You’ve probably heard someone on a job site ask “what’s the limiting height on that wall?” — or pulled up a span table to check a floor joist before ordering. These tables show up across every phase of a cold-formed steel project, from estimating to field framing. But they’re not all the same table. Depending on what you’re building, you may be looking at one of four different systems: interior wall heights, exterior curtain wall heights, floor joist spans, or ceiling framing spans — each with its own inputs and rules.
This guide breaks down all four in plain terms: what each table is for, what goes into it, how to read the numbers, and what to watch out for. All data is drawn directly from ClarkDietrich’s published load tables (AISI S100-16 w/S2-20, IBC 2024).
A limiting height — or allowable span, for horizontal members — is the maximum distance a cold-formed steel stud or joist can span before it bends too much. Not before it breaks. Before it deflects more than what the wall finish or floor system can handle without cracking, buckling, or failing.
Think of it this way: a 20-gauge stud might be plenty strong enough to hold up a wall, but if that wall is too tall for that gauge at that spacing, the stud will flex enough under wind or occupancy pressure to crack the drywall. The limiting height is the cutoff where that flex becomes a problem.
This is a serviceability issue, not a structural failure issue. The distinction matters because a stud can be within its load capacity and still exceed its limiting height for its finish type — and that shows up as cracked tape, buckled gypsum, or failed tile.
Every limiting height and span table is built around a deflection limit — written as L/something, where L is the clear height or span in inches. The number after the slash tells you how much movement is allowed: the bigger the number, the less movement is permitted.
Here’s a concrete example. If your wall is 20 feet tall, that’s 240 inches. At L/240, you’re allowed 1 inch of movement. At L/600, you’re allowed less than half an inch. See Table 1 for the full breakdown.
| Deflection Limit | Max movement on a 20' (240") span | Where it typically shows up |
|---|---|---|
| L/120 | 2 inches | Light-duty interior partitions |
| L/240 | 1 inch | Standard drywall walls; exterior EIFS/siding; floor total load |
| L/360 | ¾ inch | Tile or plaster interiors; exterior stucco; floor live load |
| L/480 | ½ inch | Stiffer floor spec — some commercial floors require this |
| L/600 | ⅖ inch | Exterior brick veneer |
| L/720 | ⅓ inch | Brick veneer, more restrictive specs |
Table 1: How deflection limits translate to actual movement on a 20-foot span. L = clear height or span in inches.
The tighter the limit, the stiffer the assembly needs to be — which means heavier gauge, closer spacing, deeper stud, or some combination. This is where a lot of the cost decisions in CFS framing happen.
Where do you find the required deflection limit? On the project’s architectural drawings or specs. The finish schedule will tell you what’s going on the wall, and that determines which limit applies. When in doubt, ask the engineer of record.
Before pulling numbers from any limiting height table, you need to know which system you’re in. The four systems have different load inputs, different deflection limits, and different member types. Pulling a number from the wrong system is one of the most common errors in CFS framing. See Table 2 for a side-by-side comparison.
| System | What it covers | Load input | Deflection limits used |
|---|---|---|---|
| Interior Wall Heights | Non-load-bearing partition walls inside a building | Lateral pressure: 5, 7.5, or 10 psf | L/120, L/240, L/360 |
| Exterior Curtain Wall Heights | Structural stud backup for exterior cladding — brick, EIFS, stucco, panels | Wind pressure (ASD, psf) | L/240, L/360, L/600, L/720 |
| Floor Joist Spans | CFS C-joists carrying floor loads | Total load + live load (psf) | Total load: L/240; Live load: L/360 or L/480 |
| Ceiling Framing Spans | ProSTUD, furring channel, or U-channel supporting a ceiling assembly | Dead load (weight of ceiling): 4, 6, or 13 psf | L/240 or L/360 |
Table 2: The four CFS load table systems. Source: ClarkDietrich Load Tables (IBC 2024 / AISI S100-16 w/S2-20).
This is the table most framers reach for first on a typical commercial job. Interior wall height tables tell you the maximum height for a non-load-bearing partition wall — a wall that divides space but doesn’t carry floors or roof structure above it.
Even though these walls don’t carry vertical loads, they still need to handle horizontal pressure — people leaning against them, HVAC pressure, and a minimum occupancy load the IBC requires for all interior partitions (5 psf). That lateral pressure is what the table is sizing the stud against.
