How to Estimate a Siding Installation | Reddit & LinkedIn

Siding is measured in squares, where one square equals 100 square feet of wall. Measure each wall's height and width, multiply for area, and total the squares. Subtract large openings like garage doors, but do not subtract standard windows and doors, because the cutting and trimming around them eats the material you would have saved.

Add 10 to 15% for waste, and more on a cut-up elevation with lots of corners, gables, and dormers. A boxy ranch wastes little. A two-story with three gables and a wraparound porch wastes a lot. Your waste factor is a judgment call that separates an accurate estimate from a guess.

Price by system, because the spread is wide. Builder-grade vinyl is the cheapest per square, insulated vinyl costs more, and fiber-cement like the common lap-board systems costs several times vinyl once you include the specialized fasteners and paint. Engineered wood sits in between. Quote the exact product line, not a category, so the client is comparing the same thing across bids.

Do not forget the accessories. Starter strip, J-channel, corner posts, trim, house wrap, flashing, and fasteners add up fast and are the first things a rushed estimate leaves out. Price them as their own lines so nothing hides.

Set a labor rate per square that reflects your crew's real pace, then adjust for the specific house. A single-story with simple runs installs fast. Add hours for second-story work, staging, steep cut-ins, and any wall that needs extensive prep or rot repair before siding goes up.

Tear-off is its own line. Removing old siding, hauling it, and dealing with whatever you find underneath, like damaged sheathing or missing wrap, is real labor and real dump fees. Estimating tear-off as zero because you are focused on the new material is a classic way to lose a day of pay.

The usual leaks are trim and detail work, tear-off and disposal, house wrap and flashing, and prep on walls that are not straight or sound. Each feels small on its own, and together they can be 20% of the job. A client comparing bids rarely sees these lines, so the contractor who priced them looks higher and the one who skipped them wins and then bleeds.

The fix is a checklist you never deviate from. Every siding estimate gets the same line items whether or not the walk-through reminded you, so tear-off, wrap, and trim are always priced.

A tool that starts from photos and your own price list removes the blank-page problem. In ContractShield, snap photos of each elevation, note the system and square footage, and the AI drafts material, accessories, tear-off, and labor line by line for you to approve. Every line shows where its price came from, your template or an AI estimate, and the AI never invents your labor rates or markup.

Because your accessory and tear-off lines live in your template, they show up on every estimate automatically. That is how you stop underbidding the details, and how a siding quote drops from a couple of hours to about 25 minutes.