I live in Canberra where 50 deg fluctuations (eg -8 to +42) are normal throughout the year. The house was 30 year old double brick with uninsulated concrete slab, thin windows albeit timber framed, no insulation in the walls, poor ceiling insulation and older sarking under the roof sheets. Cool in summer but like an icebox in winter, noting it’s colder here more often than hot. Stage 1 was blow in wall cavity insulation which made a big improvement in comfort, the cavity was quite large so lots went in but when I checked it with a mate’s thermal camera they were back to redo a fair bit soon after. Stage 2 was top up ceiling bats and cross hatched bats over the top again, transformed the house but it’s a nightmare trying to move in the roof space as all you see from the manhole cover is a solid sea of bats. Again I checked the job carefully for gaps but this time no redo. Stage 3 is…nothing yet as I haven’t found anything extra that is worth doing from a cost benefit perspective.
Taking roof sheets off would be expensive (a roofer won’t do a smaller high warranty risk job cheaply when there’s a queue of expensive full roof jobs) and runs the risk of leaks as others have said. Also new sarking without better ceiling insulation is a waste of money.
As for double glazing it’s the last thing I’d do because it’s stupidly expensive and way down on the bang for buck list, and unless you get the expensive thermally broken good stuff it’s less effective than a standard timber window. And a poorly designed ally double glazed window is worse than single glazed timber.
IMHO the best bet is to spend your double glazing money on good wall and ceiling insulation, an appropriately sized solar set up, split systems and some good window covering like honeycomb blinds. House will be comfortable and power bills low.
We live in Qld and used 100mm foil backed insulation under the tin, then 75mm polyester blanket on the ceilings, 75mm in walls. 75mm wool betwen upstairs and downstairs, huge difference during summer and winter.
How is the roof fastened? The normal way is to fasten through the blanket into the battens which squeezes the blanket down to much less than 75mm. 75mm in the ceiling seems very little, what is the R rating of that?
Depending on the construction of the walls 75mm (about R1.5) is about all you can fit in. It is still worth the effort. It is of course even less cost effective to retrofit it than the roof blanket so it is normally only done at construction.
Tin roof so yes squashs down where it crosses battebns etc, R rating honestly it was 20 years ago so cant remeber exactly but 2.3 i think.
We have 100mm cavity as 4" studs were used.
House is a 1930 house which we moved and part of councils rules were roof was to be replaced. So while roof was off insulation was done under tin, then ceiling was done once new roof was on. All interior sheeting was removed replaced and new plaster installed thus insulation installed. House was single story which we put on high stumps and built under also doing insulation as we went along.
Rachel, I can only speak from the heat perspective…
We lived for many years in Darwin (very hot and humid) with original sisalation/sarking (reflective foil) under roof sheeting and in walls. There used to be a layer of very hot air just under the ceiling and when you turned on the ceiling fans, it would blow down onto you… not nice! First thing we tried was 2x whirly type vents… didn’t make any noticeable difference. Next thing was to install batts on top of the ceiling… this made a big difference, with that hot air layer just under the ceiling almost gone. Also reduced noise from rain on the roof, planes flying overhead, etc. It did seem that the batts retained some humidity and that caused a little mould to appear under it in places on the ceiling, but then again, Darwin is pretty extreme.
Now in Far North Qld and new house already had a foil blanket (Anticon) under the roof sheeting and it seems to do a reasonable job. I don’t think it is a very thick blanket. The uninsulated (plastic) water pipes running in the ceiling produce rather warm water when conditions are hot. We had 1 pipe insulated and it helped fairly well, but also retains the warmth for longer at night, too. I recently installed Kingspan Insulshed (foil blanket) retrospectively to the underside of the roof purlins in my rather large shed… that made a massive difference to the temperature inside. No removal of roof sheeting required, but it was a big job and I doubt you could do something similar in a house roof cavity, due to lack of space to access all areas.
Based on my experiences, I would suggest installing those ceiling batts first and then see how you go. I think they will be sufficient, together with looking at shading your windows and walls. Beware of roof corrosion from tree leaves on your roof sheeting and gutters, if considering that to shade the roof. I heard from several people who had their roof sheeting painted white to improve reflectance of heat, but with very poor results due to the paint getting algae/mould growing on it quickly.
One thing that I don’t see mentioned by the replies so far, is that reflective foil or foil blanket requires a gap between it and the roof sheeting, to work properly. When installing roof sheeting over it during construction of the house, the foil should sag between the purlins to achieve this gap. Or, if installing it after construction, attaching it to the underside of the purlins will also achieve this gap.
As you point out there are also concerns with condensation which need to be considered when deciding which solutions are most suitable for some climate zones and roof types/construction.
Details of recommended practice can be found in one of the ICANZ (Insulation Council of Australia’s and NZ) handbooks.
For installing blanket type insulation under roofing.
I had previously linked the source document for the above advisory guide.
There are a number of others that may be of interest available from the same web source.
Whilst on the subject of cooling and condensation, when our solar system was being installed in February last year, one of the workers mentioned to me that our neighbour’s faulty rotary ventilator would be allowing rain to enter their ceiling as it was not rotating freely.
I mentioned it to our neighbour, by which time their other one was also faulty, and he replaced the bearings in both of them.
It would be interesting to know the make/model (& age) of it/them, plus the degree of difficulty of the bearings replacement… this lack of rotation is not something I would have even thought about!
Kudos to the solar system installers: I hope you and/or your neighbour made their employers aware of the good deed! It hopefully prevented any lasting damage (and encourages others to add it to household maintenance tasks).
