Stick built wall build up

[Thorfun]

1 minute ago, Iceverge said:

Given the constraints of your circumstance you must decide where to compromise. 

 

In opting for a rigid U value target for a given width you may have missed the wood for the trees a bit. 

 

Say you get your approx 150m2 of wall to a theoretical 0.12 instead of a realistic 0.18. that's a difference of 0.06w/m2K

 

150m2 x  dt20⁰ x 0.06w/m2K. That's about 180w in the peak heating load over say a floor area of 120m² it's 1.5w/m². 

 

At another guesstimate that's about 200kWh/annum or £32 per year. 

 

Now account for the poorer airtighess performance, material wastage during building, additional cooling load due higher decrement delay. Poorer noise and fire performance. 

 

Be very careful about putting PIR In a stud wall. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+1

 

i used Jeremy’s heat loss spreadsheet and airtightness had a much bigger impact than U-value. 
 

iirc 140mm frametherm 32 (other manufacturers are available) and 50mm PIR gives a U-value of 0.14. If I was the OP I’d be looking at that with a 25mm service cavity and not bother with the internal OSB layer. 

[Thorfun]

11 hours ago, G and J said:

Soooo, I think I’m at a point where I do need to wait for my architect input.

Yes but bear in mind that some architects are wed to Kingspan and specify it without extra thought. 
 

may I suggest speaking to some TF companies and asking to visit previous builds and talking to the owners? MBC do a glass wool/PIR wall that will suit your needs and maybe all you need is to see one in real life. 

 

Do your research and then tell your architect what you want. It is your house after all!

 

 

[MikeSharp01]

1 hour ago, SteamyTea said:

Resilience bars are normally shown fitted horizontally, but they will perform the same if fitted vertically, which is the way that cables are normally run down walls.

Yes sorry I was thinking of our setup. 

[G and J]

On 20/06/2024 at 13:38, Thorfun said:

or is it the cement particle board? I think the external build up looks different to most timber frames I've seen. definitely different to ours! from out to in we have 

 

vertical timber cladding

45mm batten and counter batten

breathable membrane

osb

140mm timber with

140mm frametherm 32

80mm PIR

AVCL (IntelloPlus)

25mm battens

12.5mm plasterboard

skim

 

I pretty much copied MBC https://mbctimberframe.co.uk/closed-panel-wall-options/

 

didn't read @IanR's response before I posted. he got there first! 😉 

@Thorfun And how does your house feel to live in?  Do you notice noises from outside?

Edited Saturday at 07:01 by G and J
Added the @ thingy (I’m slowly getting the hang of this posting stuff!)

[G and J]

12 hours ago, Thorfun said:

Yes but bear in mind that some architects are wed to Kingspan and specify it without extra thought. 

Which is kind of understandable, it is only like a plumber always using the same make of boiler through familiarity, it makes for a working solution but with the combined knowledge on here I’m going for better than that.

 

So I’m going for a modified version of your suggestion, I’m doing my research and then working with the architect for the best overall solution for us.

 

I will be using The Spreadsheet too, but I want to work through each element individually first.

[saveasteading]

Ask your architect to avoid trade names. Not even Kingspan or equivalent.⁸ If you phone a supplier and ask for Kingspan, they aren't supposed to offer any alternative.

[G and J]

12 hours ago, Iceverge said:

Given the constraints of your circumstance you must decide where to compromise. 

Definitely, though I’m still effectively analysing the options. 
 

12 hours ago, Iceverge said:

In opting for a rigid U value target for a given width you may have missed the wood for the trees a bit. 

 

Say you get your approx 150m2 of wall to a theoretical 0.12 instead of a realistic 0.18. that's a difference of 0.06w/m2K

 

150m2 x  dt20⁰ x 0.06w/m2K. That's about 180w in the peak heating load over say a floor area of 120m² it's 1.5w/m². 

 

At another guesstimate that's about 200kWh/annum or £32 per year. 

Thoroughly agree that there is a danger of being diverted by detail, and I’ve done that calculation and found similar results.  It’s kinda scary that it appears from my rule of thumb calcs that insulation much above building regs does not show a financial payback.  
 

