4.5mm hardiflex sheeting verses weathertex smooth cladding 200mm - ext granny flat

[Coastal]

Hi all,


A granny flat out the back which my parents will live in full time, its about 11 x 3.5 in size and will have a colourbond orb roof, coastal place on teh central coast of NSW

Which would provide better insulation from heat and cold 4.5mm hardiflex sheeting ir weathertex smooth cladding 200mm ?

any help at all would be great as I have no idea which one

regards
Coastal

[goldie1]

Weathertex is 9.5mm so your hardly comparing apples with apples. Hardiflex 4.5mm is a bit light for exterior wall cladding

[woodchip]

Yes, I'd want the Weathertex if I were living in it & had the choice, the 4.5mm FC sheeting(it would feel like living in a garden shed) is good eave lining & gable cladding, dont forget the sisalation whatever you use.

cheers

[Coastal]

thanks for the info guys, the builder tells me its $7 per sq metre for hardi and $40 per sq fr weathertex - my dad says it aint so... at 40 I cant afford it - anyone know pricing or where to get a good price in NSW central coast )gosford/umina

coastal

[Coastal]

Changing the comparisons some - what are your thoughts on blue board verses Weathertex?
It looks as though blue board is twice the thickness?
which one is better for cooling in summer and heating in winter?
Its for a granny flat my parents will be living in - approx 4 wide x 10 long

regards
Coastal

[Middoes]

Maybe hardiplank but with insulation in the walls & roof. Might be the same cost as just the Weathertex..Maybe also a whirlibird in the roof..Will help alot..

[shauck]

I googled a bit and found this on ebay. It's in Wadalba, which doesn't look too far north from you.

weatherboards weathertex 200 mm smooth primelock assorted | eBay (http://www.ebay.com.au/itm/weatherboards-weathertex-200-mm-smooth-primelock-assorted-/170713827189?pt=AU_Building_Materials&hash=item27bf564775)

[Bloss]

Fact is what the outside material you choose is pretty much irrelevant. Sounds an odd thing to say, but the outside material is just a skin - so long as it is specified for exterior use then use whatever is best value for you. For a DIYer used to timber Weathertex might be easier to use, but it takes more fixing time, the blueboard is in larger sections so goes up faster. They both have an 'undercoat', blueboard needs joint finishing - they both need to be installed strictly as per their instructions or problems will be inevitable.

The real factor is how you deal with thermal control - as that and ventilation control (which is part of the total thermal control design) will set how comfortable any occupant(s) will feel. Umina is a lovely spot with a mediterranean climate marginally warmer than Sydney (if that's where you'll be building) - it is Zone 5 Warm Temperate. At little additional cost you can construct a 'granpa flat' which will be extremely comfortable all year round and need little energy use for no heating and cooling.

One of the best ways is to use 140x35(or 45) studs rather than 90x45 so that you can increase the wall insulation. In any case a standard 90x45 stud wall with sisalation on the outside of the studs, then a 25mm airgap then 65mm of concertina foil batts, styrofoam sheets such as the Expol stuff (or rockwool or fibreglass or polyester) then the lining will create a very liveable space when matched with fully taped & sealed sisalation or blanket sarking (or bubble foil insulation) under the roofing and at least R5 batts in the ceiling (the BCA requires min R3.5 - the cost difference is bugger all - go more). Really important to ensure all gaps are filled &/or sealed as you build.

There are other options and other materials you could use, but those I have mentioned are accessible, easy to install and not expensive. You could increase the thermal performance if you wanted to spend a little more too, but for this type of dwelling I wouldn't bother.

Have look at the Home Technical Manual for advice Your Home Technical Manual - 4.1 Passive Design (http://www.yourhome.gov.au/technical/fs41.html) and other sections such as: Your Home Technical Manual - 4.8 Insulation Installation (http://www.yourhome.gov.au/technical/fs48.html)

Note that when insulating using foil there must be an airgap of at least 25mm - else it is simply not able to work. For walls that's why the foil batts or Expol type is best as they are self supporting and will maintain the gap, then rockwool as it too is more stable and resistant to collapse in situ.

You should also give thought to the floor. If a slab then insulate it - either fully (underneath and edges) using styrofoam, or edge insulation. If timber then expol, foil batts or even sisalation under the boards on the joists.

