Polymeric Sand Calculator

How much polymeric sand do I need?

Polymeric sand only fills the joints, so the amount depends on the paver size, the joint width and the paver thickness, not just the patio area. A 200 sq ft patio of 6 × 9 inch pavers with 1/8 inch joints needs about 3 bags of 50 lb.

The joint share is 1 − (L × W) ÷ ((L + joint) × (W + joint)). For 6 × 9 inch pavers with 1/8 inch joints that's about 3.4% of the surface. A 200 sq ft patio of 2⅜ inch pavers holds 1.3 cu ft of joint sand: 3 bags of 50 lb with 10% extra.

Polymeric sand, also called jointing sand, is a fine sand blended with polymers. You sweep it into the joints between pavers and wet it. The water activates the binder and the sand hardens into a firm, flexible joint.

How to use the polymeric sand calculator

The polymeric sand calculator works out the joint volume from your paver dimensions, then converts it to pounds and bags. The "How we calculated this" panel shows each step, and the PDF report keeps them for your supplier or client.

Step 1: Enter the paved area

Type the length and width of the patio, path or driveway. For curves or several zones, add up each area in the square footage calculator first and enter the total.

Step 2: Choose the paver size and joint width

Pick a standard paver size or enter your own, then set the joint width and paver thickness. Measure a few joints with a tape and use the average, because the widths are rarely uniform.

Step 3: Set the bag size and price

Most polymeric sand comes in 50 lb bags, but some brands sell 25 or 35 lb. Enter your bag weight and price to get the bag count and the total cost.

Joint width and depth

ICPI Tech Spec 2: joints between pavers should be consistent, between 1/16 and 3/16 inch (2 to 5 mm). Natural stone and tumbled pavers often have wider joints.

Depth matters as much as width. Polymeric Sand Store says most manufacturers require at least about 1 inch of joint depth, and many recommend 1½ inches. Shallow joints are a common reason for cracking and washout.

Polymeric sand coverage per bag

Coverage is not a property of the sand alone. It depends on how much joint your paving has. A 4 × 8 inch paver has more than twice the joint length per square foot of a 24 × 24 inch slab.

Inch Calculator says a 50 lb bag usually covers 75 to 100 sq ft with small gaps and 30 to 60 sq ft with gaps of 1/4 to 3/8 inch. It puts irregular flagstone joints at 8 to 10 sq ft per bag.

The chart below is our joint-volume result: joints filled full depth on 2⅜ inch pavers, sand at about 100 lb per cubic foot (dry sand, 2,700 lb per cubic yard), 10% extra.

Bags of 50 lb per 100 sq ft.

Polymeric sand vs regular sand

Regular sand still has a job as bedding sand under the pavers. Polymeric sand is for the joints on top. See the paver sand calculator for the bedding layer.

How to install polymeric sand

Follow the bag first, because each formula has its own watering steps. The steps below come from Techniseal's HP NextGel installation guide and Polymeric Sand Store.

1. Prepare. Pavers must be dry, clean and compacted on a gravel base with edge restraints in place. Run a plate compactor over the surface so the joints are tight and the pavers are locked.
2. Fill. Sweep the sand in with a stiff broom until the joints are full. Leave the sand at least 1/8 inch below the top of the pavers, or at the bottom of the chamfer.
3. Clean. Blow every grain off the paver surface. Sand left on top turns into haze when it gets wet.
4. Water. Use a shower setting. Techniseal wets a 200 sq ft section for 30 seconds, then again for 30 seconds until the joints are saturated. Stop when water pools on the surface.
5. Cure. Keep vehicles off for the time on the bag: 48 to 72 hours for HP NextGel, and 24 to 72 hours for most brands.

Weather and timing

Polymeric Sand Store recommends installing when pavers and air are above freezing and rising, ideally 50 °F or warmer, with dry weather before and after. Rain before the joints cure can wash the binder out and stain the pavers.

Common polymeric sand mistakes

• Joints too shallow. Remove old material until you reach the depth on the bag.
• Too much water. Soaking the joints washes out the binder. Water in short stages.
• Sand on the pavers. Blow the surface clean before you water, or it leaves haze.
• Wrong product. Wide joints, porcelain pavers and permeable paving each need a formula made for them.

Color, sealer and how long polymeric sand lasts

Polymeric Sand Store puts properly installed joints at around 8 to 12 years or more, depending on joint depth, drainage, traffic and freeze and thaw cycles. Driveways need touch-ups sooner than patios.

Pick a color for contrast: grays and tans blend in, darker sand frames each paver. Order samples first, because color looks different in sunlight. If you plan to seal the hardscape, ask the manufacturer when to do it.

Polymeric sand cost

The price depends on the brand, the joint width rating and the formula. Wide joint and specialty products cost more than standard sand. Enter your price per bag and the calculator adds up the project cost.

Before you order polymeric sand

Measure the paver size and a few joints, let the polymeric sand calculator turn them into pounds and bags, then round up and keep a spare bag for touch-ups. Check the depth, the coverage and the weather window on the bag you buy.

Frequently asked questions