Sealing and Re-Grouting an Indian Sandstone Patio
Step-by-step guide made from Tidybricks patio restore's YouTube video.
Seal porous Indian sandstone patio slabs with a roller before repointing deep, wide joints using a water-soaked polymeric jointing compound. The compound is pressed into the joints with a pointing trowel, smoothed with a spoon, and brushed clean for a permeable, puddle-reducing finish.
The full step-by-step Spetz Specs for this project (every part, size, diagram and step, free): Sealing and Re-Grouting an Indian Sandstone Patio Spetz Specs.
- Difficulty: beginner
Safety
- Wear knee pads or kneeling protection when troweling and striking patio joints for extended periods.
- Work in a well-ventilated outdoor area and avoid skin or eye contact when pouring and rolling liquid stone sealer.
Must know before you build
- Seal slabs before grouting; excess compound scrapes off easily, preventing sticking.
- Soak polymeric compound in water inside its tub; it becomes heavier, sinking deeper.
- Compact polymeric compound firmly into joints; prevents premature frost or jet-wash failure.
- Brush off excess jointing compound immediately to prevent temporary resin stain marks.
- Wait 6-12 months before sealing a new patio; allows efflorescence to escape, not get trapped.
- Never seal over permeable polymeric grout; it traps surface water and reduces permeability.
Tools
- Pointing trowel (small masonry pointing trowel)
- Hand brush (soft-bristle banister brush)
- Plastic bucket (empty square plastic tub, Joint-It, 20kg capacity tub)
- Paint roller (medium-nap roller sleeve and handheld frame)
- Garden hose with spray nozzle (garden hose with multi-pattern trigger sprayer)
- Metal spoon (household dessert/tablespoon) (optional)
Materials
- Polymeric patio jointing compound (water-activated polymeric jointing mortar, Joint-It, 20kg tub, Neutral colour (covers approx. 15m²))
- Indian stone sealer (solvent-free fluoro-polymer natural stone sealer, Bond It, 5L container (Drive Alive Indian Stone Sealer))
- Gaffer tape (heavy-duty cloth gaffer tape)
- Water (clean tap water)
Step by step
Step 1: Seal the patio slabs
Roll Indian stone sealer evenly across the dry sandstone slabs before applying any jointing compound.
- Roll sealer across the dry sandstone slabs. Pour the Indian stone sealer into an empty plastic tub and roll an even coat across the clean, dry sandstone slabs before filling the joints.
- Tip: Use an empty square jointing-compound tub as a deep roller bucket for the liquid stone sealer.
- Common mistake: Applying stone sealer over the top of finished polymeric joints, which clogs the pores and reduces joint permeability.
Step 2: Tape step overhangs and soak the jointing compound
Apply gaffer tape under overhanging step joints to retain the mortar, then fill the jointing compound tub with water until submerged by an inch.
- Tape underneath overhanging step joints. Stick strips of gaffer tape underneath the lip of overhanging step slabs where joints meet the vertical riser to stop wet compound from falling out.
- Tip: Stick gaffer tape under overhanging step edges to hold the wet jointing compound in place while you pack the joint.
- Fill the compound tub with water to soak. Spray water from a garden hose directly into the tub of polymeric jointing compound until the water level stands about 1 inch above the compound, and let it soak in.
- Tip: Add water straight into the compound tub until it sits about an inch above the mix so the compound stays thoroughly soaked during application.
Step 3: Trowel soaked compound into the joints
Stir the water-soaked compound in the tub, scoop it onto the joints with a pointing trowel, press it firmly into the gaps, and scrape excess off the sealed slabs.
- Swirl and mix the soaked compound in the tub. Insert a pointing trowel into the water-filled tub and swirl the compound around to ensure the water and polymeric sand are evenly mixed before scooping.
- Press soaked compound into the joints and scrape excess. Scoop small amounts of soaked compound onto the joint lines with the pointing trowel, push it firmly down into the gaps, and scrape the slab faces clean with the trowel blade.
- Tip: Keep the compound completely soaked when troweling so the extra weight carries it deeper into 1.5- to 2-inch joints.
- Tip: Scrape as much excess compound off the slab top with the trowel as you go so there is less residue to brush later.
- Common mistake: Skimming over the joint with a trowel without compacting the mortar all the way down, which leaves voids and causes the grout to fail.
Step 4: Smooth wide joints and brush off excess
Iron the wider joints smooth with the back of a metal spoon and sweep away all loose residue with a hand brush to prevent staining.
- Iron wide joints with a spoon and sweep off residue. Run the convex back of a metal spoon along the wider joints to compact and smooth the compound, alternating with a soft hand brush to sweep every bit of excess off the slabs.
- Tip: Use the rounded back of a metal spoon as a makeshift wide jointer to smooth and compress extra-wide patio joints.
- Tip: Finish one section at a time and immediately brush off all stray granules with a hand brush to prevent resin stains on the stone.
- Common mistake: Leaving stray polymeric granules sitting on the stone surface after pointing, which leaves resin stain marks until sunlight eventually bleaches them out.
Step 5: Submerge and seal leftover compound for storage
Cover the remaining compound in the tub with an inch of water and snap the lid shut to preserve it for future use.
- Cover leftover compound with water and snap the lid on. Ensure the unused compound in the tub is submerged under a good 1 inch of water, then press the plastic lid firmly onto the tub to seal it for future jobs.
- Tip: Submerge leftover polymeric jointing compound under 1 inch of water and seal the tub lid so you can reuse it on another job.