Choosing Timber Garden Sleepers: A Comprehensive Guide

Selecting the perfect timber sleepers to use in your landscaping project requires careful consideration. This guide helps you choose timber garden sleepers (also called railway sleepers) by considering all the important factors. 

We cover the pros and cons of hardwoods vs softwoods, grade categories, cost considerations and different applications. 

Different timber sleeper types

When it comes to choosing a garden sleeper type, you will need to decide which timber best suits your landscape. The type of wooden sleeper you choose impacts the durability, longevity and look of your sleepers. Below, we explore the timber types for garden spaces.

Hardwood sleepers

Manufacturers produce hardwood timber sleepers from dense trees like oak and teak. The wood is cut from the trunk and main branches of mature trees and milled into sleepers. A hardwood sleeper has an attractive grain and colour that adds visual appeal. 

Softwood sleepers

Softwood sleepers come from conifer evergreen trees like pine and spruce. They are not as naturally resistant to outdoor elements and often need to be pressure-treated to withstand weathering. 

Treating softwood involves adding chemical preservatives to the timber that protect it from insects and rot. When you treat a softwood sleeper, it can boost its lifespan outdoors.

What are the timber sleeper grades and standards?

They come in different quality grades that determine their structural integrity and appearance. Learning these industry grades will help match the right one for your project's needs. 

• GS Premium Grade: Top-grade sleepers with minimal knots and defects. For example, sleepers for garden walls provide maximum structural integrity. 
• GS Standard Grade: Widely used general-purpose ones. Allows some knots and variations. Suitable for most applications including garden border sleepers.
• GS Structural Grade: Economy grade for uses allowing more flaws. Best value for more hidden applications.

The British Standards Institution (BSI) outlines grading and quality standards for timber sleepers and landscape timber. Compliance with these standards is not compulsory. 

However, following the grades ensures your project meets structural integrity and safety levels. The main BSI standards relevant to timber sleepers are the following.

• BS EN 1912: Specifies strength grades for structural timber including hardwood and softwood sleepers. Defines Premium, Standard and Structural grades.
• BS EN 335: Outlines timber durability ratings based on resistance to biological hazards like rot and insects. Important for exterior use.
• BS EN 13990: Provides guidelines for visual grading parameters and acceptable knot sizes, grains and colouring.

How to choose the best timber sleeper

Depending on the type, hardwood and softwood have their own sets of pros and cons. Here, we dive deeper into the differences.

Hardwood

Softwood

What is the best sleeper type for you?

When buying sleepers, considering how and where you lay them is key to choosing the right timber type. Hardwoods and softwoods lend themselves to certain landscaping applications better than others based on their characteristics.

Hardwood applications

• Retaining walls and terraces: A strong wooden wall can hold back soil and prevent erosion, keeping the ground stable. Their longevity handles drainage issues over decades.
• Decking and steps: With their resistance to splintering and cupping, hardwood deck boards can withstand heavy foot traffic over many years. Improved stability prevents shifts and wobbling.
• Edging and borders: Hardwood sleepers keep lines straight for years when used to outline planting beds and yard boundaries.
• Planter boxes: Hardwood's stability suits raised garden beds and boxes. The material prevents long-term bulging, distortion and leakage when you fill them with soil. Its durability supports the growth of plants, vegetables and flower beds.

Softwood applications

• Gravel path edging: Use lightweight sleepers to border and contain loose stone walkways for gravel path edging. Their softness makes future adjustments easy.
• Temporary access paths: Fast-growing soft pine creates economical walkways that people can later repurpose elsewhere.
• Rustic accents: The modest appearance of unfinished softwoods blends with natural-style landscaping well.

How much do hardwood and softwood sleepers cost?

The material and labour costs can vary depending on whether you choose hardwood or softwood. Here, we compare sample projects to understand the cost differences. Note that all costs are based on estimates.

Hardwood retaining walls have a higher upfront cost but last decades with little maintenance. Softwood garden edging is budget-friendly initially. However, replacement is needed on a moderate level. 

Professional installation is best for hardwood walls while softwood edging can be a DIY job. Hardwood walls take longer to install but deliver long-term stability and durability.

Hardwood vs softwood: Which is best?

Choosing between hardwood or softwood-treated timber sleepers can be challenging. As outlined above, the right option depends on considerations like budget, lifespan, strength and appearance. To simplify the selection process, here is a checklist of key criteria to evaluate.

Lifespan needs

• Hardwood oak sleepers can last up to 25 years outdoors with proper installation. Their dense grain resists decay.
• Softwoods like pine have a shorter lifespan (between 5 - 15 years) before needing replacement. However, they are susceptible to rot over time.

Strength requirements

• Hardwoods have higher load-bearing capacities for structural elements like retaining walls and steps. Their rigidity supports heavy use.
• Softwoods lack the same structural strength but are suitable for non-critical decorative garden edging and borders.

Appearance preferences

• Hardwoods showcase attractive grains, varied colouring and wood textures. Great for visible decorative sleepers.
• Softwoods permit more knots and flaws. A good quality choice where appearance is not important.

Budget factors

• Hardwood ones have a higher upfront cost but greater long-term return on investment over decades.
• Softwoods provide budget-friendly projects with lower initial purchase prices. However, there will be more frequent replacement costs. 

Environmental conditions

• Dense hardwoods better withstand wet and humid areas. Resist direct ground contact exposure and moisture damage.
• Softwoods work best in drier above-ground applications where dampness is less likely. However, they require additional treatment.