Interlocking paving stone repairs can be challenging, on this particular project the homeowner was highly disappointed with the state of their front parking pad. The stones were extremely uneven and had major rutting, let's not even say anything about the weeds. Unfortunately far too many parking pads in the toronto are in this state. Why? It always starts with the base. Usually the granular material under the pavers is a) Incorrect base materials/wrong gradation of the granular materials b) Granular layer not deep enough. Many of these parking pads are constructed on 6" - 8" of limestone screenings. Limestone screenings should only have been used for the top 1" - 2", the bedding layer, not the full depth for the base. For years this was the de facto standard and hundreds if not thousands of driveways and parking pads across toronto are built this way. Many are failing and many have failing stones. The pavers are falling apart from underneath, yes I said underneath. How did this happen?

I have my original installation guide from Unilock, dated 1987. In this guide the recommended base materials are limestone screenings, right? Wrong! The recommended base materials is Granular "A", thickness will vary depending pedestrian or vehicular and 2" sharp sand. No where in this guide is limestone screenings mentioned. Again how did we get in this situation. I was a Unilock Authorized Contractor for many years in the 1990's , limestone screenings was just what you used.  If I can look back in my crystal ball one large reason was because none of the Toronto area dealers and stone yards stocked Granular 'A' . You could order a truck load from the quarry but what if you wanted 10 tons? It was just unavailable, so many if not most of these parking pads are built upon limestone screenings.

Another large factor to consider is simply convenience. When you only have to deal with one material it makes life easier. What if you are short Granular A during the coarse of the day. Someone will have to go out and pickup a ton or a half ton. That means time. And as they say, time is money. The worst is screeding your sand bedding layer and being short some sand. There's nothing worse because it delays laying pavers. And laying the pavers is important because that means we're close to being finished the job and close to being paid.

This is why we're a Unilock Authorized Contractor. Current installation methods and continuing education. Staying current is important. It means   What you're paying for with this type of work is the quality of the labour. Why are you hiring a handyman? Repairs can be tricky. on the outset they look easy but with patterns and older stones. The pattern has to go back together exactly as they were installed

It's all about the base. We do not use limestone screenings for any paver projects and retaining walls. On this project we left the limestone screening base in place and added 1" sharp sand for our bedding layer. Our first recommendation to the homeowner is to remove the limestone screenings and start over. The screenings would be replaced with granular A and than 1" sharp sand. This of course increases the price of the project and it's up to the homeowner to make the decision on which way they want to go. We can do a cosmetic repair but can't guarantee the long term stability due to the incorrect base materials.

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About the Author

Garry Reisky

Garry Reisky is the owner of Terraform Contracting. A landscaping and hardscaping contractor located in Toronto, Ontario. Terraform designs and installs residential hardscape and landscapes. Garry is a hardscape expert with extensive installation and product knowledge. Garry is an unofficial Rock(et) Scientest and self proclaimed guru of everything Enduracolor. Find Garry on Google+. Tired of dealing with inexperienced contractors, Contact Garry for a free estimate.