Roof sarking for IP?

Discussion in 'Development' started by Bernado, 27th Mar, 2018.

Join Australia's most dynamic and respected property investment community
  1. RyanB

    RyanB Well-Known Member

    Joined:
    1st Jul, 2015
    Posts:
    118
    Location:
    Sydney
    Roof Sarking is standard building practice for me.
    Its not even an option

    Wall Sarking is i believe mandatory (again it is for me) on light weight areas (cladding etc as it also creates a moisture barrier)
    I peronsally do not use sarking in brick Vaneer, although i do recall seeing it being used at some stage somewhere in my head
     
  2. Paul@PAS

    Paul@PAS Tax, Accounting + SMSF + All things Property Tax Business Plus Member

    Joined:
    18th Jun, 2015
    Posts:
    23,319
    Location:
    Sydney
  3. Joynz

    Joynz Well-Known Member

    Joined:
    5th Apr, 2016
    Posts:
    5,751
    Location:
    Melbourne
    If wall sarking or building wrap is not included in your climate, your builders must be cowboys.

    I'd tend to bet they are using wall sarking though.

    The reason is that sarking (apart from helping with air tightness) also keeps the weather out and holds the wall insulation in while the cladding is put on.

    It means that internal trades can continue to work inside - once the roof is on - even in slightly dodgy weather.

    Be aware, that these days permeable sarking or building wrap is recommended to allow the walls to 'breathe' and avoid sick building syndrome through condensation buildup.
     
  4. Stoffo

    Stoffo Well-Known Member

    Joined:
    14th Jul, 2016
    Posts:
    5,301
    Location:
    In the Tweed
    I've known of builders who consider the building to be at "lockup" stage without a single brick being laid, just because the house is Tyvek wrapped !

    Personally I believe that all walls should be insulated, even the internal walls (due to zoneable heating/cooling and noise transfer)
    Not just roof area's......
     
    Joynz likes this.
  5. Bernado

    Bernado Active Member

    Joined:
    16th Oct, 2017
    Posts:
    44
    Location:
    Canberra
    Thanks guys!

    Builder has confirmed that wall sarking is included! Phew one less thing to worry about.

    They have also said that the bathroom and ensuite fans are ducted to roof cavity (rangehood is ducted to external). I told them I am worried about condensation issues this may cause. They said it would cost around $700 to duct these fans to external. They have also said that they have checked with their roofing company, and they have done roof this way (sarked, bathroom/ensuite ducted to roof, no whirlybird) many times with no issues.

    I don't know... leaning toward keeping it ducted to roof..
     
  6. Joynz

    Joynz Well-Known Member

    Joined:
    5th Apr, 2016
    Posts:
    5,751
    Location:
    Melbourne
    I suggest you get them to check the relevant standards re. ducting to the outside.
     
  7. EC101

    EC101 Member

    Joined:
    24th Oct, 2017
    Posts:
    11
    Location:
    Gosford
    Impact- shower humidity straight to roof then when temperatures drop, the humidity will condense on roof material and drop onto gyroc ceilings.
    Rangehoods- humidity and grease laden air goes to roof void, again moisture in roof area but worse is atomised grease dust - food for vermin and increasing flammable risk in the roof space. Aside from hygienic issues, I would 100% duct externally.
     
    Tahli and WattleIdo like this.
  8. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    Incredibly dangerous. If the house burns down, and perhaps that should read "when", I think it unlikely insurance will pay you out. You are placing others, knowingly, in danger and could be liable for further damages including a potential charge of manslaughter. Fans should be ducted to outside.
     
  9. Joynz

    Joynz Well-Known Member

    Joined:
    5th Apr, 2016
    Posts:
    5,751
    Location:
    Melbourne
    Hi Hobartchic
    I think you may have misunderstood what is being discussed here and I want to address it so people aren’t unecessarily freaked out:

    Venting fans into the roof space isn’t usually considered a fire risk!

