Two Suppliers, One Miter: What Splitting a Millwork Package Really Costs

Why a Millwork Package Gets Split

Most split millwork packages start as a purchasing decision rather than a design decision. A cabinet shop is already on the approved vendor list. A lumber order went in early to lock a species before the trim drawings were finished. The interior trim allowance and the architectural millwork allowance live in two different line items, so they get bid to two different vendors and nobody ever asks whether the two halves have to meet.

On paper the split looks clean. One supplier has the linear runs, casing, base, crown, jamb stock, finished cladding. Another has the pieces that had to be drawn before they could be built, the radius trimwork, the box beams, the custom doors, the kitchen cabinets, the gates. The split stops looking clean the first time a piece from column A has to touch a piece from column B. That is the moment the buyer finds out what was actually purchased, which was not two scopes of work but one scope of work with a hidden interface running through the middle of it.

The Real Cost Sits in the Match

Two suppliers can each hit the drawing exactly and still deliver two different buildings. A drawing fixes dimension. It does not fix color, figure, ring count, sawing orientation or the specific log a board came out of, and those are the things a finished room gets judged on from six feet away.

Sapele is the clearest example. Quartersawn Sapele carries a ribbon stripe that shifts in width and contrast from log to log, and two shops buying the same species in the same grade from two different importers will not land on the same stripe. Iroko browns down unevenly across lots. Utile runs redder or greyer depending on origin. Teak varies enough that a careful shop sorts it before it cuts it.

Grading rules describe defect, not appearance match. The National Hardwood Lumber Association rules that govern most domestic hardwood purchases measure clear cutting yield, and an importer's grade on tropical hardwood works the same way. Both of your suppliers can be buying legitimate top grade material and still be buying material that will never match.

J. Gibson McIlvain pulls the linear trim and the true custom components for a single job out of the same yard and, where the job calls for it, out of related stock, which is the only reliable way to make a radius head casing look like it grew next to the straight casing under it.

Profiles Do Not Transfer Between Shops

A profile drawing is an instruction, and two shops will follow the same instruction to two different knives. Moulding knives get ground to a template. Grind the same section twice in two buildings and you get two interpretations of every fillet radius, every cove spring line, every quirk depth, and the differences land in the range of a 32nd of an inch.

Nobody sees a 32nd on a flat run. Everybody sees it at a miter. A crown return, a plinth intersection, a casing that dies into an apron, those are the places where two knives meet and the eye reads the step as sloppy carpentry even when the carpentry is fine.

J. Gibson McIlvain holds a moulding profile library of thousands of ground knives and grinds new knives every week, so a profile that already exists gets run rather than reinterpreted, and a profile that does not exist gets ground once and used for every piece in the package, curved and straight alike.

Historical restoration is the hardest version of this. Matching a 19th century profile means matching what the original cutter actually did, not what a clean CAD redraw of it looks like, and the National Park Service Preservation Briefs are explicit about like-for-like replacement in that situation. Industry profile numbering published through the Wood Moulding and Millwork Producers Association covers stock patterns well. It does not cover the custom section an architect drew for this building, which is exactly the section most likely to be sitting on two suppliers' desks at once.

Radius Work Is Where Two Suppliers Collide

Radius millwork is the single worst candidate for a split package. A curved casing, a sprung arch, a radius rail or a segmented head has to agree with its straight neighbors in three ways at once, section, face width and finished thickness, and it has to do it at a joint the installer cannot fudge.

ICD, the architectural millwork division of J. Gibson McIlvain, builds radius trimwork and radius millwork to the specific opening it serves, which means the shop needs the straight profile in hand, not a picture of it. Hand a curved-work shop a drawing and a promise that the straight stock will arrive later from somewhere else and you have asked it to guess.

Tolerance language helps but does not save the situation. The quality standards published by the Architectural Woodwork Institute set allowable variation for a given grade, and two suppliers can both sit inside the allowance while sitting on opposite edges of it. Stack two allowances at one miter and the gap is visible from the far end of the room.

Springing a curved member also changes how the grain presents. A radius casing is laminated or built up from segments in most cases, and the face of that assembly reads differently from a solid straight run milled out of one board unless both came from stock chosen together.

