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External Wall Insulation - DOSBODS Views (Not Inc XYY)


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Our house is a strange design. Its standard cavity wall up to the first floor and then the upper floor is clad with shiplap timber . Rather than Cavity wall its 195mm thermablock (Hanson product from the q980's) with bitumen fibre sheet over that then 25mm battens with the shiplap cladding over the top.

The cladding is reaching the end of its life and needs replacing. If I am doing this I want to improve the thermal performance of the wall. As well as keeping heat in I also want it to keep heat out in during the summer as its painted black and absorbs heat. I am somewhat reluctant to use a foam based insulator although I understand PIR chars like wood rather than melts.

Options include:

PIR (Polyisocyanurate)

Wood Fibre board (the is all made abroad)

Rockwall slabs (which are a cunt if they get wet) with a breathable vapour barrier over the top)

A couple of layers of foil back bubble insulation (I have some doubts about this stuff)

A combination of some of the above options. 

Anyone had experience of this and any issues?

Anyone got views on breathable v non breathable insulation in an external insulation setting? 

 

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9 minutes ago, Kurt Barlow said:

Our house is a strange design. Its standard cavity wall up to the first floor and then the upper floor is clad with shiplap timber . Rather than Cavity wall its 195mm thermablock (Hanson product from the q980's) with bitumen fibre sheet over that then 25mm battens with the shiplap cladding over the top.

The cladding is reaching the end of its life and needs replacing. If I am doing this I want to improve the thermal performance of the wall. As well as keeping heat in I also want it to keep heat out in during the summer as its painted black and absorbs heat. I am somewhat reluctant to use a foam based insulator although I understand PIR chars like wood rather than melts.

Options include:

PIR (Polyisocyanurate)

Wood Fibre board (the is all made abroad)

Rockwall slabs (which are a cunt if they get wet) with a breathable vapour barrier over the top)

A couple of layers of foil back bubble insulation (I have some doubts about this stuff)

A combination of some of the above options. 

Anyone had experience of this and any issues?

Anyone got views on breathable v non breathable insulation in an external insulation setting? 

 

 

XYY Translation:

I'm bragging about my house again, and don't really give a shit what you cunts think...

 

XYY

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53 minutes ago, ashestoashes said:

https://www.dotanddab.co.uk/ewi-external-wall-insulation

 

seen this done to a few houses round here

cheers. I don't want to go down the rendered route for 2 reasons. 

1. I can DIY a insulation / overcladding job

2. If something does go wrong the cladding can be removed and put back up

3. We are on clay here and the soil moves. Many of the houses with render are covered in hairline cracks. 

Do you know what the insulation material is?

Just now, Kurt Barlow said:

cheers. I don't want to go down the rendered route for 2 reasons. 

1. I can DIY a insulation / overcladding job

2. If something does go wrong the cladding can be removed and put back up

3. We are on clay here and the soil moves. Many of the houses with render are covered in hairline cracks. 

Do you know what the insulation material is?

infact 3 reasons;)

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My house is similar design.  When we extended above the garage, parts of the existing ground floor wall were only single block so we couldn't easily support a cavity wall above.

Had a long and detailed conversation with my builder about interstitial condensation, which he almost got.

Somewhere on the internet, I found a calculator that allowed me to put all the proposed layers of board and barrier and insulation and see if there might be an issue with condensation somewhere.

Might be this one: http://vesma.com/tutorial/uvalue01/uvalue01.htm

Or the trial version of this software: http://www.rusfa.com/dew3.htm

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On 09/09/2020 at 20:42, Kurt Barlow said:

This is interesting. Breathable and looks easy to install. 

https://www.superfoil.co.uk/wall/

Good U values, thing is only useable as infill would have thought so you would be looking to batten out and then another cladding / covering on top. Would be easy to install. 

Passed a house a couple of days ago and noticed a cladding system being applied - looked like small panel overcladding, simply screwed to wall, presumably that would then be stiff enough for one of the modern render coats  (isolated enough most likely form the main structure of the house to prevent cracking, much in the same way interfacing layers used for tile on wooden floor, the intermediary layer providing some flex.

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12 minutes ago, onlyme said:

Good U values, thing is only useable as infill would have thought so you would be looking to batten out and then another cladding / covering on top. Would be easy to install. 

Passed a house a couple of days ago and noticed a cladding system being applied - looked like small panel overcladding, simply screwed to wall, presumably that would then be stiff enough for one of the modern render coats  (isolated enough most likely form the main structure of the house to prevent cracking, much in the same way interfacing layers used for tile on wooden floor, the intermediary layer providing some flex.