    The main reason it is bad practice to vent into the roof - especially a metal roof - is because of the condensation effects. (Although these are less of an issue with an un-sarked tile roof because there is more air flow.) There are a number of publications that refer to this issue.

    Talk about manslaughter etc is completely OTT in this case. I wonder if you are thinking about insulation too close to downlights or stapling through RFL? Both of which can be fire risks.
     
    Last edited: 2nd Jul, 2018
  10. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    I was referring to this:
    Rangehoods- humidity and grease laden air goes to roof void, again moisture in roof area but worse is atomised grease dust - food for vermin and increasing flammable risk in the roof space. Aside from hygienic issues, I would 100% duct externally.
     
  11. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    Not fixing the rangehood so that it is ducted outside could cause a fire and lead to a potential criminal charge of manslaughter. In fact the house probably does not currently meet the criteria for occupancy in its current state.
     
  12. Joynz

    Joynz Well-Known Member

    Joined:
    5th Apr, 2016
    Posts:
    5,751
    Location:
    Melbourne
    I personally think that exhaust fans should be vented outside in metal roofs. Also, though not an Australian Standard just a guide book, the online Your Home design guide recommends venting externally too.

    However, the NCC deals with this issue in a non mandatory appendix to AS 1562.1—1992 Design and installation of sheet roof and wall cladding Part 1: Metal.
    This is the section that deals with condensation.

    However, a lot of forum members are new to building codes and standards and might find it hard to distinguish between an opinion and fact.

    Therefore, can you please post the industry references to support your comment that a house may be unfit for occupation if exhaust fans were vented to the roof cavity? Also the references for the fire hazard comments?
     
  13. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    According to Miele it relates to "B1 fire prevention regulation requirements."
    You can read further information on their website here: Expertise in the field of ventilation technology - Special Topics.

    A builder up to date with the latest Building Code of Australia would be able to provide a reference.

    If you are interested I believe that the fire prevention regulation would be contained there, or it would be contained under Australian Standard manufacturing legislation.

    I'm not the one with the issue, or interest, other than preventing house fires so I would encourage you to do further research if you are interested.
     
  14. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    Oh, and there's plenty of case history online of incorrectly installed rangehood's causing house fires.
     
  15. Propertunity

    Propertunity Well-Known Member

    Joined:
    19th Jun, 2015
    Posts:
    3,476
    Location:
    NSW
    [​IMG]?
     
    RyanB likes this.
  16. EC101

    EC101 Member

    Joined:
    24th Oct, 2017
    Posts:
    11
    Location:
    Gosford
    The fact that everyone that reads this is now aware of the high risk of atomised grease in the roof space makes it a moral issue and as a landlord makes you directly responsible for the occupants. Forget about standards etc, they are just that 'a Standard'. As an trades person, you physically can see 'grease dust' form where the air has carried the grease particulate into the roof space and when then sticks to the localised timers where the airflow is no longer strong enough to carry the weight of the dust. Have not tested it but, i do believe it would be a great accelerator . So, please have a look at your properties and ensure safety first...
     
    hobartchic likes this.
  17. Joynz

    Joynz Well-Known Member

    Joined:
    5th Apr, 2016
    Posts:
    5,751
    Location:
    Melbourne
    Luckily I have a builder in the family and the NCC as one of my online favorites so the knowledge base is pretty strong.

    I encourage forum members to listen to those who can back up their advice with actual industry references such as the NCC and Australian Standards.
     
    hobartchic likes this.
  18. hobartchic

    hobartchic Well-Known Member

    Joined:
    11th Sep, 2017
    Posts:
    1,513
    Location:
    Hobart
    Ah, I've checked things on the National Construction Code (for due diligence) but it was a while ago. Reading so much legislation in other areas lately, I reached my legal reading limit :)

    For some reason, I thought that the NCC was under the Building Code of Australia.

    For others reading this, | Australian Building Codes Board is the link to information on the NCC.