I have been told that low-voltage step lights can’t be used within 5 feet of the water’s edge. Is this true, and is it true that there are some transformers in the industry that are made specifically for low-voltage lights that are less than 5 feet from the water?

Doug Staples:

This issue is still up for interpretation. The code that specifies the distance of a light from the pool does not differentiate as to what type of light. In our area, a low-voltage light can be closer than 5 feet to the water if it is connected to a transformer that is more than 5 feet from the water and plugged into a GFCI. I recommend that you check with your local building department to see how they look at this issue.

Skip Phillips:

In San Diego the setback is actually 10 feet, not 5. The only time we were able to get around that rule was with a 12-volt fire-ignition system that required a special inspection and certification — very expensive and time-consuming.

What is the best waterproofing material to help prevent efflorescence behind tile and stone on infinity edges?

David Peterson:

Efflorescence is the white staining that occurs when natural salts within the concrete and mortars are pushed out of the concrete by the water pressure. It is often a slow process that is not necessarily driven by vessel leakage, but rather by the permeability of the materials. The plaster is only 99 percent waterproof, so some water is permeating the plaster, then through the concrete. Some of the efflorescence originates from the hydration process of the concrete itself.

The solution is waterproofing, but there is no single “best” answer, because there are so many options and variables (e.g., wet-mix vs. dry-mix shotcrete, freeze/thaw conditions, presence of chlorides, expense, etc.).

I break down waterproofing into three basic categories: integral, penetrating and topical. Xypex C-1000 admixture is our preferred integral waterproofing system. It is added to the concrete at the ready-mix plant, and it forms crystals within the concrete to seal it up. Because water can’t migrate through the watertight concrete, it can’t push the loose salts out. Aquafin, Sika, and other manufacturers have integral products similar to Xypex.

Penetrating sealers like Aquron or Endur-O-Seal’s HydraLoc also work well and in the same basic manner as the integral systems. However, freeze/thaw conditions need to be reviewed carefully, as well as potential bonding issues with dry-set  or thin-set mortars that may require removal of any waterproof films left on the substrate prior to applying veneers.

Topical sealers, like Aquafin 1K + 2K/M on the negative (dry) side and two layers of Aquafin 2K/M on the positive (wet) side, are also capable systems. As with all products, read everything, call the manufacturers, and test with mockups if necessary. The Genesis 3 Forum also is a great resource with lots of real experience shared by many builders.

I also avoid flexible membrane systems (waterborne latex). They are tricky to use and have resulted in delaminations.

What is the best way to repair a lifted deck caused by expansive soil or tree roots? I’m looking for a solution that’s  less expensive than replacing the whole deck.

Mike Geremia:

There are no shortcuts for this situation, and a repair will never match. We have not found a way to keep the existing section of concrete, which only leaves removal as an option. The amount that will be replaced is a function of your customer’s budget. A small budget means that the customer may be willing to accept the patch. A larger budget will allow for a complete tear-out, or an overlay to cover up the repair.

The bigger issue is what has been done to eliminate the cause of the lifting. Tree roots are obvious — remove them. But they may come back if the tree is still in place. Expansive soil is a different issue altogether. The main culprit here is probably the lack of drainage. Homeowners often change the drainage course that had been installed with the deck, or the drain lines have become plugged. Make sure that the water can drain away from the edge of the deck and enter a clear drainage course. Also, be sure the deck has a seal between the tile or coping. If water is allowed to penetrate in these areas, you just created a future warranty problem for yourself.

Why is it important with steel re-enforcement to make sure that it’s clean of all dirt and debris prior to the shotcrete process?

Lew Akins:

Steel is used to hold concrete together. If the concrete is not in direct contact with the steel, the steel cannot do its job. A couple other critical issues with steel are: It must be placed in the correct location within the structure, and splices should be the correct length (40 diameters).

I just poured new concrete around a 16-by-36-foot rectangular pool. It is all new stamped and cantilevered coping. After we were done, a neighbor sabotaged the skimmer with some of the leftover concrete from the truck. He lifted the skimmer lid and shoved in as much concrete as he could. No one knew until the owner started the pool up and found that one of the skimmers wasn’t working. I couldn’t figure how all the concrete got into the skimmer. After digging and blowing out the line I’ve had enough. I got a power washer and blew out as much as I could. The line was full and I could not get any further than the elbow at the bottom of the skimmer. What should I do next?

Mike Geremia:

This is a difficult situation. We had something similar happen and were ultimately successful using muriatic acid. However, in that case the concrete was less than a week old when it was discovered. Pouring straight muriatic acid and letting it sit may break down what is left in the pipe. The problem will not go away easily because, once you loosen the piece from the pipe, it  probably will move to the next fitting and cause an obstruction there. If there is any access from outside the deck to the skimmer line, you might be able to cut the pipe and chip the concrete from that direction. Beyond these efforts, which may or may not solve your situation, you will need to remove the section of concrete and cut into the pipe to remove the obstruction.

When I design spas, I like to install a couple of jets into the floor as foot jets. The problem is we get inconsistent results, depending on how the jets are looped and whether the plumber properly takes into account the added weight of water at the bottom of the spa vs. the other bench jets. Sometimes the jets are not powerful enough, and sometimes they’re too powerful. Is there some way to plumb these installations to ensure more consistent results?

David Peterson:

The apparent force of the jets depends on the water velocity through the jet and the amount of air entrained by the venturi.

The water velocity part is fairly easy to understand: A higher flow rate (gallons per minute) through a fixed diameter orifice equals more velocity; more velocity feels like more power.

The air injection is a little more complicated. It depends on flow rate and velocity too, but also on the differential pressure drop across the venturi nozzle. When the jets are located at the floor, there is more static pressure at the discharge point. Compared to the wall jets, the floor jets have less differential pressure, which can reduce the amount of air and the apparent force of the jet on your feet. It is also possible to have too much water flowing through the jets, which reduces the air. But the jets may feel strong because of the high velocity. All of this is further complicated when the floor jets are hydraulically tied to the wall jets. Some manufacturers are good about publishing performance data for the nozzles, and it is wise to design to that criteria.

My recommendation: Always plumb the floor jets on a separate pump and loop from the wall jets. This way, the relative differential pressure between the wall jets and the floor jets is eliminated. Use a variable-speed pump to provide adjustment.

Skip Phillips:

Since there is not only differential pressure, but potentially significantly different friction loss values between an upper wall jet manifold and a floor jet manifold, either use a separate pump for each application, or plumb the manifolds with separate lines. Based on the assumption you have properly sized your pump and lines for the total job description, you can adjust the flow via a three-way valve to compensate for the variation in the two lines.

Is there a sealant that is rated for stone that is set underwater? All technical documents I’ve ever seen only state that sealants are for stone that is not submerged.

Doug Staples:

I’ve had pretty good luck with an Aquron product called 1200 Stone Preservative. But I understand they’re introducing a new product that’s even better for these applications. It’s called Invisa-Shield.