Cheers (and Inigo)

I am now looking at Kingspan k15 PIR board (polyisocyanurate) . I could use 50mm board screwed direct to the wall (I'm reluctant to use adhesive bonding because if its screwed on its easily removed). I can then screw  38mm tile  battens over the top and then fit on the shiplap cladding. That will give a nice 20mm over hang over the lower brickwork and help keep water drip off. I may put a sheet of reflective breather foil in between to act as an additional  radiant barrier. Upstairs can get uncomfortably hot in a heatwave. 

I read that the thermablock construction can basically be treated as impermeable so adding another impermeable layer wont matter and the external insulation will keep the block warmer anyway which will drive off any moisture. . 

The k15 has a much higher R value than either Superfoil 40mm or 40mm Wood fibre (made by dirty foreigners). The PIR unlike polystyrene and polyurethane does not melt. It chars like wood and appears to be self extinguishing so has much higher fire resistance. 

K15 is also UK manufactured which suits my support the home front approach. I've also managed to find UK grown cedar timber for the cladding at a reasonable price. 

When I do this job I want it to last at least 35 years  which will see me towards my last wooden structure project.............

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On 09/09/2020 at 17:10, Kurt Barlow said:

Our house is a strange design. Its standard cavity wall up to the first floor and then the upper floor is clad with shiplap timber . Rather than Cavity wall its 195mm thermablock (Hanson product from the q980's) with bitumen fibre sheet over that then 25mm battens with the shiplap cladding over the top.

The cladding is reaching the end of its life and needs replacing. If I am doing this I want to improve the thermal performance of the wall. As well as keeping heat in I also want it to keep heat out in during the summer as its painted black and absorbs heat. I am somewhat reluctant to use a foam based insulator although I understand PIR chars like wood rather than melts.

Options include:

PIR (Polyisocyanurate)

Wood Fibre board (the is all made abroad)

Rockwall slabs (which are a cunt if they get wet) with a breathable vapour barrier over the top)

A couple of layers of foil back bubble insulation (I have some doubts about this stuff)

A combination of some of the above options. 

Anyone had experience of this and any issues?

Anyone got views on breathable v non breathable insulation in an external insulation setting? 

 

XPS  sheet/board it`s closed cell and has a R  rating better than all you suggestions 

Edited by Long time lurking
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2 minutes ago, Kurt Barlow said:

Polystyrene though isn't it?  Firelighter territory

No it`s self extinguishes,i have used it for years to make surf/boards and wave skis i used to use expanded polystyrene  and i burnt the waste, when using that it`s not a option for XPS  

 Won`t you be covering it anyway 

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48 minutes ago, Long time lurking said:

No it`s self extinguishes

Are you sure? https://en.wikipedia.org/wiki/Polystyrene#Fire_hazards

48 minutes ago, Long time lurking said:

 i used to use expanded polystyrene  and i burnt the waste

The products are pretty noxious unless burned at high temperature https://en.wikipedia.org/wiki/Polystyrene#Incineration

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1 hour ago, Kurt Barlow said:

Cheers (and Inigo)

I am now looking at Kingspan k15 PIR board (polyisocyanurate) . I could use 50mm board screwed direct to the wall (I'm reluctant to use adhesive bonding because if its screwed on its easily removed). I can then screw  38mm tile  battens over the top and then fit on the shiplap cladding. That will give a nice 20mm over hang over the lower brickwork and help keep water drip off. I may put a sheet of reflective breather foil in between to act as an additional  radiant barrier. Upstairs can get uncomfortably hot in a heatwave. 

I read that the thermablock construction can basically be treated as impermeable so adding another impermeable layer wont matter and the external insulation will keep the block warmer anyway which will drive off any moisture. . 

The k15 has a much higher R value than either Superfoil 40mm or 40mm Wood fibre (made by dirty foreigners). The PIR unlike polystyrene and polyurethane does not melt. It chars like wood and appears to be self extinguishing so has much higher fire resistance. 

K15 is also UK manufactured which suits my support the home front approach. I've also managed to find UK grown cedar timber for the cladding at a reasonable price. 

When I do this job I want it to last at least 35 years  which will see me towards my last wooden structure project.............

Think the Cedar is a good choice (especially if you can get it at a reasonable price) - amazing water/rot resisting capabilities compared to most other available wooden cladding, have an outdoor building with cedar finish myself and well impressed. A decent finishing oil is still a good idea unless going for the natural look - the Oslo oil is the one I went with.  Cedar mind is very flammable but you have to think of the likelihood and consequences of a fire for each circumstance.

