Calculateur de Mur de Soutènement

To find out how many blocks you need, determine your total wall height (including at least one buried foundation course), divide by your block height to get total courses, and divide your wall length by block length to find blocks per course. Multiply courses by blocks per course, then add an 8% to 10% cutting and corner buffer.

Burying the bottom course below finished grade locks the wall into the earth (providing passive earth resistance at the toe), preventing the base from kicking out under the tremendous lateral soil pressure behind the wall.

A solid retaining wall requires a minimum 6-inch deep compacted crushed stone leveling pad beneath the bottom course (extending 3 inches in front and behind), plus a minimum 12-inch wide column of 3/4-inch washed clear crushed stone directly behind the blocks.

Water is the #1 cause of retaining wall failure. Hydrostatic pressure from trapped water adds immense weight against wall blocks. Clean 3/4" crushed drainage stone and a perforated drain pipe routed to daylight allow water to freely drain away before exerting lateral force.

Under the International Building Code (IBC Section 1807.2), retaining walls measuring 4 feet (1.2 meters) or higher from the bottom of the footing to the top of the wall typically require engineering drawings and municipal building permits.

Geogrid is a high-strength geosynthetic polymer mesh rolled horizontally between block courses and extending back into compacted soil. It mechanically ties the wall face to the reinforced soil mass behind it, and is generally required for walls over 3 to 4 feet tall or on slopes.

DIY retaining wall materials typically cost $15 to $30 per square foot of wall face (including blocks, base gravel, and drainage rock). Professionally installed concrete segmental block walls range from $35 to $75+ per square foot depending on site access, wall height, excavation, and geogrid requirements.