The Paving Blog

Slab paving is an interesting and fairly dicey idea.  Currently, there are an abundance of slabs available for paving. almost of of which follow the same rules and specifications that the smaller pavers follow.  High PSI (8500, often), highly compressed concrete, up to 9 foot square in size (3′ x 3′), these large items make a dazzlingly effective look. They actually go down faster from an installer’s perspective, covering more territory with fewer pieces.  They offer the same ability to replace when damaged or discolored and, while not altogether as flexible as the smaller pavers, are indeed far more flexible than monolithic pours such as asphalt or cement.

Another supreme benefit is the options of colors and style.  Owing to their size, large paving slabs offer some intriguing mixing possibilities.  The :checkerboard look is often chosen and it can be surprisingly effective if not entertaining. Naturally, bands of color are easily inserted, either by bordering a driveway or by intersecting it across.

There is however a caveat.  Owing to their large size, the need for a perfectly graded and drained subsurface is even ore vital than for the smaller editions of pavers.  The reason is in their size.  Tires from cars and truck are dispersed by weight far easier than on these larger units.  A tire can place an imbalanced amount of weight on just one corner of one of these and, with an inadequate or deteriorating base, can cause rocking. And with rocking, comes an increasing compression underneath, yielding eventual breakage or worse, an uneven driveway.

As in all driveway constructions, pay strict attention to the subsurface.  Drainage issues also figure largely here, especially where water can flow beneath a large slab and conduct the material underneath elsewhere.  This will cause the problems listed above.

Enough of drainage, my friends. But still on the topic of driveways, this post is in response to several emails I receievd on the matter of DIY Driveways.

Doing a driveway yourself can be an amazingly rewarding enterprise. I have seen the proud constructors of such behemoths smiling away after chasing down what I originally had assumed to be just ludicrous ideas.  Once again, I face the knowledge that no one “knows it all”, and perhaps least of all, me. My one caution to every single constructor of one;s own driveway is always the same: prepare the subsurface right. If you notice a trend here, there is obviously some solid reasoning behind it, mixed with experience.  Done correctly underneath, a person can actually enjoy the next process, knowing fully that this will be the “business end” of the art supplied for the finish.

In that light, I have seen driveways composed completely out of rock either bought or scavenged from nature.  These have resulted in some fabulously beautiful projects, and I do mean just breath-taking.  The amount of time and energy a home owner can lavish on a project makes what I do pale by comparison.  Where my work is contracted and therefore time-related, yours can be a labor of love.  Listen, that is huge.

Those driveways I just referred to had cement applied between the rocks to stabilize the them. They all were rotated to supply a flatter surface and then cemented into place.  String was often used to maintain the perfect height, pulled taut and adhered to religiously as a topmost grade and level.  The placement of drains and slopes returning water to the drains was just as often very artfully done.  Whether washed river rock or “found” split rock, all these constructions were among the best I have ever run across.  Granted, they represent a highly personal aesthetic and many people would not want anything like it.  But to me, and knowing those who did the work and knowing the labor involved, I could not have been more dazzled nor more happy seeing such a fine result.

Yeah, I know, it’s August. Most places are dry this time of year, and yet it’s the best time, IMO, to address drainage issues. So let’s talk about drains for driveways today.

Draining water from the surfaces we construct, whether driveways or patios and walkways is among the very most essential considerations in all of the architecture involved.  Nothing outside of incredibly low temperatures can wreak the havoc that water can.  Standing water is one of the most corrosive elements of all seeking the micro fractures in concrete from where it enlarges holes and cracks with its small acidic content, to say nothing of its simple abrasiveness.

We see it often, puddles forming at imperfectly-installed levels of cement surfaces.  We see it in pavers and asphalt constructions, where the initial grade was insufficient to conduct the water elsewhere and the blindness of the laying mechanisms ignored what is always supposed to be a professionally-achieved perfect primary grade..

Then there are the installations already up against an impossible sloping situation.  A roadway higher than the garage, for example.  What does one do?

Well, modern property law demands that every neighbor be responsible for his own water and conduct it to an appropriately-supplied point.  When there is a point supplied which can collect positive drainage, then, while it might be hard to accomplish, it becomes possible to reach full adequate drainage.  The most remarkable aid to this process, to my mind, is the concept and the newer manufactured “Channel Drain” system.

