Sheet goods

Almost everything in a modern cabinet starts as a sheet. The sheet decides how thick every part is, how well a screw holds, how far a shelf sags, and what happens when a sink leaks. The drafter writes the sheet's name on every panel, so the drafter needs to know what the name means.

The family of panels

The Wood Handbook calls every one of these a composite: "any wood material adhesively bonded together". What separates them is the size of the piece of wood inside.

Panel	What it is	Governing standard (named in AWS Section 4)
Particleboard	Wood particles and resin pressed with heat. "Typically made in layers": fine particles on the faces, coarser in the core	ANSI A208.1, Grade M2 or better
MDF	Wood refined to fibres, then resin and heat. AWS: "among the most stable of the mat formed panel products"	ANSI A208.2
Hardwood plywood	A core of veneer, lumber, particleboard, MDF or a combination, faced with hardwood veneer	ANSI/HPVA HP-1
Softwood plywood	Construction and industrial panels, mostly rotary Douglas fir	APA PS-1
Hardboard	Fibres felted to 31 lb/ft³ (500 kg/m³) or more. Standard or tempered	ANSI A135.4
Melamine-faced board (LPDL)	Resin-impregnated paper fused to particleboard or MDF, usually by the board maker	NEMA LD3 for face characteristics
HPDL	A sheet of kraft paper and phenolic resin with a decorative melamine layer, glued to a core by the shop	NEMA LD3
Compact laminate (solid phenolic)	HPDL made thick enough to need no core	Manufacturer's data; ISO 4586-4 tolerance cited by Wilsonart
MDO / HDO	Resin-impregnated paper overlays on plywood, for paint (MDO) or as a finished surface (HDO)	APA PS-1

AWS names these reference standards in Section 4, rule 4.4.4.4. Your specification may name a later edition of each.

How the cores compare

The AWS publishes a one-table summary of core behaviour (Section 4, Table 4-007). It is the fastest way to explain a substrate choice to someone who has never machined one.

Core	Flatness	Edge	Surface	Stability	Screw, face	Bending
Particleboard	Excellent	Good	Excellent	Fair	Fair	Good
Particleboard, MR	Excellent	Good	Good	Fair	Fair	Good
MDF	Excellent	Excellent	Excellent	Fair	Good	Good
MDF, MR or FR	Excellent	Excellent	Excellent	Fair	Good	Good
Veneer core	Fair	Good	Fair	Excellent	Excellent	Excellent
Lumber core	Good	Good	Good	Good	Excellent	Excellent
Combination	Good	Fair	Excellent	Good	Excellent	Excellent

Read it as a trade. Particleboard and MDF stay flat and take a laminate or veneer face cleanly, which is why the AWS calls them "the recommended cores for high pressure decorative laminate and wood veneer work". Veneer core plywood holds screws and resists bending, but does not stay as flat. The standard is blunt about doors: "Veneer core panels should not be used for cabinet doors because they are likely to warp" (Section 4, Recommendations), and its rules say veneer core "shall not be used for cabinet door or drawer front components" (rule 4.4.4.6.6.1).

The table also separates two words people mix up. Flatness is warp resistance. Dimensional stability is how much the panel grows and shrinks. The AWS calls fair stability acceptable "unless the product is exposed to wide swings in relative humidity, generally below 25% or above 55% with swings of more than 30 points".

Stiffness: why shelves sag

The Wood Handbook, Table 12-1, gives bending stiffness (modulus of elasticity, MOE) for each panel family. Stiffer panels sag less under the same load.

Panel	Specific gravity	MOE, GPa (10⁶ lb/in²)
Particleboard	0.6–0.8	2.76–4.14 (0.40–0.60)
MDF	0.7–0.9	3.59 (0.52)
Plywood	0.4–0.6	6.96–8.55 (1.01–1.24)
Hardboard	0.9–1.0	3.10–5.52 (0.45–0.80)

Plywood is roughly twice as stiff as particleboard and lighter. The AWS turns stiffness into shelf lengths. It sets the industry deflection limit at L/144, "which permits 1/4" (6.4 mm) deflection in a 36" (914 mm) shelf", and publishes maximum adjustable shelf lengths by material (Section 10, rule 10.4.7, 16.9.1.8):

