# Forum Home Renovation Cladding  Recladding weatherboard house & insulation retrofit - two layers of wallwrap?

## 0438snappy

Hi there, 
Long time listener, first time caller  :Redface: ) 
We are about to replace the external cladding on our 1940's weatherboard house located in the inner northern suburbs of Melbourne.  The house runs south to north so has a long exposed western wall which gets a lot of sun in summer. 
We will be removing the old baltic pine weatherboards and replacing with bgc nuline fibre cement weatherboards. 
Whilst the walls are open, I plan to install R2.7 insulation batts (already purchased) and wall wrap before recladding.   
Regarding the wall wrap, I already have a roll of Tyvek HomeWrap(~2.75 or 3.00m high x 30m length) as well as a couple of rolls of sisalation wallwrap EXHD breather single sided foil (1.35M high x 30 or 60m). 
Just wondering if there would be additional insulation or draught stopping benefits by using two layers of the wall wrap? 
I've done a fair amount of reading online and my current thoughts about the wall construction would be this:  
Option A:  Batts + foil wrap + cladding
-----------------------------------------------
layer 1)  R2.7 batts - friction fit between the wall studs
layer 2)  sisalation wallwrap with the reflective side foil facing inwards (would be directly touching the studs and insulation batts)
layer 3)  fibre cement weatherboards nailed to studs  
some other variations on this approach might be as follows: 
Option B:  Batts + tyvek + cladding
-----------------------------------------------
layer 1)  R2.7 batts - friction fit between the wall studs
layer 2)  tyvek homewrap (would be directly touching the studs and insulation batts)
layer 3)  fibre cement weatherboards nailed to studs  
Option C:  Batts + foil wrap + tyvek + cladding
-------------------------------------------------
layer 1)  R2.7 batts - friction fit between the wall studs
layer 2)  sisalation wallwrap with the reflective foil side facing inwards (would be directly touching the studs and insulation batts)
layer 3)  tyvek homewrap over the top of the reflective foil
layer 4)  fibre cement weatherboards nailed to studs  
Option D:  Batts + tyvek + thermal break + foil wrap + cladding
---------------------------------------------------------------
layer 1)  R2.7 batts - friction fit between the wall studs
layer 2)  tyvek homewrap over the top of the reflective foil
layer 3)  some sort of thermal break on top of the foil over the studs(e.g. the james hardie "hardiebreak" thermal strip?)
layer 4)  sisalation wallwrap with the reflective foil side facing inwards (there would be a ~12 mm gap between the foil and the tyvek homewrap)
layer 5)  fibre cement weatherboards nailed to studs 
I'd be interested if anyone out there has any feedback on the above, or can make any suggestions for potential improvements to the above, which option they'd go for, etc.   
thanks, 
Tyrone

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## DavoSyd

I think foil needs an air gap to provide insulation properties?

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## pharmaboy2

Throw the foil in the bin.  It has no potential for insulation in any of your scenarios, especially with FC as your cladding material (different if it was colorbond) 
to increase performance try try and get things airtight.  This will involve sealing round windows, tape over joins on the wrap, some foam filler etc.  drafts are the enemy of your heating.  Look up the proctorwrap guide for how to's (similar stuff to Tybee just cheaper)

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## goldie1

Have you looked  at the manufacturers recommendations  BGC Innova - Nuline Plus | Weatherboard Style House Facades

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## joynz

Yes, needs an air gap of around 25mm to get the foil's insulation value.  No advantage in laying tyvek directly on top of foil either and potentially big condensation issues.  
If you really want to protect from heat, batten out so there is an air gap.  A layer of batts, then breather building wrap, air gap, breather foil, air gap then cladding would work.  This gives two air gaps - one each side of the foil.   
But check with the cladding company about their requirements for correct installation. 
The  online Your Home Guide is useful for insulation info.

