The short answer
To clean a skylight from the inside, protect the floor below, dust the glass and frame with a dry microfiber cloth or duster on an extension pole, wash with a damp (not dripping) sponge or mop and a little mild dish soap in water, wipe off residue with a cloth dampened in plain water, and dry with a clean microfiber cloth. Use as little water as you can, because it tends to run down the angled glass.
Safety first
- Ladders and heights. Skylights are high, and a fall can cause serious injury. Do not stand on furniture, and avoid leaning from a ladder. An extension pole lets you clean from the floor. If you cannot reach safely, hire a professional.
- Never climb onto the roof just to clean the inside. Exterior work is a different risk and is best left to a professional.
- Do not mix cleaning products. Never combine bleach with ammonia or vinegar, which can release toxic gases. Use one mild cleaner at a time. Avoid ammonia-based and other harsh products on skylights in any case, as they can damage plastic glazing and coatings.
- Children and pets. Keep them out of the room while you work overhead. Drips make floors slippery, so dry the floor afterward, and put cleaners and buckets out of their reach.
- Electrical items. Move or cover lamps, electronics and furniture beneath the skylight so drips do not reach them.
What you need
- Large drop cloths or old towels
- A telescopic extension pole
- A dry microfiber cloth or duster head, or a cobweb brush
- A microfiber mop head or lint-free sponge
- A bucket of warm water with a few drops of mild dish soap
- A second cloth for rinsing and a clean dry microfiber cloth for buffing
- Rubber gloves and eye protection when working overhead
Step-by-step
Protect the floor
Move furniture away and lay drop cloths or towels under the skylight, extending beyond where drips could fall.
Dust first
Attach a dry microfiber cloth or cobweb brush to the pole and gently remove dust, dirt and cobwebs from the glass, the frame and the light well (the shaft walls). Dusting first prevents you from smearing grit across the glazing when you add water.
Wash
Dip the sponge or mop head into the soapy water and wring it out thoroughly so it is damp rather than wet. Wipe the glass in gentle strokes. If the skylight is acrylic or plastic, avoid abrasive pads or stiff brushes, which can scratch.
Wipe and dry
Go over the surface with a cloth rinsed in plain water to remove soap, then buff with a dry microfiber cloth to reduce streaks and water spots. Dry the frame and sill too, since moisture left sitting on them is not good for finishes.
Glass versus acrylic or plastic glazing
Glass skylights are generally more scratch-resistant, while acrylic and other plastic glazing is easier to scratch and can be damaged by some chemicals. Natural Lighting notes that anything stronger than dish soap and vinegar may harm acrylic or glass coatings, and several manufacturers advise against abrasives and ammonia. If you are not sure what yours is made of, use only mild dish soap and water, a soft cloth and check the manufacturer’s care instructions. Skip vinegar if the instructions do not mention it.
Coated or self-cleaning glass may also have specific care guidance, so check before using any additional product.
Cleaning a sun tunnel
Sun tunnels (tubular daylighting devices) have a ceiling diffuser or lens inside the room. In many cases you can remove or wipe the diffuser. Dust it, wash it with mild soapy water, and dry it. Do not take the unit apart beyond what the manufacturer permits. For VELUX or other branded units, follow the brand’s care guide, and avoid scrubbing or using abrasives on any reflective tube surface.
Reaching high skylights without climbing on the roof
Extension poles with microfiber heads, pole-mounted duster brushes and lightweight mops let you work from the floor. Some people use a long-handled squeegee for the final pass, though water control matters since it will run down the slope. For skylights over stairs or double-height rooms, a professional with proper access equipment is the safer choice. Our guide to how professionals clean windows explains how pros handle high glass.
Fog, condensation and what it means
Dirt and haze on the inside surface can usually be wiped off. Moisture or cloudiness that appears between two panes, however, may mean the seal has failed, and cleaning will not fix that. If you see it, check with the manufacturer or an installer. Also look for staining or water marks around the frame, which could indicate a leak that needs attention.
Can you black out a skylight?
Yes, there are options. Many manufacturers sell fitted blackout or light-filtering blinds designed for their skylight models, and these are usually the best fit. Opaque film or temporary covers can also work, but check that they are safe for your glazing, since heat build-up can be an issue with some coverings. Ask the manufacturer or installer before adding anything.
How often to clean
Natural Lighting suggests inspecting a skylight about once a year. In practice, how often you clean depends on dust, cooking residue, humidity and whether the exterior is shaded by trees. Dusting every few months and washing once or twice a year is a reasonable starting point, and it fits neatly into a seasonal whole-house deep clean.
When to call a professional
Consider a professional if the skylight is high or over stairs, if the exterior also needs cleaning, if you see moisture between panes or leak marks, or if you are not comfortable working overhead.