[woodchip]

In any case a standard 90x45 stud wall with sisalation on the outside of the studs, then a 25mm airgap then 65mm of concertina foil batts, styrofoam sheets such as the Expol stuff (or rockwool or fibreglass or polyester) then the lining will create a very liveable space when matched with fully taped & sealed sisalation or blanket sarking (or bubble foil insulation) under the roofing and at least R5 batts in the ceiling (the BCA requires min R3.5 - the cost difference is bugger all - go more). Really important to ensure all gaps are filled &/or sealed as you build.

.

GDay Bloss,
Cheers, This is very important when considering design of any cladded building.

Im having trouble understanding your above explanation....
After you say "sisalation on the outside of the sides" are you then explaining going in(to the interior)?

So its going from outside....in...like this....
Cladding..(no gap)..sisalation(on outside of studs)....airfoil/concertina(between studs)....fibreglass/other insulation between studs....lining (plasterboard)?

OR

Should there be a gap between cladding & sisalation, ie put 25mm packers on each stud after sisalation?

cheers

cheers

[Coastal]

I googled a bit and found this on ebay. It's in Wadalba, which doesn't look too far north from you.

weatherboards weathertex 200 mm smooth primelock assorted | eBay (http://www.ebay.com.au/itm/weatherboards-weathertex-200-mm-smooth-primelock-assorted-/170713827189?pt=AU_Building_Materials&hash=item27bf564775)


MATE I cannot thank you enough for this - so kind of you,its only 40km away yep - def worth a go!!!!

Again thanks!! made my day

Coastal

[Coastal]

Old Chippy,

Your words were read over and then printed out and taken in again :-) Mate thank you for putting so much time and thought into it.

The floor will be tiles - do you recommend putting anything underneath the slab? Big tiles 60 x 60 hopefully.

re the 25mm gap -I assume this is the roof also? Its going to be cathedral ceilings so gyprock raked inside with color bond custom orb roofing - a light colour which i understands will handle heat better - a foil blanket or builders sheet under it - then I was going to go for wool bats R5 -Would be interested on your thoughts there - If I used the 90 x 45 studs would that work?

for the walls I will go the weathertex, that link shauk provided makes it more affordable, then the builders blanket around the walls, and batts inside before the gyprock goes on. Will i leave the gap between gyprock and batt or between weathertex and batt? how do you ensure this gap? stoppers?

thanks a million, grab a beer!!!

Coastal
ps - where are you located?

[woodchip]

Some years back I did a building course, they had a fella that was an expert in energy efficient building methods, & he recommended, concrete slabs on ground be simply pretected as much as possible from moisture(plastic, drainage etc) but to not use styrofoam or any other insulation under concrete, his reasoning.... the concrete slab has a lot of thermal mass, as does the earth, & this direct contact with it helps keep the space above the slab at a more constant and less variable temperature, ie warmer in winter & cooler in summer.
I am wondering if that position has now changed as we develop better insulation products??

cheers

ps, he did also mention the 25mm gap you speak of & also reverse brick veneer is better than standard brick veneer, for living comfort & energy efficiency.

[Bloss]

Woodchip - Depends on where you are building the dwelling. What you do varies according to what climate zone you are in. For a warm temperate Zone 5 as the OPs is in, then the waterproof membrane only is the go - but edge insulation is useful as it allows the thermal mass of the slab to be controlled by allowing or stopping light (and therefore heat) onto the slab at different times of the year. In a mild temperate, cool temperate or alpine zone then full slab insulation is best - again it is all about using that great thermal mass in a controlled way - which direct thermal contact with the earth does not allow. All depends on the heat flow - and hot flows towards cold (always). Simple at one level, but not necessarily a very intuitive subject - and hard to explain a few lines in a post. Materials for underslab insulation have improved, but effective ones have been around since slabs became common for residential work - what has improved more is our knowledge of what is needed.

As to reverse brick veneer vs brick veneer - well maybe, maybe not - better to say you can build a well designed and engineered thermally efficient house (for the prevailing climatic conditions) or a bad one and you can do that with pretty much all materials. Again, seems simple, and simple principles, but is actually quite complex. For example see this report: http://www.australbricks.com/Site_Assets/Files/03/038e0d4b-fc7b-4ced-9246-a43aa859c313.pdf.

The stuff on this site http://www.thinkbrick.com.au/ has been questioned and is self-serving, but it offers a different view (there is other science which does not come to the same conclusions)

As I said the issue is to allow control of the thermal conditions through good design and some human intervention (manual or automated) - plenty of 'experts', not many actually knowing, and fewer doing.

