ᐅ Professional Construction of an Attached Garden Wall

Dear forum members,

I want to build a wall in my garden, attaching it to a neighbor’s garage located on the property boundary, and I hope you can help me with some questions.

Attached is a sketch that shows the situation before and after the planned construction for better understanding.

Some initial conditions:

• A building permit / planning permission has been obtained
• The neighbor does not want any drilling or bonding on their wall
• The choice of bricks or blocks for the wall is not yet fixed – it could be aerated concrete, natural stone, brick, etc.

The plan is to first remove the existing soil and level the ground, then excavate the foundation to the required depth, and finally build the wall on top of the foundation.

The wall will consist of a relatively narrow, tall rear section that will be built in an L-shape around the corner at both ends. In front of this, there will be a lower part where a grill will be placed later.

The following questions concern me:

• How can a suitable separation joint be created between my concrete foundation and the neighbor’s concrete garage wall, to prevent moisture from being drawn into the gap, for example by capillary action?
• Before the project, rainwater used to flow away from the neighbor’s garage along the slope of the soil. During the project, a pit will be excavated at the garage, exposing part of the concrete wall. The pit will then be backfilled with gravel and concrete, but the new arrangement will almost certainly behave differently in terms of water drainage than the original situation. How should the neighbor’s garage be waterproofed in the foundation area to prevent standing water and water ingress into the concrete? The wall is currently sealed with a waterproof coating applied by the neighbor several years ago.
• How can waterproofing between my wall and the neighbor’s plastered garage wall be implemented?
• Is it possible to build the concrete foundation in two parts, as shown in the right-hand sketch? Background: in the right part of the foundation, cables and an irrigation pipe run at a depth of about 40cm (16 inches). Therefore, I would like to make the concrete section in the right foundation area shallower. I understand that a structural engineer must be involved for this (not yet done). For now, I am mainly interested in whether this is generally feasible.

I hope you can help me with these issues. Thank you very much in advance for your information and advice!

Best regards,
Mike

What is the purpose of the 2.5m (8 ft) high wall? There is already a wall there, isn’t there?

hanghaus2023 schrieb:

What is the purpose of the 2.5m (8 ft) high wall? Isn’t there already a wall there?

The question is valid 🙂. The "new" wall is mainly planned for the following reasons:
- Visual improvement
- Protection of the neighboring wall from grease splashes from the grill (if anyone has a different/better idea, I’m certainly interested)
- Possibly, the wall will later support a roof or act as the rear support for it. Additional posts would be added at the front.

Mike1701 schrieb:

The plan is to first remove the existing topsoil

What did the structural engineer say about securing the excavation pit in relation to the neighbor? We currently have a case where the building inspector stopped the pool construction just a few hours after being notified (excavation near the garage). This will be an expensive issue.

Mike1701 schrieb:

- Visual improvement

I can think of dozens of other options, but not such a high wall.

Mike1701 schrieb:

Protection of the neighbor’s wall from grease splashes from the grill (if anyone has another / better idea, I’m definitely interested)

See previous answer. There are dozens of options—from a small barbecue area to plants to rhombus cladding boards.

I think you’re overlooking an important aspect:

Mike1701 schrieb:

The neighbor does not want any drilling or gluing on their wall

So, if you want something that doesn’t affect the wall, the options become limited...

By the way, I ask you to understand the neighbor’s perspective here as well. We are in a very similar situation – the neighbor wanted to install their charging station with all the embedded wiring and water connection inside our wall (they only have a rather basic stilts carport adjacent to it). I had to put a stop to that right away. When I pointed out that otherwise, they would have to spoil the exterior wall of their own house (on the other side of the carport), I simply replied, “Good that you figured out the alternative yourself.”

Mike1701 schrieb:

A building permit / planning permission is in place

For what exactly?

As far as I understand, you are planning a masonry barbecue with a rear wall? And it has to be placed precisely right next to the neighbor’s garage? Which came first—the desire to improve the appearance or the barbecue? Or perhaps the idea to build a wall yourself?

If it’s for aesthetic improvement, I would first think of plants or a privacy screen that doesn’t necessarily have to be made of solid masonry. I would probably also look for a simpler option.

Regarding the barbecue or wall: I would try to find a location where other property owners won’t be affected. Possibly, I would use the intended wall (rear wall) to also create some privacy or wind protection in the garden, but not in a spot that clearly causes conflicts with the neighbor’s property. Even just excavating your soil (80cm (31 inches)? 100cm (39 inches)?) carries risks. Overall obstacles include stormwater infiltration, exposing the neighbor’s property, separation joints/moisture, and existing electrical installations.