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Changing insulation mid build ?

pajosjunkbox

I'm thinking of changing from Xtratherm 150mm full fill to kingspan kooltherm k8 120mm . This is simply due to cost saving.
It does not affect the BER as I overspecced in the beginning. Does anyone see and problems with this ? The Xtratherm is costing â‚¬32.50 per M2 at the moment .

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Gumbo

pajosjunkbox wrote: »

I'm thinking of changing from Xtratherm 150mm full fill to kingspan kooltherm k8 120mm . This is simply due to cost saving.
It does not affect the BER as I overspecced in the beginning. Does anyone see and problems with this ? The Xtratherm is costing €32.50 per M2 at the moment .

It has to have some effect on the BER rating.
What has tour assessor said?
What has your Engineer/architect said?

And where will the swap over occur. Can you maintain the thermal envelope and still be in compliance?

pajosjunkbox

Apologies it will have an affect on BER but it still complies.
125 full fill was specced originally but we chose to increase it to 150 full fill. Kind of regretting it now as it is very costly.
Engineer specced full fill as he felt partial fill insulation was rarely installed right by blocklayers. As it turns out the blocklayers working on our house are top notch and very professional so I'm now considering the kooltherm k8.
The detailing will be ok as the build is two buildings joined by a link. One building will have full fill 150 and one building will have 120 partial.

Gumbo

pajosjunkbox wrote: »

Apologies it will have an affect on BER but it still complies.
125 full fill was specced originally but we chose to increase it to 150 full fill. Kind of regretting it now as it is very costly.
Engineer specced full fill as he felt partial fill insulation was rarely installed right by blocklayers. As it turns out the blocklayers working on our house are top notch and very professional so I'm now considering the kooltherm k8.
The detailing will be ok as the build is two buildings joined by a link. One building will have full fill 150 and one building will have 120 partial.

I think you might be saving pennies not, but you’ll regret it in the future.
Shave the budget from items that CN be easily replaced in a year or two like woods floors, furniture etc

Insulation in theory will never have to be replaced again so always go for the best possible now.

pajosjunkbox

Yep it's a good point but is the difference between the 150 mm full fill and 120mm partial negligible. Is the law of diminishing returns valid here ?
The 120mm is available at a discounted price direct from factory. It's working out at 12 euro per m2 !

It's a bit of a difference

dfader

pajosjunkbox wrote: »

Yep it's a good point but is the difference between the 150 mm full fill and 120mm partial negligible. Is the law of diminishing returns valid here ?
The 120mm is available at a discounted price direct from factory. It's working out at 12 euro per m2 !

It's a bit of a difference

You can use the u value along with the area in square meters of of external wall to calculate the heat loss per year through the walls and knowing hour heat source convert into a money value per year. Your BER assessor should be able to advise on this or your engineer.
Have you started yet. If not I'd ditch the full or partial fill and build 200mm bead filled walls. Better for lots of reasons, read back through this forum, and look the term thermal looping in walls, but your engineer needs to carefully design out thermal bridges at every junction.

pajosjunkbox

Too late for that. Started already !

BryanF

Stick with 150mm PIR if you’ve already started the foundations

2000

I thought the minimum recommend air cavity with partial fill kingspan k8 insulation was 40mm? So if your your cavity is 150mm and you did decide to use the partial fill you might want to consider the 110mm thickness. I'm surprised your able to get the K8 for so much cheaper than the full-fill. I remember looking at the "brochure" u-values previously and I think the 110mm k8 was around the 0.01 or 0.02W/m2.k worse than the xtra 150mm but have a look yourself.

pajosjunkbox

The U value is slightly lower with the kooltherm. It is a low price due to been seconds from the factory. I know that's not everyone's cup of tea but there is a considerable saving. Not sure the price of it in builder providers.

I'm currently paying 26.50 + vat per m2 for Xtratherm 150mm full fill. It's expensive but something that cannot be redone.

