Contractor has said that bathroom exhaust fan on ceiling to suck up into the above-ceiling area is enough, and that it does not need to be vented out the window. Is this fine?

yep..me myself install in my bathroom

It is fine because you're not cooking inside. It's only to bring out stale air and some smelly air when you do your big business.

should suck out to outside. else ur ceiling will be moisture, eventually have mold problem on entire ceiling..

NO NO... NO , over the time, u dont want all the smelly air & moisture trap inside the ceiling right

do it proper way, ducted it to out side tru roof eave, won't cost u much lar

What go in must go out. Common sense.

If you have suction no out put you strain your fan motor, and forcing moisture to collect and form water. Getty big bottle or container try blowing it do you think is easy? And what happen you release your mouth?

Common sense please.

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Added on July 27, 2012, 4:11 pmIf above your ceiling is roof than is ok, cause roof have opening to outside

This post has been edited by weikee: Jul 27 2012, 04:11 PM

Agree. You can imagine what's like the like of months if not years of constant suction into ceiling space. This is more so if you have hot water, as the moisture is the starting ground for mould development.

In reality although an ideal, sometimes it's cumbersome/troublesome because toilets however have no ventilation outside due to renovation claiming backyard hence closing off vent-out spaces now reclaimed by renovated area/rooms. I've seen them mounting ceiling vent into ceiling space nia. Mine is such but I don't hv plaster ceiling but rely on fixed louvre window veniting into dry area. Installing an extractor fan on the backyard wall somewhat though not ideally deals with the air/odor wafting out away from the dry area.

In that scenario, for health reasons, it is proper to duct it outwards with ducted ceiling vents that runs out to the wall of the backyard.

For condo and apartment toilets with casement window of leaf opening up-down type, just install glass mounted suction fan.

Same for landed with the same window configuration or else just bore through masonry with exhaust fans. Some like KDK/Panasonic has one model, En (4"/10cm) and Zen (6"/15cm) extractors which is for areas that have very little overhang from roof. This series have an accessory hood that elbow downwards on the exterior to prevent rain infiltration.

Edit: One practical matter is unless you hv additional switch point for extractor fan, what I did was to branch it off the toilet light point. Hence can leave fan on while light can turn off. Otherwise in the long run cost $$$ to vent cos light must still run. The other alternative is to install pull switch for light with the obvious drawback of having to grope for it in the dark to turn it on.

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Added on July 27, 2012, 4:34 pmWithout outside roof, venting into ceiling space esp if ground floor toilet causes back pressure on the fan. The miniscule dirt and mold spores could be blown out due to backpressure.

Venting into roof space should be ducted with a roof vent/duct otherwise moisture build up inside here could affect lifespan woodwork holding up roof.

This post has been edited by halcyon27: Jul 27 2012, 04:39 PM

Is it necessary to have exhaust fan in the bathroom? I didnt put any, nobody say and i didnt notice...

can consider positive air also. not necessary suck.
just push air from room into bathroom. naturally it will escape thru window.

No, vent it out with duct or PVC pipes. Moisture trapped in the ceiling promote mould and bacteria growth. If the air is just lingering around the ceiling area, then might as well don't do exhaust fan. If the air has no where to go above the ceiling, what is the difference when the air is trapped in the bath room without window or exhaust fan. Your big business smell will still goes down to the bathroom after you off your exhaust fan cum light.

If you can open the bathroom window, it is not neccessary.

and dont cut corner by joining 2 bathroom exhaust into 1 outlet
the big business smell will permeate to the next bathroom

Roof is not critical because day time the heat will actually dry the humid.

Ground floor is a must to put ducting, if no ducting or opening, better don't put any vent fan.

In the case of roof tiles, perhaps the gap promotes air exchange then should be ok. But my preference would still be to duct it to a roof vent like those constructed for cooker hood but adapted for roof use.

In this case, I'm thinking more towards those ground floor extension in which the roof is built using corrugated zinc or steel kliplok types where it's not so "permeable" ie movement of air from inside roofspace outwards is restricted. It's true that daytime heat will cause the air to be able to hold more moisture (increased vapor pressure) but in the situation of a zinc or kliplok roofs, night time will spell trouble as the excess moisture in the air will condense as it gets cooler in the night hours. This affect something the vapor condenses upon.

This post has been edited by halcyon27: Jul 27 2012, 05:12 PM

Of topic, for roof tiles with wood truss, is really dry after some years. I know this because I apply anti termite chemical to my house roof truss. The wood absorb like sponge and not a single drop of chemical drop/slip out.

Ok, good to know. How old is your place?

Mine is build in the mid 70s and when I bought it went up to inspect. At that time when solar heater and plumbing was done, it was oozing out 'oil' even after 35 years due to excess heat in roof space. Had to put two turbine ventilators and then noticed that it hasn't been oozing since.

One thing to note about our climate that being a rainforest tropical, relative humidity is highest around 4-7am. Can get to about 90% which explains in some places, mist (kabus) in the morning.

This post has been edited by halcyon27: Jul 27 2012, 05:45 PM

yeap. its fine.



either way. It need to vent out turn roof eaves.

This post has been edited by KVReninem: Jul 27 2012, 06:08 PM

thank you for the discussion, i neglected to mention that this is a condo.
there are windows in the toilet which will be open most of the time, and outside of these windows are 2 a/c compressors.

Just use circular exhaust fans that can be mounted on the window itself.
http://www.kdk.com.my/ventilating-fans.asp?sid=9

Right...so what is the purpose of the exhaust fan again?