Channel drains are collecting drains, about 6 inches deep in size, 4-6 inches wide, which even provide a sloped interior and which are covered with a road-worthy cover which allows water to enter.  The water is then conducted down the channel to a collection point where piping and further drainage remedies can conduct the water away. The channel drain goes in a line all the way across a driveway. Most homes who have such a slope, descending TO the house, install channel drains not only across the roadway but also at the very base entry of the garage itself.  This catches what does not make it past the prior drain system and also conducts it away, often in connecting to the same pipe used by the other drain.

Channel drains can handle an enormous volume of water as well, conducting it efficiently and rapidly away. They represent a clean and efficient way of attractively dealing with the problems of runoff.

More drainage issues today – this time ;et’s talk about Catch Basins.

We have all seen those steel-grated manhole covers which are designed to catch the water on our street and roads.  There are also those curbside drains, cut into curbs on streets which perform the same function. These highly effective drainage systems rely on a perfectly graded surface which funnels all the rainwater or whatever water produced on a road into their orifices and down into the sewage system per se.

It turns out, this simple system can also function perfectly in a driveway or even a patio when a home owner faces drainage issues resulting from the tougher terrain where simple solutions like merely sloping a surface to an appropriate point is impossible. What we then arrive at is the need to conduct the water elsewhere.  This requires catching the water and providing a system to funnel it all away through piping and channels we create off the surface itself and sometimes under it.

Catching the water is the first issue.  The grading required to perform best would slope everything into “catch basins”, isolated collectors, connected to pipes running under the surface itself and conducted out.  These catch basins are either plastic, steel or concrete and have road-worthy tops, or grates, which filter things such as leaves, leaving them on top and allowing the water alone to enter.  Placed appropriately, these units can handle 100% of the water from a road surface if engineered correctly.  Needless to say, the primary grading should provide sloping to all of the various units installed.

A perfect system would not appear to be seriously sloped. The fact is that water needs very little slope top find its way downwards.  In more seriously rainy climates, naturally, there may be a need for a more serious slope owing to quantity and frequency of rainfall..Nevertheless, appropriately-placed catch basins are designed to do the work of leaving our driveways clear of water and of conducting all drainage away from the home.

Typically, any patio – in fact, any surface at all, from Driveways to pathways – should have some sort of slope, obviously away from a home or structure, to insure that water does not collect.  We’ve all seen puddles.  Heck, some of us loved them as kids………lol, I know I sure did. The vandalism aspects alone appealed top a young rascal who loved jumping in them and splashing anyone nearby!

But there are many sad souls who don;t share this opinion of the righteousness of puddles. In fact, the presence of standing water ion these surfaces is never good, the truth is.  When water puddles near a house, it can soak the foundation and thereby cause rotting in the wood above it.  Continued saturation can mean replacing an outrageous amount of construction. Puddling near the middle of a patio or driveway can mean people tracking wet shoes into a house and spoiling rugs and carpeting.

So, here we have a dilemma.  The work is finished already, the contractor paid and gone for years.  Now what? How do we retroactively address a flaw or some upset in our water-draining systems?

For many, scoring 1/4″ deep lines with a masonry blade on a skill saw can sure the worst of those problems.  Masonry blades are now pretty cheap and readily available at any retail hardware store. Make sure the cut goes in  downward direction, towards some point off the drive. More than one line is usually called for and, actually, these can be somewhat artfully arranged.

Another method is a bit more drastic:  it involves installing a drain and running pipe out of the middle of the surface.  Naturally, this means cutting the surface entirely and inserting the desired drain pipe.  However, the smaller the area involved the less obvious the repair will be. Nevertheless, there are excellent drain systems available and the drain itself does not have to be unattractive.

The best system is perfect to begin with. A flat, one or two percent slope generally takes care of all water issues.  But when there are flaws, such as indicated above, these are a couple of ways of handling it.

Naturally, a primary consideration returns to the ever-present issue of a good sub base below.  Bearing in mid most grass roots will literally firm soil up, the compaction levels necessary for pavers alone decrease just enough to consider the fact that the roots of grasses can replace a few percentage points of compaction.  We would still use a base material and compact it as much as possible.

Yet, what might lessen the impact for grass roots seeking a purchase would be the replacement of base rock with a washed sand product, every bit as compact able yet more root-friendly.  The grids and products are installed just like any other paving material, and are graded appropriately, and the driving surface becomes every bit as strong and solid as any other base. Just add grass and tell everybody to “Park on the Grass!”

More about lawns in our sister blog: Lawns Hub