I think is comparison the foils may be a bit expensive, they are good insulators for their dimensions but if you are not worried about overhang / thickness then go for cheaper solutions like the board. 

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6 minutes ago, Nippy said:

Are you sure? https://en.wikipedia.org/wiki/Polystyrene#Fire_hazards

The products are pretty noxious unless burned at high temperature https://en.wikipedia.org/wiki/Polystyrene#Incineration

XPS = styrofoam https://en.wikipedia.org/wiki/Styrofoam

The only way i have managed to "burn " it is with other fuel sources ,i am definitely not mistaken on the self extinguishing part  

It`s a totally different kettle of fish compared to ESP

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 I was chatting to the Kingspan guys, not long after Grenfell and they claim that their stuff has much better flame retardants and, at the right specification, does not burn.  They do a lot of testing and are continuously improving their product.

When my extension was built, while I specified Kingspan/Celotex, the builders would often get whatever was cheap at the local insulation warehouse.  If you are doing it yourself, this won't happen, but don't be fobbed off with the cheap stuff.

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5 hours ago, Long time lurking said:

No it`s self extinguishes,i have used it for years to make surf/boards and wave skis i used to use expanded polystyrene  and i burnt the waste, when using that it`s not a option for XPS  

 Won`t you be covering it anyway 

Yes but with timber cladding you have to leave an air gap. A 38mm batten will sit on top of the insulation that the cladding is screwed to. 

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3 hours ago, Inigo said:

 I was chatting to the Kingspan guys, not long after Grenfell and they claim that their stuff has much better flame retardants and, at the right specification, does not burn.  They do a lot of testing and are continuously improving their product.

When my extension was built, while I specified Kingspan/Celotex, the builders would often get whatever was cheap at the local insulation warehouse.  If you are doing it yourself, this won't happen, but don't be fobbed off with the cheap stuff.

Celotex was used in Grenfell. Not sure which particular type. Massive vertical voids acting like a chimney would have been a factor in this. 

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4 hours ago, onlyme said:

Think the Cedar is a good choice (especially if you can get it at a reasonable price) - amazing water/rot resisting capabilities compared to most other available wooden cladding, have an outdoor building with cedar finish myself and well impressed. A decent finishing oil is still a good idea unless going for the natural look - the Oslo oil is the one I went with.  Cedar mind is very flammable but you have to think of the likelihood and consequences of a fire for each circumstance.

I think is comparison the foils may be a bit expensive, they are good insulators for their dimensions but if you are not worried about overhang / thickness then go for cheaper solutions like the board. 

The most significant cost is the cladding rather than the insulation. 

See picture - the character is black shiplap cladding - an Essex style apparently. The extension doesn't need doing as its cavity all the way upto the eaves. 

I intend to treat the wood with a good cuprinol preservative and then stain with matt Sadolin

Wall.jpg

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15 minutes ago, Kurt Barlow said:

The most significant cost is the cladding rather than the insulation. 

See picture - the character is black shiplap cladding - an Essex style apparently. The extension doesn't need doing as its cavity all the way upto the eaves. 

I intend to treat the wood with a good cuprinol preservative and then stain with matt Sadolin

Wall.jpg

Make sure to use stainless pins/nails for the cladding. If the Sadolin comes with  UV stabilised version then go for that too.

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23 minutes ago, Kurt Barlow said:

Celotex was used in Grenfell. Not sure which particular type. Massive vertical voids acting like a chimney would have been a factor in this. 

Kingspan people were keen to point out that it wasn't their stuff at Grenfell.  They also said that there have been significant changes in legislation post-Grenfell but they were doing most of the new stuff already, I noted that most of the testing in the Grenfell enquiry was carried out by/sponsored by Kingspan.

I have loads of insulation, wherever I could squeeze some extra in the extension, and also clad in flammable timber.  Building regs guy only seemed interested in ensuring the steelwork was protected with double layers of fireproof plasterboard.  Even checking that the holes I'd put in for vents and speakers were fire rated.

Having said that, I've got smoke alarms in every room, all connected to each other and only a two story building with each window upstairs being an escape window.

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23 minutes ago, Kurt Barlow said:

I will use screws. I hate nails

You'd normally tackle that with something like a pinner - if you want a really neat job skew pinning the tongue as you go up.  I face pinned mine which was fine. Depends if you are OK with screws/ screw  holes possibly showing, not so bad with a dark stain.  Don't think you could skew screw the tongue, ceda  is quite brittle and can split.

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