Inputs
Formulas Used
Perimeter (rectangle) = 2 × (Length + Width)Effective length = Perimeter × Curve factor × (1 + Waste%)Segments effective = Σ( Segment length × Segment curve factor ) × (1 + Waste%)Pieces = ceil(Effective length ÷ Piece length)Spike count along = ceil((Perimeter × 12) ÷ Spacing)Total spikes = Along + Joints + Corners×2 + Entries×ExtraBase volume (cu ft) = Perimeter × Trench width(ft) × Base depth(ft)Haunch volume (cu ft) = Perimeter × 0.5 × Depth(ft) × Width(ft)Geo rolls = ceil( Perimeter ÷ (Roll length × (1 - Overlap%)) )Labor hours = Effective length ÷ Productivity(ft/hr)
How to Use
- Select your unit system first.
- Choose layout mode: rectangle, known perimeter, or multi‑segment.
- Enter dimensions, curve factors, waste, and piece length.
- Set spikes, corners, entries, and soil/frost/traffic parameters.
- Optionally enable geotextile and cost estimator values.
- Press Calculate, then export results to CSV or PDF.
Edge Restraint Types
| Type | Material | Typical Use | Notes |
|---|---|---|---|
| Flexible edging | Plastic | Curves, residential | Fast to install, economical, needs spikes. |
| Rigid edging | Aluminum | Straights, light curves | Clean lines, corrosion resistant, mid cost. |
| Steel edging | Steel | Heavy-duty borders | Very durable, may require coating. |
| Concrete haunch | Concrete | Vehicle areas, tight radii | Best lateral restraint, slower to install. |
Spacing & Reinforcement Guide
| Traffic class | Spike spacing (in) | Spike length (in) | Corner reinforcement |
|---|---|---|---|
| Cars | 12 | 8 | 2 spikes per corner |
| Light truck | 10 | 10 | 2–3 spikes per corner |
| Occasional service | 8 | 12 | 3 spikes per corner |
Trench, Base, and Haunch Specs
| Soil class | Trench width (in) | Base depth (in) | Haunch (W×D in) |
|---|---|---|---|
| Well-drained | 6 | 4 | 4 × 3 |
| Average | 6–8 | 4–6 | 4–5 × 3–4 |
| Poor-draining | 8–10 | 6–8 | 5–6 × 4–5 |
Cost & Productivity Benchmarks
- Typical piece cost: $7–$12 per 8 ft section.
- Spike cost: $0.30–$0.60 each; connectors: $1–$2 each.
- Concrete bag (≈0.6 cu ft): $5–$9 per bag.
- Labor productivity: 25–45 ft per hour per installer.
Results
Enter inputs and press Calculate to see results here.
Example Data Table
| Scenario | Perimeter (ft) | Pieces | Spike spacing (in) | Total spikes |
|---|---|---|---|---|
| Compact car driveway | 120 | 16 | 12 | 150 |
| Light truck driveway | 150 | 20 | 10 | 200 |
| Service access | 180 | 24 | 8 | 270 |
Worked Example
Scenario: Rectangle 40 ft × 20 ft driveway, cars traffic, curve factor 1.05, waste 7.5%, 8 ft pieces, spike spacing 12 in, 1 spike per joint, 4 corners, 2 entries with 4 extra spikes each, frost depth 4 in, trench 6 in × base 4 in, haunch 4 in × 3 in.
- Perimeter = 2 × (40 + 20) = 120 ft.
- Effective length = 120 × 1.05 × 1.075 = 135.45 ft.
- Pieces = ceil(135.45 ÷ 8) = 17 pieces.
- Spikes along = ceil((120 × 12) ÷ 12) = 120.
- Spikes at joints = 17 × 1 = 17; corners = 4 × 2 = 8; entries = 2 × 4 = 8.
- Total spikes = 120 + 17 + 8 + 8 = 153 (recommend 8 in spikes).
- Base volume = 120 × (6/12) × (4/12) = 20 cu ft.
- Haunch volume = 120 × 0.5 × (3/12) × (4/12) ≈ 5.00 cu ft ⇒ bags = ceil(5.00 ÷ 0.6) = 9.
- Optional geotextile: width 3 ft, roll 100 ft, 10% overlap ⇒ effective 90 ft/roll. Rolls = ceil(120 ÷ 90) = 2. Area = 120 × 3 = 360 sq ft.
| Item | Value |
|---|---|
| Perimeter | 120 ft |
| Effective length | 135.45 ft |
| Pieces | 17 @ 8 ft |
| Total spikes | 153 (8 in recommended) |
| Connectors | 16 |
| Base volume | 20 cu ft |
| Haunch volume | ≈ 5.00 cu ft (9 bags) |
| Geotextile | 2 rolls, 360 sq ft (optional) |
FAQs
What does curve factor represent?
It accounts for extra length at bends and radii. Higher factors add material to accommodate kerfing, flex sections, and tighter curves, reducing field splicing and waste.
How do I choose spike spacing?
Heavier traffic and poor soils need tighter spacing. Start at twelve inches. Use ten inches for light trucks, and eight inches for occasional service traffic or weak subgrades.
Which spike length should I use?
Eight inches suits mild climates. Ten inches for shallow frost or marginal soils. Twelve inches where frost is deep or soils are weak and saturated, especially on curves and entries.
When should I use a concrete haunch?
Use haunching for flexible edging under vehicle loads, tight curves, or freeze‑thaw cycles. It stabilizes borders and resists lateral movement from tires and plows.
How do geotextile rolls improve performance?
Geotextile separates base from subgrade, limiting fines migration and pumping. It helps maintain thickness and drainage, and can reduce rutting under repeated vehicle loading.
Are cost results exact?
They are planning estimates. Prices vary by region, brand, and season. Confirm current supplier pricing and local code requirements before purchasing or scheduling crews.