A schedule of openings turned into frames, leaves and the hardware that goes with them.
Foundation, roof and structure. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Doors and Windows Estimator tool.
Doors and windows are counted, not measured, which makes this the simplest estimate in the catalogue and the one most often got wrong. The reason is that the count is decided by a schedule, and a schedule that is a room list rather than a door and window list will always be short. The estimator works from the counts you enter, by type and size, and returns the units, frames and ironmongery each one needs. It does not add a waste percentage to a door, because a door is not cut from a longer door. It does not invent a count when you leave the schedule blank, because a blank schedule is a design that has not been finished rather than a house with no doors.
A three bedroom house with nine internal doors and eleven windows: the doors bring nine units, nine frames, nine linings and eighteen hinges if two hinges per leaf are specified, plus nine locksets and nine sets of handles. The windows bring eleven units with their frames and sills, and the opening restrictors or stays the specification calls for. Nothing is multiplied by a waste factor, because the order is whole units. Change a window to a door and the schedule moves by one in each direction, which is exactly what a schedule is for.
Count them from the door and window schedule, by type and size, then let the estimator add the frames, linings and ironmongery each unit needs. Two counts drive everything: how many units of each type, and what specification each type carries. A room list is not a schedule, because a bedroom door and a bathroom door are different products with different ironmongery, and a count that mixes them produces an order that has to be corrected on site.
Frames and architraves are added where your specification calls for them, and ironmongery is counted from the unit types: hinges by leaf, locksets and handles per door, stays and restrictors per window. What is not included is the installation side, which covers sealant, foam, packers, fixings and the labour to hang and adjust. Those are priced by the fitter, and folding them into a unit price hides the difference between a straightforward opening and an awkward one.
No. A waste allowance exists because a material is cut from a longer length or a larger sheet, and a door is not cut from anything. Waste on doors and windows is really damage, mis measurement or a change of mind, and the way to handle that is a stated contingency rather than a percentage applied to every unit. The estimator returns whole units, which is what arrives on the lorry.
It reports the schedule as missing and leaves the line empty. A blank door count means the schedule has not been made yet, not that the building has no doors, and filling the gap with a count per room would produce an order that looks complete and is wrong. The page is designed so an unfinished design shows as unfinished, which is more useful than a number that has to be unpicked later.
Hinges are counted per leaf, so a pair of doors carries twice the hinges of a single leaf, and the specification decides whether that is two or three per leaf. Locksets, handles and closers are counted per door, with the type following the schedule, since a bathroom lock and a front door lock are different products. The estimator links all of this to the unit type, so changing a door's specification changes its ironmongery without a second pass.