Planning For Snowmelt
Now that more and more homeowners have fallen in love with radiant heat inside their homes, it's no surprise that they're demanding snowmelt for the outside, too.
Typical residential uses include melting snow from sidewalks, driveways, car ports, decks, patios and breezeways. But while it's easy for a homeowner to see the benefits, general contractors usually start out lukewarm. As with anything out of the ordinary, overcoming objections from general contractors about the work are a mainstay for radiant contractors. Who's in charge of the design and installation? How will it affect my schedule and my bid? How will it impact my crew and day-to-day operations? Will putting snowmelt under the driveway or walkways impact the structural integrity, making them unusable for workmen and deliveries? Who works with laborers or paving subcontractors to ensure success? Who's responsible for failure?
Beyond these basics, radiant contractors also have to be prepared to work with various types of surfaces and layouts.
We recently met three radiant contractors who were happy to share some secrets about how they meet consumer demand, and beat any and all objections to snowmelt.
Down To A ScienceDan Foley's trading area of northern Virginia isn't exactly Nome, Alaska. But Arlington Heating, Arlington, Va., can count on installing several snowmelt jobs a year. As a result, Foley has his work schedule down to a science.
"We've had a lot of success turning homebuilders into receptive listeners," Foley says. "In any case, an increasing number of homeowners are demanding radiant snowmelt systems so they don't have to deal with the hassles of ice and snow." A few years ago,
Foley even installed a snowmelt system for a customer with a heart condition, whose doctor told him snow shoveling was off limits.
After years of experience with building contractors, here's how Foley plans out the work. Many of his snowmelt installations are for driveways so we'll outline a typical driveway application. As with any building project, good communication is the key to success, and above all, Foley's three-step approach takes the worry out of the work:
Step 1: Planning Meeting
Foley first sets up a meeting with the general contractor, who may call in the paving subcontractor. At that meeting, Foley presents the design, describes the procedures, coordinates schedules and determines who needs to do what and when.
Step 2: Preparatory Garage Plumbing
The snowmelt piping usually hooks up to a manifold located in the garage. Typically, the PEX piping is routed through a protective sleeve of 2- or 3-inch PVC pipe embedded in the garage floor slab. Foley's crew obviously gets called in to run the PVC pipe before the paving contractor puts the crushed stone base in for the slab. The garage slab can then be poured and finished normally.
Step 3: Driveway Preparation & Pouring
A typical production schedule looks like this:
First morning: Paving contractor lays down gravel and crushed stone, then applies a 2- to 3-inch layer of stone dust to form a solid base. He then builds a form using 2 by 4's and plywood.
- First afternoon: Laborers lay down high-compression-strength extruded polystyrene (EPS) insulation over the stone base; on top of that they lay flat sheets of 10-gauge welded wire mesh in a 6-inch grid.
- Second morning: Foley's crew unrolls piping and attaches it to the grid. Embedded slab expansion joints should be determined at this time - no control joints should be cut into the slab! Foley runs a PE sleeve around the piping at the control joint to allow
for slab expansion and contraction without stressing the piping. After installation, the piping is air-pressure tested to ensure there are no leaks. Since the piping is exposed during this period, care should be taken to avoid driving, staking, shoveling or raking the area.
- Second afternoon: Paving contractor pours concrete, usually 4 to 5 inches thick, measuring from the grid. Arlington Heating is on hand to provide technical help during this crucial phase.
Sometimes the paving contractor will mistakenly hook the grid into the concrete. "It's there simply to hold the tubing and provides no structural support," Foley says. If wire mesh reinforcement is required for the structural strength of the concrete, then another layer of wire mesh can be laid on top of the installed heating pipe.
Throughout the process, someone from Arlington Heating is present to conduct a final air pressure test, and to be sure that the paving contractor's laborers avoid using rakes, shovels or hoes to dig into the slab.
That's how the procedure works for concrete. For asphalt driveways, Jeri Donadee, vice president of H.B. McClure Co., Harrisburg, Pa., makes some minor adjustments to Foley's work schedule:
- First morning: After grading the driveway and covering it with crushed stone, the paving contractor crew should lay down 1/2-inch insulation. "One-inch insulation can be used with concrete," Donadee says. "But 1/2-inch with asphalt minimize possible compression of the insulation." These tire "valleys" happen more readily on an asphalt driveway than concrete. In this case, Donadee's crew attaches the piping to the grid.
- First afternoon: On top of the piping, the paving contractor applies finely crushed stone dust.
"We've found the best method is to recommend dumping the stone dust in piles, then use a small Bobcat loader with a flat bucket angle to push the pile ahead and down around the piping," Donadee says.
The dust is then sprayed with water to weigh it down and help with compaction. If there's time, Donadee recommend waiting a few days -- ideally one with rain -- to permit further natural compaction. Afterward, a final roller-compaction should be done just before the asphalt is delivered.
For the sake of our story, let's just say one day is enough.
- Two Days Later: The paving contractor then applies a 3-inch top coat of asphalt using the normal application equipment. Some shovel work can be used to spread the asphalt and a full-sized roller can be employed, since the 3-inch base of stone dust protects the pipe against shovel dings, compression and heat.
Throughout the process, H.B. McClure Co. monitors other workers, and ensures constant air pressure in the pipe to verify there are no leaks.
A common concern Donadee hears time and again on asphalt jobs is whether the tubing can stand up to the heat. "We tell them radiant tubing can withstand hot water temperatures up to 200 degrees F," Donadee says. "The lower temperature of the asphalt when actually applied, and the insulation of the stone dust base, keep temperatures from threatening the pipe."
However, it never hurts to play it safe, and there's no harm in applying asphalt when the day or season is cooler.
In fact, on his very first asphalt snowmelt job, Donadee was very cautious so he ran some cold water through the piping while the asphalt was going down. The water temperature only rose a degree, which was proof enough that the stone dust does a great job of insulating the pipe.
Variations On A ThemeIn addition to concrete and asphalt surfaces, radiant snowmelt works under bricks, tile, and paving stones, which are used in driveways, but especially in sidewalks, breezeways and patios. Heating and plumbing contractor Steve Speirs, director of Robert W. Speirs Plumbing Co., Kaysville, Utah, recommends pouring a 3-inch concrete cap to cover the snowmelt piping. The paving stones can then be set on top using mastic epoxy and mortar as desired.
He has also had to deal with another snowmelt variable - extremely steep driveways. Since his trading area contains plenty of mountains, one job called for a snowmelt system in a driveway with an 8 percent grade. His solution: Just put radiant snowmelt on the steep parts. He doesn't recommend creating "car tracks," because the snow alongside the tracks melts, requiring the system to run nearly continuously to prevent the tracks from freezing into icy ramps.
For home remodeling jobs, Speirs also has to deal with another variable if the homeowner wants to retrofit a snowmelt system into an existing driveway. In the case of an old and cracked driveway, simply starting over by jackhammering and removing the concrete or asphalt slab is often the very best way to go. In other cases, the driveway can be milled to prepare for resurfacing. Then 1-inch by 1-inch grooves on 12-inch centers can be cut into the driveway before applying the new layer of concrete or blacktop.