Adhered veneer
Thin masonry units bonded to their backing, by the 2022 chapter: the unit and assembly limits and fastener spacing along the framing on the prescriptive path, stresses and fastener loads on the engineered path, and the backing's deflection. The code text was not read. This type rests on one set of slides, TMS's Night School handout of November 2022, and has no worked example behind it. Treat it as a checklist that saves looking up the table, and read section 13.3 when you can.
Inputs of the adhered veneer #
- Design path. Prescriptive, or engineered.
- Load that governs, seismic design category. Category D, E or F takes 80 percent of the table's spacing. qh is on the prescriptive path, since the tables stop at 60 psf; the out-of-plane load p, at strength level, on the engineered path.
- Veneer. Unit thickness, face, weight, assembly weight as installed, thickness to the back of the scratch coat, height above grade plane. Units over 360 in.² need an approved installation procedure: your statement.
- Backing and fasteners. Wood at 16 in. or 16 ga. steel at 16 in. take the tables; concrete and masonry have no fasteners here. On a framed backing, the fastener, the cavity from the stud to the back of the assembly and the spacing along the framing. On the engineered path the capacities are yours, from the fastener's design standard, at your method's level, and the vertical deflection under strength dead and seismic load is your value.
- Backing height and deflection. Under 0.42 of the strength wind load or under the strength seismic load.
Auto-design varies the fastener spacing, widest first. The fastener, cavity and assembly stay yours.
Checks performed #
| Check | Basis, all from the handout (to confirm against the code text) |
|---|---|
| Backing deflection, h/360 or h/150 | 13.3.1.2, p. 24 |
| Unit: at most 2-5/8 in., 720 in.², under 30 psf | 13.3.2.2, p. 26 |
| Assembly: at most 50 psf, 4-5/8 in., 60 ft; sheathing on frames | 13.3.2.5, p. 28 |
| Fastener spacing, no interpolation, 80 % in D, E, F | Tables 13.3.2.5, 13.3.2.6, pp. 28-29 |
| Engineered: tension 100 psi (60 for allowable stress), shear 50 psi (30) | 13.3.3, p. 30 |
| Engineered: fastener withdrawal and lateral load on its tributary area | Principles of mechanics, p. 30 |
| Engineered: vertical deflection at most 1/8 in. | 13.3.3, p. 30 |
Limitations of the adhered veneer #
- The steel table on the handout stops part way: after the #8 screw at a cavity to 2 in. A fastener and cavity not on the page are refused, not guessed.
- The handout numbers its tables 12.3.2.5 and 12.3.2.6, as drafted; ILX reads them as 13.3.2.5 and 13.3.2.6.
- Framing at other spacings and qh over 60 psf go to the engineered path.
- On the engineered path, the tension and shear in the assembly almost never govern: they are there because the code gives them. How to apply them is ILX's plain reading, one square foot of bond face.
- Not part of it: the backing's strength, lath fastening, mortars, shear bond tests, movement joints, water penetration.
Verification examples #
Verification status: 25 values compared in 17 examples (15 published, 2 hand calculations from the cited equations): 25 within tolerance, 0 recorded deviations. Code basis: partial. Only some provisions were read in the target edition; the rest rests on older editions, examples or summaries.
No free worked example exists. Fourteen table cells are read back from the handout's pp. 28-29, including the next-band rule and the 80 percent factor; everything on the engineered path is by hand. MDG Example 16.3-1 and section 13.3 itself are in the documents to buy: when they arrive, check every limit here, complete the steel table and add that example.