What you need to look up a number:
| Finish type | Deflection limit to use |
|---|---|
| Standard gypsum board (both sides) | L/240 — IBC default per AISI S240 |
| Ceramic tile, stone veneer, plaster, cement board | L/360 — brittle finishes need a stiffer assembly |
| Utilitarian / light-duty partitions | L/120 — only where spec explicitly allows; rarely used in commercial work |
Table 3: Which deflection limit to use based on interior wall finish type.
Always check the finish schedule. The deflection limit isn’t set by the stud — it’s set by what’s going on the wall. A tile bathroom wall and a painted drywall corridor wall might use the same stud, but the tile wall needs L/360, which means a shorter allowable height or a heavier stud. Miss that and you’ll be back to fix cracked grout.
The values in these tables assume the stud has continuous lateral support along its full height — meaning sheathing or drywall is applied to both sides all the way up. If the wall won’t be fully sheathed during construction, bridging needs to be in place first. The tables also assume no vertical load on the stud. If any floor or roof load bears on the wall, you’re outside the scope of these tables and need an engineer’s input.
Where a height value is followed by an “e,” web stiffeners are required at the bearing points. Without them, that published height doesn’t apply.
Tables 4 and 5 show example reference data for 2-1/2″ and 3-1/2″ structural studs at 5 psf lateral load.
| Stud | Spacing | L/120 | L/240 | L/360 |
|---|---|---|---|---|
| 250S137-33 | 12" oc | 17' 6" | 13' 10" | 12' 1" |
| 250S137-33 | 16" oc | 15' 10" | 12' 7" | 11' 0" |
| 250S137-33 | 24" oc | 13' 10" | 11' 0" | 9' 7" |
| 250S137-54 | 12" oc | 20' 3" | 16' 1" | 14' 1" |
| 250S137-54 | 16" oc | 18' 5" | 14' 8" | 12' 9" |
| 250S137-54 | 24" oc | 16' 1" | 12' 9" | 11' 2" |
| 250S162-68 | 12" oc | 22' 9" | 18' 1" | 15' 9" |
| 250S162-68 | 16" oc | 20' 8" | 16' 5" | 14' 4" |
| 250S162-68 | 24" oc | 18' 1" | 14' 4" | 12' 6" |
| 250S162-97 | 12" oc | 25' 0" | 19' 10" | 17' 4" |
| 250S162-97 | 16" oc | 22' 9" | 18' 0" | 15' 9" |
| 250S162-97 | 24" oc | 19' 10" | 15' 9" | 13' 9" |
Table 4: 2-1/2" interior wall heights, 5 psf lateral load. "e" after a value indicates web stiffeners required at bearing. Source: ClarkDietrich Structural Interior Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
| Stud | Spacing | L/120 | L/240 | L/360 |
|---|---|---|---|---|
| 350S137-33 | 12" oc | 22' 7" | 17' 11" | 15' 8" |
| 350S137-33 | 16" oc | 20' 7" | 16' 4" | 14' 3" |
| 350S137-33 | 24" oc | 17' 2" | 14' 3" | 12' 5" |
| 350S137-43 | 12" oc | 24' 7" | 19' 6" | 17' 1" |
| 350S137-43 | 16" oc | 22' 4" | 17' 9" | 15' 6" |
| 350S137-43 | 24" oc | 19' 6" | 15' 6" | 13' 6" |
| 350S137-68 | 12" oc | 28' 2" | 22' 4" | 19' 6" |
| 350S137-68 | 16" oc | 25' 7" | 20' 3" | 17' 9" |
| 350S137-68 | 24" oc | 22' 4" | 17' 9" | 15' 6" |
| 350S137-97 | 12" oc | 30' 11" | 24' 7" | 21' 5" |
| 350S137-97 | 16" oc | 28' 1" | 22' 4" | 19' 6" |
| 350S137-97 | 24" oc | 24' 7" | 19' 6" | 17' 0" |
Table 5: 3-1/2" interior wall heights, 5 psf lateral load. Source: ClarkDietrich Structural Interior Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
Note: ClarkDietrich also publishes separate limiting height charts for all of their ProSTUD non-structural and structural drywall framing systems. The tables above are examples for 2-1/2″ and 3-1/2″. For other limiting heights tables for non-structural and structural framing members, visit ClarkDietrich’s iTools.
Curtain wall framing is the structural steel stud backup behind exterior cladding — brick, stone, EIFS, stucco, metal panels. These walls take wind, not just occupancy pressure, and that changes everything about how you size the stud.
