Many polymeric sands top out at joints of 3/4 in to 2 in, which leaves irregular flagstone and wetcast stone with wide gaps out of range. If you need polymeric sand for wide joints, SRW X-Treme is SRW's answer: its data sheet rates it for natural stone and wetcast joints from 1/4 in up to 6 in wide, with a minimum joint depth of 1-1/2 in, and says it is rain safe 20 minutes after activation.
It is also a specialty product with clear limits. SRW does not recommend it for concrete pavers, clay pavers or concrete overlays, and marks it for pedestrian use only. This guide covers what X-Treme is rated for, how SRW says to install it, and how it compares with other wide-joint sands, using figures from the SRW X-Treme data sheet (revised November 26, 2019) and the other manufacturers' data sheets named below.
Key takeaways
- SRW X-Treme is rated for joints 1/4 in to 6 in wide and at least 1-1/2 in deep, on natural stone and wetcast.
- Typical coverage is 20 to 45 sq ft per 50 lb bag, depending on joint width.
- Rain safe 20 minutes after activation, but SRW advises installing when no rain is forecast for 24 hours and waiting 28 days before cleaning or sealing.
- Temperatures must stay above 32°F through installation and curing.
- Not for concrete pavers, clay pavers, concrete overlays, pool copings or wet or heavily shaded areas.
What SRW X-Treme polymeric sand is
SRW X-Treme polymeric sand is a wide-joint polymeric sand sold in 50 lb bags, in Tan and Granite. SRW's data sheet describes an updated formula that dries clear for a haze-free installation, gives a stronger, solid cure for wide joints, and is intended to help prevent washout, weeds and insect infestation. It is listed for walkways, patios and pool decks in residential or commercial settings, and SRW labels it "for pedestrian use only".
If you want to see the two colors against your stone, the X-Treme color sample kit includes both.
Specifications at a glance
| Specification | SRW X-Treme (per the data sheet) |
|---|---|
| Joint width | 1/4 in minimum, 6 in maximum |
| Minimum joint depth | 1-1/2 in |
| Typical coverage | 20 to 45 sq ft per 50 lb bag, varies with joint width |
| Rain safe | 20 minutes after joint activation |
| Temperature | Above 32°F throughout installation and curing |
| Before cleaning or sealing | Wait 28 days |
| Colors and packaging | Tan or Granite, 50 lb bags |
Read the full SRW X-Treme technical data sheet before you start, or find it with our other sheets in the TDS and SDS library.
Where it fits and where it does not
| Surface or situation | Use X-Treme? | What SRW says |
|---|---|---|
| Natural stone patios and walkways | Yes | Listed application; sweep sand into joints |
| Wetcast stone | Yes | Pour directly into joints and keep sand off the surface |
| Pool decks | Yes | Listed application; do not use on pool copings |
| Concrete pavers and clay pavers | No | Not recommended |
| Concrete overlays or stone over a concrete bedding | No | Not recommended; do not use as a substitute for mortar |
| Wet, heavily shaded or constantly wet areas | No | Continuous dampness can prevent curing and shorten joint life |
| Vehicle traffic | No | For pedestrian use only |
SRW also warns not to sweep the sand over asphalt, because it may stain. For concrete paver joints, pick a sand rated for pavers from our polymeric sand range instead.
Conditions to check before you start
- Stable, level stone. Install the stone or wetcast to its manufacturer's guidelines. SRW calls for a proper drainage layer of sand 1 in deep, and the stones must be level and firm with no movement.
- A completely dry surface. Wait 24 hours after rain. Applying to a damp surface makes the binder activate on the stone face instead of flowing into the joints.
- Irrigation off until the sand has fully cured.
- Temperature above 32°F through installation and curing.
- A test area first. SRW recommends testing in a small, discreet area, which matters on natural stone because surfaces vary.
How to install polymeric sand for wide joints with X-Treme
- Gently tumble the bag, cut the bottom, and apply sand evenly over the surface.
- Fill joints to the full depth of the stone. On natural stone, spread sand over the surface and sweep it into the joints, avoiding moving it over long distances, which can separate the polymers. On wetcast, pour sand straight into the joints and keep it off the surface.
- Settle the sand with a rubber mallet along the stone edges. On natural stone, compact open areas with a small blunt object. If the sand level drops, add more and compact again. SRW notes that proper hand compaction is very important for joint strength.
- Remove excess sand with a soft bristle broom, then set joint height with a leaf blower on idle. The finished joint should sit 1/8 in below the top of the stone so surface water can migrate into the joint.
- Activate in sections of up to 100 sq ft, watering each for a total of 2 minutes without letting it dry: mist until the surface is wet, then switch to a light shower and shower the section twice more.
- Use a screwdriver to check that moisture has reached at least 1 in deep. If not, shower the area again right away.
- Once the depth is reached, blow excess water off the surface with a leaf blower.
Do not mix it. SRW says not to mix polymeric sand with cement or sand, and to avoid excessive wetting or flooding during installation. Always follow the instructions on the bag and the current data sheet.
Curing, rain and when to seal
X-Treme is rain safe 20 minutes after activation. That does not mean it is fully cured. SRW's data sheet explains that a flexible joint is a sign the reaction has occurred but is not complete, and that a dry environment is important for a full cure. SRW recommends installing when no rain is forecast for 24 hours, and waiting 28 days before cleaning or sealing the surface.
When you do seal, pick a product rated for natural stone. Our paver and stone sealers list the surfaces each one is made for.
How X-Treme compares with other wide-joint polymeric sands
Several other products are sold as polymeric sand for wide joints. The ratings below come from each manufacturer's data sheet, and each has its own conditions, so compare the whole sheet before you choose.
| Product | Joint width | Minimum depth | Notes from the data sheet |
|---|---|---|---|
| SRW X-Treme | 1/4 in to 6 in | 1-1/2 in | Natural stone and wetcast, pedestrian only, rain safe in 20 minutes |
| Alliance Gator Dust Bond | 1/2 in to 6 in | 1-1/2 in | Wetcast and natural stone, works above 59°F, rain safe 24 hours after activation, not for vehicular traffic |
| SEK Surebond PolySweep X-Treme Wide Joint | Up to 4 in | 1-1/4 in | Pavers, natural stone and porcelain listed |
| Techniseal NOCO | 1/4 in to 4 in | 1-1/2 in | No compaction required |
For a side by side view of more products, see our polymeric sand comparison.
How many bags of X-Treme do you need?
SRW gives a single typical range of 20 to 45 sq ft per bag across the whole 1/4 in to 6 in span. Narrow joints land at the high end of that range and very wide joints at the low end. Because natural stone joints vary so much, measure an average joint width and depth and run them through our polymeric sand calculator, then round up.
Frequently asked questions
Can SRW X-Treme be used on concrete pavers?
No. SRW's data sheet says it is not recommended for pavers, clay pavers or concrete overlays. It is made for natural stone and wetcast joints.
How wide a joint can X-Treme fill?
From 1/4 in up to 6 in wide, with a minimum depth of 1-1/2 in.
How soon can it get rained on?
SRW rates it rain safe 20 minutes after activation, but recommends installing when no rain is forecast for 24 hours so the joints can cure fully.
Can you drive on X-Treme joints?
SRW labels X-Treme for pedestrian use only, so do not plan on vehicle traffic.
When can you seal stone jointed with X-Treme?
Wait 28 days after installation before cleaning or sealing, per the data sheet.
Working on a flagstone or wetcast project? Order SRW X-Treme polymeric sand and use the polymeric sand calculator to get a bag count. Questions? Call us 24/7 at (856) 418-4895.