That's an excellent question! There's nothing more frustrating than watching a beautiful, heavy park bench slowly disappear into the lawn. The key is to create a stable, load-distributing foundation that fights sinking and stays level. Here are the most effective solutions.
The top recommendation is using concrete pavers or a slab. This is the gold standard for permanent installation. Dig a hole slightly larger than the paver and about 4-6 inches deep. Fill the bottom with 2-3 inches of compacted gravel or crushed stone for drainage. Then, add a layer of coarse sand, level it meticulously, and set your heavy-duty concrete paver or slab. Finally, place your bench legs directly on this solid, level surface. The wide area disperses the weight, preventing those legs from acting like stakes.
A fantastic and highly effective alternative is a gravel and crushed stone foundation. This method offers superior drainage and is easier to install. Dig a hole for each bench leg, roughly 8-10 inches deep and wide. Fill it halfway with coarse gravel, then add a layer of finer crushed stone or decomposed granite. Use a tamper to compact each layer firmly. The interlocking stones create a solid, non-shifting base that won't wash away or allow sinking.
For a simpler fix, consider plastic or composite patio deck tiles designed for grass. These interlocking tiles sit on the surface and spread the load. While best for slightly lighter benches, they are a quick option. Alternatively, burying large, flat stones at least 3 inches thick under each foot can work for moderately heavy benches.
Pro Tips for Success: Always ensure your base material is perfectly level. Use a long spirit level across all contact points. Compact every layer of gravel thoroughly—this is crucial for stability. Choosing a slightly wider base than the bench feet (like a larger paver) dramatically increases stability. With the right foundation, your bench will remain a steady and welcoming spot for years to come, without the slow sink into the earth.