Sealing and Re-Grouting an Indian Sandstone Patio

Step 1: Seal the patio slabs

Dry sandstone slabs are coated with stone sealer; open joints stay unsealed and permeable.

Watch this step (3:30)

You'll need: Plastic bucket, Paint roller, Indian stone sealer

1. 1.1 Roll sealer across the dry sandstone slabs
   • Pour Indian stone sealer into an empty 20 kg plastic bucket.
   • Load a medium-nap paint roller evenly in the bucket.
   • Roll one even coat across clean, bone-dry sandstone slab faces.
   • Seal before grouting so polymeric resin scrapes off and joints stay permeable.
   • Let the sealer dry completely before jointing.

Key measurements

• New stone age before sealing: 6 to 12 months minimum
• Sealer container volume: 5 L container
• Roller bucket capacity: 20 kg empty plastic tub

• Tip: Use an empty square jointing compound tub as a deep bucket for liquid sealer.
• Tip: Seal established stone before pointing so sticky polymeric compound wipes off easily.
• Heads up: Never roll stone sealer over finished polymeric joints; it clogs pores and reduces permeability.
• Heads up: Do not seal a new patio for 6 to 12 months, or efflorescence traps underneath.

Before you move on: Touch the slab; check the sealer is dry with no liquid pools in open joints.

Step 2: Tape step overhangs and soak the jointing compound

Overhanging step joints are dammed with tape, and polymeric compound sits soaked under standing water.

Watch this step (3:39)

You'll need: Garden hose with spray nozzle, Gaffer tape, Polymeric patio jointing compound, Water

1. 2.1 Tape underneath overhanging step joints
   • Find overhanging steps where open joints meet a vertical riser gap below.
   • Press heavy-duty gaffer tape strips under the overhanging slab lip across each joint.
   • Seal the underside gap so wet compound stays put while curing.
2. 2.2 Fill the compound tub with water to soak
   • Open the 20 kg polymeric patio jointing compound tub.
   • Spray clean tap water from a garden hose into the compound tub.
   • Fill until standing water sits 1 inch above the compound.
   • Let the compound soak so the water weight helps it sink deep.

Key measurements

• Soaking water depth: 1 inch of standing water above the compound
• Compound coverage: about 15 sq m per 20 kg tub

• Tip: Soak the compound in its original tub so the heavy mix drops deeper into wide joints.

Before you move on: Check water still stands 1 inch above the compound and gaffer tape holds under step lips.

Step 3: Trowel soaked compound into the joints

All patio joints are packed solid from the bottom up with water-soaked compound and the slab tops are scraped clean.

Watch this step (4:27)

You'll need: Pointing trowel, Polymeric patio jointing compound, Water

1. 3.1 Swirl and mix the soaked compound in the tub
   • Plunge the pointing trowel blade into the water-filled tub.
   • Swirl the compound in the tub until water and polymeric sand mix evenly.
2. 3.2 Press soaked compound into the joints and scrape excess
   • Scoop a saturated mound of compound with the pointing trowel.
   • Dump the wet compound onto the open 1.5 to 2 inch deep joint.
   • Press the compound down with the trowel blade, compacting it to the bottom.
   • Scrape the trowel flat across the sealed slab immediately to clear excess mortar.
   • Never skim loosely over the top; hollow voids fail under frost.

Key measurements

• Maximum joint depth: 1.5 to 2 inches
• Compacted pot drainage time: 18.5 minutes (3 minutes uncompacted).

• Tip: Keep the compound soaked as you scoop so the extra weight carries it to the bottom of deep joints.
• Tip: Scrape maximum excess off the sealed stone with the trowel to reduce brushing.
• Heads up: Less rigid than cementitious slurry grout, polymeric jointing compound will not lock down loose, rocking slabs.

Before you move on: Press along the filled joint with the trowel tip to confirm there are no soft spots or hollow voids.

Step 4: Smooth wide joints and brush off excess

Wide joints are ironed smooth and dense, and sealed stone is brushed free of stray granules.

Watch this step (5:38)

You'll need: Metal spoon, Hand brush, Polymeric patio jointing compound

1. 4.1 Iron wide joints with a spoon and sweep off residue
   • Press the rounded convex back of a metal spoon into wider packed joints.
   • Draw the spoon along the joint to compress and iron the mortar flush.
   • Immediately sweep the finished section with a soft hand brush to remove stray granules.
   • Finish and brush one small section before troweling the next.
   • Clear all granules off the slabs now so polymeric resin cannot leave stain marks.

• Tip: Use a household metal spoon's rounded back as a wide jointer to compress extra-wide joints.
• Tip: Use a leaf blower after pointing to clear loose granules off slabs without disturbing joints.
• Heads up: Stray polymeric granules left on the stone leave resin stains until sunlight bleaches them out.

Before you move on: Check the slabs in angled light and sweep remaining grit specks from joint edges.

Step 5: Submerge and seal leftover compound for storage

Unused polymeric compound sits submerged under water, sealed airtight for future repairs.

Watch this step (6:23)

You'll need: Garden hose with spray nozzle, Polymeric patio jointing compound, Water

1. 5.1 Cover leftover compound with water and snap the lid on
   • Check water level in the leftover polymeric jointing compound tub.
   • Add clean tap water until 1 inch covers the leftover compound.
   • Press the plastic lid firmly on the tub rim, sealing it airtight for another job.

Key measurements

• Storage water depth: 1 inch above leftover compound

• Tip: Submerging leftover water-activated polymeric compound under 1 inch of water preserves it for later.

Before you move on: Press around the tub lid rim to check it is snapped shut and airtight.