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## Moondog55

I'm with Joynz on this RFL works well even with FC sheet but only if it has that airgap. My proviso here tho is that in out house it works better at keeping summer heat out rather than making the house warmer in winter. I think [ but that will need research on your part] that the minimum spacing for the Tyvek can be 12/13mm

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## pharmaboy2

I think you might find that radiation won't pass through FC sheet as it's an insulator.  Thin steel re radiates heat and so an air gap with a reflective has benefit.  Either way, none of the options the OP is thinking about include an option for an air gap, and any battens will make treatment of openings vastly mire complicated than replacing like for like

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## DavoSyd

> I think you might find that radiation won't pass through FC sheet as it's an insulator.

  but the R value of FC sheet is very very low? like 0.1? (plus OP is using weatherboards) 
OP - what we are doing on our west facing wall is wrapping with:  Ametalin | Insulation | SILVERSARK® xR  fully sealed with tape.  
then in the stud openings we are adding these:  Ametalin | Insulation | PLEATED SILVERBATTSâ„¢ 
but on the east and south walls, we are wrapping with:   Ametalin | Insulation | BRANE® VHP 
and adding bulk batts  -probably earthwool HD 2.5   versus  versus

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## 0438snappy

Thanks guys for the replies, have fired off an email to BGC themselves to clarify further about some of these points, i will post back with details if/when i get a reply.   

> Throw the foil in the bin. It has no potential for insulation in any of your scenarios, especially with FC as your cladding material (different if it was colorbond).  to increase performance try and get things airtight.  This will involve sealing round windows, tape over joins on the wrap, some foam filler etc.

  Ok thanks, we are actually planning a extension to the rear of the house at some point down the track and we may end up using colourbond or similar type of metal sheet cladding on the walls.  Sounds like I might be best to use the tyvek as a vapour barrier underneath the FC weatherboards and maybe save the foil to be used when we do the extension (or just put it to some other use).  One benefit of using the tyvek as vapour barrier is that it comes in a very wide roll so hopefully would involve less taping of joins (on the flipside it will probably be more unwieldy to put on in the first place though!).     

> Yes, needs an air gap of around 25mm to get the foil's insulation value. No advantage in laying tyvek directly on top of foil either and potentially big condensation issues.  If you really want to protect from heat, batten out so there is an air gap. A layer of batts, then breather building wrap, air gap, breather foil, air gap then cladding would work. This gives two air gaps - one each side of the foil.  But check with the cladding company about their requirements for correct installation.  The online Your Home Guide is useful for insulation info.

  Thanks, yes condensation was my main fear with having two layers of wallwrap on top of each other.  So with your suggested approach of double air gap then that would mean two layers of battens on top of the studs?  25mm each?  I did have another read through the nuline plus product guide and there's a comment that says "timber battens must have a minimum thickness of 40mm to allow adequate nail penetration".  If thats the case then i would probably be looking at a single layer of battens, as 2 x 40mm is going to dramatically increase the wall thickness.  I'll try asking BGC themselves as to whether they have any other recommendations about the use of battens.  But as pharmaboy2 mentioned this will definitely introduce some complexity when it comes to handling window and door openings, so im still trying to weigh up the cost/benefit of heading down the battens path.     

> but the R value of FC sheet is very very low? like 0.1? (plus OP is using weatherboards)   OP - what we are doing on our west facing wall is wrapping with:  Ametalin | Insulation | SILVERSARK® xR fully sealed with tape.

  What sort of cladding are you going to be using Davo?  I do like the fact that the Ametalin silversark xr product is double sided foil, but again it sounds like i'd really need to be using battens to get the airgap to make it  worthwhile for me. 
Regarding taping of wallwrap, im guessing something like this is what you're going to use? Ametalin | AMETALINâ¢ REINFORCED INSULATION & DUCTING TAPE 
Does anyone have any recommendations about the best way to adhere wallwrap to studs/top/bottom plate for maximum airtightness?  I vaguely remember reading a post where someone said they'd used a line of caulk on the top/bottom plate?  any thoughts about this?  or just use staples?