Instead of 5 psf lateral load, you’re dealing with wind pressures that might be 15, 20, 25 psf or higher depending on where you’re building and how tall the building is. And instead of L/240 or L/360, the deflection limit is set by the cladding material — most critically, brick requires a much tighter limit than EIFS.
First: convert your wind pressure before using the table.
This is the step that trips people up most often. Since 2012, building codes express design wind pressure as a strength-level (LRFD) value. But curtain wall limiting height tables — including ClarkDietrich’s — are built around service-level (ASD) values. You have to convert before you look anything up:
ASD wind pressure = LRFD wind pressure × 0.6
Your structural drawings (General Notes page) will show the LRFD value. Multiply by 0.6 and use that number to enter the table. Example: drawings show 25 psf → 25 × 0.6 = 15 psf ASD → use the 15 psf column.
Deflection limits depend on what’s cladding the wall.
Table 6 shows which deflection limit applies to each cladding type. The jump from L/240 (EIFS) to L/600 (brick) is significant — a brick-clad wall at the same height and wind pressure might need a stud one or two gauges heavier than an EIFS wall. That cost difference needs to be in the bid.
| Exterior cladding | Deflection limit | Why it matters |
|---|---|---|
| EIFS, exterior siding, gypsum sheathing | L/240 | Most flexible; these materials can handle more movement |
| Exterior stucco | L/360 | Stucco cracks under movement — needs a stiffer backup |
| Brick veneer | L/600 | Brick is rigid and unforgiving — requires a significantly stiffer assembly |
| Brick veneer (more restrictive specs) | L/720 | Some project specs or jurisdictions require even tighter |
Table 6: Which deflection limit to use based on exterior cladding type. Source: ClarkDietrich Structural Exterior Curtain Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
Tables 7, 8, and 9 show curtain wall heights for 3-5/8″, 8″, and 12″ structural studs at ASD wind pressures of 15, 20, and 25 psf.
| Stud | Spacing | 15 psf / L/240 | 15 psf / L/360 | 15 psf / L/600 | 20 psf / L/240 | 20 psf / L/360 | 20 psf / L/600 | 25 psf / L/240 | 25 psf / L/360 | 25 psf / L/600 |
|---|---|---|---|---|---|---|---|---|---|---|
| 362S200-43 | 12" oc | 17' 4" | 15' 1" | 12' 9" | 15' 9" | 13' 9" | 11' 7" | 14' 8" | 12' 9" | 10' 9" |
| 362S200-43 | 16" oc | 15' 9" | 13' 9" | 11' 7" | 14' 4" | 12' 6" | 10' 7" | 13' 0" | 11' 7" | 9' 10" |
| 362S200-43 | 24" oc | 13' 8" | 12' 0" | 10' 2" | 11' 10" | 10' 11" | 9' 3" | 10' 7" | 10' 2" | 8' 7" |
| 362S200-68 | 12" oc | 19' 11" | 17' 5" | 14' 8" | 18' 1" | 15' 10" | 13' 4" | 16' 10" | 14' 8" | 12' 5" |
| 362S200-68 | 16" oc | 18' 1" | 15' 10" | 13' 4" | 16' 5" | 14' 4" | 12' 1" | 15' 3" | 13' 4" | 11' 3" |
| 362S200-97 | 12" oc | 22' 0" | 19' 3" | 16' 2" | 20' 0" | 17' 6" | 14' 9" | 18' 7" | 16' 3" | 13' 8" |
| 362S200-97 | 16" oc | 20' 0" | 17' 6" | 14' 9" | 18' 2" | 15' 11" | 13' 5" | 16' 11" | 14' 9" | 12' 5" |
