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The figures here are estimates for planning. Material quantities depend on the batch, the site and the installer; the constants used are starting points and every one of them can be changed on the page. Confirm quantities with your supplier before ordering, and confirm anything structural, electrical or code-related with a licensed professional and your local building department.
Brand names appear where a constant comes from a manufacturer's published figure. Naming a product is attribution, not endorsement, and we have no affiliation with any manufacturer or retailer mentioned.