Square up to the back wall, layout 45-degree lines, placing corners at the house and work outward
David Odell has poured a slab patio against a house in Orange County, California. The owner wants a 45-degree grid on the back patio, so David is going to show us how he goes about it.
The day after the pour, they snap layout with chalk lines.
He wet-tools a one-foot band around the outside perimeter
"What I do to get these layouts straight with the house is I just establish a 90-degree line off of the house, and then I use that to get my 45-degree angles off of that."
When snapping the diagonal lines, he starts all of the corners of the squares against the house,
"so all of the intersecting cuts at the corners will intersect right at the house, then everything else just runs out into the band."
The grid is a four ft., six-inch grid pattern.
With the chalk lines snapped, he sets a straight edge to guide the skill saw with a diamond blade.
To avoid scratches that will be visible until the concrete fully cures, he slides the saw on 1/4-inch Masonite wrapped with plastic. The plastic protects the fresh concrete surface and allows the saw to slide more efficiently, which means cleaner cuts.
He cuts the day after the pour, saying that using fiber mesh in the mix pretty much eliminates any spalling during the cut. If you do get spalling one way to fix it is to
"...run a crack chaser through 'em, and throw a little 45-degree bevel through all the cuts, just to clean it up a little bit.
But I like to keep the cuts and joints as small as possible 'cause then, it doesn't hold a lot of dirt or water. And both of those things contribute to staining and basic erosion."
He cuts between 1/2 inch and 3/4 inch With four and a half foot spacing
"the chances of you getting a crack in the concrete, that's not in one of these lines, is real remote, and that's the beauty of doing cuts that are close together. You won't get any visible cracking."
While washing the surface after cutting, he admires how slope can do its job so well,
"The water runs off really good, runs right to the drains. So this backyard won't flood again.