ᐅ Detached Garage Attached to House Wall – Plaster or Render?

Hello everyone,

We are currently building with Wienerberger Poroton blocks (T8). According to the planner and general contractor, the prefabricated garage will be placed directly against the house façade without applying plaster beforehand. They say that it is sufficient to properly waterproof the roof area between the garage and the house wall.

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

Thank you and best regards,
Florian

Since the plaster provides the airtightness (now your site manager will say that the interior plaster alone is sufficient), I would definitely recommend having it plastered.

flospeedy schrieb:
proper waterproofing 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 unnecessary. That would basically be impractical.

It has also been common practice for a long time to install precast concrete garages next to houses that have not yet been externally plastered. If this were a problem, the consequences would have been known by now. I have heard of insulation boards being used in between, but never plaster. The description of the planned execution seems professionally sound to me.

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Hello everyone,

thank you very much for the replies.

Two answers – two statements. So what is actually correct?
Our site manager explained to us again that plastering would even be wrong, and proper waterproofing is the professional way to do it.

When you drive through new housing developments, you see everything: plastered walls, unplastered walls, 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. However, this joint is not intended to prevent water penetration, so it should be sealed thoroughly and elastically.

And you are not simply placing any buildings next to each other, but specifically a heated building and an unheated building (also one with expanded clay aggregate and the other with concrete). In this case, it makes sense to allow the air in the joint to move freely without being blocked by plaster coatings on the adjoining surfaces. If later the neighbor builds a garage next to it, they will likely place unheated next to unheated, so you wouldn’t need to remove your plaster even if the garage is masonry. If my neighbor hadn’t built yet and my garage were a solid structure standing on the property line, I would also leave the exterior plaster off on that side (and only apply it if part of my wall ends up exposed later).

Seeing both methods in new development areas is explained by the mix of architect-designed and contractor-built houses. The combination “general contractor” with the “site manager knows their stuff” factor is the rarer one—congratulations!

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flospeedy schrieb:
wrong would be to plaster

Why?

11ant schrieb:
There should be a joint in between.

That is undisputed, as is the permanently elastic sealing of the roof-to-wall connection.

The question here is whether the later invisible house wall needs to be plastered, may be plastered, should be plastered, or must not be plastered. This example concerns a brick wall without external thermal insulation composite system (ETICS).

Is the garage wall plastered?