When roofs or decks can’t drain along an entire edge, or towards a central point; when run-off needs to be gathered or concentrated, crickets are required. This report describes building one type of crickets.
There are two ways to build a cricketed roof; first is the traditional stick-framed way where the slopes of the roof are built into the framing. The roof sheathing just follows the framing. The second way is what’s called a “California” cricket.
In a California cricket, the main slope of the roof is framed and sheathed entirely. Ripped sleepers are nailed on top of the main slope sheathing, and the cricket plywood is nailed to the sleepers. (We used Pressure treated lumber here to make the sleepers simply because the they’re adjacent to concrete block.) There are several advantages to this:
- If the roof plywood is being used as part of the seismic system, the diaphragm is un-interrupted at the peaks and valleys of the crickets,
- There is less fussy calculation during framing, and the carpenters can quickly roll the joists, shake out the plywood, and get the building temporarily dried-in,
- The carpenters can check heights, snap lines, and determine the run-off flow while standing on solid decking.
There are several disadvantages, the main one: cutting a long, slow taper where the cricket plywood meets the main slope plywood. Here’s how it’s done.
Get an idea of what it’s going to take for the taper. In this case, a 1/4″ in 12″ cricket slope met a 1/4″ in 12″ main slope so the taper for 3/4″ plywood was about 12″. Mark which side is the top, and where the taper runs out.
After the cricket piece is cut (generally it’s triangular) stand it on edge with the side to be tapered pointing up and level.
Set the Skilsaw at maximum depth, and eyeball the angle. My 7-1/4″ saw only cuts about 2-1/8″ deep, so that’s what I cut it.
After the long careful rip on the edge of the sheet, I put the piece down on the sawhorses. In 2-1/8″ depth of cut, it tapered about 1/2″, so I set the foot of the saw to 1/2″ for the first cut.
I snapped and cut a series of increasingly shallow reference grooves, 1/2″, 3/8″, 1/4″, and finally 1/8″. The grooves are about 2″ to 2-1/2″ apart. Then comes the tricky part: with the depth of the saw set at 3/8″, my right hip touching the piece, my right hand holding the weight of the saw and the guard back, my left hand on the trigger, I pulled the saw sideways, grinding out the plywood to the correct shape. Note that the saw motor is always between my body and the blade, and if the saw kicks, it’s going to kick towards the left out in clear air.
I used the reference grooves to tell approximately how deep I was cutting, and the plys in the plywood give a visual cue as to depth. Sort of like a contour map.
It’s important to keep the right edge of the saw brushing sideways on un-cut plywood to keep the cut smooth. If it runs over the bumpy part, the cut becomes correspondingly bumpy.
The cut can be surprisingly accurate, the limitation for me is just physically holding the weight of the running saw.
Finally, I took the little planer to knock the high spots off. A good question is why I didn’t just use the planer for the whole operation. The answer is speed. The Skilsaw has a 13 amp motor concentrated in a kerf of an eighth of an inch and is unstoppable, the Makita has a 6.5 amp motor spread over 3-1/2″ inches and is helpless.
Note that I had to take the spring out of the planer’s height adjuster to crank it down enough to get it to cut. I set it for about 1/8″ depth of cut. The planer did leave a nice flat taper.
Finally, I installed the 3/4″ cricket plywood pieces on top of the ripped sleepers – glued and screwed. In the photo, you can see that the slot in the concrete block wall for the scupper has not been cut yet.
The roofer will be able to add a couple of layers of felt to make a smooth transition at the bottom of the valley.