Pro Tip

Applying Polymeric Sand to an Existing Patio or Walkway

Over time, all patios will settle, wear and erode. Instead of simply using regular sand to fill in the missing spots between the pavers, build long-lasting beauty into the surface with polymeric sand. If you don’t, much of the sand you put in will wash out after a few heavy rains, and you may see weeds pop through before you finish packing up at the end of the job. Properly sealing paver joints will help ensure better quality for your customers, less maintenance and greater satisfaction at the end of the day.

Polymeric Sand vs. Regular Sand for Pavers

Polymeric Sand is a blend of sand and special additives designed to fill the joints between concrete pavers and brick pavers. When proper preparation is taken (such as weed killer, insect repellant/removal), this polymeric jointing sand has the potential to reduce weed growth, resist rain washout and help prevent insect penetration, compared to more traditional sand.

Polymeric Sand – The Best Sand For Paver Joints

It is a little more expensive, requires more time and more attention to detail but using Polymeric Sand will leave better results for much longer at the end of the day. Polymeric sand products such as TechniSeal NOCOSTORM or TechniSeal Polymeric Joint are designed to resist weed growth and to harden and stay in place for a long time.

In addition to the polymeric sand (hereafter referred to as “sand”) you are going to need a few other items. This is dependent on the condition of the patio. You will definitely need a garden hose, an adjustable nozzle, and a broom. Additional items may include: a pressure washer, leaf blower, a non-selective herbicide (that’s a fancy term for a weed killer that will kill anything-Roundup® works well), additional pavers, paver sealer, a small sturdy brush.

Before you get too far into this job, we need to discuss reality. Some patios are beyond help. If the pavers are so crooked and busted that you can’t walk across them without tripping you really have a major project on your hands. If this is the case you need to pick up every paver, level the ground under it, reposition the pavers replacing any that are broken. This is certainly cheaper than a brand new patio, but it is a tedious job.

Joint Size

Polymeric Sand works best when it is used to fill the entire depth of the paver. In addition, it works best on joints that are between ¼ inch and 1.5 inches wide. Wider joints take longer to harden and may require that traffic be restricted for a longer period of time. Casual pedestrian traffic would not be an issue but high heels would wreak havoc. Some pavers are made with notches on the side. If your pavers are installed in a such a way that the notches touch the next paver, polymeric sand will not work well. There simply isn’t enough space between them to allow the sand to fill the entire void. Some pavers are made with a false joint. This joint is usually about 3/8 inch deep and 3/8 inch wide and zigzags its way across the surface of the paver. These false joints can successfully be filled with sand and hold up well when done properly (see section below on false joints).

Getting Started

Let’s assume that your patio is in fairly good shape and a candidate for polymeric sand. The first thing you need to do is remove ALL of the existing sand down to the bottom of the paver. Polymeric sand works best when used at full depth. A pressure washer works well or you can get down on your hands and knees and use some sort of tool that will dislodge the sand. I strongly suggest goggles or a face shield (not just safety glasses) when using a pressure washer, and maybe even a rain coat! This will get you wet and dirty.

Materials Needed

• Polymeric Jointing Sand
• Broom
• Leaf blower
• Water hose
• Power washer

Weeds

If large quantities of weeds have taken up residence in the joints, you may want to begin this entire project by declaring war on them. Before you remove any of the old sand, apply a non-selective herbicide. You will need to let this sit a few days before you can continue. The difficulty with weeds is that simply pulling them out may not eliminate them. Weeds often have strong roots that travel below the pavers. Things like Bermuda grass form a whole colony making it tough to eliminate. The weed killer will not only kill what you see on the surface but put a hurting on what is still underground. If you have a serious weed problem, you may want to pick up some of your pavers and see if there is an extensive mat of weed roots underneath. If this is the case, it is very likely that in time the weeds will reappear. Since weeds will grow through concrete in time, there is very little chance that a polymeric sand will stop them in an area with a high infestation. Under normal weed conditions, one here and there, the process of removing the old sand will eliminate most of the weeds and deter them from returning.