U value is a predictable metric, so it’s an easy one to focus on, as is build cost.  So as I look at each possible build up I naturally calculate the u value  and yes, I’ve got build cost in the back of my mind (otherwise I’d use aerogel!) but because I have no easy accessible metrics for sound transmittance and ‘comfort feel’ I’m effectively having to glean what info I can from this and other posts.

[SteamyTea]

31 minutes ago, G and J said:

but I want to work through each element individually first.

Get LISA, it does everything you need, and is free.

Linear static, Modal vibration, Dynamic response, Buckling, Steady and transient heat flow, Acoustic, Steady fluid flow.

 

If you get to grips with it, write up how it works, all I have managed is very basic models.

Edited Saturday at 07:56 by SteamyTea

[G and J]

I am drawn towards a composite rockwool and PIR  solution like Thorfun listed.  140mm rockwool stuffed in frame (easy to do, improves sound performance) thence a skin of PIR to deliver thermal insulation, and that’s where the trade off between wall thickness and u value hit.  
 

It is likely to deliver a poorer u value than we could have but that’s ok, once I’ve looked at the other elements I can analyse the balance and we can make informed choices.

 

And I would have stopped there and moved on to the next element had ubakus not had a little red triangle.  However, I think there is a possible flaw in its analysis.  
 

If I have a build up such as:

then I get no warning triangle on drying reserve.

 

However, if I add a layer of PIR on the outside of the vapour barrier I get:

So, the addition of the PIR layer is the only addition.  It is next to and outside of the barrier which should let nothing through.  So if PIR does not absorb, store or transmit water as has been stated then it’s almost like it’s a 50.5mm thick vapour barrier - so why should it change whatever the drying reserve is?

 

If PIR was able to absorb, store and transmit water then it would be no different to the rockwool that it is next to.

 

Either ubakus has a quirk or there’s something fundamental that I’m failing to understand.

 

 

 

[G and J]

8 minutes ago, SteamyTea said:

Get LISA, it does everything you need, and is free.

Linear static, Modal vibration, Dynamic response, Buckling, Steady and transient heat flow, Acoustic, Steady fluid flow.

 

If you get to grips with it, write up how it works, all I have managed is very basic models.

That looks soooo far beyond me, but thank you.

 

I was planning on my PhD being on The Statistical Variation of Tastiness of Greggs Vegan Sausage Rolls over time of day.  Obviously significant field research needed.  That’s more my level.

[SteamyTea]

3 minutes ago, G and J said:

I was planning on my PhD being on The Statistical Variation of Tastiness of Greggs Vegan Sausage Rolls over time of day.

The title of mine was 'Short term stochastic variation in cloud cover in Cornwall: the effect on photovoltaic predictions'

 

 

[Thorfun]

1 hour ago, G and J said:

@Thorfun And how does your house feel to live in?  Do you notice noises from outside?

it's lovely! 🙂 very few external noises but we live in a very quiet area surrounded by trees (drone photos on my blogs will attest to that) so I might not be the best person to ask. although in the old pre-fab bungalow the dog would bark at the slightest of external sounds or if the neighbours across the road shut a car door etc. now he doesn't react to noises until someone actually knocks on the door. so the sound reduction is much improved over the shitty little bungalow if that helps! 🤣. I don't know how just using PIR would've been to live in I just didn't want to take the chance and, as we installed all the insulation ourselves, using glasswool in between the studs was a lot easier.

 

38 minutes ago, G and J said:

So, the addition of the PIR layer is the only addition.  It is next to and outside of the barrier which should let nothing through.  So if PIR does not absorb, store or transmit water as has been stated then it’s almost like it’s a 50.5mm thick vapour barrier - so why should it change whatever the drying reserve is?

if you speak to an insulation manufacturer (you'll need to choose one that does mineral/glass wool AND PIR they will do a condensation risk analysis on your wall build up for you. then the risk is put on their shoulders.

 

We attached our IntelloPlus on the inside of the PIR so all our insulation is beyond it. I did that as I was paranoid about off-gassing of the PIR in to the house but I'm also convinced it just makes the condensation risk reduced and simpler to calculate.

