Choosing a bathroom extractor fan: what to look for

How much airflow the room actually needs

Fans are rated in cubic metres of air per hour, written as m³/h. The right figure depends on the room's volume, not its floor area alone, so measure length, width and height and multiply them. A typical Tallinn bathroom of 4–5 m² with a 2.5 m ceiling comes to around 10–12 m³, and building guidance generally expects that volume of air to be exchanged several times an hour.

In practice this means most small bathrooms need a fan rated at 90–120 m³/h, and a combined bathroom-toilet or a room with a bath rather than just a shower does better with something closer to 150 m³/h. Buying a fan rated well above the room's needs does not clear steam faster in any useful way; it mostly adds noise and pulls more warm air out through the shaft.

If the bathroom has no window and the only ventilation is the shared duct, err towards the higher end of the range rather than the lower one, since that duct is also doing work for the kitchen extract or other flats above and below.

Humidity sensor, timer, or a plain pull-cord

A pull-cord or a switch tied to the light is the simplest option: it runs while you are in the room and stops when you leave, which often means it stops before the steam has actually cleared. A run-on timer fixes that by keeping the fan going for a set number of minutes after the light goes off, typically adjustable between 5 and 30 minutes.

A humidity sensor goes a step further and switches the fan on by itself once the air reaches a set moisture level, regardless of whether anyone has touched a switch. This suits households where the bathroom is used at odd hours, or where nobody reliably remembers to switch a fan on, since it reacts to the steam rather than to a person's habits.

The sensor version costs more and is one more thing that can fail, so a run-on timer is a reasonable middle ground for most flats. Whichever type you choose, wiring it in is electrical work, and if the existing switch or circuit needs altering to add a timer or sensor function, that is a job for a qualified electrician, from 49 € an hour.

What the noise rating on the box actually tells you

Fans are rated in decibels, usually written as dB(A), measured at a set distance from the unit under laboratory conditions. A figure below 30 dB(A) is genuinely quiet, comparable to a soft conversation; above 40 dB(A) is noticeable, and older or cheaper models can sit closer to 45–50 dB(A), which is loud enough to be heard through a bedroom wall at night.

The manufacturer's number is measured in ideal conditions, not in your actual duct, so a fan pushing air through a long or narrow shared shaft will usually sound louder once fitted than the box suggests. If the bathroom is next to a bedroom, it is worth choosing a model rated a few decibels below what seems necessary, rather than at the edge of what you can tolerate.

Vibration also matters and rarely appears on the spec sheet at all: a fan mounted loosely in an old, slightly oversized duct opening can rattle regardless of its official noise rating, which is a fitting problem rather than a product one.

Fitting a shared ventilation shaft in a panel flat

Most Soviet-era panel flats in Tallinn vent the bathroom into a shared vertical shaft that also serves the kitchen and other flats on the same stack, relying on natural draught rather than a powered system. Fitting an extractor fan into that shaft changes how it behaves, and an underpowered or badly sealed fan can end up pulling air backwards from a neighbouring flat instead of pushing it out.

Before buying, check the duct diameter behind the existing grille, usually 100 or 125 mm, and buy a fan with a spigot to match rather than forcing a mismatched size with tape and hope. A fan fitted into a shared shaft should also have a backdraught flap, which stops air and smells travelling back into your bathroom when the fan is off.

If the building has an apartment association with rules about altering shared ventilation, or if the shaft seems blocked or poorly drawing even before any new fan goes in, that is worth raising with the association or a specialist before spending money on a unit that will not solve the underlying problem.

• Measure the duct diameter behind the existing grille before ordering a fan
• Choose a fan with a backdraught flap if it vents into a shared shaft
• Match the airflow rating to the room's volume, not just its floor area
• Pick a noise rating a few decibels below what feels tolerable if a bedroom is next door
• Decide between pull-cord, timer and humidity sensor based on how the bathroom is actually used

Is fitting the fan itself a job you can do

Swapping an old fan for a new one of the same size, in the same hole, using the existing wiring, is often within reach for someone comfortable with basic tools, and falls under odd jobs from 39 € an hour if you would rather have it done than do it. The grille usually unclips or unscrews, the old unit disconnects from a simple plug or terminal block, and the new one goes in the same way.

Anything involving the household wiring itself, adding a run-on timer or humidity sensor where none existed, or wiring the fan to a separate switch rather than the light, is electrical work and should go to a qualified electrician rather than being improvised. Estonian wiring regulations and the risk of working on live circuits make this one area where the hourly saving is not worth the downside.

If the bathroom is being renovated more broadly, tiling redone, the extract point moved, or the whole layout changed, it makes more sense to fit the fan as part of that project rather than as a standalone swap. Our bathroom renovation work, from 3 500 € per job, includes getting the ventilation right as part of the wider plan rather than as an afterthought.