Shelf material (AWS MOE, psi)	Thickness	Max length at 40 lb/ft²	Max length at 50 lb/ft²
Particleboard, LPDL both sides (400,000)	3/4"	32"	30"
Particleboard, LPDL both sides	1"	39"	37"
MDF, LPDL both sides (500,000)	3/4"	34"	32"
MDF, LPDL both sides	1"	42"	39"
Particleboard, HPDL vertical grade both sides (710,000)	3/4"	37"	35"
Particleboard, HPDL vertical grade both sides	1"	45"	43"

The 40 lb/ft² column is the standard's load for general shelving. The 50 lb/ft² column is for "school, hospital, and library or book shelving".

Worked example

A library wants 36" wide adjustable shelves in melamine-faced particleboard. The AWS chart allows 30" at 3/4" and 37" at 1" for the book-shelf load. So the drawing either shows 1" shelves, or a 3/4" shelf with a division that halves the span, or it goes to the designer as a question. What it cannot do is show a 36" by 3/4" melamine book shelf and say nothing. Roseburg's own data sheet for its SkyBlend particleboard gives an MOE of 400,000 psi, the same figure the AWS chart uses, so the chart fits that board.

Thicknesses actually stocked

A drafter who draws a panel at a thickness nobody stocks has drawn a special order. Before you set a thickness, check the data sheet from the board your shop buys. Three examples, as published:

Product	Thickness range	Sizes	Thickness tolerance
Roseburg SkyBlend particleboard	1/2" to 1-1/8"	4 and 5 ft wide, up to 12 ft long. "Actual length and width panel dimensions are one inch longer than stated size"	±0.008" from specified; ±0.004" within a panel
Roseburg Medite II MDF (moisture resistant)	1/4" to 1-1/2" (6.35–38.10 mm)	4 and 5 ft wide, up to 18 ft long	±0.005"
Egger Eurodekor melamine-faced board	Not listed on the data sheet	Not listed	±0.3 mm under 20 mm thick; ±0.5 mm over 20 mm

Hardwood plywood is thinner than its name. ANSI/HPVA HP-1, as the AWS quotes it, allows a thickness tolerance of "+0/-3/64" (0 / 1.2 mm) for nominal thickness of 1/4" (6 mm) or greater" (Section 4, rule 4.4.4.7). A dado cut to 3/4" for a "3/4" plywood" shelf can be loose by that much. Draw dadoes and grooves to the measured sheet, or note that they are cut to suit.

Compact laminate is the one family where the manufacturer lists every thickness. Wilsonart's technical data for its Classic grade runs 0.100" (2.54 mm), 1/8", 1/4", 5/16", 3/8", 1/2", 3/4" and 1" (25.4 mm), with a tolerance of ±0.027" (0.69 mm) at 3/4". It also lists weight. A 3/4" Classic sheet is 5.375 lb/ft², so a 4' × 8' sheet (32 ft²) weighs about 172 lb before it is cut. That is a lifting plan, not a panel (safety).

Screws, edges and machining

A screw into the face of a panel holds better than a screw into its edge. The Wood Handbook, Table 12-6, lists screw-holding for eight MDF products. Every one holds less at the edge than at the face. The manufacturers' own sheets say the same:

Board (3/4")	Screw holding, face	Screw holding, edge
Roseburg SkyBlend particleboard	250 lbf	180 lbf
Roseburg Medite II MDF	300 lbf	250 lbf

For particleboard, the Wood Handbook (Chapter 8, "Fastening of Particleboard") says tapping screws are commonly used where withdrawal strength matters, and "care must be taken when tightening screws in particleboard to avoid stripping the threads". Plywood behaves differently: "the alternating grain direction of its layers makes plywood resistant to splitting, allowing fasteners to be placed very near the edges of a panel" (Chapter 11). That is the practical reason plywood appears where a hinge or a heavy fixing lands near an edge. Chapter 13 covers the joints.

