Cracked or crumbling pointing is one of the most common problems we're called out to look at on existing Bromsgrove patios, and it's rarely down to bad luck — there's almost always an identifiable cause. Knowing what to look for can save you from repeating the same mistake on a repair.
The most common causes
Poor preparation is the number one culprit — mortar applied to damp, dusty or dirty joints, or in cold, wet weather, often fails to bond properly and starts cracking within a season or two. An inadequate or poorly compacted sub-base is another major cause, because any movement in the ground beneath the slabs flexes the paving above it, and pointing simply isn't flexible enough to absorb that movement without cracking.
The wrong mortar mix for the job also causes problems. A traditional sand-and-cement mix that's too weak, too dry, or mixed with the wrong ratio will crumble faster than a properly specified mortar, and it's especially vulnerable to frost damage if water gets in before it's fully cured. Modern polymeric and resin-based jointing compounds are generally more flexible and weather-resistant, which is why they've become the standard choice for new installations.
What to do if your pointing has failed
Small, isolated cracks can sometimes be raked out and re-pointed, but widespread cracking across a patio usually points to a sub-base or drainage issue that a cosmetic repair won't fix for long. It's worth having the underlying cause diagnosed before repointing, otherwise you risk paying for the same repair again in a year or two.
Signs it's more than just the pointing
If individual slabs are rocking underfoot, if cracks follow a straight line across several slabs rather than sitting within individual joints, or if water regularly pools on the surface after rain, these are signs the problem sits below the paving rather than in the mortar itself. In these cases it's usually more cost-effective in the long run to lift the affected area, correct the sub-base and drainage, and relay properly, rather than repeatedly patching pointing that will keep failing until the underlying cause is dealt with. Acting sooner rather than later also limits the damage, since water getting into a failing joint over successive winters can undermine bedding and cause slabs to move.
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