nodes: improve modular cabinet constraints and finishes

docs/research/cabinet-ceiling-gap.md

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+# Closing the space above wall and tall kitchen cabinets
+
+Research completed 2026-08-24. This note focuses on the common gap between the top of a wall/tall cabinet and the ceiling: what cabinet manufacturers actually offer, when designers use storage versus trim, and what a modular cabinet planner should model.
+
+## Short answer
+
+The normal solution is **not to stretch the existing wall cabinet or tall cabinet indiscriminately**. Designers choose one of four intentional terminations:
+
+1. **A taller primary cabinet** when the cabinet system offers a height that matches the room.
+2. **A separate top/stacked cabinet** when the gap is large enough to provide useful, coordinated storage.
+3. **A cover panel, filler, crown/deco molding, or closed soffit** when the gap is too small, the contents would be hard to reach, or the goal is a clean architectural line rather than more storage.
+4. **A deliberately open gap** when it is being used for display or lighting and the design accepts the dust/maintenance trade-off.
+
+Manufacturers treat these as different products. IKEA recommends cover panels for a ceiling connection, rather than adapting a floor plinth; KraftMaid sells wall-cabinet heights that either reach an 8-ft ceiling or intentionally leave room for crown/lighting; and Medallion offers stacked wall-cabinet SKUs with a fixed intermediate rail and upper section. [IKEA: ceiling connection](https://www.ikea.com/se/en/customer-service/knowledge/articles/09b3fb5c-bgdf-4156-b0b3-48b48fc0933g.html), [KraftMaid: cabinet sizes](https://www.kraftmaid.com/kraftmaid/kitchen-cabinet-sizes), [Medallion: stacked wall cabinet](https://medallioncabinetry.com/quick-convenient-one-click-skus/)
+
+## The four practical approaches
+
+### 1. Use a taller wall or tall cabinet
+
+This is the cleanest option when the room and cabinet family have a compatible height. KraftMaid describes 42-in wall cabinets as full-height cabinets that can reach an 8-ft ceiling, while 36- and 39-in wall cabinets leave space for crown molding and above-cabinet accent lighting. It also describes tall-cabinet heights that are selected in relation to ceiling/soffit height, rather than simply scaling every cabinet. [KraftMaid cabinet sizes](https://www.kraftmaid.com/kraftmaid/kitchen-cabinet-sizes)
+
+For tall units, some manufacturers now provide unusually high products. Medallion advertises tall cabinets up to 120 in with height/depth/end modifications for floor-to-ceiling storage. That is a product-family choice, not a reason to make every tall cabinet an arbitrary height. [Medallion 120-in tall cabinets](https://medallioncabinetry.com/new-arrivals/120-tall-cabinets/)
+
+Use this approach when:
+
+- the upper reach remains reasonable for the intended storage;
+- the resulting door/front proportions still look intentional;
+- the cabinet family has a real manufactured height, finished end, and installation method;
+- appliance ventilation and service requirements are unaffected.
+
+Do not use it merely to absorb a few millimetres or centimetres of site tolerance. That is what fillers and trim are for.
+
+### 2. Add a separate top/stacked cabinet
+
+Stacking creates useful storage while preserving the main wall cabinet's height, counter relationship, and front proportions. Medallion's stacked wall cabinet is specifically marketed for taller ceilings. Its combined cabinet heights are 48, 51, and 54 in with a 15-in upper section, and 57 and 60 in with an 18-in upper section. It has a fixed floor and intermediate rail; the upper section can be used for display, glass inserts, mullions, or lighting. [Medallion stacked wall cabinet](https://medallioncabinetry.com/quick-convenient-one-click-skus/)
+
+KraftMaid likewise says that wall cabinets shorter than 36 in can be combined and stacked for customized storage. Its planning material also lists “wall top hinge cabinets,” stacked crown molding, stacked glass-door cabinets, and tall stacked cabinetry as distinct design choices. [KraftMaid cabinet sizes](https://www.kraftmaid.com/kraftmaid/kitchen-cabinet-sizes), [KraftMaid decorative details](https://homedepot.kraftmaid.com/project-planning-and-budgeting/step-4-creating-your-budget/how-decisions-impact-budget/how-cabinet-choices-impact-budget/storage-solutions-decorative-details%E2%80%8B/)
+
+IKEA's METOD installation guidance also treats a wall cabinet on top of a high cabinet as an additional cabinet requiring an additional suspension rail. That is evidence for modeling it as a separate mounted module, not as an invisible height mutation of the tall cabinet. [IKEA: suspension rail heights](https://www.ikea.com/nl/en/customer-service/knowledge/articles/0d5d657f-6d3g-4bd0-g7db-997c72590e3b.html)
+
+Use stacking when:
+
+- the gap is large enough for a useful, repeatable upper module;
+- the upper module can inherit the parent width and align its front/side panel;
+- the user wants closed storage, display doors, or integrated lighting;
+- the run benefits from a deliberate horizontal break between the main and upper doors.
