Around House Mulch Calculator

Foundation Bed Width Norms

Foundation beds around a house are usually 2 to 4 feet wide. The calculator multiplies the bed perimeter by its width to get square footage, then applies depth divided by 324 for cubic yards. A 120 ft perimeter at 3 ft wide is 360 sq ft, which at 3 inches deep is 3.3 cubic yards or about 45 bags of 2 cubic feet. Wider beds look fuller but use proportionally more mulch. The bed should slope away from the house at 6 inches per 10 feet so rainwater drains away from the foundation rather than pooling against the wall.

Mulch & Pest Prevention (Termites)

Mulch does not attract termites directly, but it holds the moisture termites need to survive. The University of Florida (UF/IFAS) confirms that the risk comes from damp mulch against wood, not the mulch itself. Keep a 6 inch bare inspection gap between the mulch and the siding so you can spot termite mud tubes early. A 12 to 18 inch dry buffer is even safer. Apply foundation mulch only 2 to 3 inches deep, because deep mulch traps moisture against the wall. Keep the gap dry at all times to break the bridge termites use to reach the structure.

Depth Around Siding

Mulch depth around siding should stay at 2 to 3 inches and remain 8 inches below the wood sill plate. The building code requires at least a 6 inch inspection gap between mulch and siding so inspectors can see mud tubes. Going deeper than 3 inches against the foundation holds water that rots siding and feeds fungi. Keep the mulch flat and never mound it against the wall. The International Society of Arboriculture (ISA) 2 to 4 inch depth standard applies, but foundation beds stay at the low end of that range for moisture safety.

What mulch is best around a house?

Cedar and cypress mulch are the best choices around a house because their oils resist insects and decay. Pine bark and hardwood also work at 2 to 3 inches. Avoid piling any mulch against the wall. Some homeowners use rock or gravel in the first 12 inches off the foundation as a dry, pest-resistant buffer, then organic mulch beyond it for the planting zone.

How often should foundation mulch be refreshed?

Foundation mulch needs a refresh once a year, usually in spring. Top-dress with 1 inch to restore color and depth rather than piling new mulch on old. Rake the old layer first to break any water-repelling crust. Check the inspection gap each refresh and clear any mulch that has crept against the siding over the season.

Drainage and Grading Around the Foundation

Grading is as important as depth in a foundation bed. The soil and mulch should slope away from the house at 6 inches per 10 feet so rainwater drains away from the wall, not toward it. Water that pools against the foundation seeps into the basement and feeds the moisture termites need. Before mulching, check that the grade falls away from the house and fix any low spots that hold water. Then apply the mulch at a flat 2 to 3 inches.

Gutters and downspouts work with the bed to manage water. Extend downspouts past the mulch bed so the discharge does not soak the foundation zone. Keep the inspection gap clear and dry year round. A bed of rock in the first 12 inches off the wall, with organic mulch beyond it, gives a dry pest-resistant buffer that still looks finished. The University of Florida (UF/IFAS) confirms that dry, well-drained foundation beds carry far lower termite risk than damp ones, so drainage is the single best defense.

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