patio Archives

July 31, 2010

Is Stamped Concrete Any Good?

It’s funny- for the longest time, I would have said no. Emphatically, in fact. After all, there have always been several flaws with stamped concrete, many of which are still a negative:

Difficult to change- once a slab is poured, that’s what you have. To reduce it for any reason, you would need to saw cut and remove a portion. To add on to it you can pour a new pad, but good luck getting the colors to match. Pavers, brick, and stone are a little easier to change out depending on how they were installed.
Life span- Concrete doesn’t last forever. If you get a section that chips, cracks, spalls, or stains, you have the same problem previously mentioned that it’s difficult to patch unobtrusively.
Cracking- this is a big one. Concrete WILL crack; anyone who tells you otherwise is full of it. The reason is that concrete is strong in compression, but not tension. What does that mean? Imagine that a piece of styrofoam is a concrete slab. If we load it so that the forces are pushing down on the slab evenly, it handles it. Now, let’s put the styrofoam on the edge of the table and put a weight on the end hanging out into space. It fails, because it is weak in tensile strength- just like concrete. This is why we put steel reinforcing rods (rebar) in concrete. We’re taking a product (steel) that has high tensile strength and giving some of that to the concrete. However, even reinforced concrete will still exhibit surface cracking.
Expansion joints- this is my pet peeve. I’ve seen too many artfully done stamped concrete slabs where the contractor does a pretty convincing job of an irregular stone pattern, then strikes a joint right through the middle of it, ruining the illusion. To avoid this you need to find a good contractor AND let him know you don’t want to see this.
Surface finish- too many slabs are sealed with a glossy, fake-looking sealer. Also, sealed concrete can get slippery underfoot. There are sealers out there that have less of a sheen to them, and there are also additives that will make them less slippery (“up the coefficient of friction” if you want to geek out)

So Dave, you say, why on Earth would you let anyone use stamped concrete? Don’t get me wrong, I will almost always design with the idea of using brick or stone first. It comes down to a budget issue. In northern Virginia, the cost of stamped concrete is usually right around $15 per square foot, essentially half the cost of wet-laid stone or brick. That’s pretty huge. If it’s a pattern that translates well to stamped concrete I would rather see the project move forward than have the client take the plans, roll them up, and put them in the closet for a decade. Where’s the fun in that?

This project actually worked remarkably well with stamped concrete. It was designed to be 2’x2′ flagstone squares, laid in a grid pattern on concrete. Instead, we used a stamp pattern that makes the slab look like one big piece of stone and used a masonry saw to cut grid lines in the concrete. Even with natural stone used for the wall and firepit, the concrete still looks good. Apologies for the picture of an unfinished site, but we’re still working on this one.

So to answer the original question of the post, is stamped concrete any good? It certainly can be, with the right design and the right contractor. Make sure you have both of those in place and you can get a great finished landscape.

UPDATE: Here’s a pretty cool little set of steps one of our stamped concrete contractors did in northern Virginia.

May 5, 2010

Flagstone Patio Pics (Northern Virginia)

In amongst the craziness of spring, I took the time to slide by a flagstone patio/ dry-stacked fieldstone wall/ planting job I designed last spring. I have to say, I’m pretty happy with how it turned out:

The “main room” of the patio is irregular (aka “broken”) flagstone with a border of granite cobbles. The rest of the field of the patio is random-laid rectangular flagstone.

We tied into the existing brick walkway through the woods. The wall replaced some old, decaying railroad ties that defined the birds’ garden.

I guess that highlights the big difference between landscape design and interior design: with an interior, some of your best shots are the day after the crews pull off the site. This landscape is still “too young for primetime” at a year old, but I’m still digging the final result. This project’s in Alexandria, Virginia, just a stone’s throw from Mount Vernon, so boxwood were a natural choice.

Anyhow, just thought I’d share. I know the posting’s been a little sparse, so I need to at least show a little of what I’ve been up to!

October 27, 2008

Your Patio- Stone, Pavers, Concrete, or….?

When designing a patio, there are times that only one type of material will do. Either the architecture of the home is so dominating that it dictates the patio, or maybe the client already knew what he or she wanted. Other times it’s not so clear-cut, and we have to weigh several different factors to decide on the “right” course of action. It’s just reality that we have to balance looks, longevity and budget. So what are our choices?

Concrete– It’s the old standby, and what most people are starting with. A basic, natural colored broom-finished concrete slab will be your least expensive way to go. Too plain? You can go with colored concrete, where pigment is added to the load in the mixer. This results in a uniform color all the way through. Or, if you’re looking for something even more decorative you can go with stamped concrete. The slab is poured, and pigment is applied to the surface and a stamp is used to create the appearance of stone or tile. The build process is the same for all: excavate the area, build forms, put down gravel and reinforcement, and pour the concrete.

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Pavers– For me, these sort of bridge the gap between concrete and natural stone. You can go with a fairly inexpensive paver, but those tend to look cheap. On the other hand, there are some really top-quality pavers. When people talk about pavers, they’re usually talking about concrete pavers. To give the paver a more natural look, the manufacturer will often tumble the paver to distress the edges. You certainly have options; I know that here in VA, I can think of a half dozen manufacturers of pavers available to me.

With a few exceptions, pavers are not mortared in place; rather, the installation process involves a compacted base layer of at least 4-6″, a 1″ layer of bedding sand, with the pavers set in the sand. Sand is then swept in between the joints of the pavers, helping to lock them in place. Manufacturers now use a product called polymeric sand, which sets up almost like a glue- no more worrying about heavy rains washing out the joints between pavers. Pavers are a great solution for driveways, because they’ll withstand heavy vehicle traffic if the base is prepared correctly. There are also some great pervious pavers that allow stormwater to percolate back into the ground instead of running off the patio or driveway and into a stormdrain.

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Natural Stone- This is by far my preferred choice. It looks great from the second it goes in, and as it weathers it only looks better. There are two methods of installation: mortared on a concrete slab, and dry-laid on stone dust. The first method is the more expensive; a 4″ thick concrete slab is poured, and the flagstone (or whatever type of stone you’re using) is mortared to the slab, and the joints between stones are mortared. It produces a very permanent, easily maintained patio. Irregularly shaped flagstones and rectangular-cut stones are both appropriate for this method.

The less expensive installation method is dry-laid on stone dust. There is a 4-6″ base layer of stone dust, or stone dust on top of road base, and the stones are set and levelled with a rubber mallet. Stone dust is then swept between the joints, wetted down, and more is then swept in to keep the stones from shifting. This is a great way of doing a patio with a rectangular-cut flagstone. If using irregularly shaped stone, you need to be careful not to use small pieces. Because there’s nothing holding them down, a small piece could create a trip hazard.

Of course, there are many other options available for your patio or walk- tumbled marble, travertine, cobblestone, urbanite, even compacted gravel. What we can do is limited only by our imaginations. Call or email for a consultation if you want to get started on planning your patio!