Edges also differ to look at. The AWS rates MDF's visual edge "Excellent" and particleboard's "Good", before any banding. Its rules let the edge of an opaque-finished MDF drawer front go without banding at Economy and Custom Grade, where a particleboard or plywood front is filled and sanded or banded (Section 10, rule 10.4.7, 27.2.5.2). Chapter 12 covers the full edge rules. MDF also makes the finest dust in the shop. The safety page covers why that matters.

Wet areas

Water attacks particle and fibre panels at the edge and through the thickness. The Wood Handbook says plywood "undergoes minimal irreversible thickness swelling if wetted", "unlike most panels fabricated from particles". The AWS lists moisture-resistant grades of both composites: particleboard "bonded with resins more resistant to swelling", most commonly ANSI A208.1 "Type M-2-Exterior Glue and M-3-Exterior Glue", and MDF made to meet the A208.2 "reduced thickness swell criteria" (Section 4, Primary core materials).

The data sheets show the size of the difference. Roseburg lists thickness swell of up to 8.0% for SkyBlend particleboard and 4% for Medite II, which it says "meets MR50 rating in all thicknesses" and is "acceptable for moderate loads and humid and damp environments". Linear expansion is listed at up to 0.40% and 0.25%. Check the test method on the sheet before comparing boards from two mills.

Moisture resistant is not waterproof. Three habits on the drawing help:

• Name the moisture-resistant core on the sink base, the vanity and anything near a dishwasher, and colour-code it on the cut list if the shop asks. The AWS requires moisture-resistant core, where specified, to be "color tinted or otherwise documented" (rule 4.4.4.5.2).
• Seal cut-outs. The Woodwork Institute sample writes CUT-OUT FOR SINK MUST BE SEALED on the detail where the cut is drawn.
• Pick the edge glue with the edge. Egger's processing instruction for its ABS edging says polyurethane hot-melt adhesives "are particularly suitable for use in damp conditions".

Heat is the other enemy. Egger's Eurodekor data sheet gives 50 °C (122 °F) as the limit for long, continuous heat exposure and asks for "an appropriate distance between heat source and Melamine surface". Draw the gap beside a wall oven or under a lamp.

Balanced panels

A panel faced on one side only will bow. The AWS rule is balanced construction: "an odd number of layers (plies) symmetrical from the center line", "using materials and adhesives on both sides that contract and expand ... at the same rate" (Section 4, Decorative face material and construction balance). In practice, every laminated or veneered panel in your set needs a named back as well as a named face. The standard's balance sheet rule accepts wood veneer of the same thickness and compatible species, HPDL of the same material and thickness, or overlay of the same material and thickness (rule 4.4.15).

HPDL makes the point with numbers. The AWS says a laminate sheet's width "undergoes greater dimensional changes than the length by a ratio of nearly two to one" and lists the cross-direction dimensional change for each grade, from 0.9% for HGS to 2.0% for cabinet liner (Table 4-047). A face and back that move differently pull the core into a curve.

The AWS thickness table for HPDL is worth pinning up (Table 4-047):

Type	Use	Nominal thickness
HGS	Horizontal general purpose	0.048" (1.2 mm)
VGS	Vertical general purpose, e.g. cabinet doors and sides	0.028" (0.7 mm)
HGP / VGP	Post-forming	0.039" (1.0 mm) / 0.028" (0.7 mm)
HGF	Fire rated	0.048" (1.2 mm)
CLS	Cabinet liner	0.020" (0.5 mm)
BKL	Backer	0.020" (0.5 mm)

One more AWS rule belongs on every refit drawing: "Lamination over existing HPDL is not permitted" (rule 4.4.4.6.10).

Grain direction starts at the sheet

A panel's size listing tells you its grain. The AWS: "48" x 96" (1219 mm x 2438 mm) means the grain direction runs with the 96" (2438 mm) direction, whereas a 96" x 48" ... panel's grain direction runs with the 48" (1219 mm) dimension" (Section 4, rule 4.1.7.1). A tall door wants the long grain vertical, so its width is limited by the sheet's short side. Chapter 12 follows grain across a run.

Two edges of every commercial sheet are also not good stock. Egger's data sheet allows edge damage of up to 10 mm on commercial-size boards, against 3 mm on pre-cut panels. Expect the shop to trim that off before cutting parts, so do not draw a part the full nominal width of the sheet.

