Vertical distance between gravel bed / splash guard and plaster facade

Hi,

I have a rendered facade. The base is insulated. The exterior wall is timber frame construction, sealed downwards to the floor slab. I received an addendum on the base execution from my house company. According to this, they recommend at least 15-30 cm vertical distance from the gravel bed to the bottom edge of the exterior wall. However, I know it more as simply piling up gravel to the desired height and that's fine.

For example, especially in the terrace area, the paving is level with the ground. With the above recommendation, there would be a trench on the left and right (which runs all around the house). I actually just want to know WHY I should maintain the 15-30 cm. Unfortunately, this is not explained and the house company stubbornly refers to this addendum without further explanation. Is it only about splash water (dirt)? I don’t think it is about moisture, because 1) the water drains away, 2) the render is a seal, 3) it is also sealed downwards.

I would also be grateful for experience reports from people who also have a rendered facade, how they solved this and if anything negative has “appeared” when just piling up gravel.

The water drains away, but moisture can remain longer and thus penetrate into the plaster. The plaster will sooner or later develop cracks, flake off, and moss and algae can grow well.

My reading recommendations for you (and for readers of this thread) are: as well as and - the topic has already been covered from all perspectives there ...

The BDF will already know what they are writing.

The joint between base coat/render and house render is probably also OKRFB for you.
Normally, the wooden structure stands on exactly that, relatively unprotected.

Water cannot get in there through the drip edge. If you fill it up now, water will splash into the ventilation behind it and might possibly not dry out anymore.
Gravel also retains water very well! Just reach deep into a superficially dry pile of gravel.

I executed the strip according to the specifications and made it flush at the terrace with a (not exactly cheap) grating.

2) The plaster is a seal

No, and that is exactly why the facade must be protected from moisture (from below). Have a quick look here where the plaster falls off after just a few months/years because it absorbs moisture (from below).

As others have already written, this is about preventing stagnant water. By the way, this is not just a recommendation from the BDF or similar, but a DIN requirement and applies not only to plastered houses but also to brick-faced houses. Many just don’t do it as would be technically correct in terms of building physics.