Box Beams, Gates and Split Joinery

Joinery chosen in one shop constrains what the other shop can deliver, and that conversation almost never happens across a vendor boundary. Take box beams. ICD builds them three ways, and the three are not interchangeable. Butt joints give the most minimal profile, the fastest turnaround and the easiest assembly on site, and they leave visible seams and visible end grain, and they are the weakest of the three. Dado joints are strong and still go together easily on site, and they still show seams and end grain. Lock miter joints show no visible seams and are the strongest option.

Now split the job. The beams arrive from one shop as lock miters and the ceiling trim that dies into them arrives from another. A lock mitered corner carries a sharper arris than the butt jointed alternative, so the returning trim has to be scribed to it in the field, which is work the installer priced as a simple butt.

Gates behave the same way at a larger scale. Pedestrian, garden and courtyard gates are craft problems. Large driveway swing gates are engineering problems, since size and weight start to govern the frame, the joinery and the hardware layout rather than the appearance. A shop building the gate leaf and a separate supplier providing the surrounding posts and trim are solving two halves of one structural question without a shared answer.

Moisture Content Resets at Every Handoff

Every supplier boundary is also a storage boundary, and wood keeps responding to whatever room it is sitting in. Interior millwork is milled to an in-service moisture content near 6 to 8 percent. Exterior work runs closer to 12 to 16 percent. Those are not arbitrary numbers, they track the equilibrium the material will reach in service, and the USDA Forest Products Laboratory Wood Handbook lays out the relationship between relative humidity and equilibrium moisture content in detail.

Two suppliers means two sheds, two schedules and two sets of assumptions about when the building will be conditioned. One package arrives at 7 percent. The other arrives at 11 percent after sitting in an unheated warehouse through a wet spring. Both were milled correctly. They will still move against each other after installation, and the panel that shrinks away from its stile is the one the buyer sees.

The same problem shows up on painted work, where a coating locks one face and the assembly has to be dimensionally settled before it goes on. Building Science Corporation has written at length about materials reaching equilibrium with their surroundings rather than with a specification. One shop can hold a conditioned package until the floor it belongs on is ready. Two shops cannot, since neither one controls when the other releases, and the half that ships early is the half that ends up stacked on a job site that is not closed in yet.

Priming and Who Owns the Painted Surface

A painted surface fails at the interface between whoever milled it and whoever coated it, which is precisely the seam a split package creates. Open-grained and oily species absorb a great deal of finish, so a primer coat evens out the eventual painted surface, and sanding or buffing after priming knocks back grain raising while keeping moulded detail crisp.

J. Gibson McIlvain primes in three levels, in both oil-based and water-based systems, and exterior primed trim carries a fungicide additive. That work happens under the same roof as the milling, on material at a known moisture content, before the piece gets wrapped. A second supplier's unprimed trim landing on the same wall gets primed by a painter on a scaffold, in whatever weather that week produced, and the two surfaces will not age the same.

Species choice on painted exterior trim matters more than most buyers expect. Sapele holds paint better than Genuine Mahogany and comes in a wider range of sizes and longer lengths, which makes it the better call for painted exterior work. Sapele is not milled 1x8 for exterior use, because that width is too wide to stay stable in that application. Cupping, when it shows up, is driven by installation detail and back ventilation rather than by the species on the invoice.

Hardness gives a useful sanity check on substitutions across a split package. The Wood Database entry for Sapele puts its Janka hardness around 1,410 lbf, close to White Oak at roughly 1,360 lbf and Hard Maple at roughly 1,450 lbf, and well above Genuine Mahogany at roughly 800 lbf. Cherry sits near 950 lbf. The test method behind all of those figures is standardized under ASTM D143, so the numbers are comparable even when the suppliers are not.

What the Split Costs, Scope Item by Scope Item

The cost of a split is specific to the piece, not general to the package, so the scope deserves a walk through item by item before the purchase orders go out. The table below sets out what a second supplier would have to match exactly for each of the custom items ICD builds, and what the mismatch looks like once the crate is open.

Read down the middle column and the pattern is obvious. Almost nothing in it can be written into a purchase order with enough precision to be enforceable, which is why these items end up settled by whoever is standing on the floor when the problem gets found.

