Hardscaping guides
The core of every hardscaping guide is the same: excavate, build and compact an aggregate base in layers, set a bedding layer, lay the units, restrain the edges, fill the joints, and give water somewhere to go. Today's Homeowner's block wall guidance describes 4 to 6 inches of dense graded base gravel - around 8 inches for walls over 4 feet - compacted in 2 to 3 inch lifts, with 4 to 6 inches of drainage gravel behind each course. Depths for your specific project depend on soil, load and the manufacturer's instructions.
You are not reading this to build it yourself. You are reading it so you can tell whether the people you hired are doing it properly, and so you know what the words in your contract mean.
Base preparation. This is the whole job. Soil is excavated below the finished level to make room for aggregate. The aggregate is spread and compacted in thin layers rather than all at once - compaction only works to a limited depth per pass, which is why lifts exist. Today's Homeowner describes tamping 2 to 3 inches at a time and warns that any soft spots allow blocks to settle and shift. The same principle applies under flatwork. A base dumped in one 8-inch lift and rolled once is not a compacted base.
Retaining walls. A block wall sits on a compacted gravel base, is built level course by course, has gravel backfill behind each course to create a drainage zone, and often has a perforated pipe at the base that daylights downhill. Today's Homeowner recommends that pipe particularly for rainy climates and clay soils. Height, soil type and anything loading the wall from above determine whether it needs an engineered design - Fixr's data reflects engineering generally being required above four feet, but the threshold is set locally.
Joints and edges. Edge restraint stops the outer units migrating outward, which is what makes the whole field loosen. Joint sand locks units together. Today's Homeowner's polymeric sand procedure is: sweep in with a coarse broom, compact to remove air pockets, blow off excess with a leaf blower on low, water in exactly per the manufacturer's instructions, then leave it 24 hours and stay off with vehicles for 48. Skipping the excess-removal step is what causes the white haze people complain about.
Drainage. Every guide ends here because every failure starts here. Surfaces slope away from the house. Walls have a gravel drainage zone and an outlet. Sites with runoff problems may warrant permeable pavement, which EPA describes as infiltrating rain and snowmelt into the soil and gravel below rather than shedding it.
Choosing hardscaping an approach
The judgement calls that decide the bill, before anyone quotes you.
- Learn to recognize a lift Watch how the base goes in. Thin layers, each compacted, is right. One deep dump with a single pass is the shortcut that costs you in year three.
- Look for the drainage zone behind walls You should see gravel going in behind the blocks as courses go up, not soil pushed straight against the back face.
- Ask where the drain pipe comes out A drain that doesn't daylight somewhere downhill isn't a drain. Ask to be shown the outlet.
- Check edge restraint exists It's cheap, it's fast, and skipping it is common. Without it the perimeter units creep and the whole field loosens over time.
- Follow the joint sand procedure exactly Excess swept off before watering, correct water volume, then left alone. Most polymeric sand complaints are procedure failures, not product failures.
All hardscaping guides
Hardscape Planning Guide
Patio Design Guide
Outdoor Kitchen Planning Guide
Retaining Wall Guide
Drainage Planning Guide
Hardscape Permit Guide
HOA Hardscape Guide
Outdoor Lighting Design Guide
Fire Feature Safety Guide
Soil and Base Prep Guide
Hiring a Hardscape Contractor
Hardscape Maintenance Guide
Seasonal Hardscape Construction
Climate and Material Durability
Hardscape Trend Guide 2026
Where these figures come from
Sources last checked
- Today's Homeowner - Leveling the Gravel Base for a Block Retaining Wall · retrieved 2026-07-26
- Today's Homeowner - Polymeric Sand · retrieved 2026-07-26
- Fixr - Retaining Wall Cost (engineering notes) · retrieved 2026-07-26
- EPA - Soak Up the Rain: Permeable Pavement · retrieved 2026-07-26
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