Timber Characteristics & Structural Guarantee

Our sleepers are made from real, pressure-treated timber. As a natural material, timber will continue to respond to its environment after installation, so this page explains what is normal to expect on delivery and over time, and what is covered under our structural guarantee.

In short: natural cracks, splits, waney edges, grain variation and minor handling marks are normal characteristics of solid timber sleepers and are not considered defects.

Our 10-year structural guarantee covers the sleepers against rot and insect attack, while still recognising the normal cosmetic and visual movement that occurs in natural timber.

Natural Characteristics of Timber Sleepers

Our sleepers are made from real, pressure-treated timber — a natural, structural material that will continue to respond to its environment after installation. As such, certain visual changes and natural features may be present either on delivery or as the sleepers settle into your garden.

Cracks, Splits & Surface Checking

Cracks, splits and surface checking are a completely normal and expected characteristic of solid timber.

These occur as the sleeper naturally dries and adjusts to changes in humidity, temperature and airflow. Following treatment, timber retains some internal moisture. As it acclimatises — particularly in warm, dry or sunny conditions — the outer layers can dry faster than the core, resulting in visible surface cracks.

These may:

Be visible on delivery or appear shortly afterwards
Become more noticeable during hot weather or in periods of low humidity
Reduce, tighten or close slightly in cooler or damp conditions
Vary in size and appearance over time

Importantly, these are natural surface characteristics and do not affect the structural integrity of the sleeper.

Movement Due to Weather & Environment

Timber naturally expands and contracts in response to changes in moisture and temperature.

In periods of strong sun, heat or dry weather, sleepers may dry further and develop more visible checking, surface cracks or movement. In wetter conditions, they may absorb some moisture again and subtly change in appearance. This ongoing movement is entirely normal for outdoor timber and is not a fault or defect.

Because sleepers are used outdoors, they are constantly exposed to changing garden conditions, including rainfall, heat, shade, airflow and seasonal humidity. These natural conditions all influence how the timber looks over time.

Waney Edges & Natural Variation

As a natural product, sleepers may also include:

Waney edges (where part of the natural curve of the tree remains)
Knots, grain variation and colour differences
Minor machining marks from cutting and processing
Natural variation from sleeper to sleeper

These features are typical of structural-grade timber and contribute to the authentic, heavy-duty character of sleeper products. They do not impact strength, performance or lifespan.

Handling & Minor Surface Marks

Due to their size and weight, sleepers are handled multiple times throughout production, treatment, storage and delivery — typically using forklift and pallet equipment.

As a result, you may occasionally notice:

Light scuffs or surface marks
Slight edge bruising or compression
Minor cosmetic imperfections from handling

These are purely superficial and are an expected characteristic of heavy structural timber products. They do not affect durability, strength or performance.

Where preferred, any more visibly marked face can usually be positioned inward, downward or below ground during installation.

Our 10-Year Structural Guarantee

While natural movement and cosmetic variation are to be expected, we stand behind the structural quality of our sleepers.

Our sleepers are pressure-treated for long-term outdoor use and are covered by our 10-year structural guarantee against rot and insect attack.

This means the guarantee is intended to cover the long-term durability of the timber itself in normal garden use, not the normal visual and cosmetic characteristics of natural timber.

The guarantee does not cover:

Natural cracks, splits or surface checking caused by drying and acclimatisation
Waney edges, knots, grain variation or colour variation
Minor handling marks, scuffs or edge bruising
Normal movement due to weather, sunlight, humidity or seasonal change
General cosmetic characteristics that do not affect structural usability

What We Will Replace

While the characteristics above are a normal part of working with natural timber, we will of course put things right if there is a genuine issue.

We will replace sleepers where:

A sleeper arrives structurally compromised (for example, broken through rather than naturally surface-checked)
There is significant damage affecting usability beyond normal handling marks
The wrong item or size has been supplied
There is a clear issue that falls outside the expected characteristics outlined above

If you believe there is a genuine problem, please contact us with clear photos shortly after delivery and we will review it promptly.

In Summary

If you notice cracks, surface marks, waney edges or other visual variation on delivery or shortly after installation, this is simply the normal behaviour of real timber sleepers settling into their environment.

It is a sign you are working with solid, heavy-duty natural timber — not thin manufactured boards — and it is exactly why sleeper-built structures are so strong, durable and long-lasting.