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## Moondog55

Of course IR radiation will pass though the FC sheet, in full sun it gets as hot as hell, the use of the RFL is to stop that radiation getting into the house and while an air-wash helps it isn't needed to prevent radiation heat transfer

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## 0438snappy

sorry about my "slow" responses to this thread, it seems that since im a newbie all of my posts need to be approved by a moderator before they are added to the thread.  update: actually I just tested the quick response and it was posted immediately so i'll add my original reply back in!  
Thanks guys for the replies, have fired off an email to BGC themselves to clarify further about some of these points, i will post back with details if/when i get a reply.   

> Throw the foil in the bin. It has no potential for insulation in any of your scenarios, especially with FC as your cladding material (different if it was colorbond).  to increase performance try and get things airtight.  This will involve sealing round windows, tape over joins on the wrap, some foam filler etc.

  Ok thanks, we are actually planning a extension to the rear of the house at some point down the track and we may end up using colourbond or similar type of metal sheet cladding on the walls.  Sounds like I might be best to use the tyvek as a vapour barrier underneath the FC weatherboards and maybe save the foil to be used when we do the extension (or just put it to some other use).  One benefit of using the tyvek as vapour barrier is that it comes in a very wide roll so hopefully would involve less taping of joins (on the flipside it will probably be more unwieldy to put on in the first place though!).     

> Yes, needs an air gap of around 25mm to get the foil's insulation value. No advantage in laying tyvek directly on top of foil either and potentially big condensation issues.  If you really want to protect from heat, batten out so there is an air gap. A layer of batts, then breather building wrap, air gap, breather foil, air gap then cladding would work. This gives two air gaps - one each side of the foil.  But check with the cladding company about their requirements for correct installation.  The online Your Home Guide is useful for insulation info.

  Thanks, yes condensation was my main fear with having two layers of wallwrap on top of each other, so that sounds like thats a no go.  With your suggested approach of double air gap then that would mean two layers of battens on top of the studs?  25mm each?  I did have another read through the bgc nuline plus product guide and there's a comment that says "timber battens must have a minimum thickness of 40mm to allow adequate nail penetration". I'm not sure if this only applies when the FC planks are installed vertically (or horizontally as we would be doing), but if thats the case then i would probably be looking at a single layer of battens, as 2 x 40mm is going to dramatically increase the wall thickness.  I'll try asking BGC themselves as to whether they have any other recommendations about the use of battens.  But as pharmaboy2 mentioned this will definitely introduce some complexity when it comes to handling window and door openings, so im still trying to weigh up the cost/benefit of heading down the battens path.     

> but the R value of FC sheet is very very low? like 0.1? (plus OP is using weatherboards)   OP - what we are doing on our west facing wall is wrapping with:  Ametalin | Insulation | SILVERSARK® xR fully sealed with tape.

  What sort of cladding are you going to be using Davo?  I do like the fact that the Ametalin silversark xr product is double sided foil, but again it sounds like i'd really need to be using battens to get the airgap to make it  worthwhile for me. 
Regarding taping of wallwrap, im guessing something like this is what you're going to use? http://www.ametalin.com/insulation-p...n-ducting-tape 
Does anyone have any recommendations about the best way to adhere wallwrap to studs/top/bottom plate for maximum airtightness?  I vaguely remember reading a post where someone said they'd used a line of caulk on the top/bottom plate?  any thoughts about this?  or just use staples?

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## phild01

> sorry about my "slow" responses to this thread, it seems that since im a newbie *all of my posts* need to be approved by a moderator before they are added to the thread.

   Just a couple.

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## DavoSyd

sorry, i should have mentioned - we are using Weathertex Weathergroove sheets using a cavity batten system... 
so my wrap will have battens holding the wrap to the studs & noggins plus the base will have a cavity closer nailed to the bottom plate at 300 centres. i doubt i will use sealant on it... but might depend on inspection after i pull off the old cedar weatherboards...

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## DavoSyd

> I do like the fact that the Ametalin silversark xr product is double sided foil,

  the XR is NOT recommended for Weathergroove installation (because it has a Vapour Barrier Classification of Medium, not Low) and i am only using it on the wall that cops the summer sun...    

