Insulation again!!

johnpawl

Ok I know this topic has been done to death and I've read all the old posts, but I'm going building soon and I really want to get this right..
From what I've read over the past few months on this forum I'm thinking something like this;
inner leaf:
first couple of rows up from foundation - quinn blocks on flat to prevent cold bridging
from there up standard blocks on flat
Top row and closer - again quinn blocks to prevent bridging
Cavity- 200mm pumped
Outer leaf, standard blocks on edge, plastered..
Still not 100% sure how to tackle window and door opes but its the air tightness I really dont get... I've looked up their websites and they dont explain much..How is it achieved??
What is ye're view on my specs, any advise appreciated..thanks..

Viking House

johnpawl wrote: »

inner leaf: first couple of rows up from foundation - quinn blocks on flat to prevent cold bridging
from there up standard blocks on flat
Top row and closer - again quinn blocks to prevent bridging
Cavity- 200mm pumped
Outer leaf, standard blocks on edge, plastered..
Still not 100% sure how to tackle window and door opes but its the air tightness I really dont get... I've looked up their websites and they dont explain much..How is it achieved??.

Using QuinnLite blocks for foundation rising walls to reduce the wall/floor cold bridge will work to an extent but only if the QL are kept dry which means wrapping them completely in dpc, which is quite difficult at joints and at corners. If water gets in behind the dpc then the dpc will prevent them from drying out. If you get settlement in the foundations the dpc will crack. Its a difficult detail and the cost of the dpc and the blocks makes this solution expensive.
As you are putting 200mm Insulation in the wall and probably a similar amount in the floor you will need the equivaent of 150mm of insulation at the wall/floor junction to meet the 0.04 cold bridge value proposed for the 2010 building regulations. To get close to the proposed 0.04 CB value you would need to additionally line your rising walls on both sides with 100mm EPS sheets. This will bring you to 0.05 which is close but its getting costly.
You could otherwise use 2 layers of foam glass blocks to achieve a similar result but at about €25/block/metre its also expensive.
A 150mm layer of hard polystyrene (EPS 300) where the wall/floor meet would seem to be the cheapest solution or use a foundation system similar to the one SAS used.

johnpawl

Viking House wrote: »

Using QuinnLite blocks for foundation rising walls to reduce the wall/floor cold bridge will work to an extent but only if the QL are kept dry which means wrapping them completely in dpc, which is quite difficult at joints and at corners. If water gets in behind the dpc then the dpc will prevent them from drying out. If you get settlement in the foundations the dpc will crack. Its a difficult detail and the cost of the dpc and the blocks makes this solution expensive.
As you are putting 200mm Insulation in the wall and probably a similar amount in the floor you will need the equivaent of 150mm of insulation at the wall/floor junction to meet the 0.04 cold bridge value proposed for the 2010 building regulations. To get close to the proposed 0.04 CB value you would need to additionally line your rising walls on both sides with 100mm EPS sheets. This will bring you to 0.05 which is close but its getting costly.
You could otherwise use 2 layers of foam glass blocks to achieve a similar result but at about €25/block/metre its also expensive.
A 150mm layer of hard polystyrene (EPS 300) where the wall/floor meet would seem to be the cheapest solution or use a foundation system similar to the one SAS used.

Okay, so when you say "A 150mm layer of hard polystyrene (EPS 300) where the wall/floor" I take it that means returning the floor insulation up along the rising wall to floor level.. Are you okay with cutting the top of this insulation at an angle so that the concrete screed goes nearer to the wall on top?With the finished floor being slightly above DPC would it not do the trick to have a row of quinn lite above DPC all round, preventing any heat from the majority of the area of the wall escaping and cold bridging neglible as a result or am I missing smething? Thanks..

Viking House

I mean the inner wall would sit on a layer of Hard Polystyrene.
10cms of Polystyrene EPS has the same insulating value as 15cms of Foam glass, 50cms of dry QuinnLite blocks, 150cms of damp (below dpc) QuinnLite blocks or 9.5 cms of XPS which is what SAS used.

I can't say too much more about it because of rules here, you could do maybe an internet search to learn more!

