Footage buys the wrong amount
Every trim estimate starts the same way: add up the linear feet, add ten or twelve percent, divide by the stick length, order that many. It is quick, it is what most material lists do, and on exterior trim it is reliably short.
The reason is that exterior trim is dominated by fixed lengths that do not nest. A corner board is the wall height, full stop. Four outside corners with a board on each face is eight pieces at nine feet. Out of sixteen foot stock each of those eight pieces takes its own stick, because seven feet is not another corner. That is eight sticks. The footage method sees seventy-two feet, adds twelve percent to get eighty, divides by sixteen and says five. You are three sticks short before a single window is cased.
The seven foot offcuts are not wasted, of course. They will cover window side casing at five feet with two feet left, and that is the real skill in a trim order: knowing which profiles produce offcuts and which profiles consume them. This calculator counts the sticks each profile needs on its own and shows the footage number alongside it, so the gap between them is visible rather than a surprise on the second trip.
What each profile actually is
| Profile | Where it goes | How it is counted |
|---|---|---|
| Corner boards | Outside and inside corners, full wall height | Fixed pieces, usually two per corner |
| Window casing | Head, two sides and a sill or apron | Four fixed pieces per opening |
| Door casing | Head and two sides, no sill | Three fixed pieces per opening |
| Frieze or band | Under the soffit, around the whole wall | Continuous run, joints anywhere |
| Water table | Bottom of the wall, above the foundation | Continuous run, joints anywhere |
| Rake trim | The sloping edges of a gable | Fixed pieces, both ends cut on an angle |
Rake trim deserves a mention because it is the profile people underestimate twice. It is longer than it looks, since the rake follows the slope rather than the span, and both ends are angle cuts, so a rake piece cannot be salvaged from an offcut of another rake unless the angles happen to match. Measure a rake along the slope, not across the gable.
Corner boards and the thickness question
Corner boards have to be thick enough that the siding butts into them rather than past them. That sounds obvious and it is where a lot of walls go wrong, because the thickness needed depends on what is behind the siding as well as the siding itself. A wall with a vented cavity behind the cladding pushes the siding face out by the depth of the furring, and the corner board has to stand proud of the new face, not the old one.
The same arithmetic runs at every window and door. The casing has to stand proud of the finished siding face by enough to look intentional and to give the siding something to die into. If the cladding assembly is deeper than the trim stock is thick, you either build the trim up or you get a siding edge running past the trim, which reads as unfinished from the first day. Work out the total build-out before you buy the trim stock; the rainscreen furring calculator reports that depth.
Trim is not flashing
A great deal of exterior trim sits exactly where water wants to go, and the trim is not what stops it. Heads of windows and doors, the top of a water table, the joint where a lower roof meets a wall, and every horizontal trim edge are places where the drainage plane behind the cladding has to be flashed and lapped so that water leaving one layer lands on the face of the next.
The failure mode is specific and worth naming: a wall built out of order looks completely finished and leaks anyway, because the flashing that should have gone behind a layer went on top of it. Nothing about the trim tells you this has happened. It shows up years later as a soft sill or a stain on a ceiling. The lapping order comes from the instructions for the specific products in the wall and from whoever inspects the work, not from a takeoff page. The window and door flashing calculator counts the tape and sealant; the caulk coverage calculator covers the joints that are genuinely sealant joints rather than flashing pretending to be one.
Three things worth checking before you order
- Whether the corner board length is the wall height or the wall height minus the water table and frieze, because those three profiles share the same vertical space and double counting it is common.
- Whether your windows are cased on four sides or three, since a brick mould or a nailing fin unit may already carry its own head and the sill may be part of the window.
- Whether the stick length you can actually buy matches the length you priced, because the difference between sixteen and twelve foot stock changes the corner board count by half on a nine foot wall.
For the interior equivalent of this takeoff, with baseboard, casing and crown, use the trim and molding calculator. For the soffit and fascia at the top of the wall, the soffit and fascia calculator, and for cutting the sticks efficiently once you have them, the cut list optimizer.
Questions people ask
Why do the sticks not equal the linear feet divided by stick length?
Because most exterior trim is cut to fixed lengths that do not divide into the stock evenly. A nine foot corner board out of sixteen foot stock uses nine feet and orphans seven, and there is no second nine foot piece hiding in that seven. Divide seventy-two feet of corner board by sixteen and you get four and a half sticks; cut it as eight nine foot pieces and you need eight. The footage answer is only correct for profiles that run continuously and can be jointed anywhere, which on an exterior is basically the frieze and the water table.
Should I count the fascia here as well?
It is cleaner not to. Fascia is sized from the roof edge rather than from the wall, its length follows the eave and rake rather than the corners, and it usually comes in a different profile and often a different material from the wall trim. Counting it in the same takeoff tends to produce a single total that cannot be handed to a supplier because half of it is one product and half another. The soffit and fascia calculator works from the roof edge and the overhang, which is the right set of inputs for it.
How much waste should I put on the runs?
Ten to fifteen percent covers a frieze or water table on a plain rectangle. Push it higher when the run is broken into short segments by bump-outs, porches and ells, because a run that is really eleven separate pieces of four to nine feet behaves like fixed-length trim rather than like a continuous run, and the offcuts pile up. The waste percentage here applies only to the continuous runs; the fixed-length pieces already carry their waste in the form of the offcut the calculator has decided is unusable.
Does the trim have to be the same thickness everywhere?
It does not have to be, and often it should not. A water table is commonly thicker than the corner boards so that the siding above it can lap over its top edge properly, and a head casing may be built up or capped where a plain board would collect water. What matters is that at every point the trim stands proud of the finished cladding face by a consistent amount, and that any horizontal top edge has somewhere for water to go. Both of those are detail decisions rather than quantity ones.
Can I reuse the existing trim when I residing?
Sometimes, and it is worth deciding before the order rather than after the tear-off, because half the trim coming off in pieces changes the count. The practical limits are that old trim is rarely thick enough once a new cladding assembly is deeper than the old one, and that trim from before the late 1970s may carry lead-based paint, which makes sanding or cutting it a testing question first. Everything about that work also happens on a ladder, and falls from height are the leading cause of serious injury on residential exteriors, which is worth weighing against saving a few sticks.