won't bridge over 3 posts.
Again, opinions vary on how to space the posts. Some fencers just start at 1.8 and keep going until the end and set the last post wherever it lands. I never liked that approach because it leaves the last space out of order with the rest and looks...bad lol.
Instead, I always measured the length of each section, from start to end or from change point to change point and work out the spacing to be equal. If the point to point measurement is 5.4m then great, that's a 1.8m post spacing. If it's 5.1m then that's a 1.7m spacing, and you work to that for that section of the run. I always found that to give me the best look to the fence and even if you have two or three change points and each section has slightly different post spacing, it's not immediately obvious to the naked eye on the finished fence, and that's what matters in my opinion.
Once you're all marked out and you know where the start and ends are, you know where your change points are, now you can start the actual work of building the new fence. Start and end posts can now be set in concrete, followed by the change point posts. You set them all to the desired fence height, cement them in place and wait for them to firm up before setting the string line along the front face to guide you on the height and line of the remaining posts.
I'll explain that process in a bit more detail on another page but first you'll need to go out and buy the new fence posts and that has some things to consider so we'll cover that next. See you there. Buying new fence posts.