How to re-point a patio
This video provides a detailed walkthrough of repointing a patio, focusing on practical tips, challenges, and lessons learned from previous attempts. The presenter shares his experience of dealing with a problematic patio that required multiple repairs and repointing efforts over several years.
Key Insights and Process Overview
->Ideal Conditions for Repointing:
-Must be done in dry weather and not freezing.
-Checking the weather forecast beforehand is essential.
Background and History of the Patio:
-Original paving slabs lifted due to poor initial laying on mortar dabs.
-Re-laid on a compacted hardcore base with a solid mortar bed by a relative.
-Initial repointing used a brushing-type jointing compound, which looked good initially but failed—turning green, remaining soft, and washing away with pressure washing.
-Lesson learned: traditional sand and cement mortar is more reliable.
Removing Old Mortar/Compound:
-Brushing compound can be removed with a screwdriver.
-Traditional mortar requires grinding out using an angle grinder with a diamond disc and a dust extraction attachment.
-Mortar raking discs, normally preferred, cannot be used with the dust extraction attachment, causing extra work (cutting joints twice).
-Grinding with dust extraction reduces visibility; sometimes traditional methods with dust masks and face visors are better.
Preparation of Joints:
-After removing old mortar, vacuum joints to clear debris.
-On hot days, wet joints slightly and brush off excess water to prevent mortar from drying too quickly.
Mixing Mortar:
-Use a 3:1 sand to cement ratio (six units sand, two units cement).
-Ratios can vary (4:1 or 5:1) for more flexibility, but 3:1 is standard here.
-Use an Evolution mixer for thorough mixing, superior to a trowel.
-Instead of water, use SBR (Styrene-Butadiene Rubber) additive to make the mix stickier, more flexible, and easier to apply with a mortar pointing gun.
-The mix must be runny enough to flow through the pointing gun without blockage.
-Mortar gun requires cleaning with water if it blocks during use.
Applying Mortar:
-Use a mortar pointing gun for narrow joints.
-Inject mortar deeply to avoid voids.
-Avoid working in direct sunlight to prevent quick drying.
-Excess mortar on slabs should not be wiped off mortar pointing gun while wet to prevent staining; wait until it dries slightly.
Tooling Off Mortar:
->Tooling (smoothing and shaping the joint) is critical and timing-dependent:
-Too early, mortar smears and makes a mess.
-Too late, mortar hardens and is difficult to tool.
->Test joints every 15 minutes for readiness.
->Use a finger pointing trowel, brick jointer, or plastic pipe for tooling.
->Remove excess dried mortar with a soft brush.
Additional Tips:
-Use kneeling pads or knee pads for comfort during the job.
-Textured or riven paving slabs make perfect pointing lines difficult.
-Take time and work carefully to avoid mistakes.
Final Outcome and Aftermath:
-Despite extensive effort and expense, the patio was destroyed in January 2024 by a fallen tree during a storm.
-Most of the patio was replaced professionally with pattern imprinted concrete.
-The presenter rebuilt the boundary wall (to be featured in a future video).