Staining

A few things are key to making the results look great. The biggest challenge you will face is how to avoid staining. Every polymeric sand that I know of will stain under the right conditions. There are two keys to success here. The first is to make sure the pavers are dry. Not just the surface but most of the way through. That means that if it has rained for three days, then stops, and the sun pops out you can’t just run out and put down sand. The water will wick up through the pavers and cause stains. The same applies if you need to use a pressure washer to remove the sand that is left from the original installation. You can’t pressure wash and apply polymeric sand on the same day. I should warn you that getting the stain off is a huge problem so it’s best to take the time to avoid it in the first place. One suggestion: don’t use these products on red clay bricks. They will stain no matter what you do. The second thing that is important is to remove all of the dust created when you put the sand down. After you have swept everything that you can into the joints, a leaf blower set on low and held at about a 30-degree angle will gently remove excess dust. This dust is what causes the stains once it is wet.

Applying Sand

The process of placing the sand also requires attention to detail. Pour the sand onto the pavers and sweep it into the joints. Using a broom handle or some other blunt object, tap on the pavers. This will cause the sand to consolidate. Sweep more sand into the joints until the sand is within 1/8” of the top of the paver. You don’t want the sand to be even with the top of the paver, especially if the top of the paver has a bevel. If the paver is beveled the sand should be even with the bottom of the bevel. Using a small broom or brush carefully sweep all sand off the pavers. If you have access to a leaf blower, adjust to the lowest setting, hold the blower about waist high and blow excess dust from the pavers. Be careful that no one is standing immediately downwind. Once all dust has been removed, you are ready to spray water.

False Joints

Polymeric Sand can be used in pavers with false joints that are at least ¼” deep and ¼” wide. Specialized products such as TechniSeal SmartSand are designed for these applications. However, special care must be taken while cleaning off excess dust from pavers, especially if a leaf blower is used. It is very easy to blow the sand out of the joints if the blower is not angled properly. Additionally, closer observation is necessary when watering, as the false joints will become saturated faster than the full depth joints. Thus, it may be necessary for you to apply more water to the full depth joints versus the false joints (see section below on watering).

Watering

The watering process is critical. You need to add enough water to saturate the sand but not so much that you float the polymers out of the sand. If this happens, you will see a white milky substance. Floating polymers will also cause staining. The most effective way to water the sand is to adjust the nozzle to “shower” and water the pavers until no more water will soak in. Spray for a few seconds, then stop and observe. If the joints continue to take water, keep spraying. When they won’t take any more water, and before you float the polymer out of the sand and onto the pavers, stop spraying. It will not be possible to come back at a later time and get the sand to accept more water. The polymer will begin to set and no more water will penetrate. The danger in not watering thoroughly is that the top will harden and the bottom will not. If this happens, it is only a matter of time before the sand at the bottom of the paver gives way and the top falls in. If you have a large area, it is best to do this in sections no larger than 10’ x 10’ at a time.

Traffic and Protection

Since most polymeric sand jobs are done in the summer and thunderstorms occur without warning around the same time, you will need to be prepared to protect the patio in the event of a downpour. A casual rain is not a problem. However, a real gully washer within the first 24-48 hours can dislodge the sand. Simply covering with plastic or a tarp will help prevent this. Downspouts that empty directly on a patio can also be a problem in the first few days. Try to divert this water somewhere else until the sand hardens.
You will need to restrict pedestrian traffic for 24 hours and vehicular traffic for 72 hours. The exact amount of time will vary with weather conditions. The hotter and dryer the faster it will cure.

Applying a Sealer

While applying a water-based sealer like Sakrete Wet Look sealers does a great job in making old pavers look like new or keeping new pavers looking great. Since you have already invested a large amount of time in this job, I suggest you do it right and apply the sealer. The sealer is easy to apply and not very expensive. It will be necessary to wait until the paver set hardens, usually in a few days, before applying the sealer.

If you still have questions give us a call at 866-Sakrete for project tips from the concrete experts.