Ask The Builder: How to use polymeric sand with pavers

DEAR TIM: I need to use polymeric sand on an upcoming job. I’ve never used it before and some of the instructions and videos I’ve watched are confusing and have conflicting information in them. Have you used this material before? Did you find it hard to work with? I’m terrified of having mottled stains on my new pavers! What did you do to ensure your job came out perfect? – Diane K., Roselle, Illinois

DEAR DIANE: Polymeric sand is a newer product that’s creating lots of interest among homeowners, contractors and material suppliers that sell the product. It’s fascinating to me to see how many building products mature as they march through time.

When concrete paving brick was first brought to market back in the early 1980s, the joints between the bricks were just filled with fine sand. It didn’t take long for homeowners to grow dissatisfied with this because weeds would quickly grow and any cleaning efforts washed away the sand.

Polymeric sand is best described as outdoor grout. Depending on the manufacturer, it’s a blend of different colored sand grains as well as chemical binders or glues that are activated by water. When the polymers dry and cure the sand between the joints gets quite hard and it cements the pavers together. Weeds won’t grow between the joints and the sand doesn’t wash away.

Some polymeric sand might have a blend of Portland cement and dry colored pigments as well as the polymer adhesives. The key point here is that you can get the sand mixture in different colors that will match or compliment the color of your pavers. You can even use the polymeric sand on existing paver installations that have just sand in the joints, but it’s quite a bit of work to remove the existing sand without disturbing the pavers.

I recently used polymeric sand at my own home. I constantly preach to my newsletter followers to read product label instructions before using a product. I did that with my bags of sand and came away quite confused myself. I then went online to watch a few videos, some done by my manufacturer, and discovered they had a few oversights that I felt were very important to mention.

First and foremost, to get a great result the pavers need to be dry. The dryer the pavers are, the better the job’s going to turn out. You want even the sides of the joints dry if possible so no moisture inhibits the dry polymeric sand from flowing to the bottom of each joint.

The top surface of the pavers needs to be clean. If somehow the pavers got muddy during the installation, you need to clean off that mud. This may mean it could take days for the pavers to dry after you wash the tops of the pavers. So be it. I can’t emphasize enough how mission critical it is that the pavers are dry.

Be sure all bags of the polymeric sand come from the same batch. Look at the labels to ensure they all were made at the same time. If you have any doubt, open the bags and mix the dry sand all together in a large container to ensure the color is the same.

I used a large floor broom with medium bristles to install the sand. The dry sand flowed into the joints with no effort at all. I went back and forth across the joints at a 45-degree angle. Most of the videos I watched showed the broom strokes parallel or at a 90-degree angle. Doing it that way can cause the broom to dig out some of the sand from the joints.

You want light finish strokes as you try to brush the sand from the pavers. Don’t dig the sand out of the joints.

I read many nightmare stories online about stained pavers during installations gone awry. The common cause was that the installer failed to remove all the sand and dust from the pavers before activating the sand with the water.

I own a fantastic brush I bought years ago to wash the side of my house. It’s a brush made to wash RVs. The bristles are stiff enough that they don’t flop but soft enough that they don’t scratch automotive paint. It’s a perfect brush to do a fine brushing of the pavers.

I took my time and carefully brushed all the sand grains and as much dust as possible off each paver. I was careful to not dig any sand out of the joints. After doing this, I used a backpack leaf blower to blow off any of the colored pigment dust. I was shocked to see how much dust came off the pavers even though I thought I had brushed them well. Do NOT skip this step – use a blower.

Next, wet the sand with a gentle nozzle that acts like a soft rain shower. You don’t want a direct stream that can dig sand out of the joints. Move the nozzle across the pavers back and forth and just put a light amount of water down. Most instructions say to wet the pavers several times. I did it three times in about 15 minutes.

After turning off the hose, I immediately fired up my backpack leaf blower. I blew off all standing water from my pavers to complete the job. Standing water will have the color pigments in it and can foul the pavers. Get all the water off the pavers and be careful not to blow any sand out of the joints. Do all this and you’re pavers will look perfect in two hours!