Polystyrene (WDVS) alternatives?

Hello everyone,

we are currently building a KfW55 house and the exterior wall is a 24cm lime-sand solid brick and 16cm ETICS with WLG 035 insulation is planned. For cost reasons, polystyrene is planned as the ETICS insulation.

If the weather cooperates, the insulation should be installed in the next few weeks. The reinforcing mesh and plaster will probably come later. However, the insulation would at least be in place before winter. Now I heard that this should not be done. Although the insulation is supposed to be moisture-resistant, if it is not plastered immediately and it rains in the meantime, the insulation performance decreases.

My question is whether this is true and if I can install the insulation without problems now and plaster later, or if it is better to do everything at once. The problem would be that the house would be uninsulated over the winter.

As a small side question, since we are at it... Is there an alternative to polystyrene? I mean there is nothing comparable unless you want to invest significantly more, but maybe my information is outdated.

cheers

First clarify whether it is warm enough to glue the insulation. Our expert insisted on gluing at the beginning of October to ensure it is definitely warm enough. My component temperature is at least 5 degrees.

Plaster came in January thereafter.

If you have concerns about later disposal
Google once
Polystyrene + Frauenhofer + mealworms
And more likely
Polystyrene + Frauenhofer + recycling
Or creasolv

Polystyrene contains raw materials and is therefore eventually too valuable for incineration.

You can also use rock wool, but it is more expensive. Or switch to a ventilated facade, which I always find the nicer solution, but then significantly more expensive.

From an economic perspective, there is no reasonable alternative to polystyrene; one can debate extensively about the advantages and disadvantages of mineral wool or stone wool or other alternatives, but personally, I would currently always choose polystyrene. If processed properly (that's what matters, as with almost everything!), it will outlast the rest of your house.

There is a nice study from the Frauenhofer Institute about WDVS ([mainly polystyrene]) (can be found by googling), with the key statements (as far as I remember): fewer facade damages with WDVS facades compared to monolithic construction (the assumed cause is fewer thermal bridges since you have a continuous insulation layer and no real joints); almost no wear after XX years (I don't have the average age in mind right now, I believe somewhere between 25-40 years).

Thank you for the answers!! I gather from this that using polystyrene in my situation actually works well, and it even has advantages over monolithic construction that I was not aware of.

It is also not a problem to apply the insulation now and the reinforcement later. Of course, it depends on the temperatures, but currently we still have relatively mild days and according to my measuring device, the walls are above 5°C during the day. So if next week still looks good, I can apply the polystyrene and have insulation for the winter. When the temperatures allow, the reinforcement and so on will follow.

Must not fall below at night either. Check the technical data for how long and how much. It is cold here and I am waiting for snow