Garden room base preparation – When problems show up in a garden room, they’re often blamed on the cabin itself. In reality, the cause is usually much simpler — and hidden underground. Issues like movement, sticking doors, damp smells or water pooling almost always trace back to poor garden room base preparation.
In Ireland’s climate, where soft ground, high rainfall and drainage challenges are common, getting the base right is just as important as choosing the right cabin. This 2026 guide explains the most common mistakes buyers make, what a good base actually needs, and how to prepare your site properly before installation day.
Base For Your Building – Why Garden Room Base Preparation Matters
A garden room is only as good as what it sits on. Even the best-built structure can suffer long-term issues if the base beneath it is uneven, poorly drained or unstable.
Proper base preparation affects:
- The structural stability of the cabin
- Door and window alignment
- Moisture and damp control
- Long-term durability
- Warranty and aftercare
In short, a solid base protects your investment and ensures your garden room performs as intended for years to come.
Garden Room Foundations – The Biggest Garden Room Base Mistakes Buyers Make
Mistake #1 – Assuming Any Flat Area Is Good Enough
Grass, patios and old concrete pads often look flat on the surface, but appearances can be misleading. Lawns can hide soft spots, while older slabs may have settled unevenly over time.
Without proper preparation and compaction, these surfaces can shift under load, leading to movement in the cabin.
Mistake #2 – Ignoring Drainage
Water management is one of the most overlooked aspects of garden room base preparation. If water has nowhere to go, it will collect under or around the cabin.
This can lead to damp conditions, splash-back onto walls, and long-term damage to timber components.
Mistake #3 – A Base That Isn’t Level or Square
Even small level discrepancies can cause problems. Doors may not close properly, windows can bind, and roof structures can experience unnecessary stress.
Installers work to tight tolerances, and a base that looks “nearly level” often isn’t good enough.
Mistake #4 – Using the Wrong Base Type for the Site
There is no one-size-fits-all base. Soil type, slope, drainage conditions and access all influence what base will work best.
A solution that works perfectly in one garden may be completely unsuitable in another.
Mistake #5 – Making the Base Too Small
The base should match the cabin footprint precisely. A base that’s too small can expose edges to water runoff and reduce overall stability, particularly during heavy rain.
Garden Buildings – Types of Garden Room Foundations Explained
Concrete Slab Base
A concrete slab is one of the most robust options, particularly for larger or heavier garden rooms.
- Pros: Extremely stable, long lifespan
- Cons: Higher cost, more groundworks, permanent
Strip Foundations
Often used on sloping or uneven sites, strip foundations support the cabin at load points rather than across the full footprint.
- Pros: Suitable for difficult ground
- Cons: More complex and labour-intensive
Timber Frame (Raised) Base
A raised timber base can work well when properly designed, particularly where airflow underneath the cabin is beneficial.
- Pros: Faster installation, adaptable
- Cons: Requires excellent drainage and ventilation
Ground Screw or Pile Systems
Ground screws are increasingly popular for sloped gardens or sites with restricted access.
- Pros: Minimal ground disturbance, fast install
- Cons: Must be professionally installed
Drainage: The Most Overlooked Part of Base Preparation
Water always follows the easiest path. If the area around your cabin is flat or slopes towards it, water will naturally collect at the base.
Good drainage planning includes:
- A slight fall away from the cabin
- Gravel margins or drainage channels
- Considering where rainwater will go during heavy downpours
If your garden is already prone to waterlogging, drainage should be addressed before the base is built — not after.
Concrete Bases – Site Access, Machinery & Ground Conditions
Base preparation often requires machinery, materials and waste removal. Narrow side access, steps or soft ground can affect how work is carried out.
Soil type also matters. Clay-heavy ground behaves very differently to sandy or well-draining soil, especially after prolonged rain.
These factors can influence cost, timing and the type of base recommended.
How Level Is “Level Enough”?
Installers typically work to millimetre-level tolerances. A base that’s slightly out can cause visible problems once the cabin is assembled.
If a base fails inspection on installation day, the build may be delayed until it’s corrected — adding unnecessary time and cost.
Who Should Build the Base?
Some homeowners choose to prepare the base themselves, while others use a local builder or specialist groundworks contractor.
Whichever route you choose, responsibility matters. A poorly built base can affect warranties and long-term performance.
Loghouse can advise on base requirements in advance and help ensure your site is ready before installation.
Timing Your Base Preparation
Concrete bases need adequate curing time before installation. Rushing this step can compromise strength and level.
Seasonal conditions also matter. Winter rain and frost can slow progress, so planning ahead is always recommended.
Planning Permission & Base Preparation in Ireland (2026)
The base itself rarely triggers planning permission. Decisions are usually based on cabin size, height, location and use.
However, a permanent-looking base can influence how a structure is perceived, so it’s always wise to confirm requirements before starting work.
Pre-Installation Base Checklist
- Base matches the cabin footprint
- Surface is fully level and square
- Drainage has been considered
- Site access is clear
- Concrete bases fully cured
Garden Room Base Preparation FAQs
What is the best base for a garden room in Ireland?
It depends on the site. Concrete slabs, ground screws and raised timber bases can all work when chosen correctly for soil, drainage and access conditions.
Can I build a garden room on grass or paving slabs?
Grass is generally unsuitable, and paving slabs often lack the stability needed unless they sit on a properly prepared sub-base.
How long before installation should the base be ready?
Ideally, the base should be completed at least one to two weeks before installation, allowing time for checks and curing.
Does the base affect damp or condensation?
Yes. Poor drainage and airflow can contribute to damp conditions beneath the cabin.
Get the Base Right — First Time
A properly prepared base prevents problems before they start. If you’re planning a garden room in 2026, take the time to get the groundwork right.
Talk to the Loghouse team before installation day — we’ll help you choose the most suitable base for your garden, soil and layout.
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