DIY iQ-Therm

[Frank.T]

We have been using iQ-Therm for few years on a couple of old properties. First the 1.0 system that used the larger boards (much preferred to newer ones) and on our latest project we have to use the new iQ therm 2.0 as the old stuff is all gone. Both systems are v.expensive. Our latest home requires a lot more m2 of external stone walls than we can afford to insulate using iQ-Therm.

To cut costs we have ditched all the Remmers glues and plaster and just use NHL3.5/playsand mix to stick the boards to the wall along with some plastic fixings to be sure. We are plastering on it with NHL2/sand mix imbedded with plastic mesh and skimming with NHL2/playsand mix. Our first walls were finished using this system over 6 months ago and came up great.

After looking at the new iQ-Therm 2.0 boards they seem to be just PIR boards with paper front and back similar to Kingspan TR27 boards that we use on flat roofs. They don't seem to have any calcium injections like the iQ-Therm 1.0 boards. The part that "wicks" the moisture in the 2.0 boards seems to be the lime mortar you use between the boards (like the mortar between bricks in a wall) instead of the injected calcium that the 1.0 boards had in them.

My question to the experts on this forum is will my below system work. It is basically the iQ-Therm system with lower cost materiels:
- NHL3.5/sand mix (glue)
- paper faced PIR boards cut to 1175*125mm with horizontal joints mortared with lime mix and also fixed with plastic fixings
- NHL2/sand mix base coat with plastic mesh
- NHL2/sand mix skim coat
- breathable paint

Anyone see a problem with any of the above? Any help/advice on this would be.very much appreciated.

 

[a twig]

If you’re doing it for insulation reasons then I’m sure most of the advice on here would be to ditch the PIR as it will not allow any moisture through it.

I have no idea how the I-Q therm does it but they claim a mu value of 39 by using laminate PUR, whereas paper PIR has a mu value around 1500 - essentially it doesn’t let any through at all! (Low numbers good, high numbers bad in this case)

Most folk on here look to wood fibre for breathable insulation which has a mu value between 2 and 4 depending on brand

This thread is a good starting point and there are a lot of other threads about DIY wood fibre insulation on here as well

 

[Jblakes]

@Frank.T Do you have any pictures of the NHL2/ Playsand finish, we have aload of NHL2 to plaster the house with just unsure which sand to use for the finish we want.



Also we have used wood fibre and wood wool boards for internal insulation and both worked well.

 

[Frank.T]

That's few pictures of the window reveals behind the shutters. Our plasterer is not too happy with us as we want a rougher finish and he wants perfect finish like gypsum skimcoat but this is kind of a happy medium

 

[aockenden]

Expanded agglomerated Cork board is another option. No mechanical fixings needed, just butter the backsides with sticky lime plaster and mush them onto the wall.

No PIR anywhere for me, lime mortared joints or not.

 

[Kearn]

I don’t much like the sound of any of these systems. Injected calcium isn’t an answer. Nor are joints alone. The analogy with a brick wall isn’t fair, as bricks are porous also, the pointing is just weaker and sacrificial as it’s easier to replace.

PIR boards negate any lime work, and using NHL is overkill - especially indoors, maybe a weak 2 mix if you must, but 3.5 is too much.

A thick stone wall is brilliant insulation already present, less is more on the lime plaster - allow the stone to heat up and maintain warm fabric, instead of insulating to fight it and warm only the internal air.

 

[mardinor]

A thick stone wall is brilliant insulation already present, less is more on the lime plaster - allow the stone to heat up and maintain warm fabric, instead of insulating to fight it and warm only the internal air.

This should be printed in huge font on a sheet given to every purchaser of a period house.