[MikeSharp01]

1 hour ago, G and J said:

The Statistical Variation of Tastiness of Greggs Vegan Sausage Rolls over time of day

Probably already been done or in progress although I could not find anything like it in any of the listings. I did find one piece of research that would definitely be in the bibliographic remit of such work: "Chewing it over - public attitudes to alternative proteins and meat reduction." https://bryantresearch.co.uk/wp-content/uploads/2023/10/Chewing-It-Over.pdf  supposing that you might want to investigate the psychological / attitudinal approach to the 'snack' as this effects the way one tastes it and how perhaps frame of mind is somewhat a function of more than the time of day.

 

However apropos the thread topic I found an interesting chapter on how heat affects our eating habits - a somewhat profound statement of the bleeding obvious but with nuances that make you think along the lines of: 'So if I keep my house warmer I will eat less and be healthier' , 'I can afford to keep my house warmer because it is very well insulated', 'the air tightness of my house forces the use of MVHR which allows me to control, via filtering and flow, the indoor air quality', 'So if I build a well insulated, airtight house and keep it warm I will be healthier' QED . The question is what price / value do you put on that then and how might it affect the way the house should be built and, should you happen to get your vegan sausage roll home - unlikely because of the current evidence of shards of flaky pastry stuck in the seams of the car seats and your trousers indicating that self control in these matters is somewhat lacking, how it tastes there? (Read the chapter here: https://books.google.co.uk/books?hl=en&lr=&id=MFhTp_wtPDMC&oi=fnd&pg=PT201&dq=The+effects+of+insulation+on+food+awareness&ots=h1YqHjdtdo&sig=O0sjlZumkeQJ-O6-y7m1o3OA9vo&redir_esc=y#v=onepage&q&f=false)

[SteamyTea]

6 minutes ago, MikeSharp01 said:

The question is what price / value do you put on that then and how might it affect the way the house should be built and, should you happen to get your vegan sausage roll home - unlikely because of the current evidence of shards of flaky pastry stuck in the seams of the car seats and your trousers indicating that self control in these matters is somewhat lacking, how it tastes there?

Easy, take the accountancy approach. Convert the kCal to kWh and compare it to how much energy is needed to heat your house.

 

Or just get a second job cheffing, we hardly eat a thing all day, even though freshly cooked bacon makes me feel hungry.

[G and J]

18 minutes ago, MikeSharp01 said:

shards of flaky pastry stuck in the seams of the car seats

Have you been snooping in my car?

[SteamyTea]

Greggs don't make pasties.

[G and J]

43 minutes ago, Thorfun said:

it's lovely! 🙂 very few external noises but we live in a very quiet area surrounded by trees (drone photos on my blogs will attest to that) so I might not be the best person to ask. although in the old pre-fab bungalow the dog would bark at the slightest of external sounds or if the neighbours across the road shut a car door etc. now he doesn't react to noises until someone actually knocks on the door. so the sound reduction is much improved over the shitty little bungalow if that helps! 🤣. I don't know how just using PIR would've been to live in I just didn't want to take the chance and, as we installed all the insulation ourselves, using glasswool in between the studs was a lot easier.

That’s more than good enough for me.  I’m sure you are a sensible person, but I trust your dog’s senses completely.

 

45 minutes ago, Thorfun said:

if you speak to an insulation manufacturer (you'll need to choose one that does mineral/glass wool AND PIR they will do a condensation risk analysis on your wall build up for you. then the risk is put on their shoulders.

Noted, though I’d rather not have to rely on such things.

 

45 minutes ago, Thorfun said:

We attached our IntelloPlus on the inside of the PIR so all our insulation is beyond it. I did that as I was paranoid about off-gassing of the PIR in to the house but I'm also convinced it just makes the condensation risk reduced and simpler to calculate.

It also stops warm, wet(ish) air from inside getting to a cold surface inside the wall which would risk condensation, so that is a very good thing. 
 

May I ask what your wall airtight strategy is?

[G and J]

12 minutes ago, SteamyTea said:

Greggs don't make pasties.

No but they make yummy Mexican style vegan bake thingys.  
 

And their booby buns are vegan too, but not marked as such, I think because it would adversely affect sales.   Obviously this is on topic as keeping me warm will reduce my bun and savoury bake requirements and so save money long term and help me live longer to see the payback.

[SteamyTea]

24 minutes ago, G and J said:

Mexican style vegan bake thingys.  

It has 1819 kJ of energy, that is 0.5 kWh.  So you need about 4 a day to keep you sustained.

