Polymeric sand is fine sand mixed with polymer binders. Swept into paver joints and wetted, it hardens into a firm but flexible joint that resists weeds, ants and washout far better than plain sand. Buying the right number of bags depends on the joint volume, which grows with narrow pavers, wide joints and thick pavers.
How the calculation works
For a grid of pavers of length L and width W with joints of width J, the share of the surface taken by joints is about:
joint share = J × (L + W) ÷ (L × W)
- Joint volume = area × joint share × fill depth
- Fill depth = paver thickness − 1/8 in (the sand stops just below the top edge)
- Weight = volume × about 100 lb per cubic foot, plus waste
Example
For 100 sq ft of 4 × 8 in pavers, 2 3/8 in thick, with 1/8 in joints, the joints cover about 4.7% of the surface. Their volume is about 0.88 cu ft, so with 10% waste you need about 97 lb, or 2 bags of 50 lb. One bag covers roughly 50 sq ft in this case.
Typical coverage
Manufacturers usually give coverage for one 50 lb bag:
| Joints | Pavers | Coverage per bag |
|---|---|---|
| narrow (1/8 to 1/4 in) | standard brick pavers | 30 to 75 sq ft |
| wide (1/2 in and more) | natural stone, flagstone | 8 to 25 sq ft |
Large pavers need much less sand than small ones: a 24 × 24 in slab has a joint share three times lower than a 4 × 8 in brick.
Installation steps
- Make sure the pavers and the joints are completely dry, and that no rain is expected for 24 hours.
- Spread the sand and sweep it diagonally into the joints.
- Run a plate compactor (with a protective pad) or tap the pavers to settle the sand, then top up.
- Fill the joints to about 1/8 in below the top of the pavers.
- Blow off all the dust from the surface with a leaf blower: any residue left on the pavers hardens into a haze.
- Mist the joints lightly, following the product instructions, in several passes without flooding them.
Keep foot traffic off for about 24 hours and vehicles for 48 hours or more.