8 Questions to ask your Hardscape Contractor

“Hardscaping” is a relatively new term.  It refers to the elements of your yard that aren’t actually “alive” such as patios, decks and walls.  Hardscapes are often large, complicated, heavy projects and can be difficult to build.  They are, however, very cool and can make or break a landscape.  And their construction methods are critical.

When it comes to hardscaping, we’re not just talking about a shrub dying or a patch of lawn turning brown.  Hardscapes are often attached to, and become part of, your house.  Most times, they are designed to support additional structures, like a patio that needs to carry the load of a hot tub, built in BBQ, or outdoor fireplace.  Or a driveway that has to hold a car or two.  Or a retaining wall that holds up an entire section of your back yard.  A lot is riding on proper construction of these types of projects. (Not to mention, they usually represent the biggest portion of the cost of any landscape renovation.) 

In short: “they gotta be done right”.  And we’ve seen plenty that haven’t been.  (Be very wary if your lawn company or snow plow guy tells you they “do pavers” or can build you a retaining wall).

There are some specific technical questions that should be asked of any hardscape contractor that will be working on your home. Some starters are provided below.  Any reputable, licensed contractor should be able to answer these questions to your satisfaction.

  • How is the excavation and sub-base preparation done? (ANSWER:  Excavation for typical hardscapes should be done so that the project can be built on undisturbed soil.  All sub-soils must be compacted and segregated from the base material with Geotextile fabric. Total excavation depths of 9-12” are common for most pedestrian pavements.)
  • What do you use for base material and what is the compaction process? (ANSWER: Base material should consist of a granular stone base with fines, such as a 21AA designated gravel.  Slag sand and pea stone are not acceptable base materials. Compaction of the base layer should be done as the base is being constructed, preferably every 2-3” of base installed.)
  • How much base material do you use (minimum for walk or patio)? (ANSWER:  Base depths can range from 4-12” depending on soil conditions and traffic usage. Treasured Earth uses a minimum of 5” of properly compacted base material for patios and walks, and 12” for driveways)
  • Do you use Geotextile fabric and where? (ANSWER: Geotextile fabric should be used between the subsoil and the base gravel to prevent intermixing.  Geotextile fabric should also be used at any vertical surface where washout of base gravel or sand could be a problem, i.e. behind retaining walls.)
  • Do you use plastic or concrete edge restraint and why? (ANSWER: Concrete is generally an unacceptable choice as an edge restraint.  This is Michigan; concrete WILL crack.   When it does, the cracked area can lose it’s ability to stabilize the paver pavement.  Almost all paver manufacturers recommend vinyl edge restraint and steel spikes in our climate.  (The exception would be if concrete were installed at footer depth and reinforced.)
  • What type of drainage do you plan for with a patio?  With retaining walls? (ANSWER: This varies, based on the application.  At the minimum, pavement surfaces should have a 1% slope or greater away from foundations and house structures. Internal drainage may be necessary in raised patios and retaining walls to prevent static water pressure behind the wall, and ultimately, wall failure.)
  • What type of jointing sand do you use in hardscape construction? (ANSWER:  Either standard angular jointing sand, or acrylic (Polymeric) sand is acceptable.  The benefit of Polymeric sand is that it sets up like mortar, but remains flexible.  This can help prevent weeds from germinating, and ant hills from forming in the pavers.  In no case is regular play sand ever an acceptable alternative, as it will not provide the paver interlock that assures good service life.)
  • Do you use Geogrid reinforcement in retaining walls? (ANSWER: Geogrid reinforcement is usually necessary for retaining walls over 4’ in height, but may be required for shorter walls as well.  The purpose of the geogrid is to lock in to the face of the retaining wall and run back into the slope, thereby using the weight of the wall and the backfill as an anchor to keep the wall in place.)

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