How to Install IKEA Runnen Decking on Grass: Step-by-Step Guide

Installing Runnen decking directly onto grass is a popular and cost-effective way to create a stable, outdoor living space without the need for extensive groundwork or a permanent foundation. This method involves preparing the grass surface, laying a permeable weed barrier, and then securing the deck boards with appropriate fixings. The result is a low-profile, durable surface that feels solid underfoot and blends well with a natural garden setting.

Understanding Runnen Decking and Grass Foundations

Runnen is a robust composite decking brand known for its wood-plastic composite (WPC) boards. These boards are designed to be both durable and lightweight, with a texture that provides reliable grip even when wet. When planning to install Runnen decking on grass, it is essential to recognize that the grass and topsoil alone will not provide a stable base. The ground must be levelled, compacted, and supported to prevent future sinking or unevenness, ensuring the longevity of your deck.

Site Preparation and Ground Assessment

Before any materials arrive, clear the area thoroughly of grass, weeds, and debris. For a successful installation, you need to address the soil conditions. If the ground is soft, clay-heavy, or prone to pooling water, consider installing a simple sub-base. A 50mm layer of compacted MOT Type 1 aggregate or a similar crushed stone, topped with a layer of sand, provides excellent load distribution and drainage. This step is crucial for preventing future maintenance issues and ensuring a flat, stable surface for your Runnen boards.

Once the sub-base is in place, compact it thoroughly using a plate compactor. This creates a firm foundation that mimics the stability of concrete without the same level of formwork and curing time. After compaction, lay a permeable weed membrane over the entire surface. This membrane prevents weeds from growing up through the gaps in your decking while still allowing moisture to escape, protecting both the boards and the sub-base from rot and decay.

Laying the Boards and Fixing Methods

With the groundwork complete, you can begin installing the Runnen decking boards. Start by placing the first row along a straight edge, ensuring a consistent 5-8mm gap between boards for drainage and thermal expansion. Use stainless steel or coated screws to fix the boards into the underlying joists. If you have not installed timber joists over the base, you can fix directly into the compacted sub-base using specialized ground fixings, though adding a simple frame is recommended for long-term stability.

As you continue to lay subsequent rows, use timber spacers to maintain uniform gaps. Stagger the joints between rows by at least 400mm to create a visually pleasing and structurally sound pattern. When you reach the final edge, carefully measure and cut the boards using a fine-toothed saw, ensuring clean edges and a professional finish.

Finishing Touches and Long-Term Care

After the last board is secured, inspect the entire deck for any wobbling or uneven boards and tighten the fixings as needed. For aesthetic purposes, you might choose to install a small perimeter channel or trim to conceal the edges and give a polished look. Runnen decking is inherently low maintenance, but to preserve its color and slip resistance, a simple rinse with a garden hose during the spring and autumn is usually sufficient. Avoid using harsh chemical cleaners that could degrade the surface finish over time.

By following these steps, you transform a patch of grass into a reliable outdoor area that can withstand heavy use and adverse weather. The key to success lies in the preparation—investing time in creating a solid, level base will ensure your Runnen decking remains flat, stable, and attractive for years to come.