Some brands of whirly vents don’t have very good bearings. My parents had them installed and went through a cyclone in Townsville. They made one heck of a racket at high speed and frightened the daylights out of my parents, who didn’t realise they were the cause of the noise. Another thing worth knowing is that if the wind speed is high enough, they are (should be?) designed to fold flat against the roof, preventing water ingress. If wind speed is getting around cyclonic, soffit failure is also a major concern, with this being the path for water entry into the roof cavity in many modern houses, leading to ceilings collapsing, water damage to the house contents. You wouldn’t expect winds of that strength in Vic, but who knows these days… some pretty severe storms occurring in some places down south.
The problem with it not rotating properly was obvious, as when it started to rotate, it sounded like a crypt being opened in a horror movie, and even in a strong breeze, it only rotated at a fraction of the speed of the other one or our 2.
However, it did not occur to me that driving rain would be forced throught it due to it remaining stationary.
Our home was completed in March 2000 so I expect that the neighbours’ home was completed around the same time as both blocks of land were purchased in 1997.
Their rotary ventilators would have been around 18 years old when they started to develop problems but I have no idea what the brand is.
I don’t think our neighbour had any trouble in replacing the bearings but he is very handy with such tasks.
Here is one of a number of video clips regarding replacing the bearings in them.
As for the solar installation business, we are both still waiting for them to return after some 18 months.
It’s easy to do. I did mine myself. The corrugated iron can be awkward to move around because of their weight, but aside from that it’s all pretty easy and straight forward.
A blanket is also meant to be good because it helps stop condensation forming on the underside of the corrugated iron (due to heat outside and aircon inside, or conversely heating inside and sub-zero temps outside). Apparently condensation is bad, probably for the supporting wood beams in the roof.
able to cope if a wind comes up and wants to take you and the loose sheets of iron away for a trip,
can reliably get the right tension on the screws so the sheets are held down without destroying the washers that are part of keeping out the water
can get the loose sheets and ridge capping back on properly before a sudden storm.
The sheets are also a problem due to their size as well as weight, it is hard for one person to handle a sheet alone even without any wind. You are likely to end up dragging them rather than lifting them.
Being easy and straightforward depends on who you are and what you know. I would not suggest people rush out to try this little DIY task.
A word of caution, it is worth checking with your house insurer if such DIY work will be covered by future insurance claims…such as damage caused by leaks or roof dislodging in a storm. They may asssess that roof work, especially removal and replacement, needs to be done by a qualified tradespeople and this is the case, doing major DIY roofing work could impact on future claims.
Apparently something to watch out for is the screw holes in the sheeting no longer lining up with the original holes in the battens/purlins. The firmer the screws are tightened, the more the sheeting spreads out as the corrugations compress. Might not be an issue if you are happy to put screws into new locations in the battens/purlins, but metal purlins may require new screws as the original screws may no longer be sharp enough to drill new holes in steel.
After the big hail storms in SE Qld this time last year and another round this year many roofs locally have needed replacing. Four of the neighbours tin roofs have been done. There are two still waiting.
The professionals have arrived with teams of 4 who have required a week or longer to complete. Solar PV, HWS, flue pipes, chimneys all take extra time. Roof sheeting is readily available in long lengths (ridge cap to gutter overhang) minimising joints. They can require more than just two to handle safety for a high roof.
The local roofing teams have not commenced until the roof on each house has been fully scaffolded on all sides. Even the lowest slab on ground houses have received the same treatment. The scaffold has costs to deliver, erect, and remove. There is an ongoing weekly hire cost, hence DIY over many weekends adds to the potential cost. Scaffolding and it’s erect ion is subject to state government regulation. Safe Work Australia nominates an at risk fall height of 4m as requiring a license for erection. Individual State & Territory Govts may also have requirements for work performed at lower heights. It pays to be certain.
P.S.
It’s a good point, corrugated or folded metal.
Personal experience from needing to do the occasional repair or lift a sheet or two for access. Unless the roof is very new not all screws come out of hardwood battens without breaking off. Lining up one sheet takes time. A whole roof would be very time consuming. I’d not trust the sealing rings a second time. Many roofing screws are also only lightly protected. Unscrewing and refastening will damage the weathered coating which will lead to rust. With steel purlins reusing the same holes the screws that go back in are no longer assured a tight fit and may come loose.
The professionals would not bother and use new fasteners and new holes. It’s quicker and easier (saves labour costs) and less risk of leaks. Of course for DIY, the saving is all in the labour which is free, and materials, tools etc are typically purchased at full retail. The best way to DIY IMO. Collect a cohort of tradie mates and ensure an adequate supply of steak, onions, bread rolls and a slab of two. It’s amazing how much you can get done on a weekend with a little help.
The phenomenon you are talking about can happen with the flat sections like multiclad, trimclad, trimdek etc, very unlikely with the rounded corrugated profiles that are much stiffer.
Some people seem to think that because a screw gun can put huge torque on a screw that you ought. The screws should not be that tight because before you get that far the rubber washer under the head has been squeezed into oblivion. This is the same idea as those who put screws in the valleys instead of the hills (duh!) so they can hold tighter.
Regarding roof ventilators, some I have seen advertised are electrically powered (mains) or Solar power plus rechargable batteries. Theses have 2 advantages: They don’t run when not needed eg winter and secondly, on a hot night with no wind, they will run on battery or mains.
They cost more, but will do the job better.
We have found that shade cloth blinds very effective for any windows where the sun strikes them during the day. We hung our blinds from the eaves but they could equally be attached to a timber window frame. They are very effective at keeping house interiors cool in summer. The blinds are easy to make with either 90% or 70% shade cloth purchased from your local hardware store.
Hi grahroll (bit slow on this one sorry!) but can you advise me how I find someone to install whirleybirds? That is, what tradie type does this work? Is it just a roofer or a different trade? Thanks, L
