Locks and door seals in mountain homes

People tend to think of weather stripping as a comfort item and locks as a security item. In a mountain home the two are tied together. A door that seals well keeps snow, moisture and cold air away from the lock. A door that leaks lets all of it blow across the latch and bolt.

The seal also affects how the door sits. Compression seals press against the door when it closes, and that pressure changes how much force the latch needs to hold the door shut. A seal that is too stiff can push the door back, so the bolt does not seat. A seal that is crushed or missing can let the door rattle in the frame, so the bolt wears against the strike.

Thinking about the door as a system is the clearest way to solve problems. Instead of asking what is wrong with the lock, ask what the door, the seal, the threshold, the frame and the lock are each doing. In many cases the answer is hiding at the edge of the door, not in the cylinder. A strip of foam that has flattened, a sweep that has curled or a threshold that has risen a little with frost heave can each change the way a lock feels, and none of them look like lock trouble at first glance.

Around Mount Shasta, Dunsmuir, McCloud and Weed, winter can bring heavy snow, hard frost and wide swings between day and night. Snow piles against the door, melts in the afternoon sun and freezes again after dark. Each cycle puts water into the cracks, the keyway and the track of the seal. By midwinter a door can carry a thin skin of ice that nobody sees until the key will not turn. Homes at higher elevations, such as those near the foot of Mount Shasta, tend to see the cycle repeat more often, while the lower valley towns see it only on the coldest nights.

Wind drives snow and rain sideways into gaps. A door on the weather side of the house can end up with packed snow in the threshold and ice along the edge. When that ice forms around the bolt or the latch, the lock may stop moving even though nothing inside is broken.

Cold also changes the door. Wooden doors swell and shrink with the season. Metal doors conduct cold into the lock hardware. Foam and rubber seals stiffen. All of these effects can make a lock that behaved well in autumn feel poor in January. Our guide to winter lockouts and frozen locks in the mountains goes into more depth on what ice does inside the lock.

A door seal has several parts, and it helps to know their names. The weather stripping runs along the sides and the top of the frame. It may be a foam strip, a rubber bulb, a vinyl flap or a metal strip with a spring edge. It presses against the door when it is closed.

The door sweep is the strip along the bottom of the door that brushes the threshold. The threshold itself is the sill under the door, often with an adjustable section that can be raised or lowered to meet the sweep. Together, the sweep and the threshold keep out drafts, water and snow at the bottom.

On the latch side there is usually a seal as well, and this is where the lock comes in. The latch bolt and the deadbolt pass through this edge into the frame. If the seal is too thick, the door cannot close completely. If it is too thin or worn, the door can move and rattle. Either problem can make locking harder. The gap you want is a small, even one, with the seal lightly touching the door all the way around and the latch bolt entering the strike with a little room to spare.

A new or oversized seal is a common reason that a door suddenly becomes hard to lock. The door has to compress the seal to close, and if the seal is too thick, the door stops short of the frame. The latch bolt then reaches the strike at the wrong depth and may not engage, or the deadbolt may rub against the edge of the hole.

You can recognize this when the door seems to push back as you close it, when you must lean on it to lock, or when the lock turns easily with the door open but binds when it is closed. The cure is to adjust the seal, to use a thinner one or to move the strike slightly. A locksmith can reposition the strike when that is the cleanest answer. Moving the strike a small distance toward the door stop can let the latch bolt engage without the door having to fight the seal. Some strikes are adjustable, with a slotted plate that allows the lip to be moved in or out, which is useful for a door that has to be tuned to a seal.

Be careful about solving the problem by shaving the door or the frame. Removing wood lets even more air in, and it can weaken the area around the bolt hole. Try adjusting the seal first, and check the hinges before you reach for a plane. The guide on doors that do not latch shows how to test for alignment, using nothing more than a pencil and a screwdriver.

The opposite problem is equally common. Weather stripping wears out with use and with the sun. A seal that is flat, cracked or missing no longer takes up the gap, and the door has room to move in the frame. Wind then pushes the door in and out, and the bolt chafes against the strike each time.

Over a winter this movement can enlarge the bolt hole, loosen the strike screws and wear the bolt. The lock begins to feel sloppy, and the door no longer closes with a firm, solid feeling. Replacing the seal is a simple job that often restores the original fit and takes pressure off the lock. Buy the type that matches the groove or the surface, because stick on foam, kerf mounted bulbs and nail on vinyl are not interchangeable. If you are unsure, take a short piece of the old seal to a hardware store as a sample.