> but again it sounds like i'd really need to be using battens to get the airgap to make it worthwhile for me.

  be aware that your 'air gap' must be sealed for it to function, and as you can see this is easy with the concertina batts (flattened and stapled to the studs), but very difficult with the bulk batts...

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## Moondog55

Option D:  Batts + tyvek + thermal break + foil wrap + cladding
---------------------------------------------------------------
layer 1)  R2.7 batts - friction fit between the wall studs *>Tick*
layer 2)  tyvek homewrap over the top of the bulk insulation *-> Tick*
layer 3)  some sort of thermal break on top of the foil over the studs(e.g. the james hardie "hardiebreak" thermal strip?) *-> 25mm batten to the stud Over the Tyvek under the RFL*
layer 4)  sisalation wallwrap with the reflective foil side facing  inwards (there would be a ~12 mm gap between the foil and the tyvek  homewrap)
layer 5)  fibre cement weatherboards nailed to *BATTENS
At least that is how I would do it*

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## 0438snappy

> ... At least that is how I would do it

  Thanks, yes that's what im thinking if I decide to go down the battens path...     

> be aware that your 'air gap' must be sealed for it to function, and as you can see this is easy with the concertina batts (flattened and stapled to the studs), but very difficult with the bulk batts...

   Are you also planning to block off the cavity created with your battens?  I will get busy with the search dialog but what is the typical approach to vermin proof / block off the tops and bottoms of the cavity when using battens?   
 I found this article via another forum about using battens to create a rain screen, has a good cross section diagram of their proposed solution and mentions a product called "cor a vent", seems like it's a US product though. Just wondering if there is a similar local product that anyone knows of? http://www.greenhomebuilding.com/pdf/RainScreen.pdf

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## CraigandKate

Hey mate, 
This is how I did my place (well still going), not saying it's Ideal but put a fair bit of research into it and I think it is best for my application. The last layer of wrap is probably not required it is just a extra layer of water proofing really to ensure the cavity stayed dry. 
Stud frame (R2.7 Earthwool) >> 4.5mm bracing ply >> 6.5mm kingspan Aircell >> 25mm Hardwood Batten >> Thermal Brane wrap >> Timber weatherboards

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## DavoSyd

I'm not sealing the cavity between the boards and wrap. 
I am using the weathertex cavity closer...  
methinketh you could benefit from reviewing the weathertex installation guide (or the Shadowclad one, or Hardie version)   http://www.weathertex.com.au/wp-cont...de-low-res.pdf

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## 0438snappy

> Hey mate,  This is how I did my place (well still going), not saying it's Ideal but put a fair bit of research into it and I think it is best for my application. The last layer of wrap is probably not required it is just a extra layer of water proofing really to ensure the cavity stayed dry.   Stud frame (R2.7 Earthwool) >> 4.5mm bracing ply >> 6.5mm kingspan Aircell >> 25mm Hardwood Batten >> Thermal Brane wrap >> Timber weatherboards

  ok thanks, gives me some more options to think about   :Smilie:   what was your reasoning behind the bracing ply, is it mostly for an additional windbreak layer?  do you have any links for suppliers so I could do some checks on the price, am curious to see how much it would add per m/2.  I did a quick search but seems like its a specialty wood supply shop type of product / could be expensive?  also would be interested to know where you got your battens from....  the system you're going with looks like it would give a very decent final R value though!   Update:  ok I just saw the other thread here, will have a read  https://www.renovateforum.com/f224/p...adding-122243/    

> I'm not sealing the cavity between the boards and wrap.  I am using the weathertex cavity closer...  methinketh you could benefit from reviewing the weathertex installation guide (or the Shadowclad one, or Hardie version) http://www.weathertex.com.au/wp-cont...de-low-res.pdf

  thanks, yep i saw your link to that in the other cladding > cavity batten thread, i did have a very quick read but didnt spot the cavity closer.  will check it out in more detail tonight

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## Moondog55

Cecile and I used bracing ply as well US style over the whole house, mainly to cheaply get the house weatherproof but also to tie it all together and especially the top plate to the bottom plate, So much stronger and also quieter,

