Snow Fence is Not an Alternative to Geogrid

06 Aug 2013 | Categories: News | Posted by: admin

Retaining walls are serious business and a lot of bad things can happen if they are not done the right way.

As contractors, we are all responsible for ensuring our work is done properly. Homeowners trust contractors to know what they’re doing. If you’re ever not sure on specifics, you should ask – lots of people willing to teach what they know. Case in point – we saw this recently and its bad news: A property with a brand new 7-foot retaining wall, and obviously built without engineering or permits. It was very poor construction.

On top of the wall, cars are being parked within 2 feet of the drop, with only a tiny curb and no guardrail to prevent anyone from driving or falling off the edge.

The wall is split and set back about 10 inches at 2/3rds of the way up. The installer told the homeowner “this meant the wall was less than 4-feet tall because it was not continuous…” This is absolutely ridiculous, and the typical requirements for most municipalities require un-engineered walls to be a maximum of 4 feet exposed, AND additional walls set back at least twice the height of the next lower wall. This is to avoid overloading the lower wall with the weight of the upper wall.

In this case, the contractor is liable for damages to repair/rebuild correctly, and if the wall fails, the homeowner is NOT covered by his insurance for the cleanup.

This will be a very costly cleanup, involve removing 150-200 tonnes of poor quality fill materials, rebuilding the wall correctly, and reinstallation of asphalt paving, and supply and installation of appropriate curbs and railings, drainage, and also incurring costs for engineering and any export trucking and disposal.

So remember
1. Snow fence IS NOT an alternative to geogrid
2. River sand is cheap fill material, but IS NOT considered structural fill on its own.
3. Un-engineered walls must fit within the ‘4-feet up 8-feet back’ rule that applies in many municipalities (but not all)
4. And finally, that engineers and permits are our friends.

We see around 5 to 10 dangerous jobs a year like this, and most are far more precarious than this one. Let’s do it right and stop those who can’t do or who don’t care.