Clennls

Hi all, I am looking to decide which insulation I want to use for our cavity wall. We want to use either mineral wool or glass wool. However, the insulation that comes with an aluminum layer for reflective heating and windproofing is quite expensive. We have found the insulation Petralight 20 cm, which is affordable and has good density, but we can't find a thin insulation with an aluminum layer. They all seem to be at least 130 mm or so. We can install 240 mm of insulation. Are there any brands with thin insulation that has an aluminium layer or are there very damp-open PUR, PIR insulations on the market? Otherwise we have found a very damp-open aluminium cover for insulation but are not sure how to attach it. We could only use the insulation plug's but i am not sure if the foil will not tear arround the plugs. Otherwise we would need to install some wood in between the insulation, but that is also a lot more expensive, and we would lose some insulation vallue. There are some wool insulations on the market which have a white glass fiber layer on them, but I can't find if these are any good for reflective insulation. Thanks in advance

Hi all, I have about 20 m where i need to underpin my existing wall. Between the new foundation and the existing wall i would like to install a thermal break (the height would be perfect for our underslab insulation). The problem is i don't see a way to use Celcon blocks or xps-concrete blocks because i don't think it is possible to place them and protect them from water and damp. Currently we plan to use Perinsul because it is water and damp proof without the need for extra foils or membranes. But this is very expensive. Are there any other solutions? Liquid waterproofing?

Thank you all for the replies. I live in Belgium and we just use the term black PE foil and use the right thickness instead of DPM. But i am sure it is the same thing. For the seams we just use 50 cm overlay. Not sure if i need to add some tape for it. I read about what insulation is better under a plate and if it is above the groundwater, EPS seemed better because it can dry out. XPS eventually gets saturated by moisture from the damp and can't really dry out. However when it is under the groundwater level XPS was better as it does not absorb groundwater. Its also why i think i need a thinner DPM on top of the EPS. That sheet is only so the water from the concrete does not flow in the insulation. And i think if damp gets in the insulation, it will try to dry out on the side with the least ammount of DPM. I will think about using 30 cm of EPS insulation. I was also going to use 30 cm on the roof. Maybe one last question, how do you do the seams of the geotextile? Is 50 cm overlay enough? Currently al the architect that we ask just seem to really brush the issue away of the groundwater. Here it is standard to place the insulation on the slab. Though there are contractors who want to do this work, i really want to make sure it is done proper.

Hello everybody, We want to place EPS insulation under our slab and we have very high ground water. We currently think about doing the following (from top = inside - to bottom = underside): - Concrete slab - PE foil 0,10 mm - 20 cm EPS insulation - 2 x PE foil 0,20 mm each - Coarse sand 5 cm - Geotextile - Gravel 25 cm - Geotextile Normally the ground water is 20 cm under the gravel. Is this a correct order to use to make a proper Capillary break? We hear that we don't need to use a geotextile between the gravel and the sand, but then i think the sand will get in the gravel and thus the gravel will no longer work as a capillary break.