Detached garage on house wall - plaster?

Hello everyone,

we are currently building with Wienerberger Poroton stones (T8). According to information from the planner and the general contractor, the prefabricated garage is to be placed directly against the house facade without being plastered beforehand. According to statements, it is sufficient if a proper sealing of the roof between the garage and the house wall is carried out.

Is that really enough or should the exterior wall also be plastered behind the garage?

Thank you very much and best regards, Florian

Since the plaster ensures airtightness (now your site manager will say the interior plaster is sufficient for that), I would definitely have it plastered.

proper sealing of the roof between the garage and the house wall

Still remains important.

I think plastering the joint between the house and the garage is nonsense. That would basically be a misalignment as well.

It has been common practice for a long time to set up precast concrete garages next to houses that have not yet been plastered on the outside. If that were critical, the consequences would be well known by now. I have heard of insulation boards being used in between, but never plaster. The description of the planned execution seems professional to me.

Hello everyone,

thank you very much for the answers.

2 answers - 2 statements. So what is correct now? Our construction manager explained to us again that it would even be wrong to plaster and that proper sealing is a professional execution.

When you drive through the new development areas here, there is everything: plastered wall, unplastered wall, with insulation in between, without insulation in between.

You want to place two buildings next to each other. There needs to be a joint between them. The joint is not meant to prevent water ingress, so you seal it thoroughly and elastically.

And you are not placing just any buildings next to each other, but specifically a warm building and a cold building (also one is made of expanded clay and the other of concrete). It makes sense to let the air in the joint do its work unhindered by plaster coatings on the boundary surfaces. If later the neighbor builds his garage next to it, he places cold to cold, so you wouldn’t need to remove your plaster on a masonry garage either. If my neighbor had not yet built and my garage was solid and standing on the boundary, I would also omit the exterior plaster towards him (and only apply it later if a part of my wall remains exposed afterwards).

That you see both in new housing estates can be explained by the corresponding mix of architect-designed and contractor-built houses. The blood group combination "GC" with the Rh factor "site manager is useful" is the rarer one – congratulations!

wrong would be to plaster

Why?

There needs to be a joint in between.

That is indisputable, as is the permanently elastic sealing of the roof-to-house connection.

The question here is whether the later invisible house wall has to be plastered, may be plastered, should be plastered, or even must not be plastered. Here as an example of a brick wall without ETICS.

Is the garage wall plastered?