Whose decision is the substrate?

Often it is not yours, and the drawing has to show whose it is.

• The specification governs. AWS Section 4: "Contract documents shall govern if in conflict with these standards."
• Where the specification is silent, the manufacturer chooses. The AWS makes the core "manufacturer's choice" for veneer, HPDL, LPDL, MDO and HDO panels, within its rules (rules 4.4.5.2, 4.4.7.9, 4.4.8.2, 4.4.10.2, 4.4.11.3).
• The grade narrows the choice. For exposed surfaces with an opaque finish, AWS Section 10 allows particleboard, MDF, MDO, softwood or hardwood plywood and solid stock at Economy; MDF, MDO, close-grain hardwood plywood and solid stock at Custom; and only MDF and MDO at Premium (rule 10.4.5, 9.1.3). Chapter 20 covers grades.

So for each panel the drawing says one of two things: the material the specification names, or the material the shop chose where the specification left it open. If the shop wants to change a named material, that is a substitution request, submitted separately, before fabrication (chapter 10).

What to write on the sheet

1. Core material and thickness for every panel type, in a materials schedule or on the section.
2. Face and back: species and cut for veneer, product and colour for laminate, with the backer named.
3. Moisture-resistant or fire-rated core where required, flagged.
4. Shelf material, thickness and span, checked against the load.
5. Grain direction on every veneered or woodgrain panel.
6. Any thickness that is not a stocked thickness, marked so purchasing sees it early.

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Sources

• USDA Forest Products Laboratory, Wood Handbook: Wood as an Engineering Material, General Technical Report FPL-GTR-190, Centennial Edition, April 2010 (fpl.fs.usda.gov/documnts/fplgtr/fpl_gtr190.pdf). Chapter 11: composite definition, plywood, particleboard and fibreboard descriptions, plywood's edge-fastening and wetting behaviour. Chapter 12, Table 12-1: specific gravity and MOE by panel type; Table 12-6: MDF screw holding, face and edge. Chapter 8, "Fastening of Particleboard": tapping screws, stripping. Primary.
• Architectural Woodwork Standards, 2nd Edition, 1 October 2014, © AWI, AWMAC, WI, full text hosted by the Woodwork Institute. Section 4, printed pp. 73–76 (core materials, Table 4-007, balance), 85–86 (HPDL types), 88 (recommendations), 89–91 (basic considerations and rules, grain direction, thickness tolerance, reference standards), 103–105 (Table 4-047, LPDL, balance and backer rules). Section 10, printed pp. 291 (shelf deflection), 306 (material rules by grade), 318–319 (shelf span chart). Superseded for jobs bid under later editions; see chapter 19. Primary (superseded edition).
• Roseburg Forest Products, SkyBlend particleboard technical data sheet, dated 16 Oct 2023 (roseburg.com). Thickness range, sizes and oversize note, MOE, screw holding, thickness swell, linear expansion, tolerances. Values for 3/4" panels. Primary for the product's properties.
• Roseburg Forest Products, Medite II MDF technical data sheet, dated 29 Aug 2025 (copy hosted by BuildSite). Thickness range, sizes, MR50, screw holding, thickness swell, linear expansion, tolerance. Primary for the product's properties; "acceptable for ... humid and damp environments" is the maker's description of its own product, Claimed.
• Egger, Eurodekor technical data sheet, TD ED EN revision 09, approved 13 Nov 2017 (copy hosted on Cloudinary). Thickness and edge-damage tolerances, heat limit, batch colour note. Primary.
• Egger, Processing instruction, EGGER ABS Edging, revision 04, approved 6 Aug 2025 (egger.com). PUR hot-melt for damp conditions. Primary.
• Wilsonart, Technical Data, Wilsonart Compact Laminate (wilsonart.com). Grades, nominal thicknesses, tolerances, weight per square foot, sheet sizes. Primary.
• Woodwork Institute, Sample Shop Drawings, typical joinery detail sheet 4 of 10: the sink cut-out note. Document.

Left out for lack of a source I could open: a list of the exact thickness steps a particleboard or plywood distributor stocks (the data sheets give ranges, not steps), and any statement of what each panel costs.