Build a sandstone wall

Sandstone has been a proven building material for millennia. You can build sandstone walls dry, but also with mortar. While building a sandstone wall as a drywall anyway is a construction technique of its own, not only DIY enthusiasts often commit building defects when walling and grouting a wet sandstone wall. Mostly only because they are passed on as a "real tip". Therefore, we will explain how to wall and grout a sandstone wall, which you firmly bind with a binder.

Sandstone has been used as a building material by humans for millennia. As soft rock, it is easy to work with, and it's also ecologically valuable because a true biotope can form in a sandstone wall - provided it's a drywall. You can create sandstone according to two basic techniques to a natural stone wall:

  • Drywall, the stones are tilted without binders
  • masonry wall, the stones are built using a binder (mortar, glue)

Create foundations for sandstone walls yourself

The first important differences in these two construction techniques already exist in the foundation. For the bricked sandstone wall you need a poured concrete foundation. Bear in mind that you need to condense the concrete.

For a drywall, the foundation is also made "dry". Click here for a guide, and to learn more in detail: Drywall Foundation.

Mortar and grout for sandstone walls

When setting your own natural stone wall, you can often resort to special natural stone mortar. Sandstone, however, is an exception. A little digression into the history of the building explains why choosing the right mortar is so important, but also why so many wrong tips are given.

Construction of sandstone

Sandstone is a sedimentary rock that consists of at least 50 percent sand. Rock is finely ground again in the course of Earth's history and deposits especially in waters. Various forces (water, new deposits) act on these sand deposits and squeeze. The result is sandstone. Therefore, sandstone also has a layer structure.

In principle, wherever primeval rivers and ancient seas were, but also in primeval valleys, through which rivers meander today, sandstone can be mined. It is not only a soft, but also often occurring rock.

Roman construction technology helps

Already in ancient times the meaning of sandstone was great. The Romans used sandstone for the construction of numerous facilities: buildings, arenas, walls, aqueducts etc. Sandstone was often bricked up and grouted by the Romans with Opus Caementitium.

Opus caementitium and trass mortar

The most important component of this Roman cement are pozzolans. Pozzolans are of volcanic origin. Similar rock in Germany today is trass, which is also processed into trass mortar or trass cement. In many Roman buildings, exactly these building materials were used. This is the reason why trass mortar is often recommended as mortar for sandstone.

Follow an important rule of thumb

However, an important principle should always be taken into account when walling and grouting: mortar and grout should always be softer than the building block used. But sandstone is very soft now. What is often used as an argument for the wrong tip of trass mortar, in fact, even shows why you should not use this mortar just.

Why is trass mortar unsuitable?

Take a look at photos of old Roman aqueducts. The Roman builders even had to use trass mortar to make the water pipes watertight. But as you can see on numerous photos of the Roman aqueducts, the sandstone has largely disintegrated and still the mortar to see. This will ultimately accelerate the decay of the Roman ruins.

Trass mortar accelerates the weathering of sandstone

Because these exposed trass mortar surfaces absorb water and lead it directly to the remaining sandstone, which then weathers even faster. Therefore, for sandstone walls, always use a mortar that is softer than the stone.

NHL-Lime is the right product

This mortar can be found in NHL-Kalk. This is nothing but natural, hydraulic lime. You can also determine the grain sizes yourself. As a mortar for setting the stones, a grain size up to 4 mm should be used, for smooth grouting then between 1 and 2 mm.

Tips & Tricks

When constructing sandstone walls and other structures, always observe the building laws: the nationwide templates, the state building regulations, regional and municipal decrees and statutes, as well as development plans. From a height of 2 m you have to carry out a static calculation and have it approved when building a wall, also for sandstone walls of this size.

Video Board: How to Build a New England Fieldstone Wall by David Croteau