Plan the work in the right order
Terraces do not all use the same layers. Keep only the steps that fit your base and finish. Excavation and a concrete slab are not automatic requirements.
Measure the area and choose a finish
Draw the outline, including recesses. Adjust lengths on the plan, then choose boards, pavers or tiles. Check thresholds and available height too: the finish and its support need enough room.
Draw and configure my terraceEstimate soil to remove
If ground level must be lowered, enter excavation depth. Area × depth gives the in-place volume. Excavated soil may take up more space: the bulking allowance helps estimate removal volume and skips.
Calculate excavationAllow for geotextile where specified
Enter roll size and overlap between strips. Terrace area is not necessarily the fabric area to buy: overlaps and cuts add material. Check the product and installation method for your base.
Calculate geotextile rollsEstimate each gravel layer
Calculate the foundation separately from any decorative finish. For each layer, enter depth and material. Bulk density converts volume to weight; ask the supplier for the relevant compaction and delivery figures.
Calculate gravel volume and weightAdd a slab only where needed
Bonded tiles and pedestal systems do not automatically need the same preparation. If a slab is selected, enter a thickness confirmed for the project. The tool calculates concrete, then bags or ingredients for the chosen supply method.
Calculate slab concretePlan the structure and supports
For decking, joists support the boards and any pedestals support the joists. For pavers placed directly on pedestals, the supports follow the pavers. Check spacing and edge supports in the system instructions.
Understand joists and pedestalsOrder the finish and complete the budget
Enter dimensions, layout, allowance and pack sizes. Add board or tile prices per m², joist prices per piece and pack prices for fixings or pedestals. Include preparation, delivery, edging and labour.
Check quantities and budgetFor a tiled finish, the guide explains layout, waste allowance and supplies. Outdoors, check the fall, substrate and suitable products separately for your installation system. Tiling guide
One plan, several calculations: a 20 m² example
A 5 × 4 m zone has an area of 20 m² and a perimeter of 18 m. Using depths chosen only for this example, excavating 25 cm gives 5 m³ of in-place soil; a 10 cm gravel layer gives 2 m³; a 12 cm slab gives 2.40 m³ of concrete. These are separate items before their allowances. The depths are not a construction specification to copy.
Keep the same shape through to the shopping list
“Continue my project” links in the terrace result reuse the zone in subsequent tools. Add only the missing depth, roll or material. Save in My projects to return to your settings on this device. If the shape changes, review and update calculations marked as out of date.
