Why Does Interlock Always Sink?  Or Does It?

A couple of years ago I took my daughter out for Hallowe’en.  As we walked from house to house, I noticed that several places had yellow caution tape across their front steps to keep people from using them.  Closer inspection showed that the interlocking pavers were dangerously sunken and might cause anyone not paying attention to trip and fall.  In fact in this almost new neighbourhood, most of the interlock walkways and steps needed repair.  Why?

The part you don’t see under the interlock will determine if the job is durable.  A good base is at least 6″ deep for a walkway and 10″ deep for a driveway and consists of a mix of 3/4″ sized gravel down to the size of sand particles.  The large stone gives stability and the fines fill in the voids between the larger particles when it is compacted.  But this material must also drain away water which causes slump and frost heave.  Granite based gravel (usually granular A) compacts well and drains well and is recommended by all paver manufacturers as well as the I.C.P.I. (Interlock Concrete Paver Institute) which represents the major producers.

Most contractors still use limestone, particularly limestone screenings.  Limestone has 3 problems.

1.  It breaks down over time and causes rutting.

2.  It holds water which causes frost heave and instability.

3.  The alkalinity disintegrated the pavers.

This is the major cause of a poor interlock job – the use of limestone screenings.  If you want a job that will last, make sure the contractor used granular A gravel.

Aurora Landscape Contractors has been building beautiful landscapes in this area for 35 years. The company constructs patios, walkways, steps and driveways with interlocking brick, stone pavers, flagstone and concrete.  Our first interlock driveway was done in 1981 and it’s still looks perfect without repair in 2012!

For design and quotation of your next project, contact Al Trimble B.L.A.  O.A.L.A.  auroralandscape@gmail.com