When planning a garden room, it’s natural to look for ways to keep costs down. One question we sometimes get asked is whether you can use existing paving slabs as a base for a new garden room.
While it might seem like a smart way to save money (and it sometimes can be), there are important factors to consider before building a not-so-cheap garden room on existing paving.
Can you use existing paving slabs for a garden room base?
The short answer is: technically yes you can use existing paving slabs, but we generally don’t recommend it.
Our preferred method for solid garden room foundations is to use stainless steel ground screws. That said, we have built gardens room before on paving slabs but only when we know the base is absolutely sound and solid.
And yes for those asking, every garden room should be built on solid foundations.
Here’s why you should think carefully before proceeding with an existing paving slab base:
Condition and age of the paving slabs
Paving slabs that have been in your garden for years may have weathered considerably. They might have invisible cracks, be worn thin in places or have become brittle with age.
Building a structure that weighs several tonnes on less than ideal paving is risky.
Levelness and stability
Garden paving often settles unevenly over time. What looks level to the eye may actually have subtle slopes or dips that could cause major problems once you place a building on top.
Your garden office or garden gym needs a perfectly level base to avoid structural issues down the line.
What’s underneath matters
Perhaps the biggest concern is what’s beneath those paving slabs. Were they professionally installed with proper foundations or simply laid on sand or soil?
Without knowing the preparation that went into the original paving, you’re taking a significant risk.
Weight considerations
Modern garden rooms are substantial structures. A well-built, insulated garden room with proper glazing, electrics, furniture and interior finishes will weigh considerably more than the occasional foot traffic or garden furniture set your paving was designed for.
Potential issues with using existing paving slabs
Even if your paving looks good now, problems can develop over time when it’s supporting a garden room. Things such as:
- Uneven settlement once your garden room is installed
- Cracking and movement
- Drainage issues
A garden room is a significant investment, usually costing between £15,000 and £35,000 depending on the size and specifications. Attempting to save a fraction of that cost by using existing paving could put your entire investment at risk. Learn more on garden room costs here.
Better alternatives for garden room foundations
Ground screws – our recommended option
At Lux Garden Rooms, we strongly recommend ground screw foundations for garden rooms. These modern foundation systems offer a number of great benefits:
- Quick and clean installation without digging up the ground
- Minimal disruption to your garden
- Strong, stable support for your garden room
- Environmentally friendly with 60% lower carbon emissions than concrete
- Can be installed in all weather conditions
- Perfect level base for your garden room
We think ground screws are a fantastic option and will provide stability and longevity for decades to come.
Concrete foundations
In some circumstances, concrete foundations may be appropriate. This may be very large structures or specific ground conditions.
While more disruptive, messy and time-consuming than ground screws, concrete does provide excellent stability when properly prepared.
Have a read of our post on concrete vs ground screws for foundations.
Why proper foundations are worth the investment
Whether you’re building a simple garden office or a luxury outdoor sauna, proper foundations are essential.
Cutting corners here will cost you money in the long run. The foundations are literally what everything else rests on – if they fail, the entire structure is compromised.
At Lux Garden Rooms, we include proper foundations in all our garden room prices – no hidden extras or cut corners. As mentioned, our preference is environmentally friendly, solid, stainless steel ground screws.
Our approach is simple: build it right from the ground up. This starts with appropriate, professional foundations that will support your garden room for decades to come, not just a few years.
FAQs
Can I save money by using my existing patio for a garden room base?
While it may save money initially, we don’t recommend it due to the risks of uneven settlement and long-term stability issues. The potential repair costs far outweigh the initial savings.
What’s the minimum foundation requirement for a garden room?
All garden rooms need proper foundations. The two main options are ground screws (our preferred choice) or concrete foundations. Learn more about why foundations are essential.
How much extra will proper foundations cost compared to using my existing paving?
Although proper foundations add to the initial cost, they’re included in our garden room prices. The peace of mind and long-term stability they provide make them an essential investment, not an optional extra.
Can I build a small garden room without foundations?
No, even small garden rooms need proper foundations for stability and protection from ground moisture. Size doesn’t eliminate the need for proper support.
What if my paving slabs look perfectly level and stable?
Even paving that appears level can have subtle slopes or weaknesses that become problematic once several tonnes of building are placed on top. Without knowing how they were installed or what’s underneath, you’re taking a significant risk.
What foundation method do you recommend?
We strongly recommend ground screws for garden room foundations. They’re quick to install, environmentally friendly, create a perfectly level base and provide superior long-term stability compared to using existing paving.
Can I remove the paving slabs and then install proper foundations?
Yes, this is a much better approach. Removing the paving slabs allows us to properly assess the ground conditions and install appropriate foundations.