How to Keep an Outdoor Flagstone Walkway From Cracking

Use Thick Flagstones

• Two areas of your flagstone walkway are prone to cracking: the mortar between the stones, and the actual flagstones. The easiest way to prevent the actual flagstones from cracking is to use nice thick stones. Thin flagstones can be quite a bit cheaper than thick ones, but you’ll end up regretting the money you originally saved when your thin stones start cracking in half after use. Invest in flagstones that are at least an inch and a half thick to minimize cracking issues and make your walkway last longer than a few years.

Stabilize the Stones

• Another good way to keep flagstones from cracking over time is to stabilize them with a solid base. A concrete base underneath the stones will support the walkway, which helps prevent natural wear and tear from causing cracks. The concrete base is especially good for walkways that get a lot of use or frequently support large structures as well as human feet. You can stabilize smaller walkways that do not consistently carry much weight with a gravel or sand base that is tightly compacted for maximum support.

Be Wary With Mortar

• When constructing a walkway with a concrete base, landscapers often use mortar mixtures to further stabilize flagstones. This method of construction involves laying stones over a concrete base with a mixture of concrete or mortar, which keeps stones firmly in place and creates a more permanent walkway. While this method usually requires less maintenance in the long run, keep in mind that if you live in a cold climate, the mixture between stones can crack during freezing and thawing temperatures.

Patch Existing Cracks

• There is no magic solution to prevent cracks in a flagstone walkway, but when you see cracks, it’s easy to patch them. Most cracks occur in mortar between the stones. To patch cracks in the mortar, start by chiseling away the cracked mortar pieces, then filling in the gaps with new mortar solution. You can potentially patch cracks within flagstones using the same method, or you may want to replace the cracked stone with a new one.