How to install exhaust fan in skillion roof shed?

[Ritar]

I want to cool my shed in summer and reduce condensation under the corrugated colour bond roof. Shed made out of weathertex. Not insulated at all.

My shed:

- 6m long 1.6m wide 1.9 - 2.2m high

- there is a wall divide to separate the pool equipment section from tool storage section. The dividing wall is 5cm from the roof, so there is a gap between pool and tool sections. The tool section is about 5m in length

I thought a solar exhaust fan to circulate air about may be better than Foilboards under the roof, If you agree that would work, would one exhaust fan on the tool end of the shed do, and if so, what size? Will the air gaps from the colour bond corrugations allow enough air flow in or do I need a vent somewhere, if so, where do I place that?

[Jewelleryrescue]

Hi @Ritar

Every step you  take will help reduce heat and condensation so try your prefered steps first.

My stages I am in to free cooling passive stuff  just so you know my adgenda.

1 foil roof insulation

2  static (non powered roof vents 300mm) start at the highest pitch of the roof that gets the most 3 pm sun you can also install a 2nd one  so think about 2 high locations ( 2 for MOSTLY FOR CONDENSATION  reduction.)  (If you thinking solar:  Not all solar powered roof fans are strong enough  so beware not to get a puny one.)

3 Big fan 450  for use while your in the shed ,

Try passive insulation and cooling in stages. OR put in a big ass fan 450mm- 700mm, Bunning has huge fan selection of industrial  fans.

Insulation Fixed or ocilating

On ebay type "Garage Insulation"  (This insulation is like a roll where as foil boards may leak more at edges if  not a tight fit.)   look for double foil +EPE foam 4-6mm tack with  builders glue to the inside of your shed. roof and wall this is similar to how space craft are insulated you know they dont have room in there for pink batts lol.   The double foil will greatly reduce  heat the  foam layer forms a thermal break and the foam will trap warmer air in winter.  Cost for your shed roof  approx $200 with the left overs use it on sun side walls.

If  the condensation persists and there will still be some heat try using a static vent. Some also have clear lids to let light in so its a vent/solar light tube.  Heat goes up out of the roof naturealy pulling in cooler air at door way mostly or under edges

You can also use whirly birds  just make sure it is made to fit your corregeted roof profile  ask the staff to help you pick the right one to match your roof,

AS a static guide make sure it is fit for corregated roof you choose another.

Ezylite Black DIY Static Roof Vent I/N: 0820197 $69

good luck in your search for coolness

[Jason]

Hi @Ritar,

Great to see you receive a prompt and helpful reply from @Jewelleryrescue. I'm sure @MitchellMc will be happy to share his thoughts when he's back on the site tomorrow, and @MikeTNZ and @CSParnell might also like to add their electrical expertise. 

In the meantime, you might be interested in the advice community members shared for this article - How do you add insulation to a garage or shed?

Are you based in Australia? I should point out that the New Zealand Ministry of Business, Innovation and Employment (MBIE) issued a ban on the use of foil insulation in July 2016. The ban applies to the installation and/or repair of foil insulation in residential buildings. More information is available here: Foil insulation ban | Building Performance. 

Jason

[Jewelleryrescue]

Yes @Jason  I can see the poor use of  foil being a shock hazzard mainly  during installation.  

But any electrician who left exposed wirers or the potential for exposed wires on lights etc like that  for the foil to  touch really is the real danger.

But in NZ  you cant  fight city hall.   Thanks for the information.

[Jewelleryrescue]

Hi @Ritar 

I havent seen any half decent solar powered vents around most of them have only 100mm vent  holes and is  a bit restrictive.

I do like the whirybirds as some of them  turn with an additional  wind  powered fan in the throat of the vent .But when there is no sun or wind the heat under the roof will still vent out.

There is the static vents  to at approx 300mm dia  I like the clearcover versions acting like a bonus skylight.

To  properly address your concern re instalation different vents  have there own normally included kits  and instructions for your corrugate roof.  Grab a tube of  roofing silicon too it cant hurt,  JUST make sure its  the right one with the correct roof kit mounting for your shed.

[CSParnell]

Thanks @Jason I think this one comes best to natural airflow be it by solar fan and enough intake through gaps or addition of vents.

Addining of electrical exhaust fans would be an over kill.

[MikeTNZ]

Hi @Ritar,

Thanks for contacting us in this respect.

Is there any chance that you could provide us with some pictures of your current building?

Possibly with annotations to where you want to put the fan?

This would make it so much easier to visualise.

Thanks,

Mike T.

[MikeTNZ]

Hi @Jason,

Yes there have been issues with foil insulation, mainly with homeowners installing foil sheet.

When they staple this to the timber in the roof or under the floor, there is a risk that a staple could go through a power cable feeding either lights or socket-outlets and hence livening the entire metal foil, which causes a shock hazard if there is no RCD protection in the house.

By rights, things like this should not happen, the duty of care is on the person installing this material.

Where cables might be damaged by staples, the homeowner is required to have the cables fitted with extra mechanical protection (either flexible or rigid PVC conduit) over the cables themselves, by an Electrician.

[MikeTNZ]

Hi @Jewelleryrescue,

We aren't talking about exposed wires, what we are talking about is homeowners that don't check cabling before they start stapling foil to joists and the like.

The Electricity Regulations and common trade practice dictates that you always run your cables on the side of a timber member in a domestic building.

Regardless of this, this does not stop Joe Homeowner from using nails, screws or whatever fixings to hold the foil up.

Also, there is no City Hall in New Zealand, we all have to comply with the Building and Electricity Regulations here and also ECP 51, that pertains to

Domestic Electrical Installations.

Maybe you should have a read of this ECP, it could explain a lot.

Cheers,

Mike T.

[Jewelleryrescue]

Hi  @MikeTNZ   Good to talk again.

The  foil to my mind runs under the sheeting on top of the rafters like sarking.  But if they pin foil to the underside of same rafter they should miss all power given you said power is supposed to  be pinned to the side of the rafter.  

No city  hall?  that explains a lot. No batman for  Christchurch

I dont think I will be building in NZ to soon to much work to do here.

Your  country will have a whole  bunch of extra earth quake building codes too I would hope If they are sensible it  would be good to know some new approaches to  make  structures safer.

In Oz most houses built on a timber frame supporting the roof the brick walls are all but decorations and will fail and crack if the earth moved but house wont fall down as the timber is doing all the load bearing.

Dosnt NZ use RCD? re the fools drilling into  power cables.