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## NZC

> Option D:  Batts + tyvek + thermal break + foil wrap + cladding
> ---------------------------------------------------------------
> layer 1)  R2.7 batts - friction fit between the wall studs *>Tick*
> layer 2)  tyvek homewrap over the top of the bulk insulation *-> Tick*
> layer 3)  some sort of thermal break on top of the foil over the studs(e.g. the james hardie "hardiebreak" thermal strip?) *-> 25mm batten to the stud Over the Tyvek under the RFL*
> layer 4)  sisalation wallwrap with the reflective foil side facing  inwards (there would be a ~12 mm gap between the foil and the tyvek  homewrap)
> layer 5)  fibre cement weatherboards nailed to *BATTENS
> At least that is how I would do it*

  
The only problem with adding in a batten on a retrofit is the amount of worked created around windows and doors. Because the weatherboards are further forward. You end up having to put rebated facings around everything.

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## pharmaboy2

> The only problem with adding in a batten on a retrofit is the amount of worked created around windows and doors. Because the weatherboards are further forward. You end up having to put rebated facings around everything.

  correct. 
its ok when you have a specific problem, or want a specific look, but for an average home.... 
no one has asked about paint colour, wall direction, shading, glass sizes and how much heat is a problem versus cold.  Given he is in Melbourne, it's probable that 80 - 90% of energy use for temperature is to warm it up.  Walls get far less heat than a roof which is probably why the systems for battens I see all are using products like Tyvec or proctorwrap. 
if you want to go the extra mile, tape the proctorwrap/hardiewrap and make it airtight.  I'm at a loss as to why so much love for RFL in walls, when all the technical documents on batten systems recommend Vapour permeable membrane, eg CSR, weathertex, woodform, hardies. 
if in doubt, always follow the manufacturers std to the letter.  They have dumped sarking because modern products are better, they are more watertight, they breath, and any heat benefit is marginal at best (especially in an insulated wall)

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## Marc

I like Colorbond vertical snap lock cladding. That stuff goes over plywood. The installation instructions don't mention any sarking. Plywood 15mm seems a tad overdone though.

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## Moondog55

Actually we find the main problem is keeping the heat out; Geelong is only 80klicks South of Melbournes Northern suburbs and I am familiar with the problems of a wall facing West in summer. RFL can be permeable or impermeable depending on what you pick off the rack You only use the VB wrap on the roof but the permeable on the walls. Sarking is a term that can be used to describe all wall and roof wraps it applies to Tyvek too
Western facing walls in this area need all the techniques available to reduce heat gain in summer, heating a house in winter is a minimum cost when compared to cooling costs in summer. You really need to use all the techniques available to you, if this means using deep reveals on the windows you use deep reveals on the windows because that is all you need; a Brick Veneer reveal because we are talking about the depth of the venereal brick here
Of course external shading using a pergola and/or shade cloth roller blinds and other methods all need to be employed
Marc I agree but I don't recall seeing 15mm ply being mentioned, we used 7mm because I got a great deal at $4- a sheet and then what ever was cheapest
Cecile and I both love the look of steel cladding and if we were starting now the new Colorbond is what we would choose

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## 0438snappy

> ... no one has asked about paint colour, wall direction, shading, glass sizes and how much heat is a problem versus cold. Given he is in Melbourne, it's probable that 80 - 90% of energy use for temperature is to warm it up.