Table 7: 3-5/8" curtain wall heights (ASD wind). Wind pressures are service-level ASD values — if your drawings show an LRFD value, multiply by 0.6 first. Curtain wall studs use a 2" flange (S200) rather than the 1-5/8" flange common in interior work. Source: ClarkDietrich Structural Exterior Curtain Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
| Stud | Spacing | 15 psf / L/240 | 15 psf / L/360 | 15 psf / L/600 | 20 psf / L/240 | 20 psf / L/360 | 20 psf / L/600 | 25 psf / L/240 | 25 psf / L/360 | 25 psf / L/600 |
|---|---|---|---|---|---|---|---|---|---|---|
| 800S162-54 | 12" oc | 32' 8" | 28' 7" | 24' 1" | 29' 9" | 25' 11" | 21' 11" | 27' 7" | 24' 1" | 20' 4" |
| 800S162-54 | 16" oc | 29' 9" | 25' 11" | 21' 11" | 27' 3" | 23' 7" | 19' 11" | 25' 1" | 21' 11" | 18' 6" |
| 800S162-68 | 12" oc | 35' 4" | 30' 10" | 26' 0" | 32' 1" | 28' 1" | 23' 8" | 29' 10" | 26' 0" | 22' 0" |
| 800S162-68 | 16" oc | 32' 1" | 28' 1" | 23' 8" | 29' 2" | 25' 6" | 21' 6" | 27' 1" | 23' 8" | 19' 11" |
| 800S162-97 | 12" oc | 37' 9" | 32' 11" | 27' 10" | 34' 3" | 29' 11" | 25' 3" | 31' 10" | 27' 10" | 23' 6" |
| 800S162-97 | 16" oc | 34' 3" | 29' 11" | 25' 3" | 31' 2" | 27' 2" | 22' 11" | 28' 11" | 25' 3" | 21' 4" |
Table 8: 8" curtain wall heights (ASD wind). Source: ClarkDietrich Structural Exterior Curtain Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
| Stud | Spacing | 15 psf / L/240 | 15 psf / L/360 | 15 psf / L/600 | 25 psf / L/240 | 25 psf / L/360 | 25 psf / L/600 |
|---|---|---|---|---|---|---|---|
| 1200S162-68 | 12" oc | 48' 7" | 42' 6" | 35' 10" | 41' 0" | 35' 10" | 30' 2" |
| 1200S162-68 | 16" oc | 44' 2" | 38' 7" | 32' 6" | 35' 8" | 32' 6" | 27' 5" |
| 1200S162-97 | 12" oc | 55' 1" | 48' 1" | 40' 7" | 46' 5" | 40' 7" | 34' 3" |
| 1200S162-97 | 16" oc | 50' 0" | 43' 8" | 36' 10" | 42' 2" | 36' 10" | 31' 1" |
| 1200S200-97 | 12" oc | 57' 4" | 50' 1" | 42' 3" | 48' 4" | 42' 3" | 35' 8" |
| 1200S200-97 | 16" oc | 52' 1" | 45' 6" | 38' 5" | 43' 11" | 38' 5" | 32' 4" |
Table 9: 12" curtain wall heights (ASD wind) — used for high-rise and high-wind applications. Source: ClarkDietrich Structural Exterior Curtain Wall Heights (IBC 2024 / AISI S100-16 w/S2-20).
Floor joist tables are different from wall tables in one important way: you have to satisfy two deflection checks at the same time, not just one.
The two checks are:
Both have to pass. The one that gives you the shorter allowable span is the one that governs. The ClarkDietrich tables show both columns side by side so you can see which one controls for your configuration.
Single span vs. two equal spans
The tables also break out two scenarios. Single span is a joist running between two supports with no bearing point in the middle. Two equal spans is a joist running continuously over an interior bearing wall or beam — the table value in that case is the distance from the end support to the center support, not the total joist length. Continuous joists can span noticeably further than single-span joists of the same size, which is worth knowing at layout time.
Web stiffener notations
Floor joist tables use three stiffener notations:
These are requirements, not suggestions. If the table value has a notation and you don’t install the stiffeners, that span value doesn’t apply to your assembly.
Tables 10 and 11 show reference spans for 6″ and 8″ joists.
