FIELD NOTE · SUPPLEMENTAL SET
Aluminum at the floor line: the mullion that stops and the mullion that runs past
ISSUEDJULY 11, 2026DRAWN BY THE NIGHTLY SWEEP
Cut a vertical section through a glass wall at the second floor and one of two things is true where the framing meets the slab. Either the vertical member stops at the floor and starts again above it, or it runs past the floor, continuous, anchored back to the building through the mullion itself, with the gap between the floor and the wall left open.
That is the whole distinction. Everything the two systems do not share follows from it: where the anchors land, what fills the gap, whether the state architect would exempt the assembly from structural review, and how many subcontractors stand at the floor line.
From the sidewalk they read as close to the same object. Set Kawneer's Trifab VersaGlaze 451 storefront against its 1600 Wall System 1 curtain wall and the sightline moves half an inch, 2 inches against 2 1/2, while the frame depth goes from 4 1/2 inches on the storefront to somewhere between 6 and 10 1/2 inches on the curtain wall, chosen by span.
And the permit need not say which one is going in, because in San Diego the whole exterior envelope sits on the list of what may be deferred, and a deferred submittal cannot be filed until after the building permit is issued.
"A non-load-bearing wall system in which the vertical framing members of the system run past intermediate floors," says the curtain wall entry on the same glossary page.
Two definitions on one page, differing almost entirely in a clause about floors.
That document does not govern a private retail center, since DSA's jurisdiction runs to public schools, community colleges and state essential services buildings. The geometry travels anyway.
Anchorage follows the geometry: a storefront sits inside an opening and is held around its perimeter, head and sill and jambs, while a curtain wall carries load through the mullions into anchors taken at the floor line, floor by floor, which is why its frame depth is a structural decision rather than a profile choice.
An estimator pricing both by the square foot of glass is pricing the same trade and two different jobs.
That gap is a scope item a storefront never generates, because a storefront never runs past a floor. On private commercial work the binding sections are 2025 CBC 715.4 and 715.5, perimeter fire containment at fire-resistance-rated and at non-rated floor intersections, and a building officials summary of the 2025 cycle records new exceptions added at both, while the work itself is carried on most jobs as a separate firestop scope, interleaved with the erection sequence floor by floor.
Review is the other thing a curtain wall picks up. Under the state architect's rule a window wall system is exempt from DSA structural safety review only when all of seven conditions hold, among them every mullion and intermediate member spanning 10 feet or less and no reliance on structural sealant glazing to resist code-prescribed loads. "Multi-story curtain walls are not exempt," the rule says in the condition that settles the argument, the same one that requires the system not to run continuous between adjacent stories across floor or roof levels.
Those thresholds belong to DSA and to DSA projects, but what they name is portable. Past the floor line the mullion, the anchor and the splice go out for calculation to a delegated engineer working for the glazing subcontractor after award, which is a structural scope sitting inside a bid written as glass.
What sits underneath the sentence did not hold still. The 2022 CBC referenced ASCE/SEI 7-16 with Supplements 1, 2 and 3 while the 2025 CBC references ASCE/SEI 7-22 with Supplement 1, so anyone who checks the section number and stops there concludes that nothing moved and writes the design criteria against a superseded standard.
Deflection is keyed to span rather than to system name, with framing supporting glass held to L/175 where the span is 13 feet 6 inches or less and to L/240 plus 1/4 inch above that, per CBC 1604.3.7, and CBC 2403.3 applying the same two tiers to glass edge length. The tier a member lands in is set by the clear distance between its supports, not by whether it crosses a floor, which is why the curtain wall frame depth is chosen by span and runs from 6 to 10 1/2 inches on one product line while the storefront stays at 4 1/2.
One row. Four scopes.
So the permit can carry criteria and not systems. On DSA projects the construction documents must "define the design criteria and all building design information necessary to accurately design the window wall systems," meaning the wind and seismic load criteria, the inelastic seismic drift demand, and the deflection limits of the supporting structure.
Deferral is not automatic, though, since IB 188 requires the building official's prior approval. The bulletin offers the other road in the same breath: an applicant who wants the envelope inside the permit set adds it to the scope of the building permit, and the item is no longer deferred.
Then the clock runs. Deferred submittal items cannot be submitted until the building permit is issued, nothing is installed until the building official has approved the documents, and the deferred submittal processing fee is $329.26, while on DSA work the gate sits earlier, since fabrication may not begin until the submittal is approved.
30 business days MINIMUM BETWEEN THE EXTERIOR ENVELOPE SUBMITTAL AND SETTING GLASS, SAN DIEGO IB 188 10 feet LONGEST SPAN THE STATE ARCHITECT'S REVIEW EXEMPTION ALLOWS ON AN EXTERIOR WINDOW WALL SYSTEM $329.26 SAN DIEGO'S DEFERRED SUBMITTAL PROCESSING FEE
The architect or engineer of record lists the deferral with the building official's prior approval, then states in writing that the documents have been "reviewed and found to be in general conformance to the design of the building," a statement that lands after the permit has issued and not less than 30 business days before the glass goes up.
The 2025 California Building Standards Code has been in force since January 1, 2026 and attaches to a project by application date rather than by issuance, and San Diego reviews a deferred submittal against the building codes the structure was permitted under, so a building that got its permit on the 2022 code has its 2026 glazing submittal read to the 2022 code.