  paint colour is going to be wattyl thunderbolt (sort of a grey with a bit of brown in it).   
front of the house faces pretty much directly south.  the house is a Californian bungalow - front porch has a 2130 x 850 door and a 1300 x 1670 window but this is very well under cover (the original weatherboards are actually still in great condition here).  the gable end has a bay window coming out of it, with cedar shingles around the bottom, weatherboards start from the sill upwards. 
the west wall has a 700 x 2100 window and pretty much zero shading. 
the east wall has a 1300 x 1670 window. 
the northern end of the house wont be getting reclad at this point as it is going to get demolished and new kitchen / living area / deck / pergola added.   
the house had absolutely zero insulation when we moved in so we get the best of both worlds....  freezing cold in winter and then boiling hot in summer!   :Smilie:   Master bedroom is on the west side of the house so on a hot day it gets nice and toasty in there.  the roof is corrugated zincalume (?) with rfl sarking underneath, condition is fairly good so am guessing this was redone at some point before we bought it.  Since we've moved in we've had the place restumped and put R5 batts in the ceiling and R2.5 underfloor.  the house still has the old original baltic pine floorboards which were a bit leaky in places, some of the cracks between boards were so large that on summer days you could see daylight through them and would get a bit of a breeze!  we've also replaced the three windows mentioned above with timber framed double glazed, the new window frames do extend about 25mm past the existing weatherboards so battens might actually work well to bring the weatherboards out flush and make putting the architraves on easier.  the window on the east wall will be getting taken out and moved during the recladding job so will be able to apply vapour barrier to the opening and properly flash it.      

> if you want to go the extra mile, tape the proctorwrap/hardiewrap and make it airtight.  if in doubt, always follow the manufacturers std to the letter. They have dumped sarking because modern products are better, they are more watertight, they breath, and any heat benefit is marginal at best (especially in an insulated wall)

  I've had a look at the bgc nuline product brochure but their examples for timber framing seem to be pretty simplistic, just the standard framing > batts > vapour permeable sarking > cladding.  yes i'll definitely be trying to get it as airtight as possible.  I do like the idea of the bracing ply layer for this, as well as giving additional strength to the structure & noise reduction.      

> I like Colorbond vertical snap lock cladding. That stuff goes over plywood. The installation instructions don't mention any sarking. Plywood 15mm seems a tad overdone though.

  We were originally keen on the bgc nuline plus weatherboards as they seem to be the only FC weatherboard that comes in a bullnose profile.  We want to try to keep the old/original part of the house looking like it used to, with a more modern extension on the back.  Wasn't really keen to use timber weatherboards though as the painting and maintenance on them along the west wall that cops all the sun would be too much work.  for the extension we will definitely look at more modern claddings like the colorbond vertical etc, i do like that as well.    

> You really need to use all the techniques available to you, if this means using deep reveals on the windows you use deep reveals on the windows because that is all you need;

  definitely this, we're not planning on selling the place anytime soon so I'm keen to do this recladding job once and try to do it as "right" as possible.  I'm not adverse to a bit of extra work or cost to make battens / bracing ply / etc work with our place if it means the end result will mean more comfort inside or added longevity.      

> Marc I agree but I don't recall seeing 15mm ply being mentioned, we used 7mm because I got a great deal at $4- a sheet and then what ever was cheapest

  $4 a sheet, wow that is a great price.  I only did some very quick searching last night and im still not really sure what i should be looking for yet but found these prices for F22 4mm bracing ply from Bowens.  Given our place has 3m ceilings im guessing we would need the 3050 x 1200 / 900 sheets which are $25 - $35 a sheet!  Bowens   
I also found this pdf online regarding bracing ply and am going through it, it does mention that they no longer provide support of 3/4/4.5 mm bracing systems.  i'm not sure if it would really matter though if we did end up using 4 or 4.5mm though, our place has already been standing for 80 odd years so id imagine any additional ply bracing is going to be an added bonus!  http://ewp.asn.au/library/downloads/...ll_bracing.pdf

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## Marc

> ...; a Brick Veneer reveal because we are talking about the depth of the venereal brick here
> Of course external shading using a pergola and/or shade cloth roller blinds and other methods all need to be employed
> Marc I agree but I don't recall seeing 15mm ply being mentioned, we used 7mm because I got a great deal at $4- a sheet and then what ever was cheapest
> Cecile and I both love the look of steel cladding and if we were starting now the new Colorbond is what we would choose

  Yes ... well Colorbond states 19mm ply for roof and . 15 for walls ... wow!
That's ok ... as long as there is nothing venereal about it  :Rofl5:

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## ChocDog

Been there done that. Since you have an old cal bungalow (like us) how ever long you think it will take you, double it. Maybe triple it. And more... Its amazing how many issues you will find along the way. There is some great advice from others above about wraps/gaps. My 2 cents: I thought heavily about battening out for air gap, but decided at the end of the day not to bother. The additional effort, details, cost involved for the benefit didnt seem worthwhile. Plus ultimately not possible - we have a skillion roof add on at rear hence no eves so w/b's would come out passed roof overhang. 
We ripped out the orig baltic pine floor, installed under floor insulation, yellow tongue base then new tas oak boards on top. Insulation and sarking on walls. replaced all windows (accept the very original stained glass double hungs at front) with double glassed units (with low-E glass). 
A couple of comments: 
1. Make sure you have a sound subfloor before starting all this work. Otherwise you are throwing away good money and effort. Ie restumped and level floors.
2. Your old hardwood frame wont be plumb or flat. If you plan to batten out (or even if you dont) I'd recommend sistering new studs to the old to achieve a plumb and flat external wall to mount your new w/b's to. Otherwise you will install battens and still have to plane/pack them out. 
Enjoy the fun times ahead!

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## 0438snappy

> A couple of comments:
>  1. Make sure you have a sound subfloor before starting all this work. Otherwise you are throwing away good money and effort. Ie restumped and level floors.
>  2. Your old hardwood frame wont be plumb or flat. If you plan to batten out (or even if you dont) I'd recommend sistering new studs to the old to achieve a plumb and flat external wall to mount your new w/b's to. Otherwise you will install battens and still have to plane/pack them out.

  yep the floor has been restumped and levelled, which in turn did a great job of cracking all the old lath & plaster walls so those have come down also and drywall has gone up!  point taken about the frame, sistering studs sounds like quite a bit of extra work and expense though?  is that what you did?  when we redid the internal plaster from memory the walls weren't **too** bad, not sure if that's any indication of what to expect on the external walls     

> Since you have an old cal bungalow (like us) how ever long you think it will take you, double it. Maybe triple it. And more... Its amazing how many issues you will find along the way.

  yeah this is one of the things that's worrying me!  this is also another reason why I'm liking the idea of the ply bracing, since we've already redone the internal plastering it will be a race against time between taking the old w/bs off, getting the batts in and then getting some sort of weatherproof barrier back on again.  having something like the ply could be quickish to put up and provide some additional weatherproofing whilst the actual w/bs are being put back on.  the plan is to start on the porch area as its fairly protected from the weather and come up with a workable process before we tackle the big walls.

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## Moondog55

Lots of pictures of our total recladding effort in our build thread
Also being 7 years + into a 2 year project *we are not done yet  https://www.renovateforum.com/f176/o...ovation-93648/*

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## pharmaboy2

Sistering the studs may also depend on how hard the frame is.  When it's old it can be the case that you just can't hand nail the weatherboards , and bent over nails on weatherboards will look pretty nasty. Straight pine base would make it nice and easy. 
though Matt paint hides a multitude of sins......

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## DavoSyd

> I'm at a loss as to why so much love for RFL in walls, when all the technical documents on batten systems recommend Vapour permeable membrane, eg CSR, weathertex, woodform, hardies.

  higher R value (what's your definition of "marginal" benefit?) is one reason for the RFL *love* if that's what you want to call it... sure it is more work and materials, but some people have a problematic wall/s... 
you will also note that in post #14 there was a specific qualification regarding the use of RFL in walls.

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## pharmaboy2

> higher R value (what's your definition of "marginal" benefit?) is one reason for the RFL *love* if that's what you want to call it... sure it is more work and materials, but some people have a problematic wall/s... 
> you will also note that in post #14 there was a specific qualification regarding the use of RFL in walls.

  Marginal is the .1 out, up to .9 in assigned by Bradford in their own tech documents when combined with an insulated stud wall. This includes the 0.5 airtightness gain.  So recommended for warm climates, but condensation risk means they recommend breathable membranes for cooler climates. 
 the tech documents for the cavity systems all seem to recommend a vapour permeable membrane - it seems reasonable to me to follow their recommendations. 
btw I can see the logic for sydney on a western unshaded wall, though really if we were being smart we'd paint our western walls white , but I'm too vain.....  :Wink:

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## Marc

Western? Isn't the northern wall the hottest?
Agree on white, roofs should all be white, yet they are mainly black

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## pharmaboy2

Eaves Marc - mean the northern wall gets limited sun in the summer, and very little past midday.  West however and SW get plenty of sun into the afternoon as the sun gets lower.  Lots of northern sun in the winter however   :Wink:

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## Marc

You r right ...
this tablet is torture ,I hate it :Crash:  give me my laptop back!!!

