Polymeric Sand & Sealing · Cambridge
Polymeric Sand and Paver Sealing in Cambridge
Polymeric sand and sealer are maintenance, not magic. Done right they add years to a surface; done on a damp day they leave a white haze you will look at for a long time.
The joints are what make interlock interlock. The CMHA/ICPI construction standard calls for joints of 2 to 5 mm filled with sand, and it is that sand, compacted into the joints, that transfers load from one paver to its neighbours. When the joint sand washes out, which it does on any driveway with a slope and a few years of rain, the pavers start to rock individually, the edges chip, weeds and ants move in, and water goes straight to the base. Polymeric sand is joint sand with a binder that sets when it is wetted, so it stays in the joint and resists all of that.
What the job involves
- Cleaning. The surface is pressure-washed and old joint material is removed to depth. Polymeric sand sitting on top of old dirty sand does not bond and fails in the first season.
- Drying. The pavers and joints have to be dry. This is the step that gets skipped when a crew is in a hurry, and it is the reason for most haze and most early failures.
- Sweeping and compacting. Sand is swept into the joints, the surface is run with a plate compactor so the sand consolidates, and more is swept in until the joints are full to just below the chamfer.
- Blowing off and activating. Every grain is blown off the paver faces before water is applied, because what is left on the face sets there. Then a controlled misting activates the binder without flushing the joints.
- Sealing, if wanted, after the joints have cured, in a dry window with no rain coming.
Sealing: when it helps and when it does not
A good sealer darkens the colour slightly or a lot depending on the product, makes oil and road salt easier to wash off, and slows the surface wear of the polymeric joints. It is worth doing on a driveway that gets salted and parked on, and on a patio where the look matters. It is not worth doing on pavers that have not been properly cleaned, on a surface that still has efflorescence coming through, or on a day with humidity in the forecast. Sealer is also a commitment: once a surface is sealed it is re-sealed every few years, and switching products later can be a problem. We tell you what we would use and why.
What it costs to get wrong
Polymeric haze is a film of binder set onto the paver faces because the sand was not fully blown off, or the surface was damp, or it rained before it cured. It is difficult and expensive to remove. Joints that stay soft were installed over damp sand or were not compacted. Both are avoidable by doing the steps in order on the right day, which is why this is a job we would rather postpone a week than do in the wrong weather.
A two-car driveway or a mid-size patio is typically a one-day job for cleaning and re-sanding, with sealing on a second visit once the joints have cured. The quote depends on area, how much old joint material has to come out, the condition of the pavers, and whether any settled areas need re-levelling first, which is the sensible time to do it.
Frequently asked questions
How often does polymeric sand need redoing?
A well-installed joint on a residential driveway lasts several years before the top wears enough to need topping up. Shaded, damp patios tend to go longer; steep driveways that shed water fast go shorter. If it failed in the first year, the installation was the problem.
Will sealing stop the weeds?
Sealing helps by locking the joint sand, but it is the polymeric joint that does most of the work. Weeds in interlock grow from seeds landing in open joints, not from underneath, so full, hard joints are the fix.
Can you seal in the fall?
Yes, if there is a dry window with daytime temperatures the product allows and no frost overnight. Late fall and early spring are often too damp. We will not seal on a day the forecast argues with.
Serving Cambridge and surrounding areas. Contact us for a no-obligation quote specific to your property.