 

No idea what they cost  but heating a house will be cheaper.

 

Energy is really cheap.

 

Found a price, £1.90 so £3.60 a day.

Edited Saturday at 10:28 by SteamyTea

[G and J]

32 minutes ago, SteamyTea said:

It has 1819 kJ of energy, that is 0.5 kWh.  So you need about 4 a day to keep you sustained.

 

No idea what they cost  but heating a house will be cheaper.

 

Energy is really cheap.

 

Found a price, £1.90 so £3.60 a day.

Some things you can’t put a price on.  (Said the man who uses his Greggs app for his loyalty freebies A LOT! I ).        😉    

[SteamyTea]

22 minutes ago, G and J said:

Some things you can’t put a price on

My lunch.

 

 

[Thorfun]

2 hours ago, G and J said:

but I trust your dog’s senses completely.

Are you sure about that? His senses tell him that other dog/horse/cow shit is nice to eat. 😂

 

2 hours ago, G and J said:

May I ask what your wall airtight strategy is?

Belt and braces! Tape everything meticulously. 😉

 

i’m sure it’s documented on here somewhere. I’m out and about at the moment but will write something up later for you if you want. 

[G and J]

1 hour ago, Thorfun said:

Are you sure about that? His senses tell him that other dog/horse/cow shit is nice to eat. 😂

 

Belt and braces! Tape everything meticulously. 😉

 

i’m sure it’s documented on here somewhere. I’m out and about at the moment but will write something up later for you if you want. 

I’m going to have a good read through your blog, so if it’s in there that’s great.  But if not headlines would help so thank you.  

[Thorfun]

4 hours ago, G and J said:

I’m going to have a good read through your blog, so if it’s in there that’s great.  But if not headlines would help so thank you.  

I stopped writing the blog once the internal work started. I was just too busy doing the work to carry on writing about it!

 

headlines are simple. follow passive house principles. a continuous membrane layer around the external walls of the house and taping all windows and doors. I did a lot of reading on this forum as there are many knowledgable folk on here who have done it all before I even started down our self-build route.

 

my first hint is to do a search on here for Tony tray. get that right in the design stage and the rest should be simple.

my second piece of advice is if you're going for a warm loft then consider a cut roof rather than roof trusses. even with attic trusses we had it was a real pain to maintain the airtight barrier up in to the loft and around the trusses. with a cut roof it would be a lot more simple.

 

this might be a good place to start https://passivehouseplus.ie/magazine/guides/the-ph-guide-to-airtightness? then see where your research leads you. I guarantee it will be a rabbit hole but you'll come out of it wiser and with a plan of action.

[Iceverge]

17 hours ago, G and J said:

I am drawn towards a composite rockwool and PIR  solution like Thorfun listed.  140mm rockwool stuffed in frame (easy to do, improves sound performance) thence a skin of PIR to deliver thermal insulation, and that’s where the trade off between wall thickness and u value hit.  
 

It is likely to deliver a poorer u value than we could have but that’s ok, once I’ve looked at the other elements I can analyse the balance and we can make informed choices.

 

And I would have stopped there and moved on to the next element had ubakus not had a little red triangle.  However, I think there is a possible flaw in its analysis.  
 

If I have a build up such as:

then I get no warning triangle on drying reserve.

 

However, if I add a layer of PIR on the outside of the vapour barrier I get:

So, the addition of the PIR layer is the only addition.  It is next to and outside of the barrier which should let nothing through.  So if PIR does not absorb, store or transmit water as has been stated then it’s almost like it’s a 50.5mm thick vapour barrier - so why should it change whatever the drying reserve is?

 

If PIR was able to absorb, store and transmit water then it would be no different to the rockwool that it is next to.

 

Either ubakus has a quirk or there’s something fundamental that I’m failing to understand.

 

 

 

 

Ubakus isn't perfect. It just predicts one set temperature for outside and inside. 

 

If for instance your buildup doesn't dry at -5⁰ don't fret as it's unlightly it'll be that cold for long enough to actually do any damage. 

 

On the structural side of things I think you'll need to have the OSB connected to the studs as it provides the racking strength to prevent them folding over like a house of cards.

 

From a fire perspective I would prefer to see the OSB on the inner face of the studs or if it is external to them behind a good layer of fireproof material like rockwool or cement board.