The short answer
Yes, a roof window is louder in heavy rain than a wall window, because raindrops hit the glass directly and the pane sits close to the ceiling. The noise is a patter or drumming, not a leak. It is reduced by laminated or acoustic glazing, thicker panes, a good seal and well-insulated lining. Any room directly under bare tiles or sheet is also quiet or loud depending on the roof above it, so the window is only part of the answer.
Why rain sounds louder on glass
A raindrop striking a tile or slate lands on a solid, heavy surface, and the sound is dulled by the roof build-up and the loft insulation beneath. A drop landing on a roof window strikes glass only a few millimetres thick. The pane acts like a thin drum skin, and the sound passes straight into a room with a sloping ceiling and little soft furnishing. Add a wind-driven shower and the effect is a continuous hiss or tapping.
The same is true of flat rooflights. Polycarbonate and thin glazed units can be noisy in a storm, which is one reason flat roof glazing in a bedroom gets a second thought. Our guide to flat roof rooflights compares the glazing types.
What affects how loud it is
The glazing is the biggest factor. A standard double-glazed unit, with two panes and a gap, is the baseline. Laminated glass, in which a plastic interlayer bonds two sheets, damps vibration far better than a single plain pane, and it is also safer if broken. Some makers sell their own noise-reducing glazing for this purpose, as a rain-noise option. A thicker outer pane and a wider cavity help too.
Position and the roof around matter. A window in a quiet, heavily insulated loft room, with plasterboard lining and soft furnishings, sounds mild. A bare room with a vaulted ceiling and hard floor is like a drum. The pitch also changes the effect: rain falls on a steeper pane more as a run-off, and on a shallower one it strikes more squarely. The window frame, flashing and the seal between pane and sash can rattle in wind if they are poorly set.
What you can do about it
If you are choosing a new window, ask about noise. Acoustic or laminated glazing costs more than standard, and the supplier will state the noise reduction. Do not rely on a rating alone, and ask how it compares with the standard unit. If the window is to go in a bedroom or a study, it may be worth the upgrade.
For an existing window, adding thicker lining and insulation round the opening, closing gaps at the reveals and fitting a heavy curtain or a blind can soften the sound. A fabric blind absorbs part of it. If the glass itself is the cause and the frame is sound, the sash or the pane can sometimes be replaced with an upgraded unit, which the page on replacing just the glass in a roof window explains. Check also that the seal is intact, as a failed seal makes a rattle as well as letting in damp.
The roof around the window
How noisy the whole room is depends on more than the glass. A loft room under a thin metal or fibre-cement roof will drum in rain whatever window is fitted. A room under tile or slate with good insulation is much quieter. If you are converting a loft and want a quiet bedroom, the build-up of insulation, plasterboard and, if specified, an acoustic layer matter as much as the window. We suggest you discuss the whole roof, and not just the window, at the design stage.
Noise from the outside can also be a sound of water doing something unexpected. A dripping or gurgling sound, rather than a patter, may mean water is getting through a flashing, a gutter above is overflowing or condensation is running down the glass. Our article on leaking roof windows sets out the causes.
Rain, hail and the other noises
Rain is not the only sound a roof window makes. Hail is louder than rain, and a hailstorm on glass can be startling, though laminated glass copes well. Wind produces a hum or whistle if a seal has gaps. Heavy snow sliding off the glass can thump onto the roof below, and a window above a door or patio is worth a thought for that reason. Thermal movement can cause the occasional tick as the frame warms in the morning sun. All of these are normal noises of a structure exposed to the weather, and none of them signals a defect unless it changes or gets worse.
Is it a reason not to fit one?
Not usually. Many people find the sound of rain on a roof window pleasant, a sign of weather without the wet. If it is a worry, laminated glazing deals with most of it. The sensible approach is to match the glass to the room, so the nursery and the main bedroom get the quietest option and the landing gets standard.
When we survey, we look at the room and the existing roof build-up and tell you what to expect, then price the standard and acoustic glazing options side by side. Our fixed quote shows both. More on the work is on the roof windows and skylights page.
Every roof is different. A free survey with photos settles it for yours.
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