Insulation - Kingspan or equivalent question

Insulate between the batons and put a 50 or 70mm insulated slab over the top of it. It will give you 100mm of insulation. Use the low expansion foam to seal behind/around the insulation.

teflon wrote: »

Hi. Thanks for reply. The vents are just a hole in the wall leading to an outside vent. They aren't covered and do let the wind in as they are wide open to the elements but I wouldn't cover them.

I've no real issue removing the plasterboard but I just want to make sure it's entirely necessary first.

Before an expensive plasterboard replacement (and DIY'ing it can be a great choice) you could try a layer of breathable membrane behind vents, ive seen this done in many older Irish houses that have huge holes in the wall going outside, and as you said, you would never consider closing it up or stuffing anything in there, as they are bedrooms this is a good alternative but not say in a sitting room with a fireplace (carbon monoxide etc). If all else fails my friend fitted a "Black Hole" vent in her house, which is a draught baffle, it has a maze inside, it stops draughts and ensures airflow, these cost about 20 euro, and fit in your existing (huge hole in the wall )

You need to be careful with this, if you pin the boards direct to the wall with no insulation in the cavity then the dewpoint can happen between the cold wall and insulated plasterboard with the possibility of blue mold forming

Woodie.ie wrote: »

You need to be careful with this, if you pin the boards direct to the wall with no insulation in the cavity then the dewpoint can happen between the cold wall and insulated plasterboard with the possibility of blue mold forming

This is why imo EWI is likely to be better, wall if block construction can act like a thermal mass, absorbing heat (and retaining it) pushing the dew point outwards, would be possible to calculate by hand based on insulation, add each thermal resistance by layer/material type
as in 1/Rt=1/r1+1/r+1/rn...
Been a while so I think it would be possible to determine what the DeltaT is across the wall to see where the Dew pt may fall and thereby the thickness of material with a certain lambda value, would take longer to dig out old notes, but so long as the Dew pt doesnt fall inside the inner later of EWI, I believe thats the equivalent of it falling outside the outside layer (gets pushed out to the outside, or based on what I read about Polyiso, maybe just under the surface of the exterior layer).

edit, I honestly believe in the do nothing option vs the not do right one,
As one poster mentioned, if the temp moisture condenses at (dew point) occurs within the block (because you have insulated it internally) and this varies with temp and I would say RH, you might be running the risk of mould forming, where it cant be seen.

I also dont think its a good idea to insulate (internally for sure, but even externally) if you end up still just having a large vent hole in the wall or somewhere, where the heat can leak out.

Woodie.ie wrote: »

You need to be careful with this, if you pin the boards direct to the wall with no insulation in the cavity then the dewpoint can happen between the cold wall and insulated plasterboard with the possibility of blue mold forming

Would the plasterboard and the foil backed slabs not provide a vapour barrier that would "prevent" any vapour barrier from getting into the wall?
(obv won't be 100% tight)

GreeBo wrote: »

Would the plasterboard and the foil backed slabs not provide a vapour barrier that would "prevent" any vapour barrier from getting into the wall?
(obv won't be 100% tight)

Always assume vapour will get past the barrier so make sure it doesn't get trapped behind the barrier.

teflon wrote: »

Some of the formula and stuff being discussed here is way over my head tbh..

Who would you get in to give you an idea of where heat is escaping and what cost effective ways to retain heat? Based in Dublin 7. Would a general builder be an appropriate step to take?

Thanks for all the replies.

It is just adding fractions, forget that, I'd have to check my old notes, for adding layers (different materials, ie concrete+insulation+an air layer for example).


U and R are measures of how heat transfers (U) or resistance to that (R).

They are reciprocals (inverse) of each other,

So U value is 1/R, and R= 1/U.
You usually see materials properties quoted in R values (but sometimes U values are mentioned), I think that U values are more usually used to represent the total heat lost through a structure with layers of different materials more in an design calculation sense, whereas R values are more commonly specified on materials.


R values are more on material, so you could add up the R values for each layer and then just invert it to get the total U value.