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## DavoSyd

northern walls ideally have deciduous vegetation in front of them  :Wink:

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## Moondog55

Seen pix of our front yard?
Well in a couple of years the Wisteria should be providing plenty of dappled shade in the front yard which faces North

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## NZC

> correct. 
> its ok when you have a specific problem, or want a specific look, but for an average home.... 
> no one has asked about paint colour, wall direction, shading, glass sizes and how much heat is a problem versus cold.  Given he is in Melbourne, it's probable that 80 - 90% of energy use for temperature is to warm it up.  Walls get far less heat than a roof which is probably why the systems for battens I see all are using products like Tyvec or proctorwrap. 
> if you want to go the extra mile, tape the proctorwrap/hardiewrap and make it airtight.  I'm at a loss as to why so much love for RFL in walls, when all the technical documents on batten systems recommend Vapour permeable membrane, eg CSR, weathertex, woodform, hardies. 
> if in doubt, always follow the manufacturers std to the letter.  They have dumped sarking because modern products are better, they are more watertight, they breath, and any heat benefit is marginal at best (especially in an insulated wall)

  
True, I wouldn't even bother with the RFL on a renovation to be honest. In this case they're going from no insulation or wrap, to insulated and wrapped. You r not going to notice whatever the extra gain is from RFL and the amount of work involved to me makes it not worth while. 
I weould just insulate it, wrap and tape the joins then direct fix the boards.

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## Moondog55

Practical experience says different NZC
If you can afford the extra mile and you are going to be staying there for a while I say it is well worth it
It is noticeable Very much so

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## CraigandKate

> Western? Isn't the northern wall the hottest?
> Agree on white, roofs should all be white, yet they are mainly black

  Yes and no Marc, depends on eave size, with decent eaves sun is higher during the middle of the day so less of the wall is directly exposed. Later on summer days the western wall of my place is certainly the hottest, as the sun drops lower and is not quite as hot but more of the wall has direct sun.

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## phild01

Western wall easily the hottest wall.  As mentioned, eaves protection but also the angle to the sun is more direct.

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## DavoSyd

> Practical experience says different NZC
> If you can afford the extra mile and you are going to be staying there for a while I say it is well worth it
> It is noticeable Very much so

  this "it is worth it" is supported the insulation manufacturers... who seem happy to provide advice regarding their products and how to best implement insulation strategies specific to particular scenarios... 
who btw also opine that the cladding manufacturers are primarily interested in preventing mould and rust (with their wrap recommendations), not improving homeowner energy consumption...

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## pharmaboy2

> this "it is worth it" is supported the insulation manufacturers... who seem happy to provide advice regarding their products and how to best implement insulation strategies specific to particular scenarios... 
> who btw also opine that the cladding manufacturers are primarily interested in preventing mould and rust (with their wrap recommendations), not improving homeowner energy consumption...

  Prabably, but at least can someone provide some evidence of the superiority and quantify it so you can make a cost judgement. 
i did cavity at my place but I'm in the top 1% of exposed conditions in the windiest city in the country so I had other reasons as well, and certainly could not find any evidence that RFL gave any substantive advantage over breathable, but that breathable had advantages long term for the building envelope.  
Anyway, from around page 40, you can figure out whatever versus whatever in terms of r values  http://icanz.org.au/wp-content/uploa....1.2015_hr.pdf

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## 0438snappy

thanks, very useful.  I think I'd seen the older version of this book, time to go back and have another read up.

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## DavoSyd

> Anyway, from around page 40, you can figure out whatever versus whatever in terms of r values

  i have never once suggested using RFL + bulk insulation.

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