| Member | Fy (ksi) | Single span — LL: L/360 | Two equal span — LL: L/360 | Single span — LL: L/480 | Two equal span — LL: L/480 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | ||
| 600S137-43 | 33 | 15' 10" | 13' 8" | 11' 2" | 15' 10" i | 13' 8" i | 11' 2" i | 14' 11" | 13' 7" | 11' 2" | 15' 10" i | 13' 8" i | 11' 2" i |
| 600S137-54 | 50 | 17' 8" | 16' 0" | 14' 0" | 19' 10" | 18' 0" i | 14' 11" i | 16' 0" | 14' 7" | 12' 9" | 18' 0" | 16' 4" | 14' 4" i |
| 600S162-54 | 50 | 18' 5" | 16' 9" | 14' 7" | 20' 8" | 18' 9" i | 16' 1" i | 16' 9" | 15' 2" | 13' 3" | 18' 9" | 17' 1" | 14' 11" i |
| 600S162-68 | 50 | 19' 9" | 17' 11" | 15' 8" | 22' 2" | 20' 2" | 17' 7" i | 17' 11" | 16' 4" | 14' 3" | 20' 2" | 18' 4" | 16' 0" |
| 600S162-97 | 50 | 21' 11" | 19' 11" | 17' 4" | 24' 7" | 22' 4" | 19' 6" | 19' 11" | 18' 1" | 15' 9" | 22' 4" | 20' 3" | 17' 9" |
| 600S200-68 | 50 | 20' 9" | 18' 10" | 16' 6" | 23' 4" | 21' 2" | 18' 6" i | 18' 10" | 17' 2" | 15' 0" | 21' 2" | 19' 3" | 16' 10" |
| 600S200-97 | 50 | 23' 1" | 20' 11" | 18' 4" | 25' 11" | 23' 6" | 20' 7" | 20' 11" | 19' 0" | 16' 8" | 23' 6" | 21' 4" | 18' 8" |
| 600S300-97 | 50 | 25' 2" | 22' 10" | 20' 0" | 28' 3" | 25' 8" | 22' 5" | 22' 10" | 20' 9" | 18' 2" | 25' 8" | 23' 4" | 20' 4" |
Table 10: 6" floor joist allowable spans. Total load deflection limit: L/240. Live load deflection limit: L/360 or L/480 — check both columns; shorter span governs. "i" = web stiffeners required at interior support. Source: ClarkDietrich Floor Joist Span Tables (IBC 2024 / AISI S100-16 w/S2-20).
| Member | Fy (ksi) | Single span — LL: L/360 | Two equal span — LL: L/360 | Single span — LL: L/480 | Two equal span — LL: L/480 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | ||
| 800S137-43 | 33 | 18' 4" | 15' 10" | 12' 11" e | 18' 4" i | 15' 10" i | 12' 11" i | 18' 4" | 15' 10" | 12' 11" e | 18' 4" i | 15' 10" i | 12' 11" i |
| 800S137-54 | 50 | 22' 2" | 20' 2" | 17' 4" | 24' 6" i | 21' 3" i | 17' 4" i | 20' 2" | 18' 3" | 16' 0" | 22' 7" i | 20' 6" i | 17' 4" i |
| 800S137-68 | 50 | 23' 11" | 21' 9" | 19' 0" | 26' 11" | 24' 5" i | 20' 5" i | 21' 9" | 19' 9" | 17' 3" | 24' 5" | 22' 2" | 19' 5" i |
| 800S162-68 | 50 | 25' 7" | 23' 3" | 20' 4" | 28' 9" | 26' 1" | 22' 9" i | 23' 3" | 21' 2" | 18' 6" | 26' 1" | 23' 9" | 20' 9" |
| 800S137-97 | 50 | 26' 7" | 24' 2" | 21' 1" | 29' 10" | 27' 1" | 23' 8" | 24' 2" | 21' 11" | 19' 2" | 27' 1" | 24' 8" | 21' 6" |
| 800S162-97 | 50 | 28' 7" | 25' 11" | 22' 8" | 32' 1" | 29' 2" | 25' 5" i | 25' 11" | 23' 7" | 20' 7" | 29' 2" | 26' 6" | 23' 2" |
Table 11: 8" floor joist allowable spans. Total load deflection limit: L/240. Live load: L/360 or L/480 — check both; shorter governs. "e" = web stiffeners at end support; "i" = web stiffeners at interior support. Source: ClarkDietrich Floor Joist Span Tables (IBC 2024 / AISI S100-16 w/S2-20).
Ceiling framing spans cover the members that support suspended ceiling assemblies — ProSTUD used as ceiling joists, hat/furring channel in direct-attach systems, and cold-rolled U-channel in grid applications. The load input is simply the dead weight of the ceiling assembly: gypsum board, finishes, insulation, and any fixtures or mechanical elements hanging from it.
ClarkDietrich publishes three ceiling span tables — one each for ProSTUD, furring channel, and U-channel. Dead load values used are 4 psf (light assembly), 6 psf (medium), and 13 psf (heavy — multiple gypsum layers, tile, or significant mechanical load).