Accountability When Something Arrives Wrong

A split package splits responsibility, and responsibility does not divide cleanly on a job site. When a radius casing does not match the straight casing, each supplier can demonstrate that its own piece is correct to the drawing. Both are telling the truth. The buyer still owns the remake and the schedule hit.

"When a job comes to us as one package, I have one shop to call and one record to pull. When it is split, I am watching two schedules and I cannot promise what the other half is going to do."

Norm Moton, Director of Sales, J. Gibson McIlvain

Warranty expectations deserve a plain answer here. There are no warranties on solid unmodified wood, and there cannot be, since it is an organic material that keeps responding to its environment. Warranties exist on modified products, and those carry their own hard limits.

Thermory and Abodo Vulcan, along with Accoya, top out around 16 ft, and most of that material sells on metric lengths just under 16 ft because of kiln size. Thermally modified Ash is not available wider than 8 inches, so a wide board in a modified product means Accoya or Abodo Vulcan. A second supplier quoting longer lengths than that is quoting something it cannot deliver. Accoya itself runs around 1,600 lbf on the Janka scale and acetylation gives it dramatically reduced shrinkage and swelling, which is why it shows up where exterior dimensional stability governs the detail.

J. Gibson McIlvain has been family run and in business since 1798, now in its seventh generation, which is the practical reason a knife and a record stay on file long enough for phase two of a building to match phase one.

When Splitting the Package Is the Right Call

Splitting is sometimes correct, and the honest version of this answer says so. If a cabinet shop already holds the contract, already has approved shop drawings and already has a finish sample signed off, moving that scope buys nothing but risk.

Installation is the clearest legitimate division. J. Gibson McIlvain supplies and mills, and it does not install. Field measurement, install coordination and the actual hanging of the work belong to the buyer's own installer or fabricator, and the millwork package should be built to hand that installer material ready to go up.

What the shop can do is make the installer's side easier. Box beams get delivered with a joinery choice picked for site assembly rather than for the shop's convenience. Trim arrives primed so the painter is applying finish coats instead of sealing raw wood on a ladder. Radius pieces arrive with their straight partners so the fit is proven before anyone reaches for a saw. The line that should not be crossed is splitting two items that touch. Two suppliers can share a building. They should not share a miter.

How J. Gibson McIlvain Would Specify This

Draw the boundary between suppliers where nothing physically meets, and keep every touching pair inside one shop. Mark up the millwork drawings with a highlighter, one color per supplier, then look for every place two colors meet at a joint. Those intersections are the scope that has to be consolidated, and on most jobs there are fewer of them than the bid package implies.

Specify the profile once, and specify it to a section rather than to a catalog number. J. Gibson McIlvain grinds a knife to match a submitted section, including difficult historical and contemporary profiles, and runs every member of that family off the same knife. A returned length of original casing works as well as a drawing.

Call the moisture content in the specification, 6 to 8 percent for interior work and 12 to 16 percent for exterior, and state that the custom pieces and their linear neighbors are to be milled and conditioned together. Name the priming level on painted work and let the primer go on in the shop instead of in the field. Where a panelized or painted face has to stay flat, call quartersawn or rift stock, which moves less across its width than plainsawn.

Keep the species palette to what a millwork house actually machines well. Sapele, Iroko, Afrormosia, Teak and Utile are the working palette for milled, glued and machined components. Buyers who know the tropical decking species sometimes ask for Ipe, botanically Tabebuia spp, or for Cumaru, Garapa, Jatoba or Red Balau on a bench or a rail. Those species are extremely hard and carry high oil content, which makes them difficult to glue, so a millwork shop reaches for Sapele, Iroko, Afrormosia, Teak or Utile on anything that gets assembled rather than simply fastened down.

Cedar remains a sound default for shutters and exterior trim, and the specification should say which cedar, CVG for clear vertical grain where a painted or stained face has to stay quiet, STK for select tight knot where the knots are part of the look. Where a CITES-listed species is involved, documentation and chain of custody travel with the material, so that paperwork belongs in the submittal schedule rather than in a phone call three weeks before delivery.

J. Gibson McIlvain runs a full millwork shop on site at the Maryland lumber yard for linear trimwork, finished cladding and primed trim, and ICD, its architectural millwork division, handles the true custom work planned around a specific space, rafter tails, gates, box beams, custom doors, custom cabinets, custom kitchen cabinets, radius trimwork, radius millwork, pergolas, shutters, benches and railings. Both come off one order and ship nationwide, regularly to California.