On another note I'm getting the feeling the blocklayers would rather use the partial fill rather than full fill. They mentioned that if I wanted to save a bit of money I could use 120mm with 30mm cavity in single storey block of house. Maybe the full fill is a little slower to install for them or am I being cynical !

dfader

pajosjunkbox wrote: »

The U value is slightly lower with the kooltherm. It is a low price due to been seconds from the factory. I know that's not everyone's cup of tea but there is a considerable saving. Not sure the price of it in builder providers.

I'm currently paying 26.50 + vat per m2 for Xtratherm 150mm full fill. It's expensive but something that cannot be redone.

On another note I'm getting the feeling the blocklayers would rather use the partial fill rather than full fill. They mentioned that if I wanted to save a bit of money I could use 120mm with 30mm cavity in single storey block of house. Maybe the full fill is a little slower to install for them or am I being cynical !

It's a lot more labour intensive for them. Really slows them up and is difficult to work with. I know of one very good blocklayer who said he's going to have to start charging more than his normal rate with it. Understandable really when they get paid per block, not for handling insulation. As bryan said, put the best possible in now. Also if you only leave 30mm air gap you might not get to pump the remainder in future if you wanted because 40mm is minimum for pumping I think.

Gumbo

pajosjunkbox wrote: »

The U value is slightly lower with the kooltherm. It is a low price due to been seconds from the factory. I know that's not everyone's cup of tea but there is a considerable saving. Not sure the price of it in builder providers.

I'm currently paying 26.50 + vat per m2 for Xtratherm 150mm full fill. It's expensive but something that cannot be redone.

On another note I'm getting the feeling the blocklayers would rather use the partial fill rather than full fill. They mentioned that if I wanted to save a bit of money I could use 120mm with 30mm cavity in single storey block of house. Maybe the full fill is a little slower to install for them or am I being cynical !

Who is signing off on the house as building regulation compliant?

pajosjunkbox

Engineer signing off on build. So the general consensus is stick with the full fill and suck up the cost. Anyone have any experience of seconds from insulation factories ? I've only come across it recently.

massey265

dfader wrote:

Also if you only leave 30mm air gap you might not get to pump the remainder in future if you wanted because 40mm is minimum for pumping I think.

From what I see off this full fill insulation there isn't much to it for the price off it, what ever happened to having a cavity? especially in Ireland, it's there for a reason,

dfader

massey265 wrote: »

From what I see off this full fill insulation there isn't much to it for the price off it, what ever happened to having a cavity? especially in Ireland, it's there for a reason,

I agree the cavity to the front of partial fill insulation makes sense in this country with our strong winds and rain, but what concerns me about it is the unintentional cavity behind it and its effect on U value. Even the very best blocklayers will leave gaps. See this; http://www.josephlittlearchitects.com/content/partial-fill-cavity-walls

Gumbo

pajosjunkbox wrote: »

Engineer signing off on build. So the general consensus is stick with the full fill and suck up the cost. Anyone have any experience of seconds from insulation factories ? I've only come across it recently.

The enginerr may not be happy with the seconds

Dudda

You can get good seconds and bad seconds. The quality of seconds varies wildly and you won’t know how good they are until they arrive generally. I’ve used Seconds in areas where it didn’t matter as much and it was cut to fit between timbers as a thin secondary layer of insulation, not the primary. Therefore damaged parts, voids and incorrect thickness parts could easily be omitted during the cutting and fitting process which I did myself on my own self build. You won’t have that luxury with the external wall. The block layers won’t cut out voids or be able to trim off damaged parts from you’re second sheets as they’ll be looking to use them whole and therefore will just put them in as best they can which won’t be good enough.
The other area I used some seconds were around the rooflight tunnels. I’d loads of cutting to do to fit them between triangles and other awkward irregular shapes. I had the attic space so doubled the thickness to offset any voids or other issues in the insulation I missed.
It’s these types of circumstances I’d use the seconds for where you can cut out the damaged parts or where it’s not the primary layer.