[Bloss]

I'll answer a few in blue:


Old Chippy,

Your words were read over and then printed out and taken in again :-) Mate thank you for putting so much time and thought into it.

The floor will be tiles - do you recommend putting anything underneath the slab? Big tiles 60 x 60 hopefully.

In Umina a well placed, taped and sealed regular builders plastic membrane under the slab and laid with enough to lay well up all sides too.

re the 25mm gap -I assume this is the roof also? Its going to be cathedral ceilings so gyprock raked inside with color bond custom orb roofing - a light colour which i understands will handle heat better - a foil blanket or builders sheet under it - then I was going to go for wool bats R5 -Would be interested on your thoughts there - If I used the 90 x 45 studs would that work?

The colourbond needs sisalation foil type vapor barrier underneath it shiny side facing down you could use blanket, but made ineffective where it is compressed over the rafters/ purlins/ battens (depending on how you are constructing the roof)In between the rafters you could use batts, but they must leave that air gap - and not touch the foil - that means no way R5 will work. The expol styrofoam are a better choice or the aluminium batts.

for the walls I will go the weathertex, that link shauk provided makes it more affordable, then the builders blanket around the walls, and batts inside before the gyprock goes on. Will i leave the gap between gyprock and batt or between weathertex and batt? how do you ensure this gap? stoppers?

From outside in it will be Waethertex/foil wrap (breathable sisalation)/airgap/ batts/plasterboard (optionally airgap/batts/foil wrap (vapour barrier ie: non-breathable)/plasterboard). To make sure there is gap I use gal wire (or mesh - you can buy for this purpose) zig zagged between studs and stapled into place. Batts don't move much once in place - it's simply to have a 'stopper' as you say when placing. Batts must not be compressed - for a wall like this R1.5 or R2 are the go.

thanks a million, grab a beer!!!

Coastal
ps - where are you located?

I am in the ACT and in any case no longer earn a living doing this stuff - just help friends & family and offer advice when I can.

[Bloss]

GDay Bloss,
Cladding..(no gap)..sisalation(on outside of studs)....airfoil/concertina(between studs)....fibreglass/other insulation between studs....lining (plasterboard)? :2tsup:
OR
Should there be a gap between cladding & sisalation, ie put 25mm packers on each stud after sisalation?


The former, so cladding can sit against sisalation - gap has to be between the reflective foil surface and whatever is next - minimum of 25mm - can be more - but if the foil is in contact to its adjacent surface then it will conduct heat. It's about it emissivity vs conductivity. With sarking for example the gap will be all the air from the shiny surface to the top of the batts (or whatever other material is insulating the ceiling.

[shauck]

MATE I cannot thank you enough for this - so kind of you,its only 40km away yep - def worth a go!!!!

Again thanks!! made my day

Coastal

All in a days work. Google is your friend. Google loves to help. They sound a lot cheaper than what you were quoted. You will find some damaged ones tho, still heaps cheaper. 40km away. How lucky are you?

[Coastal]

The former, so cladding can sit against sisalation - gap has to be between the reflective foil surface and whatever is next - minimum of 25mm - can be more - but if the foil is in contact to its adjacent surface then it will conduct heat. It's about it emissivity vs conductivity. With sarking for example the gap will be all the air from the shiny surface to the top of the batts (or whatever other material is insulating the ceiling.


So from the outside working in:
Weathertex then the builders wrap then the wire mesh then the batts then gyprock?

Should I do the reflective foil also? weathertex,builders paper then foil?

Coastal

[Bloss]

So from the outside working in:
Weathertex then the builders wrap then the wire mesh then the batts then gyprock?

Should I do the reflective foil also? weathertex,builders paper then foil?

Coastal

Not quite sure what you are calling 'builder's paper' - I assume you mean breathable insulation wrap - usually blue or green on the outer side (although maybe you mean Tyvek)? If Tyvek then I wouldn't bother for this job - or in most Australian climates either (maybe Cool Temperate & Alpine). Note too - I use gal wire, but the mesh I mentioned is a polymer mesh, not metal. You can also use polypropylene duct strapping - it doesn't take much. Remember the rule - if you use foil as a thermal barrier then the reflective surface must face an air gap - or else it cannot do its job. So in your case it would form outside - cladding (Weathertex) then wrap (breathable foil eg: Sisalation) then an air gap then batts then the lining (plaster board).