Is it necessary to duct exhaust fan externally?

eho · Dec 27, 2008 11:16 am

Hi,

I am planning to install those Light/Heater/Fan units in my bathrooms located upstairs in my house-to-be. I have sarking for my roof. For the fan exhaust, should it be ducted externally?

I spoke to couple of electricians who installs these units, they say it is ok to just vent the steam to the roof space. But, I am not sure if they understand about sarking. I believe sarking provides moisture barrier. This also means steam will be trapped inside the roof space. Wouldn't that be a problem?

stonecutter1309 · Dec 27, 2008 12:50 pm

I though NSW building standards required all exhaust vents to be ducted to external point? (for new house construction anyway)

eho · Dec 27, 2008 11:03 pm

You are right. I was told the same thing during my electrical appointment. The funny thing is, exhaust fan is not required for new build since it is not in the standard. If I chose to install one, I had to make it externally ducted. I thought I could have it installed post hand over so I did not include it in my electrical plan.

Hmm, if I need to have it ducted anyway, maybe I should have included in the plan in the first place...oh well. :roll:

Mr Ed · Jan 16, 2009 9:47 pm

We have the same issue as eho, double story home and sarking in the roof.

The electrician has externally ducted the fan's for the laundry, powder room and kitchen range hood located on the ground floor. However there is no external ducting in the upstairs bathroom and ensuite?

We are having IXL Tastic's installed in both bathrooms upstairs so should we be ducting the upstairs bathrooms given we have sarking installed?

chuth77 · Jan 17, 2009 7:05 am

Do you have roof ventilation?

IF not, and becuase you have a tiled sarked roof, the building code requires external ventillation...

Mr Ed · Jan 17, 2009 8:00 am

Good question chuth, I don't know? I can see a couple of flue's on my roof but they appear to be for the ceiling-mounted Brivis heater and water pipes.

Do they usually use those spinning caps for roof ventilation? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅

eho · Jan 17, 2009 11:01 am

I think I am going to get them externally ducted anyway. My question is...are electricians generally qualified to do the external ducting? I don't want a leaking roof!

Snake · Jan 17, 2009 1:57 pm

eho

I think I am going to get them externally ducted anyway. My question is...are electricians generally qualified to do the external ducting? I don't want a leaking roof!

You need a plumber not electrician for ducting.

chuth77 · Jan 17, 2009 3:03 pm

You could duct it to the eaves, and get some eave vents... Then you could do it, rather than pay an electrician, or plumber...

eho · Jan 17, 2009 8:45 pm

Snake

You need a plumber not electrician for ducting.

I initially thought the electrician installing the fan would be doing the duct work too. Now you mention it, it makes sense :-)

eho · Jan 17, 2009 8:46 pm

chuth77

You could duct it to the eaves, and get some eave vents... Then you could do it, rather than pay an electrician, or plumber...

Do you mean getting those whirlybirds thingy??

The Data Guys · Feb 15, 2009 5:12 pm

Sparkies can do the ducting. its just cutting a hole (or using a well placed foot/hammer) and fitting a vent and taping the duct to the fan.
It is an easy job.

I have three fans and i haven't ducted them at all. I have sarking too. Since I have spent most of my apprenticeship in a roof, I know first hand there is airflow through a roof and the moisture will dry out quickly in a roof space.

I have seen mould growing on external air vents from exhaust fans since the moisture can condense in the duct tube leaving stagnant water.

hysterical1144 · Feb 15, 2009 5:21 pm

The Data Guys

Sparkies can do the ducting. its just cutting a hole (or using a well placed foot/hammer) and fitting a vent and taping the duct to the fan.
It is an easy job.

I have three fans and i haven't ducted them at all. I have sarking too. Since I have spent most of my apprenticeship in a roof, I know first hand there is airflow through a roof and the moisture will dry out quickly in a roof space.

I have seen mould growing on external air vents from exhaust fans since the moisture can condense in the duct tube leaving stagnant water.

What about a double storey ? Should the exhaust fan in the toilet downstair be ducted externally ?

Cheers

The Data Guys · Feb 16, 2009 5:29 am

Yes.
I forgot about two storey houses. oops.

The powder rooms with no windows need to be ducted to.

fruitty · Mar 03, 2009 12:11 am

We're going to have sarking on our new single story house. In Victoria does the building code specify that exhaust fans & rangehood must be ducted?? As we are already paying extra for sarking we don't want to pay any additional ducting charges if the builder must have it by default!

When I asked it cost nearly $300 just to duct the kitchen canopy

it will cost more if the toilet & en suite also needs to be ducted.

chuth77 · Mar 03, 2009 7:19 pm

Fruitty....Couple of questions...

Does the roof space have any ventilation... Open Eaves? Roof Vents?

Does the toilet have a window?
Does the ensuite have a window?

Hoffies · Mar 03, 2009 8:48 pm

eho

chuth77

You could duct it to the eaves, and get some eave vents... Then you could do it, rather than pay an electrician, or plumber...

Do you mean getting those whirlybirds thingy??

No, eave vents are just small vents fitted to the soffitt. A small cut out of the soffitt is all that is required and fix the vents into place. You can get them from any hardware.

fruitty · Mar 03, 2009 9:20 pm

chuth77

Fruitty....Couple of questions...

Does the roof space have any ventilation... Open Eaves? Roof Vents?

Does the toilet have a window?
Does the ensuite have a window?

Not as far as I know (from looking at the plan). The toilets has no windows as it is in the middle of the house. Ensuite does have a window but probaly won't be open all the time when being used especially in Winter!

chuth77 · Mar 03, 2009 9:38 pm

I've checked the BCA... Any sanitary compartment must be ventilated as per Clause 3.8.5.0...

Take the following to your builder and ask how they comply with BCA 3.8.5.0...

3.8.5.0
Performance Requirement P2.4.5 is satisfied for a mechanical ventilation system if it is installed in accordance with AS 1668.2—Mechanical ventilation for acceptable indoor air quality, except that any contaminated air from a sanitary compartment or bathroom must—

(a) exhaust directly to outside the building by way of ducts; or
(b) exhaust into the roof space provided—
(i) it is adequately ventilated by open eaves, and/or roof vents; or
(ii) the roof is clad in roofing tiles without sarking or similar materials which would prevent venting through gaps between tiles.
Mechanical ventilation includes electric exhaust fans.

fruitty · Mar 03, 2009 9:46 pm

chuth77

I've checked the BCA... Any sanitary compartment must be ventilated as per Clause 3.8.5.0...

(b) exhaust into the roof space provided—
[/i]

I'm a bit confused, if I was the builder I would choose option (b) as least cost??