If you’re investing in a garden building, the base underneath it matters more than most people realise. We’ve been called out across Slough to look at sheds that lean, doors that won’t close, and concrete that’s cracked within a year. In most cases, the issue isn’t the shed — it’s the base.
When a concrete shed base in Slough homeowners rely on is built, it should remain level and stable for decades. When it’s rushed, under-prepared or poured onto poor ground, it can start to sink surprisingly quickly.
Slough properties vary a lot. Some gardens sit on firm, well-draining ground. Others have softer subsoil, old made ground, or areas that were previously landscaped. We regularly see problems caused by:
A common situation is where someone lays concrete directly onto soil with minimal preparation. It might look solid on day one, but once the ground beneath settles or becomes saturated in winter, the slab begins to drop unevenly.
Concrete itself is strong in compression, but it relies entirely on what sits beneath it. If the ground isn’t properly compacted, the slab simply bridges weak spots. Over time, those weak spots compress and the concrete follows.
In Slough, we often encounter clay-heavy areas. Clay expands when wet and shrinks in dry spells. Without correct depth and sub-base preparation, movement is almost guaranteed.
Preventing sinking isn’t complicated — but it does require proper procedure.
We excavate to a suitable depth based on the size and intended use of the structure. A lightweight garden shed differs from a log cabin or workshop. Removing topsoil is essential — organic material decomposes and causes settlement.
A layer of MOT Type 1 sub-base is installed and mechanically compacted in stages. This forms the true load-bearing layer. Without this, even thick concrete can fail.
Accurate shuttering ensures clean edges and correct levels. We also consider slight falls where appropriate so water doesn’t sit against the slab.
For heavier buildings, we include steel mesh reinforcement. This doesn’t stop settlement caused by poor ground, but it does control cracking and improve long-term durability.
A typical domestic shed base in Slough is usually around 100mm thick, depending on load requirements. Thinner pours are one of the main reasons we see slabs fail.
One thing that often surprises homeowners is how much access affects quality. Tight side passages in older Slough terraces mean materials must be moved carefully. If installers try to shortcut preparation because access is awkward, that’s when problems start.
We plan access before the day of the pour. That includes checking:
Taking time at this stage prevents disruption and ensures the slab is built properly rather than adjusted on the fly.
Most standard shed bases don’t require planning permission, but larger garden buildings sometimes fall under permitted development rules. Homeowners can review official guidance here:
Permitted development rights for householders – GOV.UK
It’s always sensible to check before installing larger log cabins or structures near boundaries.
Enquiry: We discuss size, intended use, and access details.
Site check: Ground levels, drainage and soil condition are assessed.
Preparation: Excavation, sub-base installation and shuttering.
Pour: Concrete is placed, levelled and finished.
Curing: The slab is left to gain strength before heavy loading.
Aftercare: We advise on when to position the shed safely.
Rushing curing time is another mistake we see. Concrete continues strengthening for weeks. Loading it too soon can cause hairline cracking or surface damage.
Can a sunken shed base be repaired?
Minor edge settlement can sometimes be addressed, but widespread sinking usually means replacement is the safest long-term solution.
How long should a concrete shed base last?
With proper preparation, decades. Settlement issues usually show within the first couple of years if the groundwork was poor.
Is thicker concrete always better?
Not on its own. Thickness helps, but ground preparation matters more than simply pouring deeper concrete.
If you’re unsure about your existing base, or planning a new installation, you can read more about our approach on our concrete shed base install Services page