Question 1

Why does my bathroom extractor fan not clear the steam?

Accepted Answer

Usually because the fan cannot move air, rather than because the fan is broken. An extractor is only as good as the path the air takes out of the building and the path fresh air takes in to replace it.

Start with the ducting, which is the most common culprit. Flexible duct that sags, kinks or loops adds enormous resistance, and a long run of it can cut actual airflow to a fraction of the fan's rating. Rigid duct, kept as short and straight as possible, moves far more air. Check also that the duct actually goes somewhere — fans that terminate into a loft void rather than through a vent are a frequent and damaging installation error, dumping moisture into the roof space.

Then check the external grille. Backdraught flaps stick, painted-over vents block, and insects and debris fill the mesh. A grille with a fine insect screen can halve the flow.

Next, replacement air. A fan cannot extract air unless the same volume can enter. A tightly fitting modern door with no undercut and no vent effectively seals the room, and the fan strains against a partial vacuum. A 10mm gap under the door usually resolves it.

Only then look at the fan itself. Cheap axial fans are only suitable for short duct runs; anything longer needs an inline or centrifugal fan. Dust on the impeller reduces output significantly and is worth cleaning annually.

Finally, check the run-on timer. Steam takes several minutes to clear after a shower, and a fan that stops the moment the light goes off has not had time to do its job. Fifteen minutes of run-on is a reasonable setting.

Question 2

Why does my fire or wood burner smoke back into the room?

Accepted Answer

Because a chimney works by draught — hot gas rising creates suction that pulls smoke up — and anything that weakens that suction or starves it of replacement air sends smoke the other way. How the

Question 3

What causes condensation on the inside of my windows?

Accepted Answer

Condensation forms when moist air meets a surface cold enough to bring it below its dew point. Windows are usually the coldest surface in a room, so they show it first. The moisture is not coming

Question 4

What are trickle vents and do I need them?

Accepted Answer

Trickle vents are small, controllable slots in a window frame or head that provide continuous background ventilation without opening the window. Why they exist. Modern homes are sealed far more

Question 5

Why does the paint in my bathroom keep peeling?

Accepted Answer

Peeling in a bathroom is almost always moisture defeating adhesion, and it happens through one of two mechanisms. The first is surface condensation. Repeated cycles of a warm humid room and cool

Question 6

What causes a musty smell in a room?

Accepted Answer

A musty smell is produced by mould and mildew growing somewhere, releasing compounds you can smell before you can see any growth. Air freshener masks it; finding the moisture source is the only real

Question 7

What is MVHR, and does a house need mechanical ventilation?

Accepted Answer

Mechanical ventilation with heat recovery continuously extracts stale air and supplies fresh air, passing them through a heat exchanger so most of the warmth in the outgoing air is transferred to the

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