First of all, just what exactly is grading? Grading is simply the controlling or manipulation of slope to ensure that surface drainage runs in a specified direction.
In otherwords, when you go to hose off your new patio, or it rains on your new walkway the water flows in a desired direction, typically away from the house, so it doesn’t puddle or collect on the hardscaping surface.
Now most lay people will tell you that they want their patio to be flat. Of course. Nobody wants to feel like they’re on the slopes of Mt Kilimanjaro as they’re grilling out or kicking back on their Adirondack chairs.
But a perfectly flat patio will collect water, and just as you don’t want to be enjoying your patio on a slope, you also don’t want to feel like you’re trudging through a pond as you enjoy your patio.
Now I will say that walkways can get by with a bit more slope than patios, based on the surrounding grades. Some people don’t mind having a bit of ramp to their walkways, and indeed a ramp or slope can be more accommodating to disabled individuals than a set of steps. At that point it really becomes a bit of personal preference. But just be careful – too much slope and things can get a bit slippery when the ice and snow arrive.
In fact, even on patios I try to cheat just a bit by reducing the slope just a tad. But you have to be careful if you’re trying this yourself. Any less slope than 1/8” per foot and you will have drainage issues. I would draw the line around 3/16” per foot at the bare minimum. And if the stone you’re using has a bit of a textured natural cleft to it, you’ll be prone to getting some little “micro” puddles in the nooks and crannies of the stone – better to err on the side of ¼” per foot.
All of the above having been said, on a relatively flat lot the grading can be fairly simple. Identify the natural direction the water flows, and slope your patio in that direction. What you need to be careful of is not to slope a patio in a direction that will result in water puddling or pooling in other areas of the yard. And you need to be careful that the patio or walkway placement won’t act as a dam to water flowing across the yard.
Where things get tricky is when you have a sloped or uneven yard. In these instances even the simplest of hardscaping projects can incur additional costs in the form of retaining walls, drainage plans, code compliance, permits, etc. If you don’t have a whole lot of experience, then I wouldn’t try to this yourself.
As you’re formulating your drainage plan in conjunction with setting the grades, just make sure you know where the water will go once it has shed off the patio. Just because it drains off the patio doesn’t mean it won’t create a puddle somewhere else in the yard. And you need to be careful that your project isn’t creating a new headache for your neighbor. Plan your work and work your plan.
So no, grading and drainage certainly aren’t the most glamorous aspects of your upcoming hardscaping project (unless you have some wacky turn-ons, but hey, who am I to judge?), but it is perhaps the most important in terms of dealing with the overall functionality of your yard, not to mention the costs of fixing these problems.
Next week – we’ll take a quick side detour to discuss man-made pavers as our hardscaping series continues.