A few days ago, we had a big storm and some of the rain water came through the light fixture of my room. I shut off the electricity straight away, removed the light bulbs and drained the water. It came through the screw holes of the light and didn't get near the wires of my light but it soaked the insulation foil. It's been about 30 hours and the insulation is still damp to the touch but I'm unable to remove anymore via pressing towels to it. How much longer should I wait until putting new light bulbs in and turning back on the electricity to my room? Is there a way to speed up the drying of the insulation? or should I let it air dry the rest of the way? How long will that take?

Edit: I've already located the leak, the vent pipe near my room seal has broken and that's how the water has come in. I'm going to have someone come over and fix it soon, I'm concern about causing a fire in the meantime which is why I asked about the light fixture in the first place. Need to fix the seal to prevent further damage to the light fixture but damage has probably already happen to the light fixture and I might start a fire by doing so...

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    A small fan blowing air up might help, but setup would be difficult. Imagine this is a ceiling, so you now know you have a leak in your roof that needs fixing.
    – crip659
    Jul 11, 2021 at 18:05
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    Just note that the presence of water alone doesn't magically cause electricity to turn into fire. The water needs to 1. Actually contact bare wire and 2. create an alternate circuit (typically with ground, but can cause a live-neutral short). As long as the wiring is not old an cracking, water typically shouldn't cause a whole lot of problems since that's the entire point of having wires. If you see rust near the wiring endpoints, then you may need to be more careful because that indicates persistent water presence long before the leak.
    – Nelson
    Jul 12, 2021 at 15:33
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    "putting new light bulbs in" - Why new bulbs? Just dry off the old ones, a little water doesn't typically hurt light bulbs, at least not incandescent. In fact, the heat from the bulbs would help to dry out the insulation.
    – Glen Yates
    Jul 12, 2021 at 16:04
  • @GlenYates I don’t know where OP is, but incandescent bulbs are pretty rare in the U.K., at least, nowadays.
    – Tim
    Jul 12, 2021 at 19:59
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    You probably need to clarify whether you are talking about heating insulation or electrical insulation.
    – Nelson
    Jul 13, 2021 at 2:11

5 Answers 5


To just answer your question, since the insulation is just damp dry because you've done the "pressing towel" thing, you can reassemble the light and turn the power back on. The heat from the bulbs will dry out the insulation.

But you have an additional problem, the leak in the roof. Personally, I would remove the light fixture, wire nut the wires and twist the wire nuts upwards until you get that leak fixed. @Harper stated in their answer the importance of fixing the roof and he is so right. Any new rain storms will cause the fixture to fill with water and become a hazard if water ever got to the connections or inside the sockets.


Wet insulation is generally disposed and replaced by new material to mitigate mold growth. A light fixture might work normally after it is completely dry and the mounting surface is completely dry, however the fixture is now damaged. This damage would also affect the circuit conductors if they were exposed or submerged by leaking water, in which case part of the circuit might need to be replaced. No amount of waiting or pressing towels can be prescribed for this.

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    That's rather extreme! Other than replacing any insulation inside the fixture, there's no reason to replace the fixture or wiring. I don't know what you mean by "circuit conductors" -- we all call those "wires" . Jul 12, 2021 at 19:01

Is there a way to speed up the drying of the insulation? or should I let it air dry the rest of the way? How long will that take?

Hire an industrial dehumidifier, and as soon as possible. Ambient air drying will eventually get the dampness down, but it can take a long time to dry out drywall, and as long as it's damp then it'll be getting progressively more damaged and more mould spreading. The standard remedy for flooding is a dehumidifier.

If you have insurance, it's possible that they'll cover the cost, or at least part of it. It's also possible that if you haven't taken appropriate steps immediately (i.e. hiring a dehumidifier) and then make a claim later (even if it's unrelated), your insurance company may use this as an excuse to stiff you by saying the damage is your fault because you didn't do anything about it.

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    Any kind of dehumidifier will work, but an industrial one will work better. Also, simply having a fan to move air around will help the dehumidifier. Jul 12, 2021 at 21:27

You can typically rent the dehumidifiers and blowers at a big box or go to an industrial supplier to rent the equipment.


You mentioned "insulation foil", so I'm assuming that you're talking about the foil-faced insulating disc that some light fixtures - particularly enclosed ones - have on the base behind the bulb. That insulation's purpose is to reflect the bulb's light and heat into the room and away from the fixture's wiring. Without it, the bulb's heat can build up and melt the insulation off the wiring, causing a short or worse.

When most types of insulation get wet, they lose some of their ability to insulate. Until it dries out, that insulation's effective R-value will be significantly reduced. This means that the soggy insulation may no longer be sufficient to protect your wiring from the heat generated by the fixture. I do not recommend operating the light fixture while this type of safety feature is compromised.

Some light fixtures will allow you to remove the insulating disc from the fixture. If you can do that, set the insulation somewhere more conducive to drying, like outside in direct sunlight on a hot, dry day. Insulation doesn't dry quickly, but avoid the temptation to wring out any remaining moisture. Compressing the insulation can prevent it from fluffing back up and can reduce its ability to insulate. If the insulation doesn't go back to looking relatively normal after drying out, you may want to look into replacing it.

If you can't remove the insulation from the fixture, the best you can do is to provide maximum airflow through the material and use a dehumidifier if available.

Most importantly, make sure you've stopped the source of the leak. You're never going to dry anything out if there's still water coming in from above.

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