Garden Room Directory

Garden Room and Annexe Site Preparation

Published: 7 July 2024

Reading Time: 5 minutes

When you have design consultations about your garden room or annexe project and reach the site survey stage, you will want to clarify what site preparation they expect you to do before the on-site phase of the project starts and which elements they will undertake as part of their service.

The beauty of garden room and annexe design is that it is less invasive than many other building methods, with much of the work being done off-site to streamline the on-site build process. However, the area where the new building will sit needs to be prepared, and you will need to designate a space for materials to be stored prior to use. Additionally, you will want to ensure the route from the vehicle offload point to the site is obstacle-free.

Ascertaining all this is one of the main roles of a site visit, so the company can walk the route, see the space available, and advise you accordingly. Most companies conduct in-person site visits, but several other firms have perfected remote surveys, where they do a video call with you to show them the access route and the garden, or they ask you to record a video and take different measurements to send to them.

The most common site preparation tasks you will be asked to undertake include removing plants and overhanging tree branches that might compromise the build. If there is existing hard landscaping like patios or concrete slabs or existing outbuildings, you may be asked to organise the removal of these before the installation team arrives.

Learn how to get your garden ready for your garden room or annexe project

Garden room & annexe designers aim to cause as little upheaval to your garden as possible, so your new building blends in as soon as it is built.

Some Garden Room or Annexe Companies Undertake Site Clearance for Clients

There are garden room and annexe companies that offer site clearance as part of their overall service. These companies are most likely to be those that offer a turnkey service. If you want them to handle the site preparation, discuss this with them at the design consultation, and they will then be able to factor the work into the quote they prepare for you.

Common Site Preparation for a Garden Room or Annexe

The area you have chosen for your building probably has an existing use, whether that be a planted border, a patio, or an existing outbuilding. These elements will need to be removed prior to the installation team starting work on the new building.

Garden room and annexe designers aim to leave little impact on the surrounding garden, so they will try to protect the surrounding lawn as they work. However, the weather during the build will play a part in the success of this aim.

Removing Plants and Overhanging Branches

You need to assess if tree branches are hanging over the proposed site which may obstruct the build

You will need to assess the site to see if there are overhanging tree branches which will impinge on the building when it is built.

You would need to remove plants from borders where the new building will sit

Any plants within the building plot will need to be cleared, although favourite plants can often be protected during the build.

If you have plants in close proximity to the new building, you will have to remove them before work starts. You will also need to assess if any branches of surrounding trees need to be reduced so they don’t compromise the build. You may need to organise a tree surgeon for this task.

If you have a favourite plant in close proximity to the build site, measures can be taken to protect it during the build so that it springs back into shape once the work is complete. Over the years, we have written about several projects where the team has worked around a favourite tree or shrub. Using the Site Challenges filter in our directory tool, there is an option for trees, and this will show you the companies that can accommodate trees in their projects and examples of how they have achieved this.

Stripping the Lawn

If there is grass where the building will sit, you will want to ascertain if this needs to be removed. Some companies prefer it to be stripped away, while others install their foundation through it, and once light is blocked by a weed suppressant membrane and the building itself, the grass will die.

You will need to remove any hard landscaping from the proposed site

You will need to remove any hard landscaping elements from the proposed site.

Removing Hard Landscaping

If you have an existing building where you plan to position the new one, this will need to be dismantled before work can start. It may be that the installation team would do this for you, but it would need to be discussed during the design consultation process so time is allowed for the work.

If you have paving slabs or a concrete slab, you will need to discuss these with your designer. Some ranges of small garden rooms can be built onto an existing patio. Otherwise, you would need to remove any slabs or concrete so they do not obstruct the new foundation system.

Levelling the Ground

The foundation systems used in garden room and annexe design are relatively easy to level, so you don’t have to worry about levelling the site. Ascertaining the right foundation for your ground is one of the primary reasons for a site survey. The surveyor will assess what type of soil you have and how level the ground is. There are occasions when a retaining wall is required to hold back the ground; the requirements for this would be discussed during the site survey and laid out in your quote.

The modern foundations used in garden room and annexe design are easy to level.

The modern foundations used in garden room and annexe design are easy to level.

Organising the Foundation

Many garden room or annexe companies organise the foundation system as part of their installation service, but some companies ask you to arrange a suitable base before they arrive on site to assemble the building.

These companies often require a concrete slab foundation. They will give you a specification and dimensions for the base, and you would organise this to be installed by another company. You will need to closely follow the requirements and dimensions to avoid issues when it comes to the main build. With a concrete slab foundation, you will need to time its installation so it has time to fully set and be strong enough for the main build to go ahead on your agreed installation date.

You can see which companies include the foundation system in their quoted price and service by using the “Which elements do you want the service to cover” filter in our directory tool. Select the foundation option, and you will be given the names of the companies that include the foundation in their service and work in your area.

See which companies install the foundation as part of their overall service

Parking and Material Storage

One of the important elements of site preparation you will need to discuss during your site survey is where the lorry with the materials will park when delivering and where the installation team will park. You might want to have a word with your neighbours, particularly on the days when the materials are delivered, to keep the parking clear.

You will also want to discuss during the site survey where the materials will be stored while waiting for use. Some companies, often on larger and more complex builds, like to have a skip and portaloo on-site, so you would need to allow space for these in your preparations if that applies to your project.

Talk to Your Neighbours

In our experience, it is worth talking to your neighbours prior to the on-site stage commencing. Tell them what work you are having done and how long it is estimated to take. Informed neighbours tend to be happier neighbours if they know what is going on and how it might impact them.


Proper site preparation is essential for a smooth and successful garden room or annexe project. By understanding your responsibilities and what the installation team will handle, you can ensure a streamlined process. From clearing the site to arranging foundations and communicating with neighbours, thorough preparation will lead to a successful and less stressful build.

Preparation is the key to a successful project

Preparation is the key to a successful garden room or annexe project.