Plumbing: Installing A Frost-Proof Sillcock – On the House

Plumbing: Installing A Frost-Proof Sillcock

By on November 13, 2016

Growing up out West, we didn’t see much snow, less the occasional trip to the mountains for a day or so where we could frolic to our heart’s content. As children, we always associated snow with fun and pleasure. It wasn’t until, as an adult, one of us lived in snow country and the “less pleasurable” aspects of snow (such as shoveling snow and dealing with ice dams) became apparent.

We also became familiar with a device that we had never before seen – a frost-proof sillcock. Prior to that time, not only were we not familiar with the device, we had never heard the term “sillcock” used before. What we soon learned was that a sillcock is also called an outdoor water faucet or “hose bib.” Things began to click. What we had yet to understand was how a hose bib could be frost-proof. After all, on those rare occasions when the mercury dipped low enough to be a threat, we simply wrapped the hose bib and adjacent pipes with rags to prevent the pipes from freezing and, thus, bursting.

So, a sillcock is just another name for a hose-bib and vise versa. It is called a sillcock because it is typically located just above the “sill” – the board that is anchored to the top of a foundation. It is also mounted to the “header joist” which in some parts of the country is referred to as the “sill.” Still in other parts of the country it is referred to as the “rim joist.” Yet, it is neither called a headercock or rimcock. Go figure! The pipe that supplies water to the sillcock has a shut off valve located in the basement some ways in from the exterior wall. Thus, when the weather gets cold, the valve can be turned off and the valve drained to prevent a burst pipe. It’s a reasonably good means of preventing a burst pipe, but can be somewhat inconvenient and what happens when one forgets to close the shut off valve and drain the pipe? The consequences can be disastrous.

Enter the “frost-proof sillcock” – a very cool device! It looks very much like your run-of-the-mill hose bib with the exception of the vacuum breaker that sits atop the valve. When a frost-proof sillcock is turned off, air rushes into the sillcock through the vacuum breaker to break the seal of water and help the residual amount to drain.

What is more amazing is what one can’t readily see. Unlike a traditional hose bib where the valve stem is an inch or two in length, the valve stem for a sillcock is 6 to 30 inches long. Thus, the valve is well within the exterior wall and protected from the cold and freezing. What’s more, you know need to worry about whether you remembered to close the shut off valve – none is required.

Installing a frost-proof sillcock is reasonably simple – especially if you have previous experience soldering. In addition to the sillcock, you’ll need a torch, solder, flux, a flux brush, fine sandpaper or steel wool, a copper tubing cutter and a rag. Start by removing the existing sillcock. Close the shut off valve and drain residual water from the faucet. Adjust the tubing cutter to surround the pipe and tighten the handle while rotating the cutter around the pipe. Remove the old sillcock and position the new frost-proof sillcock in its place. Check the length of the supply line, make a pencil mark and, using the tubing cutter, cut the pipe again to correspond with the length of the new sillcock.

Use fine sandpaper of steel wool to polish the end of the water supply and the inside of the copper fitting at the end of the sillcock. Apply a small amount of flux (soldering acid) to both the end of the supply line and the interior of the fitting at the end of the sillcock and join the two together. Next, light the torch and, with the torch in one hand and a length of solder in the other, apply the tip of the flame to the fitting at the end of the sillcock. Be sure that the sillcock valve is open all the way to prevent damage to rubber gaskets from the heat. Place the tip of the solder at the joint between the pipe and the fitting and continue to apply heat until the solder is drawn into the joint. Move the tip of the solder around the joint and remove the flame to prevent the pipe from overheating. Use just enough heat to cause the solder to flow. Immediately after removing the flame, use the flux brush to brush a small amount of flux around the entire joint.

Turn the torch off and allow the fitting to cool. Use a rag to remove excess flux and clean the joint. Finish the job by fastening the sillcock flange to the exterior siding with a couple of screws. First, apply a generous bead of caulk between the siding and the flange for a good waterproof seal. Turn on the water supply (once and for all) and flush the new sillcock before turning it off. You can also visit sites like and hire a professional to install one.

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