Regulations in these parts are quite strict with respect to pool fencing. Anything containing - or able to contain - 300mm of water or more must be fenced in accordance with a set of strict, but unfortunately somewhat ambiguous, standards. Even during construction, we had to ensure everything was fenced in accordance with the standards.
Design to avoid a "fenced-in" appearance
The key to a good fence design is to ensure that the fence doesn't detract from the site or isolate the pool visually or practically. In designing the pool, we were careful to maintain adequate height of the lower retaining wall to ensure no additional fencing would be required atop the wall. The opposite, uphill side of the pool deck is cut about 1.2 meters into the slope. The fence that will sit on the edge of the decking above provides a natural railing and is visually pleasing.
With the flower bed end of the pool already fenced by the privacy fence, there is only one edge of the pool that would naturally remain unfenced (absent the regulations and safety concerns). Since the stairs descend down to the pool deck on this side, a balustrade would have been required here regardless.
The end result is a pool, deck and fencing combination that looks natural and integrates well with the existing house and deck. Use of non-tinted glass panels for the fence fence itself means it is largely unnoticeable.
Glass fencing panels are held in place by vertical, stainless steel spigots that are attached to the base of each panel at one end and cemented into the ground at the other.
Since the ground/pool walls are already concreted, large cylindrical holes need to be drilled into the existing concrete, the spigots are placed inside at the correct position/angle, and the hole is filled with rapidly setting, cementitious, non-shrink grout (effectively high performance concrete without the aggregate).
It would be virtually impossible to grout the spigots in place at the correct angle and attach the panels after. To ensure accurate alignment, it's necessary to first attach the spigots to the panels and then hold the panels in their final position using wooden blocks and braces.
Before that can happen though, we need to drill some holes. And for that, we use a core drill.
While regular drills are designed to drill holes by cutting directly into the hole, taking small chips at a time, core drills cut a hollow circle, removing a large cylinder of material in one piece. They are used when a large diameter, deep hole is required (e.g. our pool fence) or when the material being removed must be preserved (e.g. Antarctic ice core).
As with all things related to this pool, budget is key, and thus I secured the cheapest core drill I could find. A proper core drill for the task would cost about US$500-1000, mine cost about $125.
Core drills differ from regular drills in a few significant ways, but paramount amount these is having a safety clutch. A clutch is needed because when drilling a narrow ring deep into concrete, it's very easy for the core bit to catch and become stuck if the drilling angle changes even a little. When this happens, the bit stops moving and the drill itself takes up the responsibility of spinning. With a clutch to disconnect the bit from the drill, broken arms and dislocated shoulders typically ensue.
The water attachment that came with the drill was laughable and I was forced to construct an apparatus that looked like more like a hospital drip than drill cooling system.
A delicate balance
After coring the holes and drying them out, it was time to suspend the fence in place. With my laser ensuring straight lines, I placed wooden blocks under each panel and used angled beams to position the top edge. I also planned to clamp the top edges of the panels together, but some of the panels were slightly bowed. Not enough to cause an issue when they were aligned properly, but sufficient to result in the clamps pushing the panel into the wrong position.
Once firmly held in the correct position, the holes can be filled with grout to lock everything in place. This is the simplest part of the job - mix the group and pour it into the hole using a funnel. The only challenging part is that the grout starts curing very rapidly, so it must be done quickly.
For the wall section in the image above, the fence was installed prior to finishing the top of the wall as the surface will be finished with wooden decking that extends from the residence here.
Squares are cheap. Any other shape is not
Given economies of scale, standard square, temperated glass panels in varying widths are relatively inexpensive. Anything custom is not. The primary reason is that tempered (i.e. hardened) glass cannot simply be cut to size. The tempering process means that any attempt to cut the glass would result in it shattering into thousands of tiny pieces. The cutting must be done on the plain glass first, and only then can it be tempered.
Our design requires a rather large, custom "rake" panel on the edge of the pool deck stairs. The top edge of the panel is diagonal and the bottom edge follows the stair line. Having it manufactured and delivered was eye-wateringly expensive, but there was no way around it.
In anticipation of the fence being installed close to the edge of the stairs, I placed vertical rebar in the steps during their construction where the spigots were to be located, secured into the footing at the base and extending up to just below the surface. This is to prevent the edge of the stairs from breaking away in case any significant lateral force is applied to the fence, through wind or accident.
Final adjustments required to ensure approval
Under the standards, any protrusion or indentation in the pool fence >= 10mm is not permitted. Inspection of the lower wall showed several stacked stone pieces protruding around 12-13mm. To protect against the apparent ability of 3-5 year old children to scale vertical walls using 13mm finger grips, these were chipped away with a hammer and chisel.
Additionally, to eliminate the possibility of walking around the end of the fence on the side wall, I built a long wedge that sits between the glass and the wall edge, creating a >60 degree surface. To minimize the visibility, I used clear acrylic and shaped it with a heat gun, clamps, hacksaw, and lots of patience. Although not the best angle, it can be see highlighted in the image below.