Plan the doweling
Inspect the job to determine the best spots to begin doweling.
For instance, doweling right next to a corner isn’t a good idea since it would require drilling and inserting the rebar into a hard turn — a near impossibility. In that case, it’s best to knock out the corner and reshoot it, tying into the existing steel where the corner was, then doweling into the existing wall on the other side.
“I’m going to wipe the existing corner out, go back 3 or 4 feet, then I’m going to recreate it all over again,” Toth says.
The relationship of the new and old rebar affects the strength of the structure. It’s best if the new dowels sit within 2-1/2 inches above or below existing steel. “If you’re expecting one load from one bar to be transferred to another bar, they need to be about 2 inches or less apart,” Peterson says. But the bars shouldn’t bump up against each other, or it could compromise the integrity of the existing concrete.
To locate the existing steel, some builders invest in a metal scanner. It functions much like a stud finder, indicating where each individual bar is located inside the wall. It can scan through 6 inches of concrete and even indicate how deeply the bars are embedded. This makes it easier to drill in the right spots.
“You don’t want to start drilling and then hit a piece of rebar 3 inches down,” Peterson says. “If it’s possible, you want to stay clear of the other steel.”
The scanner also will indicate the steel’s concrete coverage. “There are times when the plaster looks fine, and you take that off and realize the steel is just underneath there,” Peterson says. “How do you know whether you have 1/8 inch of coverage or 4 inches?”
In addition to the proper rebar layout, some epoxy dowel jobs benefit from a footing placed underneath the new work. “I put what I call a key beam underneath it so I’m not relying on the gunite to support it and the doweling alone,” Toth says.
The beam sits directly underneath the new area, measuring at least 18 inches deep by 18 inches wide, with rebar tying the two together. Shallower features should rest on the same kind of soil as the rest of the pool, so when adding them, installers may have to dig the beam deeper to reach stable soil.