One layer of QL blocks above the dpc only barely scratches the surface, if you don't do it correctly you can end up with condensation above the skirting because it will be the coldest place in your house.

johnpawl

Viking House wrote: »

I mean the inner wall would sit on a layer of Hard Polystyrene.
10cms of Polystyrene EPS has the same insulating value as 15cms of Foam glass, 50cms of dry QuinnLite blocks, 150cms of damp (below dpc) QuinnLite blocks or 9.5 cms of XPS which is what SAS used.

I can't say too much more about it because of rules here, you could do maybe an internet search to learn more!

One layer of QL blocks above the dpc only barely scratches the surface, if you don't do it correctly you can end up with condensation above the skirting because it will be the coldest place in your house.

So, if you were me and building a cavity wall house, what would be your approach? Thanks

macbrada

hi..

re insulation..was involved in manufacturing in a past career for many years.... many systems are designed to reduce cold bridging and produce impressive U -Values on paper....

however, the key to acheiving real U Values is workmanship. i.e polyurethane or polystyrene sheets achieves good u values in principle. However, at corners, windows, wall plates etc problems occur. the installer cuts the boards with a standard saw out on site...... not mm perfect. A 3 mm gap in vertical insulation can increase heat loss ( via termal looping ) by 198%

Pumping the walls is a bad plan. inner and outer leaf are held by stainless steel wall ties ( 3 - 5 per m2). Imagine your wall built and ready for pumping with insulation. 50 m2 wall will have approx 200 permanently fixed wall ties in place. If you pump from left, a void is left on the right of wall ties and vice versa. this leaves many small pockets poorly insulated. Saw this personally using thermal imaging camera on live building site years ago when there were sites!!


best system i have seen is relatively old technology but new enough to ireland... Polystrene system as follows in brief

outer leaf polystyrene
inner leaf polystyrene
build these first tied with plastic wall ties. Pour concrete in between inner and outer leaf.

Continuous uniform layer of insulation provide inside and out. No cold bridging through wall ties. Seen a house in meath recently built this way. Cant remember company name but can get from site if interested.

Don't know but imagine sound proofing would be fairly good too....



Either way good luck with the build

Poor Uncle Tom

macbrada wrote: »

best system i have seen is relatively old technology but new enough to ireland... Polystrene system as follows in brief

outer leaf polystyrene
inner leaf polystyrene
build these first tied with plastic wall ties. Pour concrete in between inner and outer leaf.

Continuous uniform layer of insulation provide inside and out. No cold bridging through wall ties. Seen a house in meath recently built this way. Cant remember company name but can get from site if interested.

Don't know but imagine sound proofing would be fairly good too....



Either way good luck with the build

ICF

https://www.youtube.com/watch?v=nUoWsmRD9mA

johnpawl

macbrada wrote: »

hi..

re insulation..was involved in manufacturing in a past career for many years.... many systems are designed to reduce cold bridging and produce impressive U -Values on paper....

however, the key to acheiving real U Values is workmanship. i.e polyurethane or polystyrene sheets achieves good u values in principle. However, at corners, windows, wall plates etc problems occur. the installer cuts the boards with a standard saw out on site...... not mm perfect. A 3 mm gap in vertical insulation can increase heat loss ( via termal looping ) by 198%

Pumping the walls is a bad plan. inner and outer leaf are held by stainless steel wall ties ( 3 - 5 per m2). Imagine your wall built and ready for pumping with insulation. 50 m2 wall will have approx 200 permanently fixed wall ties in place. If you pump from left, a void is left on the right of wall ties and vice versa. this leaves many small pockets poorly insulated. Saw this personally using thermal imaging camera on live building site years ago when there were sites!!


best system i have seen is relatively old technology but new enough to ireland... Polystrene system as follows in brief

outer leaf polystyrene
inner leaf polystyrene
build these first tied with plastic wall ties. Pour concrete in between inner and outer leaf.

Continuous uniform layer of insulation provide inside and out. No cold bridging through wall ties. Seen a house in meath recently built this way. Cant remember company name but can get from site if interested.

Don't know but imagine sound proofing would be fairly good too....



Either way good luck with the build

Hi, thanks for the reply... To be honest after following threads on this site relevant to insulation I hadn't really considered this option. Alot of people seem to be in favour of the wide cavity and pumped insulation, but I will look into this method.. Is it not very similar in principle to simply putting an insulated slab on the inner leaf, with the same inherent pros and cons??

Viking House

When building with ICF make sure 65% of the insulation is outside the concrete and that you eliminate the cold bridge where the concrete meets the ground like in the sketch.