Yes, you can put a skylight in a bathroom, and it can work well, but only if the room can get rid of its steam. The glass is often the coldest surface in the room, so shower steam lands on it first. A skylight in a bathroom needs a working exhaust fan, a good seal on the roof and the right type of unit.
The short version
- A skylight in a bathroom is fine when a working fan vents outside, not into the attic.
- Fogging on the glass is usually a humidity problem, not a bad skylight.
- A tubular skylight is a good pick over a shower or tub when you want light and nothing else.
- The roof seal matters more than the glass, so ask about the flashing.
- If your bathroom has no fan, fix that before anything else.
Will a skylight fog up in a bathroom?
Sometimes, and that is not always a fault. Warm, wet air from a shower hits the coldest thing in the room, and in winter that tends to be the skylight glass.
The EPA says to prevent moisture from condensation (opens in a new tab) by raising the surface temperature or lowering the moisture in the air. You can’t warm a pane of glass much, so in a bathroom the fix is less steam in the room. A skylight shows you the problem sooner than a wall does.
Condensation diagnosis is part of our skylight repair work. Fog trapped between the two panes is a different problem, a failed glass unit, and we replace those.
How much humidity is too much?
The EPA says to keep indoor humidity below 60 percent (opens in a new tab), ideally 30 percent to 50 percent. A closed bathroom after a hot shower is a place where that is hard to do without help.
That is why the fan matters more than the skylight. A Department of Energy lab says bath fans remove moisture from the home (opens in a new tab) to help keep humidity down, which discourages condensation and the growth of mold and mildew. The same guide suggests leaving the fan running for one hour after a shower (opens in a new tab). A timer switch does that for you.
Does the fan have to vent outside?
Yes, and this is the part that goes wrong in attics. The same guide says to vent the fan directly outside (opens in a new tab), not into an attic or crawlspace.
When a bath fan ends in the attic, warm wet air condenses on the cold underside of the roof deck in winter. The deck soaks it up and dries out again through dozens of cycles, then starts to break down. It can ruin a deck without a drop of rain getting in from above. We find bath fans ending in the attic during ventilation work, and it often leads to mold and new decking.
If your fan already drips, our article on a bathroom exhaust fan leaking water walks through the causes.
Which skylight works best over a bathroom?
It depends on where it sits and whether you want air or only light. We put in fixed, vented and tubular skylights. Here is how they compare in a bathroom.
| Type | Good for | Watch for |
|---|---|---|
| Fixed | Plenty of daylight, few moving parts | Can fog in winter, no way to let steam out |
| Vented (opens) | Daylight plus a way to let steam out | More parts to seal, and you have to remember to open it |
| Tubular | Light over a shower or tub in a small footprint | Light only, no view and no fresh air |
The Department of Energy says tubular daylights (opens in a new tab) are one way to bring daylight into rooms that have little of it. That suits a small bathroom, where a round diffuser in the ceiling takes the place of a big pane of glass.
If you are weighing a tube against a regular skylight, solar tube skylights have an article of their own.
Will it leak?
A skylight leaks at the roof, not at the glass, most of the time. The frame is sealed to the roof with metal flashing, and we cover the pieces in our guide to skylight flashing.
Two things help a lot. One is flashing that is new, not reused. The other is ice-and-water shield around the skylight’s edges, a sticky waterproof layer under the shingles. It is commonly left off at skylight edges, and Ellicott City’s freeze and thaw cycles are hard on those spots. On a new roof, our install includes new flashing around skylights unless you ask us to reuse it.
What does it cost?
These are area ranges, not a quote. Replacing a skylight during a reroof typically runs $800 to $2,000+ each, and we strongly recommend doing it then. Replacing one on its own as a repair typically runs $1,200 to $3,000. A reflash typically runs $900 to $2,000.
Interior work, such as drywall and paint, is never included in roofing prices. A new opening in a ceiling means that work, so ask for it to be listed in any estimate you get.
Common questions
Can you put a skylight over a shower?
You can, but a tubular one or a small vented one is the safer choice. Steam rises straight to it. A fan and a good roof seal matter even more there.
Do you need a fan if the skylight opens?
Yes, we would still add a fan. An open skylight helps only while somebody remembers to open it. A fan on a timer works every time.
Should I fix the roof first?
If the roof is near the end of its life, put the skylight in during the reroof. New flashing goes in then anyway, so it is the cheapest time to get the seal right.
What to do next
Our skylight installation page shows how a skylight should go in. If you are not sure the roof or the bathroom fan is ready, our free roof inspection is a good start, with the attic checked when we can reach it. Call us any time, day or night.
