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This summer, we installed a new front door. It was right until winter arrived. The problem is the following. When temperature goes below -5/-10 celcius, the door gets really cold and condensation freeze and form ice inside the house. As a result, it gets hard to close the door and the ice/condensation melts and everything gets wet around the door. Also the ice thickness close to the floor gets as thick as 4cm in some areas...

More about the actual door, it's "wooden"/metallic door. The frame is metallic and the exterior side of the door is also metallic while the inside part of the door has some kind of "wooden" panel.

It's clear that the problem is caused by the metallic frame, the room cannot heat the frame enough so the colds gets into the house and condensation starts... The door is inside a small "room" of 2m x 2m.

Installing a new door isn't a solution.

I have some ideas but I have no idea how effective.

  • Install a wooden frame on the outside so air cannot directly have contact with the door's frame.
  • Heat the room (I only have space to install something that would keep the floor warm. I'd pretty much have to redo the whole entrance and it's not clear if we can heat it enough so to prevent condensation.
  • Drill holes in the frame and spray some foam like Penosil.
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    How is the indoor humidity level? I live in a colder climate than you, and commercial buildings often have steel door frames, but there's rarely any frost buildup. – isherwood Feb 1 '17 at 21:33
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    Also, do you have a good seal with the weatherstripping? When I do see severe frost it's because there's an air leak. – isherwood Feb 1 '17 at 21:34
  • The seal is good, even when there is no ice, it's a bit difficult to close it. And I can't feel any leak. The bottom of the frame is frozen most ice is on the left and right bottom corners. The bottom doesn't get as much ice as the corners but does. The top is never frozen but ice can get pretty high when below -20. – Loïc Faure-Lacroix Feb 1 '17 at 21:46
  • @isherwood the minimum temperature we have here is around -30 so far. But ice starts appearing at -5/-10. Not sure how to measure humidity. But there is a problem... Windows in the new rooms we repaired are also pretty wet. But other rooms do not suffer from this problem with the old windows. – Loïc Faure-Lacroix Feb 1 '17 at 21:49
  • @LoïcFaure-Lacroix If you're getting ice at the bottom but not the top, yet still feeling a good seal when closing, it's likely that the top is closed tightly but the bottom isn't, creating a draft. Bring a tissue or lit candle near the door frame (being careful not to light anything on fire!), see if you can't find a draft there. – mmathis Feb 1 '17 at 22:00
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I've seen similar situations (although not with 4cm of icing!) in situations where there doesn't seem to be any leaking of exterior air, but the interior humidity was quite high in a localized area of freezing. Simple answer: consider dehumidifying, or venting to interior air, the affected area. [Since there is no further work to be done with the door, according to your post.] Heating the affected area may also work, but I'll explain why I consider this a last resort.

The problem

It sounds as though you have an entryway (or foyer) enclosing this entry door, for practical purposes of airflow (or limiting air flow). If you are using this area as a "mudroom" or area where wet/cold/snowy coats/boots/outerwear can be left or changed from, then the moisture brought in by that wet material could be evaporating, then condensing on the sub-freezing surface of the door, then of the ice as it builds up.

The Solution

Removing this moisture from the air will assist in limiting the amount of icing occuring. This could be done by any combination of the following: - Remove clothing/outerwear/footwear that has moisture from the affected area after initial entry. Moving that snow-covered coat in from the foyer will mean that it dries inside the main dwelling, instead of in the foyer. This could be drips/puddles in the house, but this evaporating water will also humidify the main living space, and not condense/freeze on the entry door. A rubber mat/tray can also help with this. Footwear can be removed to bang off loose moisture on the exterior of the dwelling, then set to dry in the living space. - Dehumidify the entry. A simple dehumidifier can do this, or simply open the door to the outside/inside for a few minutes each day. The air exchange (although wasteful of conditioned air) will also exchange the moisture in the air. Depending on the amount of moisture, however, the air exchange may need to be done multiple times daily. On the up-side, this air exchange, if done to the interior, may warm the space enough to thaw the ice off of the door itself, giving a "reset" of the situation. - Heat the entry. I'd consider this a last resort, because heating will not solve the problem. The problem is a sub-freezing surface, which you will not be heating - the air surrounding the sub-freezing surface will be heated, and the heat will be quickly conducted through the thermally-efficient conductor of the door surface to the exterior of the dwelling, once again returning to the state of maintaining a sub-freezing surface on the door.

Provided there is truly no leakage of air, this is actually a humidity issue. It may be worth it to buy an inexpensive (but accurate) humidistat to check the humidity levels. The tool would have future uses, so it's not a one-time purchase without future utility. Lowering the humidity level in that space is the best way to solve the problem.

For the future

In the future, (or perhaps this can be done in the short-term as well,) consider treating the interior surface of the door. A non-stick spray (silicone lubricant) or wax (for skis, cars, even just regular candles) would help the moisture (and ice) be more easily removed from the surface. If the condesation cannot be stopped, it could at least be mitigated by quick removal when someone passes through the doorway. 4cm of ice isn't good, but 1cm of ice that falls off everytime someone slams the door closed coming or going may limit the thermal compromise of that room, and ease in operating the door. There's also the added bonus that ice is solid moisture - so dehumidifying the room of that chunk is a simple as throwing or sweeping it out the door.

A long shot

There is one other option, but it's not necessarily adviseable. Venting the room completely to the outside or inside of the dwelling will provide constant air circulation, especially if induced via convection. This would circulate the higher-humidity air with the larger vented-to area. However, this would provide a heat-sink if vented to the inside, and/or a very cold room if vented to the outside. (You may also transfer your freezing problem to an interior door if ventin gthe room to the outside.)

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It's not a complete answer, but it's a beginning from my observation.

As the door is mostly in metal and the frame is in metal. The real problem is that metal is a pretty good thermal conductor. After investigating the door carefully, I see there is a big gap between the door frame and the wall around the frame. In other words, not only the door poorly isolate from heat but the people who installed the frame didn't properly injected isolation foam around the frame. Filling every holes with foam clearly helped with heat transfer.

After doing that, the door didn't freeze as much as before. But it was still getting ice on the floor. After I filled some crack on the floor the amount of ice got reduced too. It's still possible to freeze (Yet I won't be able to tell until next year probably).

As filling some cracks next between the wall and the veranda (cement). I believe one of the problem is that the veranda was actually sucking heat from the wall as it's completely open to the outside. Adding some isolation between the veranda and the wall seems to keep the wall warmer than as usual.

Here are my conclusions:

  • Make sure the frame is completely isolated with foam or something else. Fill all the gaps and cracks so less metal is in contact with air.
  • Isolate the wall where the door is standing from the outside. (Note that it is a brick house)
  • If the wall is touching some concrete blocks, it would make sense to add something to isolate the wall from the concrete. Even if the wall is isolated, heat will dissipate there thus making the wall cold anyway.
  • Building a closed veranda would certainly help keeping the veranda warmer and making the wall around the door frame less cold.

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