+
+The upper module should usually be shallower or flush with the selected wall-cabinet depth, depending on the system. It should not silently inherit the tall cabinet's full base depth.
+
+### 3. Close the gap with panel, filler, crown, or soffit
+
+This is the appropriate answer when the remaining gap is not useful storage. IKEA explicitly recommends cover panels for a “ceiling connection” and says its plastic plinth is designed for cabinet legs/floor closure, not for adapting to a ceiling. IKEA also notes that the ceiling connection can match the cabinets or use a contrasting color; cover panels are available in widths and lengths that can be cut to fit. [IKEA: ceiling connection](https://www.ikea.com/se/en/customer-service/knowledge/articles/09b3fb5c-bgdf-4156-b0b3-48b48fc0933g.html)
+
+KraftMaid defines crown molding as a transition from cabinet to ceiling and as a way to hide accent lighting. It describes soffits as the architectural space commonly found above wall cabinets in older homes. [KraftMaid cabinet terminology](https://www.kraftmaid.com/getting-ready/cabinets-101/glossary/)
+
+Wood-Mode documents a modern example where floor-to-ceiling cabinets are capped with matching recessed trim to close the ceiling gap. Medallion also offers taller crown profiles for higher ceilings. [Wood-Mode: Savannah Trails Modern](https://www.wood-mode.com/get-inspired/kitchens/savannah-trails-modern/), [Medallion: Quiet Contemporary](https://medallioncabinetry.com/product/quiet-contemporary/)
+
+Use trim/soffit/panel when:
+
+- the gap is too short for a practical door and shelf;
+- the top should be dust-free and visually quiet;
+- a traditional room calls for crown, or a modern room calls for a square recessed cap;
+- the gap contains ducting, wiring, or a lighting void that needs concealment;
+- the designer wants one continuous ceiling datum across cabinets of different heights.
+
+Do not model a decorative cap as storage. It has a different depth, front, material, and installation behavior, and may need an intentional ventilation opening.
+
+### 4. Keep an intentional open gap
+
+An open shelf/gap can be used for display or uplighting, but it should be an explicit design mode rather than the accidental result of an unfilled ceiling. The manufacturer examples above distinguish crown/trim and closed storage from display sections with glass and lighting. If the user chooses this mode, the planner should make the dusting, lighting, and reach implications visible.
+
+## Wall cabinets versus tall cabinets
+
+### Wall cabinets
+
+Keep the normal wall cabinet height and counter relationship fixed. If the ceiling is higher, offer a stacked/top cabinet whose width comes from the wall cabinet's parent/base alignment. The top module can use a shorter door, glass door, open shelf, or a closed front. For a small residual gap, use a top filler or crown rather than creating a very short cabinet.
+
+KraftMaid's examples make the intent clear: a 42-in wall cabinet can reach an 8-ft ceiling, while 36/39-in cabinets leave space for crown and lighting. Thus the planner should expose a choice of system height, stacked upper, or decorative termination—not continuously scale the wall cabinet. [KraftMaid cabinet sizes](https://www.kraftmaid.com/kraftmaid/kitchen-cabinet-sizes)
+
+### Tall cabinets
+
+Tall cabinets are usually composed as a floor-to-ceiling mass around pantry/appliance functions. The choices are a system tall height, a separate top cabinet above the tall cabinet, or a matching cap/trim. IKEA specifically provides a rule for adding a wall cabinet on top of a high cabinet: it needs an additional rail above the existing rail. When a wall unit is next to a high cabinet, IKEA recommends using the same rail height so the tops are flush. [IKEA suspension rail heights](https://www.ikea.com/nl/en/customer-service/knowledge/articles/0d5d657f-6d3g-4bd0-g7db-997c72590e3b.html)
+
+For a run containing both tall and wall cabinets, the top of the tall composition and the top of the wall composition should be designed as one elevation. Either align their top datums, or use a clearly intentional step. Avoid a one-off tall cabinet ending slightly above or below an adjacent stack without a trim/end-panel explanation.
+
+## What an architect or kitchen designer checks
+
+The ceiling closure is an elevation/composition decision as much as a storage decision:
+
+1. **Measure the actual room.** Use finished floor-to-ceiling heights at several points; ceilings and floors may not be level. The top closure needs a scribe/tolerance strategy.
+2. **Choose the datum.** Set the counter, wall-cabinet bottom, cabinet top, crown/cap line, and ceiling relationship before selecting individual modules.
+3. **Group masses.** Tall pantry/oven/refrigerator units read as one vertical mass. A top box or cap should continue that mass across the full group, with finished end panels where visible.
+4. **Keep proportions legible.** A very small upper cabinet can look like leftover space; a stacked module with a consistent height or a continuous trim band looks deliberate.
+5. **Respect use and access.** Upper storage is only useful if the intended occupants can reach it. Place infrequently used items higher and offer display or trim options where upper storage would be impractical.