A big difference in ProSTUD ceiling spans: bracing
ProSTUD ceiling tables split values into two conditions based on whether the compression flange is braced at mid-span or not. Adding a single bracing point at mid-span makes a meaningful difference. For example, a 600PDS125-33 at 24″ spacing and 4 psf jumps from 11’3″ (unbraced) to 16’3″ (mid-span braced) — a 44% increase in allowable span from one bracing point. See Table 12.
| Member | Fy (ksi) | 4 psf — Unsupported | 4 psf — Mid-span braced | 6 psf — Unsupported | 6 psf — Mid-span braced | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | ||
| 162PDS125-15 | 50 | 7' 3" | 6' 8" | 5' 11" | 7' 10" | 7' 2" | 6' 3" | 6' 5" | 5' 11" | 5' 3" | 6' 10" | 6' 3" | 5' 5" |
| 250PDS125-15 | 50 | 8' 4" | 7' 8" | 6' 11" | 10' 11" | 9' 11" | 8' 8" | 7' 5" | 6' 11" | 6' 2" | 9' 7" | 8' 8" | 7' 7" |
| 362PDS125-15 | 50 | 9' 2" | 8' 6" | 7' 7" | 12' 9" | 11' 8" | 10' 3" | 8' 3" | 7' 7" | 6' 9" | 11' 3" | 10' 3" | 8' 11" e |
| 600PDS125-15 | 50 | 10' 8" | 9' 10" | 8' 10" | 15' 0" | 13' 9" | 12' 2" | 9' 6" | 8' 10" | 7' 11" | 13' 3" | 12' 2" | 9' 11" e |
| 362PDS125-33 | 33 | 11' 8" | 10' 9" | 9' 8" | 16' 8" | 15' 5" | 13' 11" | 10' 5" | 9' 8" | 8' 8" | 15' 0" | 13' 11" | 12' 6" |
| 600PDS125-33 | 33 | 13' 6" | 12' 6" | 11' 3" | 19' 6" | 18' 1" | 16' 3" | 11' 9" | 10' 11" | 9' 10" | 17' 0" | 15' 8" | 14' 1" |
Table 12: ProSTUD ceiling spans, L/240 deflection limit. A single mid-span bracing point substantially increases allowable span — a 600PDS125-33 at 24" oc, 4 psf goes from 11' 3" unbraced to 16' 3" with mid-span bracing. "e" = web stiffeners required at support. Source: ClarkDietrich ProSTUD Allowable Ceiling Spans (IBC 2024 / AISI S100 / AISI S220).
Table 13 shows furring channel ceiling spans at L/360.
| Member | Span type | 4 psf | 6 psf | 13 psf | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | 12" oc | 16" oc | 24" oc | ||
| 087F125-18 | Single | 4' 5" | 4' 0" | 3' 6" | 3' 10" | 3' 6" | 3' 1" | 3' 0" | 2' 9" | 2' 5" |
| 087F125-18 | Multiple | 5' 6" | 5' 0" | 4' 4" | 4' 9" | 4' 4" | 3' 10" | 3' 8" | 3' 4" | 2' 10" |
| 087F125-33 | Single | 5' 7" | 5' 1" | 4' 5" | 4' 10" | 4' 5" | 3' 10" | 3' 9" | 3' 5" | 3' 0" |
| 087F125-33 | Multiple | 6' 11" | 6' 3" | 5' 6" | 6' 0" | 5' 6" | 4' 9" | 4' 8" | 4' 3" | 3' 8" |
| 150F125-33 | Single | 8' 6" | 7' 8" | 6' 9" | 7' 5" | 6' 9" | 5' 10" | 5' 9" | 5' 2" | 4' 6" |
| 150F125-33 | Multiple | 10' 6" | 9' 6" | 8' 4" | 9' 2" | 8' 4" | 7' 3" | 7' 1" | 6' 5" | 5' 7" |
| 150F125-43 | Single | 9' 2" | 8' 4" | 7' 4" | 8' 0" | 7' 4" | 6' 4" | 6' 2" | 5' 8" | 4' 11" |
| 150F125-43 | Multiple | 11' 4" | 10' 4" | 9' 0" | 9' 11" | 9' 0" | 7' 11" | 7' 8" | 7' 0" | 6' 1" |
| 150F125-54 | Single | 9' 10" | 8' 11" | 7' 9" | 8' 7" | 7' 9" | 6' 10" | 6' 8" | 6' 0" | 5' 3" |
| 150F125-54 | Multiple | 12' 2" | 11' 0" | 9' 8" | 10' 7" | 9' 8" | 8' 5" | 8' 2" | 7' 5" | 6' 6" |
Table 13: Furring (hat) channel ceiling spans, L/360 deflection limit. "Multiple" = continuous over several supports, which allows longer spans than single. Source: ClarkDietrich Furring Channel Properties and Spans (IBC 2024 / AISI S100-16 w/S2-20).