To scope a package that does not need a second supplier, send the millwork drawings and the species intent to J. Gibson McIlvain at 800-638-9100, review the millwork services run at the yard, and see how ICD works through a custom project from drawing to delivered crate. For case work specifically, the ICD cabinets and case work page shows how cabinetry gets engineered around how a room is used rather than assembled from standard modules.

Frequently Asked Questions

Which millwork items should never be split between two suppliers?

Any pair that physically meets. Radius trimwork and the straight runs it dies into, box beams and the ceiling trim that returns against them, custom doors with their jambs and casing, and kitchen cabinets next to adjacent case work all have to agree on profile section, face width, finished thickness and species selection at a joint the installer cannot adjust. Scope that never touches, a set of exterior shutters on one elevation against interior base on another floor, can sit with different vendors without consequence.

If both suppliers work from the same profile drawing, why does the profile still not match?

A drawing is a section, and a knife is a physical interpretation of that section. Two grinders will resolve fillet radii, cove spring lines and quirk depths slightly differently, in the range of a 32nd of an inch. That difference disappears on a flat run and becomes obvious at every miter and return. J. Gibson McIlvain holds thousands of ground knives in its profile library and grinds new ones every week, and every member of a profile family, curved and straight, comes off the same knife.

Does splitting a millwork package ever make sense for the buyer?

Yes, when the split falls on a real boundary. A cabinet shop that already holds a signed contract with approved shop drawings and an approved finish sample should keep that scope. Installation is a legitimate division as well, since J. Gibson McIlvain supplies and mills but does not install. What does not work is splitting two items that have to meet at a joint, then discovering the mismatch once the crates are open.

Can I get a warranty on the millwork if the whole package comes from one supplier?

Not on solid unmodified wood, and no supplier can offer one honestly, since wood is an organic material that keeps responding to its environment. Warranties exist on modified products. Those products carry limits worth knowing before a specification depends on them, including a length ceiling around 16 ft for Thermory, Abodo Vulcan and Accoya, and a width ceiling of 8 inches on thermally modified Ash. Single sourcing does not buy a warranty. It buys one party who is accountable for the match.

How does moisture content go wrong across two suppliers when both did their job correctly?

Each supplier controls its own kiln schedule and its own storage, and wood equalizes with the air around it. Interior millwork is milled near 6 to 8 percent and exterior work near 12 to 16 percent, but a package that sat in an unheated warehouse through a wet spring arrives several points wetter than the one that shipped from a conditioned shop. Both were milled to specification. They still move against each other once installed, and the shrinking panel is the one the owner sees.

Which species should a package be specified in to limit split risk?

For milled, glued and machined components the working palette is Sapele, Iroko, Afrormosia, Teak and Utile. All five machine cleanly and glue predictably, which matters on box beams, doors, radius work and case work. Buyers familiar with tropical decking sometimes request Ipe, botanically Tabebuia spp, or Cumaru, Garapa, Jatoba or Red Balau for a bench or a rail. Those species are extremely hard and carry high oil content that makes gluing difficult, so a millwork shop reaches for the first five instead.

What should the specification say so a single package actually arrives matched?

Name the profile as a section rather than a catalog number, state that custom pieces and their linear neighbors are milled and conditioned together, call 6 to 8 percent interior and 12 to 16 percent exterior moisture content, specify quartersawn or rift stock where a painted or panelized face has to stay flat, and name the priming level and system so the primer goes on in the shop. For cedar, say CVG for clear vertical grain or STK for select tight knot rather than leaving the grade open.

Sources and Standards Referenced

• Wood Handbook, Wood as an Engineering Material (FPL GTR-190), USDA Forest Products Laboratory
• Architectural Woodwork Standards and Quality Certification, Architectural Woodwork Institute
• Rules for the Measurement and Inspection of Hardwood and Cypress, National Hardwood Lumber Association
• Wood Moulding and Millwork Producers Association
• Preservation Briefs, National Park Service Technical Preservation Services
• BSD-138: Moisture and Materials, Building Science Corporation
• Sapele (Entandrophragma cylindricum), The Wood Database
• ASTM D143 Standard Test Methods for Small Clear Specimens of Timber