7 Step Cobblelock Driveway Sealing Method with Resiblock 22 Over a 30-Square-Metre Area

Why 30 square metres needs 10 litres, not 7

Resiblock 22 is rated by the manufacturer at approximately 6 to 8 square metres per litre on a porous cobblelock surface, with the lower end applying to aged or sand-hungry blocks. A 30-square-metre area therefore consumes around 4 to 5 litres per coat. Two coats are standard for a previously unsealed driveway, so the realistic order quantity is a 10-litre drum plus a small allowance for the soak-in around joints and the inevitable roller absorption. Ordering a single 5-litre tin and hoping to stretch it across both coats is the most common reason a finish ends up patchy and uneven in sheen.

The second coat behaves differently from the first. The first coat penetrates and is largely swallowed by the block pores and the jointing sand, which is why coverage at that stage often drops to the 6 square metres per litre figure. The second coat sits more on the surface and spreads closer to 8 square metres per litre, building the film that delivers the wet-look or matt finish depending on the product variant. Plan the quantity around the thirstier first coat and the surplus carries the second comfortably.

Step one through three: clean, repair, dry

Strip the surface before anything else. A pressure washer at 150 to 200 bar lifts moss, lichen and the grey biofilm that otherwise traps the sealant above a contaminated layer, where it peels within a season. Work in overlapping passes and pay attention to the joints, where weed root and spent jointing sand collect. Anything growing in the joints comes out now, because Resiblock 22 will not stop a weed already rooted beneath it.

Step two is repair and re-sanding. Wherever washing has flushed out joint sand, refill with kiln-dried sand, typically a 0.1 to 2 mm grade, brushed in dry and vibrated or tamped so the blocks lock against each other again. A driveway with hollow joints flexes under a car and cracks the surface film. Step three is the one that governs the entire job: drying. The surface and the jointing sand must read below roughly 5 percent moisture before any sealant touches it. A pinless moisture meter held against the block and the joint sand gives a usable reading. After pressure washing, that means three to five dry days in temperate conditions, longer in an Irish or British autumn when overnight dew never fully clears. Sealing over trapped moisture produces a milky white bloom that no amount of subsequent work removes without stripping back.

Step four: the joint-sand pass that most people skip

Resiblock 22 is partly a joint stabiliser, not only a surface coat. The first flood of sealant is deliberately worked into the joints with a soft brush so the kiln-dried sand binds into a semi-rigid matrix. Skip this and the sand washes out at the first heavy rain, the blocks loosen, and the whole purpose of sealing is defeated within a year.

Step five and six: two coats, wet edge, no puddles

Apply the first coat with a medium-pile roller or a low-pressure sprayer, keeping a wet edge across the full width of each working strip so the laps do not show as darker bands. On 30 square metres, divide the area into four or five strips running the length of the drive and complete each strip before starting the next. The sealant should look wet and even with no pooling in the low spots between blocks. Pooled Resiblock dries glossy and tacky and attracts dirt, which is the visible signature of an over-applied job.

Leave the first coat to touch-dry, which is roughly 2 to 4 hours at 15 to 20 degrees Celsius and considerably longer below 10 degrees. The product is moisture-sensitive while curing, so the forecast matters as much as the surface reading: a minimum 24-hour dry window after the final coat, with no rain and no heavy dew, is the operative constraint. Apply the second coat the same way, this time spreading further because the pores are sealed. Watch the spots where two strips met on the first coat and feather the second coat across them to even the sheen.

The finish at this stage tells you whether the moisture work in step three was done properly. An even, faintly darkened cobblelock with consistent sheen and no white patches means the substrate was dry. Any milky clouding appearing as the coat cures is trapped moisture flashing off through the film, and it sets permanently. Foot traffic can usually return after 24 hours; vehicle traffic should wait 48 to 72 hours depending on temperature, because a car turning its wheels on a half-cured surface scuffs the film and prints tyre marks that stay.

Step seven: the cure window and what undoes it

Full cure runs well beyond the point the surface feels dry. Resiblock 22 continues hardening for several days, and the first 48 hours decide most of the outcome. Rain inside that window is the single largest failure cause on domestic jobs, ahead of poor cleaning and ahead of over-application. A drum sealed onto a drive on a bright morning that catches a 6 pm shower has a measurable chance of blooming along the lowest-draining run of blocks.

Temperature sets the rest. Below 10 degrees Celsius the cure stalls and the film stays soft enough to mark; above 25 degrees in direct sun the sealant skins too fast and can trap solvent underneath, giving a wrinkled surface. The workable band sits between roughly 12 and 22 degrees with cloud cover or shade. Drainage falls under this step too: any area where surface water sits for hours after rain will fail first, because the cured film is water-resistant, not a substitute for a gradient that moves water off the cobblelock toward a channel or gully.

A worked quantity and cost check for 30 square metres

Run the numbers before ordering. At 6 square metres per litre for the first coat, 30 square metres needs 5 litres. At 8 square metres per litre for the second, it needs 3.75 litres. Total is 8.75 litres, so a 10-litre purchase covers the job with a usable margin for the joint-flood pass in step four. A 5-litre tin will not stretch to two honest coats across 30 square metres, and the temptation to thin the second coat to make it reach is what produces the patchy sheen.

Kiln-dried jointing sand for re-sanding a 30-square-metre drive with average joint width typically runs to one or two 20 kg bags depending on how much washed out. Factor a moisture meter into the kit if there is not one already in the shed, because the 5 percent reading in step three is not a figure to estimate by eye. The total consumable outlay is modest against the labour and the cost of stripping a failed coat, which involves chemical removers and a return to bare, pressure-washed block before any of the seven steps can begin again.

Where this method leaves a gap

The sequence assumes a sound substrate: blocks that are level, joints that hold sand, and a fall that drains. It says nothing about a drive that has already started to sink at one corner or where tree roots have lifted a run of pavers, because no surface sealant corrects a base that has failed beneath the blocks. The open question on any older cobblelock is whether the unevenness you are seeing is a surface problem the seal will fix, or a sub-base problem the seal will merely gloss over for a season before the same fault reappears through the film.