Ridiculous interlock base suggestions
I’ve been hearing ever since I started paying attention things like “put at least 20cm of crushed stone under your interlock”.
Just now I read one like that again: https://www.finehomebuilding.com/2021/03/17/getting-patio-bases-right
This one says to put 13 inches of aggregate under flagstone.
Come on guys, can we stop the BS? 13 inches of aggregate under a flagstone path? Who the hell does that? Not only is it an enormous amount of heavy material that needs to be brought in and moved and compacted in multiple layers, but the dirt it displaces needs to be dug out and moved out. And everything in that dirt like roots, construction garbage, and who knows what else.
That would easily double, maybe even triple the cost of any kind of paving job compared to a nice, drainable, levelable 5-10cm of crush with 1-2 cm of limestone screenings.
And the same for driveways. I don’t know about the rest of the world. But here in the Toronto area (where we get plenty of freezing weather) asphalt driveways are put directly onto compacted soil. That’s right: right on top of dirt. There’s sometimes a few cm of crush added. And these driveways work just fine and last plenty long enough.
And it’s not just homeonwers. When the city puts in new concrete sidewalks – guess how much clear aggregate is under them? That’s right, none. And these sidewalks also last forver.
Why do people keep pushing this ridiculous idea about 8-10-12-andmore inches of aggreage under a residential patio or path or driveway? Is the source of that the interlock companies that need an excuse to deny warranty claims?
Replies
When I was a teenager one of my buddies got roped into putting a flagstone patio down for his mother. He scraped up most of the grass and laid the flags down on top of the soil. I was at the house last October for a reunion and the patio is still there and looks fine, 50 years later. It's in western NC on clay soil.
13 inches is silly.