Floating deck support grid estimator

Deck Block Spacing Calculator

Estimate deck blocks, pier blocks, or TuffBlock-style supports from deck length, deck width, target support spacing, waste, and block cost. Use it for floating deck planning before checking manufacturer load tables and local code.

Units

Deck length (ft)Deck width (ft)Max length spacing (ft)Max row spacing (ft)Waste / extra supports (%)Cost per block ($)

Deck blocks to buy

Support grid

Actual spacing

Rough cost

Deck blocks do not replace structural checks

This calculator counts supports from spacing only. Soil bearing, frost movement, uplift, beam spans, joist spans, block rating, product instructions, permits, and local deck code must be checked before building.

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Deck block spacing formula

Columns = ceiling(deck length ÷ max length spacing) + 1

Rows = ceiling(deck width ÷ max row spacing) + 1

Base blocks = columns × rows

Deck blocks to buy = base blocks × (1 + waste %)

Sample takeoff

A 16 ft by 12 ft floating deck with 4 ft maximum spacing lays out a 5 by 4 grid, or 20 deck blocks. With 5% extras, buy 21 blocks.A 4.8 m by 3.6 m floating deck with 1.2 m maximum spacing lays out a 5 by 4 grid, or 20 deck blocks. With 5% extras, buy 21 blocks.

Deck Block Spacing Calculator FAQ

How many deck blocks do I need?+

Divide deck length and width by the maximum spacing you plan to use, round each direction up, add one support line at each edge, then multiply rows by columns.Divide deck length and width by the maximum spacing you plan to use, round each direction up, add one support line at each edge, then multiply rows by columns.

Is this the same as a TuffBlock calculator?+

It can estimate a TuffBlock-style support grid, but the final spacing and load must follow the product manual and local deck rules.It can estimate a TuffBlock-style support grid, but the final spacing and load must follow the product manual and local deck rules.

Can deck blocks support every floating deck?+

No. Soil, frost, deck height, loads, beams, joists, and permits decide whether deck blocks are allowed. Treat this as a quantity takeoff only.No. Soil, frost, deck height, loads, beams, joists, and permits decide whether deck blocks are allowed. Treat this as a quantity takeoff only.