Roof with no sarking

Hi all - I finished building my house October last year in Melbourne. I have a metal roof and had sarking in my contract - but they forgot to put it in (materials were not ordered in). I am not in a BAL zone and therefore legally did not need it but chose to have it to help keep the roof cavity clean. The builder was not going to change the battens and the screws would be going back in the same holes if I got them to rip it up so left the roof as is. I asked my builder for an additional whirly bird and got it. I didn't notice the missing sarking until further on into construction (struggling to find a builder for 3 years (ditched Mimosa and Dennis) and was a bit run down). Apart from this I had a good build and had an independent inspector. I did not realise until well after handover that sarking is also recommended for keeping moisture out of your roof cavity and as you can imagine, I am now quite stressed. The builder refunded the cost of the metal roof on my contract and gave me a few other freebies.

You can't retrofit sarking without ripping the roof off, and I was wondering if there were any other options I could pursue to keep an eye on or reduce the amount of water/condensation that will inevitably come into my roof. I intend to get a roofing inspector in once a year to keep an eye on things - any recommendations on where I should go to find a good roofing inspector?

I get very dismayed when I see a new house going up nearby with a tin roof and a thermal blanket going in. Why is it that it is not an Australian Standard to have sarking in all metal roofs, not just BAL?

There is a fair bit of difference to just sarking (silver foil) to thermal insulation (anticon) I would say if you have a good quality insulation on your ceiling and the roof ventilator is working then condensation build up on the underside may be minimal. You may need to have some form of suffit vents so that you can create an airflow through the roof area trying to keep the temp difference between the outside air and roof air as close as possible to prevent the condensation. It is amazing that a builder would "forget" to install it. When the shoe is on the other foot they are quick to say "but thats not what is in the contract" line.

If your colourbond is a very light colour compared to my dark colourbond roof the temperature of the light colour will be half of a dark colour,60 degrees for dark ,30 degrees for light colour so i went high quality anticon as I also love quiet roof over noisy rain(personal choice).

AFAIK there are no Australian standards tho I may be corrected
Search condensation in the following publications
lysaghts technical information
CSIRO
You haven't stated your region/State? I would say a must in Victoria and Tassie
optional in perth

The energy assessor of the builder is giving me a 6.7 rating, where six is supposed to be the present "best" rating, but without anticon and only R4 ceiling insulation. But I will put in anticon (> $3,000) at R1.3 60mm and R5 instead of R4 at a cost of more than $1,000 extra. No insulation in the brick cavity is required?

Littered,

The condensation that you raised is very minor. The fact that you have a well ventilated space, given the extra vent installed, has mitigated the condensation issue.

The best way I can explain it is to suggest that a tiled roof is ventilated via the small gaps around the tiles. You have two large vents that are allowing a free flow of cross ventilation.

You are correct that the only way to fix at this late stage is to pull the roof. However given that the builder has provided freebies and returned your money, any claim against the builder at this late stage could be very problematic.

StructuralBIMGuy has given you some pointers on reading. However please note that some of those documents to present with worst case condensation issues.

I would ask who is the builder.

Cheers

I would be more concerned with Condensation-> Mould -> associated health issues
Sorry, I can't see how that relates to energy?
BTW those energy assessments aren't all that accurate, open a door and watch the calculations/simulations go out the window

It's sort of a light grey. Photo uploaded.

My roof isn't tiled, it's colorbond. I don't want to name the builder but it was one of the big major ones. Apart from this muck-up they did a good job of my house.

I'm in Melbourne, as mentioned at the start of my original post.