If you have the R value from the material, usually marked on the wrapper and want to determine what the U value is for that item, just put 1 onto a calculator and divide it by R.

If you have the U value from the material, not as usually marked on the wrapper, but just say you had that and want to determine what the R value is, just put 1 onto a calculator and divide it by U.


You might also see the lambda value (λ), which is more true measure of the insulation materials performance, the R value is just calculated from that based on how thick it. R=length/λ, so if you have the R value from the product wrapper and you know the thickness, then you can calculate the Lambda (λ) value, some examples in the link. If you have the lambda value (λ) and you know the thickness, you can calculate the R value.
EDIT, length will be in S.I. units of meter, so 1 meter will be 1, 100mm would be 0.1, 200mm 0.2, and so on.


R is the thermal resistance, a measure of resistance to heat flow

U is the thermal transmittance, a measure of heat flow, because these are reciprocals of each other (inverses) The higher the R value the better it is at insulating, then that means the lower the U value the better is at insulating.
Something that is a good insulator will have high R values and low U values.
If you say the calcs are over your head, don't get overawed, when you take out all the naming terminology, it boils down to some basic dividing calculations, Im not trying to bamboozle you.


The important part imo is Dew point, or when water vapour will condense out of air, and someone mentioned this above (the entire reason for doing a calculation is to ensure what you are doing will work and to know that water isn't condensing on a surface you cant see, like behind your insulation on a cold wall, otherwise mould could form, which isn't healthy).
imo the do nothing option is a good one, rather than do something wrong.


eg if you insulated your wall internally, and it isn't airtight (and it probably wont be completely unless you have an airtight layer) then air movement carrying water vapour that travels to that surface (like an external wall which now is as or more subject to the external temperature, water can condense on that like happens on a bathroom window, but you might be creating the right conditions for mould.


Regarding Dew point, ie the temperatures water vapour in the air condenses into liquid water, we can see this on bathroom windows, warm moist air meets a cold surface, cold air can hold less water vapour than warm air, so the air becomes saturated sooner, meaning it cant sustain as high levels of moisture and it comes out as liquid water.


https://www.thegreenage.co.uk/article/thermal-conductivity-r-values-and-u-values-simplified/

edit, tbh, your vapour layer mentioned in your OP, is likely to be pierced by nails already, your insulation layer may be working or not, IMO it doesnt sound like the best option is on the cards to do, it may be that you are getting a gale blowing in your vent, maybe a baffled vent, or maybe your window is like a heat sink if it has poor performance in terms of heat loss or air leaks.

[QUOTE=ElderWanderer;
In terms of mould though, the only place I actually found evidence of mould was in the crappy unducted hole-in-the-wall "vents" which I made as airtight as possible. Long term ventilation is going to be mechanical heat exchange ventilation in a few month time, but installing an extractor fan through the roof from the bathroom made a surprisingly big and a immediate difference to indoor air quality- no more condensation on cold nights (although there was only every only a little).
).[/QUOTE]

Looking at both of these myself; in terms of heat recovery, have you done much work to ensure general air-tightness of the house. Is the extractor fan a powerful one that runs while showers are on, or is it something slower that runs continuously?
Thanks

ElderWanderer wrote: »

My house had a similar setup before I insulated it. I went with taking everything back to the bare block. Mechanically fixed 100mm rigid insulation to the block (taped on the joints, and expanding foam & tape where there were any gaps), battened it with 35mm thick timber, then plasterboard on top. Taped & filled the plasterboard joints.

That solution lost me about 150mm on every outside wall, plus I needed to insulate the reveals around the windows, and get a new window board everywhere. I went to a fair amount of effort to get the house reasonably airtight & get a continuous insulation cover.

The house is now (a) a lot warmer and more comfortable and (b) a lot cheaper to heat-- as in I'm using 50% or less heating oil compared to what I was using before under the same conditions.