+6. **Coordinate services.** Hood ducts, refrigerator ventilation, lighting, and electrical routes can occupy the upper zone. The Medallion designer example describes modifying cabinet heights for exhaust piping and using crown molding to conceal it. [Medallion designer profile](https://medallioncabinetry.com/evamarie-sibilia/)
+7. **Resolve installation tolerances.** Use fillers/scribes at walls and a ceiling scribe or adjustable cap at the top. Do not rely on a rigid cabinet box being an exact fit to a variable ceiling.
+
+## Recommended Pascal model
+
+The cleanest product model is a separate **ceiling termination** attached to a wall or tall cabinet/run:
+
+```text
+parent cabinet/run
+  └── ceiling termination
+      ├── none / open gap
+      ├── top cabinet (storage)
+      ├── stacked display cabinet (glass/open + lighting)
+      ├── soffit / closed box
+      └── crown / recessed cap / cover panel
+```
+
+Suggested behavior:
+
+- The termination inherits **width and horizontal placement** from its parent cabinet or aligned run. This is the same visual rule the user described for wall cabinets matching their base parent.
+- Its **height** is computed from the measured ceiling datum minus the parent top, with a configurable installation tolerance/scribe. The user may choose a fixed upper-module height, leaving the remainder for trim, or let the termination fill the available zone.
+- Its **depth is independent**. A top cabinet may be shallower than the parent, while a cap/soffit may be flush, recessed, or project as a trim profile.
+- A stacked top cabinet gets its own front, hinge, shelf, and lighting properties. It must not mutate the base/wall/tall carcass height or counter alignment.
+- A soffit/cap is non-storage and should render as a solid/trim volume, not as a cabinet with a fake door.
+- If the calculated gap is below the minimum practical top-cabinet height, automatically recommend trim/soffit and keep the storage option disabled or marked impractical.
+- For a tall cabinet with a top module, preserve an explicit second mounting/attachment relationship. For an adjacent wall/tall group, offer “align top datums” as a run-level action.
+- Validate appliance ventilation and service zones before allowing a closed cap. IKEA explicitly calls out ventilation grilles at ceiling connections for appliances that require them. [IKEA ceiling connection](https://www.ikea.com/se/en/customer-service/knowledge/articles/09b3fb5c-bgdf-4156-b0b3-48b48fc0933g.html)
+
+### Sensible first implementation sequence
+
+1. Add a run/module side-panel section called **Top / ceiling finish**.
+2. Start with modes `None`, `Top cabinet`, and `Trim/soffit`; keep all controls in the existing side panel.
+3. For `Top cabinet`, inherit parent width, expose independent height/depth, and place it directly above the parent.
+4. Add a ceiling target only when the scene has a ceiling/room datum; otherwise provide an explicit manual top height rather than pretending the gap is known.
+5. Add `Crown` and `Recessed cap` profiles after the basic top-box geometry is stable.
+6. Add alignment rules and tests for wall-over-base, top-over-tall, mixed wall/tall runs, width changes, and non-level/unknown ceiling conditions.
+
+## Sources
+
+- [IKEA — Can I use a plinth as a ceiling connection in my kitchen?](https://www.ikea.com/se/en/customer-service/knowledge/articles/09b3fb5c-bgdf-4156-b0b3-48b48fc0933g.html)
+- [IKEA — How high do I mount the METOD suspension rail?](https://www.ikea.com/nl/en/customer-service/knowledge/articles/0d5d657f-6d3g-4bd0-g7db-997c72590e3b.html)
+- [IKEA — METOD installation guide](https://www.ikea.com/th/en/files/pdf/31/1d/311d88a8/th22-kitchen_installation_guide.pdf)
+- [KraftMaid — Kitchen cabinet sizes](https://www.kraftmaid.com/kraftmaid/kitchen-cabinet-sizes)
+- [KraftMaid — Cabinet terminology](https://www.kraftmaid.com/getting-ready/cabinets-101/glossary/)
+- [KraftMaid — Storage solutions and decorative details](https://homedepot.kraftmaid.com/project-planning-and-budgeting/step-4-creating-your-budget/how-decisions-impact-budget/how-cabinet-choices-impact-budget/storage-solutions-decorative-details%E2%80%8B/)
+- [Medallion — Stacked wall cabinet](https://medallioncabinetry.com/quick-convenient-one-click-skus/)
+- [Medallion — 120-in tall cabinets](https://medallioncabinetry.com/new-arrivals/120-tall-cabinets/)
+- [Medallion — Designer profile: Evamarie Sibilia](https://medallioncabinetry.com/evamarie-sibilia/)
+- [Medallion — Quiet Contemporary](https://medallioncabinetry.com/product/quiet-contemporary/)
+- [Wood-Mode — Savannah Trails Modern](https://www.wood-mode.com/get-inspired/kitchens/savannah-trails-modern/)
+
+These are manufacturer/product sources and design examples, not a substitute for local building code, appliance installation instructions, structural fastening requirements, or a site measurement.