Complete On-site Builds
Updated: 1 December 2025
Reading Time: 3 minutes 10 seconds
When it comes to building a garden room, companies take different approaches during the manufacturing phase.
Many of the big names in modular garden room design have factories where they construct the individual modules that make up their buildings. These modules are designed to lock together, allowing for quick installation once on-site. Some smaller garden rooms built this way can be installed in just a day.
Companies specialising in SIPs (structural insulated panels) garden rooms also complete much of the work off-site. Rather than managing their own expensive workshops, they source various building elements from specialist suppliers and coordinate their arrival on-site as needed.
Another approach is to build the garden room entirely on-site. Garden rooms built this way typically use a traditional insulated timber frame structure.
With a complete on-site build, raw materials are delivered directly to the site. The installation team then cuts the materials to size and constructs the core structure from scratch. Skilled carpenters usually lead these teams.
In this article, we’ll explore the benefits of choosing this approach.
Often Smaller Companies Led by Skilled Carpenters
In our experience, companies that build garden rooms on-site tend to be smaller, often family-run businesses. Their smaller size allows them to offer a more personalised service to each client.
These companies usually focus on fewer projects at a time compared to larger modular builders, enabling them to give individual attention to each build.
While some companies offering on-site builds work nationwide, this approach is more commonly adopted by local firms. Working with a nearby garden room manufacturer can also reduce costs, as delivery charges that would apply for long-distance services are often eliminated.
No Expensive Workshops
Companies that build garden rooms entirely on-site don’t need large, costly workshops, nor do they require large teams to handle both off-site and on-site phases.
This saves a significant amount in wages, facilities, and equipment costs. For instance, some of the CNC machinery used in modular garden room manufacturing can cost as much as a small house. Avoiding such expenses helps these companies offer more competitively priced garden rooms.
Often Traditional Timber Frame Builds
Garden rooms built entirely on-site typically use a traditional timber frame for the core structure, though more companies are starting to adopt light-gauge steel frames.
Traditional timber frames provide a solid core structure, which is further strengthened by an exterior sheathing layer. The framework is filled with insulation, and multiple layers are added to both the exterior and interior of the structure.
On-site Builds can Overcome Challenging Sites
On-site builds are particularly advantageous for non-standard designs or sites with challenging access.
If access to your rear garden is limited, it’s often easier to transport loose timbers and sheet materials rather than heavy pre-built modules. We’ve featured many projects where materials were walked through the house due to a lack of rear access, and in some cases, large garden rooms have had their materials craned over the house.
This approach also excels when owners want to maximise available space. For example, creating an angled wall to fit an oddly shaped plot is far easier with a timber frame build than with pre-built modules.
On-site Builds Offer Flexibility
Some companies that specialise in complete on-site builds offer flexibility in making design changes during the build process.
For instance, we’ve known clients to stand inside the frame of their new garden room and realise they’d prefer a window positioned to capture a particular view. In such cases, the company has accommodated this change, quoting for it separately.
It’s wise to ask during the initial design consultation whether the team is open to making adjustments on-site. Not all companies will deviate from the original plan once construction begins, but this level of flexibility is not available with garden rooms built largely off-site.
Complete On-site Builds Take Longer – But Not Much
Modular garden rooms, which are mostly pre-built off-site, are designed for quick assembly. A small garden room can be installed in a day, while larger modular rooms are often completed within a week.
SIPs-based garden rooms typically take about two weeks (Monday to Friday) to complete on-site.
The duration of a complete on-site build will depend on the size and complexity of the project, as well as the number of people on the installation team. Based on our experience with medium to large garden rooms built entirely on-site, the process usually takes 2 to 4 weeks (Monday to Friday). This timeframe is quite reasonable considering the level of customisation and craftsmanship involved.