Look along the edge of the door for light. Close the door in a dark room and shine a flashlight along the frame from outside, or have someone inside look for pinholes of daylight. Any gap that lets light through also lets cold, moisture and snow into the lock area.

• Check the seal along the latch side, hinge side and top.
• Look for light showing through gaps with the door closed.
• Inspect the door sweep for tears or flat spots.
• Clean snow and ice from the threshold before it packs.
• Replace any seal that is cracked, flat or missing.

The bottom of the door takes the worst of the weather. Snow and meltwater collect on the threshold, and if the sweep is worn they find their way inside. Water on a threshold also freezes, locking the door to the sill. Opening such a door can tear the sweep or pull on the latch and hinges.

Keep the threshold clear. Shovel or sweep away snow before it packs against the door, and chip away ice gently with a plastic scraper instead of a metal tool. Check that the threshold is adjusted to the right height so the sweep brushes without dragging. A sweep that drags too hard pulls the door down and out of alignment. Every time you open the door, the drag works against the hinges, and over a season it can loosen the top hinge screws and let the door sag. A sweep that just kisses the threshold gives a good seal with the least strain.

If the door must be forced open in the morning, address the cause rather than the symptom. Frozen sweeps, swollen wood and an unsealed edge all create the same feeling. Repair the seal, and then check the lock with the door open to make sure the bolt has not been strained by months of pushing.

Cold air that leaks through the door brings moisture with it. When warm indoor air meets the cold metal of a lock, condensation forms. That moisture can freeze on the latch, the thumb turn or inside the cylinder, and it can rust steel parts over a season.

You may see frost on the inside face of a deadbolt on a very cold morning, or a ring of ice around the keyhole. Those are signs that cold is conducting through the metal and moisture is condensing. Better sealing reduces the draft, which reduces the amount of moist air reaching the lock, and a well made lock with a decent finish handles the damp better.

In some homes a storm door adds a layer that keeps the weather away from the main door and the lock. A storm door must be installed so it does not interfere with the lock, and its own latch should be kept in order. The idea is to reduce the number of freeze and thaw cycles that reach the hardware. For more on how lubricants fit into this picture, see lock lubricants, what helps and what hurts.

Many mountain homes are cabins or second homes that sit closed for weeks. A door left alone through a hard winter takes the full force of the weather without anyone to notice small problems. Seals dry out, snow drifts against the threshold and moisture sneaks into the lock.

If you own a place like this, build a routine. Before you leave, check the seals, clear the threshold and confirm the lock operates smoothly. When you arrive, test each lock before you unpack, so you learn about trouble while you can still do something about it. Keep a spare key in a safe place off site in case a lock refuses to turn. If a neighbor or a caretaker checks the place during the winter, make sure they know how to work each lock and who else has a key, and ask them to tell you if a door feels different.

Our guide on a lock strategy for cabins and second homes covers key control and access in more detail, and hunting season cabin access and key care looks at the busy autumn season when many cabins are opened and closed.

Autumn is the time to do the work, before the first storm. Start by examining each exterior door. Close it and look at the gaps. Replace worn weather stripping, check the sweep, and test the threshold height. Make sure the door closes without needing to be forced.

Next, test the lock. Turn the key with the door open and watch the bolt. Then close the door and test again. If the bolt binds, find out why. Clean the keyway, add a small amount of dry lubricant, and tighten hinge and strike screws. Replace any batteries in electronic locks, and know where the backup key is.

Finally, think about how you would get in or out if the lock failed. Do you have another entrance? Is there a spare key somewhere safe? Having a plan is a good habit when winter makes help harder to reach. Roads close, storms linger, and the drive to a lock supply store may not be possible on a particular day. A few spare parts, such as extra screws for the strike and hinges and a spare seal, let you handle small repairs on the spot. The guide on preventing snow day lockouts adds habits you can start now.

Some problems need a professional. If a deadbolt will not seat after you have tried adjusting the seal, if the strike has been worn away, if the cylinder has frozen repeatedly or if the door itself has shifted, a locksmith can help. We can reposition a strike, replace a cylinder, install a more weather resistant lock or improve the way a door and lock work together.

We serve the mountain communities of Siskiyou County, including Mount Shasta, Dunsmuir, McCloud and Weed, and come to you in a branded van with professional tools and common hardware. See our Mount Shasta service area page and Dunsmuir page for what we do in those towns.

If you are locked out because of ice or a failed lock, our house lockout and 24 hour emergency locksmith pages explain what we can do. For planned work, use the request form to describe the door, the weather and what you have noticed. The phone line is coming soon.