Siding Calculator
Squares of vinyl siding and house wrap for a home.
Siding squares
13.9 sq
Wall area
1,260 sq ft30×40 footprint, 9 ft walls (gross)
Siding to buy
13.9 squares1 square = 100 sq ft, incl. 10% waste
House wrap
2 rolls9×100 ft rolls
Siding cost (est.)
$4,410~$3.50/sq ft vinyl
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Vinyl siding is one of the more approachable exterior projects — it clips together and needs no painting. The one rule that governs everything: vinyl expands and contracts a lot, so it must hang loosely and be free to move, or it buckles in the heat.
DifficultyIntermediate
TimeSeveral weekends for a whole house
SkillsComfortable on ladders/scaffold and keeping long courses level
PermitsRe-siding often needs a permit; house wrap (weather-resistive barrier) is typically required by code.
Tools you'll need
- Snap-lock punch and a zip (unlock) tool
- Tin snips and a utility knife
- Chalk line and a long level
- Hammer or nail gun set for loose nailing
- House wrap and tape
Step by step
- Wrap the houseInstall house wrap over the sheathing as a weather barrier, taping seams, before any siding goes up.
- Set a level starter stripSnap a level line and install the starter strip — the entire wall follows it, so get it dead level.
- Trim out openingsRun J-channel and corner posts around windows, doors, and corners to receive the panel ends.
- Hang panels looseLock each panel into the one below and nail in the center of the slots, leaving ~1/32" — don't drive nails tight. Panels must slide.
- Overlap and finishOverlap panel ends away from the main view, stagger seams course to course, and finish under eaves with utility trim.
Common mistakes
Nailing vinyl tight
Nailed-tight vinyl can't expand and buckles in summer. Center nails in the slots and leave them slightly loose.
An unlevel starter strip
Every course copies the starter. Snap a level line and check it before nailing.
Caulking panel butt joints
Overlaps are designed to move — caulking them traps water and causes buckling. Leave them free.
Safety
- Set up stable scaffold or ladders; never overreach with long panels.
- Mind power service lines where siding meets the eave.
Frequently asked questions
How much siding do I need?
Enter your home's footprint and wall height above — the calculator returns squares of siding (with 10% waste) plus house wrap.
Do I need house wrap?
Yes — a weather-resistive barrier behind the siding is code in most areas and keeps the wall dry.
Why hang vinyl siding loosely?
Vinyl moves up to ~1/2" over a long panel with temperature. Loose nailing lets it expand without buckling.
Next steps for this project
Sources & references
- Vinyl Siding Institute installation manual