There's no perfect solution though. External wall insulation is great in terms of preserving internal space and thermal mass, but it costs a fortune, will take a long time to warm up in the evening if the house is unoccupied during the day, and you're relying on the contractor to do it right. (Experience has taught me that you can never rely on the contractor to do it right, and it makes no difference what "it" is). Insulated plasterboard is relatively quick & easy, but harder to get a continuous vapour barrier I would think and leaves no room for services or for attaching anything heavy to the wall after. Rigid + battens leaves room for services & you could attach anything to it, but it has also made small rooms significantly smaller.

In terms of mould though, the only place I actually found evidence of mould was in the crappy unducted hole-in-the-wall "vents" which I made as airtight as possible. Long term ventilation is going to be mechanical heat exchange ventilation in a few month time, but installing an extractor fan through the roof from the bathroom made a surprisingly big and a immediate difference to indoor air quality- no more condensation on cold nights (although there was only every only a little).

Key point though is: decide on which downsides you dislike least (because there's always significant downsides), and pick those ones as your way forward. Having cold bedrooms may be your least worst option (although it definitely wouldn't be mine).

I have considered different methods to insulate (internal vs external, I somewhat ruled out bead filling of cavitiy block because I'd like to see an argument for and against to see what the potential pro's and con's are, its possible it might not get to every cavity and there might be a lot of a cavity uninsulated after paying for it). I should look into seeing what the options are regarding airtightness, the best method is going to be a complete airtight membrane barrier internally which is difficult to retrofit).
I had thought of doing an internal insulation but was/am concerned about interstitial moisture (small spaces between layers) forming and the risk of mould, the problem is you cant see it if it's there. I'd even considered the possibility of carrying out a low level of insulation internally, more like an improved mildly insulated dry lining, rather than really beefing it up so that "some" heat is being preserved inside but enough escaping to heat the blocks, enough to prevent them cooling to a point to allow water condense on them somewhere.



In the end, my house isn't that old so its performance while questionable imo, still isn't the worst, now I'm planning on moving, so I went with the "Do Nothing" option but for a few reasons, the work would be disruptive internally and I really think the external wall insulation (EWI) method is better and less disruptive than trying to insulate internally.


If I can find a means to do airtightness by some synthetic layer externally under an EWI then that's what I'm planning to do, I heard it mentioned years ago, but I think it was a method being discussed as potentially a better idea for retrofit. I'm going to look into the adhesives available for bonding EW, maybe a complete layering of that might be viable.

I can't see a contractor would want to do a complete layer, more likely blobs here and there (maybe even if you paid them to do it), so unfortunately I agree, you really cant rely on someone to do the job right, some or many might, but it's determining how to find that person and knowing if they are that person.

To that extent, I've considered seeing if I can locate a course on installing EWI and do it myself (because the devil really is in the detail, the attention to detail) and then get someone to render it, I believe traditional sand and cement is an option, but there are also synthetic options, for which I pay someone for that work. MVHR is the next (necessary) step, assuming someone has blocked up their vents.


With EWI, I'm not inclined to think it would take any longer to heat an insulated airtight house than a poor preforming one with leaks and poor or no insulation. Aside from not losing heat as easily it should be quicker to heat up. If you include a well designed air or ground sourced heat pump, you could get continuous heating at a low cost too.

teflon wrote: »

I was on to Kingspan about my issue and they have offered the following advice. Any thoughts? They seem to think its straight forward enough.

"I would recommend removing any existing plasterboard and replacing it will our Kooltherm K18 insulated plasterboard. 62.5mm of K18 will greatly improve the quality of your building."

:rolleyes:

With the greatest of respect to Kingspan, they would say that, wouldn't they?

That's a salesmans advice rather than an engineers!

teflon wrote: »

Really? It came from their technical department though.

Their technical department exist to sell Kingspan products, and are experts in Kingspan products, rather than anything else.

Nothing wrong with that, but the fact is, you're never going to ring up the Kingspan technical department to be told anything other than "here is a simple solution to your problem using a Kingspan product"

It may not be the best solution, or even a good solution, but it will be a simple one, and it will use Kingspan products!

BTW, I should add - if it was my house I would probably do what Kingspan advised in this case, as it is the easiest solution, though not the best, so I'm not saying they are wrong in this case, just that I wouldn't be taking the advice of a manufacturers technical department as gospel!