How to Calculate Siding
Formula: Net area = perimeter × height + gables − openings. Add 10% waste. Panels = ceil(area ÷ (exposure/12 × panel length)). Squares = area ÷ 100.
Related: Try our roofing calculator, insulation calculator, or paint calculator for your project.
Siding Material Comparison
| Material | $/sq ft (installed) | Lifespan | Maintenance |
|---|
| Vinyl | $3-7 | 20-30 yrs | Low (wash yearly) |
| Fiber cement | $5-10 | 30-50 yrs | Paint every 15 yrs |
| Wood (cedar) | $6-12 | 20-40 yrs | Paint/stain every 5-7 yrs |
| Metal (steel) | $5-9 | 30-50 yrs | Low |
Tip: Don't forget accessories: starter strip, J-channel, corner posts, trim, soffit, fascia, and house wrap. These add 15-25% to material cost.
How to Install Siding: Step by Step
Proper installation is as important as choosing the right material. Follow these steps for vinyl or fiber cement siding — the two most popular DIY-friendly options.
- Prepare the wall. Remove old siding, repair any rotted sheathing, and install house wrap (Tyvek or similar) with taped seams. House wrap is your secondary weather barrier.
- Install trim and corners. Put up corner posts, J-channel around windows and doors, and starter strip along the bottom edge. The starter strip must be perfectly level — it sets the angle for every row above.
- Hang the first row. Lock the first panel into the starter strip and nail through the top nail slot. Leave 1/4" gap at corners and trim for thermal expansion. Nails should be loose enough that the panel can slide.
- Work upward. Each panel locks into the one below. Stagger vertical seams by at least 24 inches between rows. Check level every 2–3 rows.
- Finish around openings. Cut panels to fit around windows and doors, leaving 1/4" expansion gaps. Install J-channel or drip cap above windows to shed water.
- Top row and soffit. Measure and rip the final row to fit under the eaves. Install soffit and fascia to complete the enclosure.
Siding Needed by Home Size
| Home Size | Stories | Wall Area (approx) | Squares | Vinyl Panels (12ft, 8" exp) |
|---|
| 1,000 sq ft | 1 | ~900 sq ft | 9 | ~135 |
| 1,500 sq ft | 1 | ~1,300 sq ft | 13 | ~195 |
| 1,500 sq ft | 2 | ~1,600 sq ft | 16 | ~240 |
| 2,000 sq ft | 2 | ~2,000 sq ft | 20 | ~300 |
| 2,500 sq ft | 2 | ~2,400 sq ft | 24 | ~360 |
| 3,000 sq ft | 2 | ~2,800 sq ft | 28 | ~420 |
Wall area = perimeter × wall height − openings (windows/doors). Gable ends add ~50–100 sq ft each. Use our square footage calculator for irregular wall shapes.
Accessory Checklist
Siding panels are only part of the job. Budget for these accessories:
- Starter strip: One continuous strip along the bottom of each wall (~$0.50/ft)
- J-channel: Around all windows, doors, and at the top row (~$0.75/ft)
- Corner posts: One per outside corner (~$10–$15 each)
- House wrap: Covers entire wall area (~$0.15/sq ft)
- Soffit and fascia: Eaves and rake edges (~$3–$6/lin ft)
- Nails: Aluminum or galvanized siding nails, ~1.5 lb per 100 sq ft
Maintenance and Longevity
- Vinyl: Wash annually with a garden hose and mild soap. Pressure wash on low setting only — high pressure can drive water behind panels. Avoid dark colors in hot climates (warping risk).
- Fiber cement: Paint every 15–20 years (pre-primed boards need paint at installation). Caulk joints annually. Very durable but heavy — wear a dust mask when cutting.
- Wood: Paint or stain every 5–7 years. Replace rotted boards promptly. Cedar and redwood naturally resist rot but still need finish.
- Metal: Wash as needed. Touch up scratches to prevent rust. Very low maintenance.
Common Siding Mistakes
- Nailing too tight. Panels need room to expand and contract with temperature. Nail heads should sit 1/32" above the panel, not crimped tight.
- Forgetting house wrap. Without it, water that gets behind siding can rot the sheathing. Always install with taped seams.
- Not leveling the starter strip. A crooked starter strip means every row above is crooked. Use a laser level.
- Overlapping seams incorrectly. Overlap panels by 1 inch, with the overlap facing away from prevailing winds and sightlines.
- Cutting fiber cement dry. Always use a dust-reducing blade or shears. Silica dust from cutting is a health hazard.
FAQ
How much siding for 1,500 sq ft home?
~1,200-1,400 sq ft of wall area = ~13-14 squares = ~200 panels of 12ft vinyl (8" exposure).
What is siding exposure?
The visible portion after overlap. A 12" panel typically has 8" exposure. Only exposure counts toward coverage.
Average siding cost?
Vinyl $3-7/sq ft, fiber cement $5-10/sq ft. 1,500 sq ft home = $7,000-15,000 installed.
Vinyl vs fiber cement?
Vinyl cheaper, low-maintenance. Fiber cement (Hardie) more durable, paintable, termite-resistant, costs 50-100% more.