My door lock keeps freezing to the point I can’t open it, any idea why this would happen?

Anonymous Nov. 13, 2016, 1:15 p.m.

I have a newly built home (3 years) that is extremely well-insulated and airtight house that had a blower door with results near 1 ACH. I am thrilled with it in every way except that on the coldest days and nights my door lock freezes and I can’t get in and out of the house. My contractor says he followed every procedure properly and that there is nothing I can do. Any ideas?

Responses (1)

Ecohome Nov. 13, 2017, 1:26 p.m.

I have the same problem, so I can sympathize. It’s possible that it is weather related if you don’t have a storm door, but given your air change rating I suspect it’s the same thing that is happening with me.

Due to warm air rising (the stack effect), air will leak in on the lower levels and leak out on the upper levels, and as warm humid air leaks out, it condenses and freezes. Air may be coming in through the basement door knob but that won’t cause a freezing problem. It is the warm humid air leaking out through upper floor door knobs that can freeze.


The most important thing would be to lower the humidity level in your home if it is too high, so first hit the hardware store and pick up a hygrometer to measure the indoor relative humidity, They cost about 20 bucks. If you normally have high humidity (50% RH or more) it would be wise to work to reduce it, and not just for your door knob but many other reasons. Some quick ways to work towards that are putting lids on pots when you cook, using a stove hood, don’t hang clothes to dry inside, and always use a bathroom fan when bathing. Given the quality of your home it likely has a well-sized HRV system, but make sure that it in good working order and runs the appropriate number of hours per day, and that it is properly balanced. If it is pressurizing your house that will exacerbate your door knob problem.

Try to keep the humidity below 40%, even aim for the low 30s if you can. If your wooden furniture starts to crack and your nose bleeds endlessly, then maybe it’s a bit too low, but strike a balance between nose bleeds and being able to get into your house :)

You can also use a graphite lubricant on the inside of the door knob, that is a good short-term fix. Taking a door knob off shouldn’t be much more effort than loosening two screws. If you haven’t installed one before, don’t be intimidated but keep a close eye on how it comes out so you can put it together again properly.

And for my final trick…. when it looks like it will be a cold night, I put one of my kid’s mittens on the outside door knob, held on with an elastic band (I don’t use his instead of mine because I’m a mean dad, it's just that they are the right size). That helps keep it much warmer and seems to prevent it from freezing.