Exhaust fans ducting into the ceiling

Hi,
Our rental (eventually to be home) is having some mould issues in the bathrooms - which is apparently quite common as northern NSW gets a bit...humid.

The agent has given us a few quoted at about the $500-$600 mark for installing 2 exhaust fans (3 in 1) in the ensuite and family bathroom. This price includes ducting into the ceiling cavity.

I'm after advice about this. Given the humidity issue I've asked about ducting externally. It's a single story house with a wood and tin roof, but this is apparently going to cost much more. From the agent " have spoken to several electricians who have all said it is a very big job to duct the exhausts through the roof, meaning several more hours of labour.As a general rule, the exhausts are generally ducted into the roof cavity as it is only steam going through."

Is it worth it to duct externally?

Definitely worth ducting through (and I actually thought it was required by the building code of Australia).

All you are doing is creating a potential problem by moving the steam and humidity into the roof space. You could then have condensation issues with water dripping onto the backside of the ceiling ruining your ceilings.

What you need is two different trades. An electrician to install the fans (do you need the 3 in 1?). A standard exhaust fan is a 5th of the cost of a 3 in 1. And then get a roof plumber to install the vents.

Thanks ChargerWA. How much should it be all up, approximately? The contractors seem to be making out that it is a difficult job. This is the roof in question, and I would have thought it wouldn't be so hard. http://www.flickr.com/photos/22537051@N03/10092852734/

From what I can gather we're being charges $340 for labour and wiring just to duct into the roof.

I'm not sure where you are located so costing is difficult. I'm in country WA and the price for the install of two 3 in 1's quoted in your first price seems really fair for the electrical work.

My roof vents I think cost me about $50 in colour bond when I bought them 18 months ago. Mine just came with the roof quote, I'm sure you could find them cheaper as yours will be zinc. A roof plumber would install 2 in an hour. So maybe $150-$200 labour then you will need the flexible duct from the vent to the fan. So maybe another $300 all up, but it would be done right.

Bit of a storm in a tea cup really!

You think about how big your roof space is. The steam from a bathroom will have little to no effect up there. Most bathrooms are vented into this space. If it was a kitchen rangehood then it would be a different story.

In this situation I beg to differ. The house has cb roof and if it doesn't have whirly birds then no matter how good the fans are the would not be very effective as cb roof are better sealed. Inside of ducted everything outside including range hood my preference would be to install whirly birds to help create negative pressure. This is a better long term solution and has other benifits.

Not really, which is why I'm asking for advice. I don't know until I ask. The house in in northern NSW where there is a lot of problems with damp. It's also in a valley, which has it's own set of issues. Are Whirley birds easy to install?

Isn't that interesting. Because I thought it's usually roofing plumbers who put the ducting in. At least if you want it done properly. There's more to it than simply sticking a tube on top. I doubt the agent is really doing all that research on your behalf, more like repeating some vaguely remembered factoids which might or might not apply to your particular building in order to to keep the task simple and reduce the organisational workload for him. As a general rule indeed!




I agree with B STAR that in a sealed roof you absolutely need something. Sorry, I'm not in a position to offer opinion on ducting versus whirlybirds.
Only recently I was looking at this website, scroll down and see the explanation of why you should "Always vent". I liked his description so it stuck in my mind. http://www.houzz.com/ideabooks/16699741 ... portunity-

We're still having issues with this. Get two electricians willing to do this..but one wants to go out throug ht external bessa brick wall!

If you are having trouble finding someone to do the ducting then do the following,

Have an electrician fit the extractor fan and then employ a rangehood ducter to duct it out.

There are plenty of guys out there that duct rangehoods for a living, there isn't any difference between a rangehood and what you need done. They have all the ducts, vents and grills needed.

Will have a look at that

Every state is different, not all require roofing plumbers.



If the roof cavity is sealed then there is problem one. Roof cavities need to breathe hence there is a gap, even on metal roofs. The gaps are low near the gutter/eve and on the ridge cap. With the gutter/eve make sure someone doesn't come and fill those gaps with insulation. With houses that have a tiled roof the point work along the ridge cap should be done with weep holes which also allow any trap condensation to come out, something people don't know the importance of when doing DIY. Metal roofs the ridge cap isn't a tight fit so breathes as well and condensation can drain.

Things like whirlybirds can be added to increase the airflow, they are designed to pull more air in from around the eve and vent it out. Though in most cases shouldn't really be needed.

Only comment about venting fans into the cavity is it depends upon the house.

PS the cost of 3-1's seems about right, one thing to remember is because of the amount of current the heat lamps draw they need their own circuit, so the cost will be new breaker in switchboard and new cable from switchboard to switch and finally to the 3 in 1.

I wasn't talking legally or anything, I just meant it's one of those things where people who specialise in that type of work can make a better more thorough result, not putting down ALL general tradesmen cos some have a wide range of excellent skills but ours did simply stick a tube on top which needed fixing. Its not nice when someone comes to fix something or do some work and rolls their eyes and says who did this and were you an owner/builder when you thought you had paid an expert to do something the way its meant to be done.

Finally got a quote for what we are after . $699, including appliances, for both bathrooms. Fair?

Something i've seen at a friends place was venting to the eaves. IE ducting the exhaust fans through the ceiling, then drilling through the eave and fitting a grate.

Doesn't look the best - but would be cheaper than cutting through colorbond i would imagine - and really if it's down the dead side of the house where no one goes it doesn't have to look pretty.

I've seen old houses with eaves that aren't solid at all, they're like an open grille all the way round. But I thought in newer houses when there's vents in the eaves its something to do with enabling air flow out a whirly bird, a way to make the whirly birds more efficient by increasing incoming air? That's what I read the purpose was anyway. Btw don't fit vents in eaves in older houses without checking for asbestos cos eaves is one of the places to specifically check.

The house isn't actually that old - just a self-build done on the cheap.

Sorry, the tv ads warning about working on old houses must be having an effect. That wasn't the focus of your original question. So I read the thread over and your followup question is this.


Is that for the electrician to fit them, what brand/type, and with ducting, and what sort?

Our eaves dip down, so you can't see the vents unless you happen to be walking under and looking up. It was going to be too expensive to duct through the roof, as although we are in suburban Sydney, we have a fire rating of BAL-FZ, and it would have to be a fire resistant vent.

Well-
the electrician we chose was more expensive than the others, but would do the ducting.

...and then didn't. He installed the fans and decided not to do the ducting after all. He says there isn't enough room, although wasn't clear why, and will "take the ducting off the price of installation" which is great, except he wants to charge more than anyone else quoted for installation only.

Freakin nightmare!