Every stud, joist, and furring member uses a designation code that tells you exactly what you’re looking at. Once you know the pattern, you can decode any member instantly. Table 14 breaks it down, and Table 15 shows the gauge-to-mil conversion you’ll need when ordering.
| Segment | What it means | Example: 600S162-54 |
|---|---|---|
| First number (e.g., 600) | Web depth in hundredths of an inch | 600 = 6" web |
| Letter(s) — S, F, or PDS | Shape: S = C-stud, F = furring channel, PDS = ProSTUD | S = C-stud |
| Middle number (e.g., 162) | Flange width in hundredths of an inch | 162 = 1-5/8" flange |
| Number after dash (e.g., 54) | Steel thickness in mils (thousandths of an inch) | 54 mil ≈ 16 gauge |
Table 14: How to read a CFS member designation code.
| Nominal Gauge | Design Thickness (mils) | Where it's typically used |
|---|---|---|
| 25 ga | 18 mil | Lightest partition / ceiling framing |
| 20 ga | 33 mil | Standard commercial partition |
| 18 ga | 43 mil | Heavier partition, light structural |
| 16 ga | 54 mil | Structural — walls, joists, curtain wall |
| 14 ga | 68 mil | Heavy structural — tall walls, curtain wall, floor joists |
| 12 ga | 97 mil | Very heavy structural — high-rise curtain wall, long-span joists |
Table 15: Gauge-to-mil reference. Always specify by mils when ordering — nominal gauge labels can vary by manufacturer.
The thickness (mil) number is the most important one to get right when ordering. Nominal gauge numbers can vary by manufacturer; mil thickness does not. Always spec and order by mils.
Using the wrong table for the assembly. An interior wall table and a curtain wall table might both list an 800S162-68, but the numbers mean completely different things. The interior table sizes against 5 psf occupancy pressure; the curtain wall table sizes against 15–40 psf wind. The floor joist table works off gravity loads entirely. Pull the wrong table and the number you read out doesn’t apply to your wall.
Skipping the wind pressure conversion on curtain walls. Project structural drawings show LRFD wind pressures. Manufacturer curtain wall tables use ASD values. Multiply the drawing value by 0.6 before entering the table — if you go straight to the table with the LRFD number, you’ll land in the wrong column.
Checking only one deflection limit on floor joists. Both the total load check and the live load check have to pass. Check both and use the shorter span.
Using the wrong deflection limit for the finish or cladding. L/240 is right for standard gypsum. It’s not right for tile, plaster, stucco, or brick. Tile needs L/360. Brick typically needs L/600. Using the looser limit means the stud will flex more than the finish can handle — and you’ll find out about it after the job is done.
Ignoring the “e,” “i,” and “a” notations. When a table value has one of these letters next to it, web stiffeners are required at that bearing location. Without them, the published value doesn’t hold.
Assuming limiting height means the stud can carry a vertical load. Every table covered here is a deflection check under lateral or gravity load — not a vertical load capacity check. If a wall is load-bearing, these tables don’t cover it. That’s a separate calculation requiring an engineer.
The Formetal Company has been supplying cold-formed steel studs and track in Forest Park, Georgia since 1959. We supply structural and non-structural framing to contractors across Atlanta, the Southeast, and nationwide — with custom lengths available for tall walls and long-span applications where standard stock won’t reach.
All limiting height and span data in this article is sourced from ClarkDietrich’s published load table documents — Structural Interior Wall Heights, Structural Exterior Curtain Wall Heights, Floor Joist Span Tables, ProSTUD Allowable Ceiling Spans, and Furring Channel Properties & Spans — all complying with AISI S100-16 (2020) w/S2-20 and IBC 2024. Wind pressures in exterior curtain wall tables are ASD service-level values; multiply LRFD values by 0.6 before use. Web stiffener notations (“e,” “i,” “a”) are required conditions. Always verify values against current manufacturer documentation and applicable local codes. For load-bearing, engineered, or code-critical work, consult a licensed structural engineer.