Somewhere in the design meeting before any of that, with the floor-to-floor dimension fixed and the elevation drawn, somebody put the vertical member either into the slab or past it. The anchorage, the fire containment assembly, the second subcontractor and the delegated calculations all arrived with that line.
PermitFeed reads every SoCal filing nightly and scores it for glass and glazing contractors. The Trade Sheet shows the live numbers for your territory.
That is the whole distinction. Everything the two systems do not share follows from it: where the anchors land, what fills the gap, whether the state architect would exempt the assembly from structural review, and how many subcontractors stand at the floor line.
From the sidewalk they read as close to the same object. Set Kawneer's Trifab VersaGlaze 451 storefront against its 1600 Wall System 1 curtain wall and the sightline moves half an inch, 2 inches against 2 1/2, while the frame depth goes from 4 1/2 inches on the storefront to somewhere between 6 and 10 1/2 inches on the curtain wall, chosen by span.
And the permit need not say which one is going in, because in San Diego the whole exterior envelope sits on the list of what may be deferred, and a deferred submittal cannot be filed until after the building permit is issued.
Aluminum that stops at the slab, and aluminum that runs past it
California writes the distinction down in an unlikely place: DSA IR 24-2, the state architect's rulebook for window wall systems on school and state essential services projects, revised January 13, 2026 under the 2025 CBC. In its glossary a storefront is a system of doors and windows whose vertical framing members "typically run between the top of the floor and the structure above," and the anchorage is typically at the perimeter."A non-load-bearing wall system in which the vertical framing members of the system run past intermediate floors," says the curtain wall entry on the same glossary page.
Two definitions on one page, differing almost entirely in a clause about floors.
That document does not govern a private retail center, since DSA's jurisdiction runs to public schools, community colleges and state essential services buildings. The geometry travels anyway.
Anchorage follows the geometry: a storefront sits inside an opening and is held around its perimeter, head and sill and jambs, while a curtain wall carries load through the mullions into anchors taken at the floor line, floor by floor, which is why its frame depth is a structural decision rather than a profile choice.
An estimator pricing both by the square foot of glass is pricing the same trade and two different jobs.
The gap at the floor line, and the trade that fills it
"The gap between the floor and the curtain wall shall be completely filled with an approved fire resistive material/assembly to form both a heat and smoke barrier," the state architect's rule for school projects says. The fill is rated at or above the rating of the floor it runs past, and covered by something able to carry normal occupant live load, or guarded.That gap is a scope item a storefront never generates, because a storefront never runs past a floor. On private commercial work the binding sections are 2025 CBC 715.4 and 715.5, perimeter fire containment at fire-resistance-rated and at non-rated floor intersections, and a building officials summary of the 2025 cycle records new exceptions added at both, while the work itself is carried on most jobs as a separate firestop scope, interleaved with the erection sequence floor by floor.
Review is the other thing a curtain wall picks up. Under the state architect's rule a window wall system is exempt from DSA structural safety review only when all of seven conditions hold, among them every mullion and intermediate member spanning 10 feet or less and no reliance on structural sealant glazing to resist code-prescribed loads. "Multi-story curtain walls are not exempt," the rule says in the condition that settles the argument, the same one that requires the system not to run continuous between adjacent stories across floor or roof levels.
Those thresholds belong to DSA and to DSA projects, but what they name is portable. Past the floor line the mullion, the anchor and the splice go out for calculation to a delegated engineer working for the glazing subcontractor after award, which is a structural scope sitting inside a bid written as glass.
Glass in both systems, under one sentence of Chapter 24
What the two systems share is the glass and the arithmetic. "Glass in glazed curtain walls, glazed storefronts and glazed partitions shall meet the seismic requirements of ASCE 7, Section 13.5.9," says CBC Section 2404.1, in one sentence that covers both. That sentence and its section number read identically in the 2022 and the 2025 CBC.What sits underneath the sentence did not hold still. The 2022 CBC referenced ASCE/SEI 7-16 with Supplements 1, 2 and 3 while the 2025 CBC references ASCE/SEI 7-22 with Supplement 1, so anyone who checks the section number and stops there concludes that nothing moved and writes the design criteria against a superseded standard.
Deflection is keyed to span rather than to system name, with framing supporting glass held to L/175 where the span is 13 feet 6 inches or less and to L/240 plus 1/4 inch above that, per CBC 1604.3.7, and CBC 2403.3 applying the same two tiers to glass edge length. The tier a member lands in is set by the clear distance between its supports, not by whether it crosses a floor, which is why the curtain wall frame depth is chosen by span and runs from 6 to 10 1/2 inches on one product line while the storefront stays at 4 1/2.
One row on San Diego's deferred submittal list
City of San Diego Information Bulletin 188, dated February 2026, lists what may be deferred on commercial and multi-family residential buildings, and the first row of Table 1 reads "Building exterior envelope," then names four things in a parenthesis: storefronts, exterior cladding, curtain walls, windows.One row. Four scopes.
So the permit can carry criteria and not systems. On DSA projects the construction documents must "define the design criteria and all building design information necessary to accurately design the window wall systems," meaning the wind and seismic load criteria, the inelastic seismic drift demand, and the deflection limits of the supporting structure.
Deferral is not automatic, though, since IB 188 requires the building official's prior approval. The bulletin offers the other road in the same breath: an applicant who wants the envelope inside the permit set adds it to the scope of the building permit, and the item is no longer deferred.
Then the clock runs. Deferred submittal items cannot be submitted until the building permit is issued, nothing is installed until the building official has approved the documents, and the deferred submittal processing fee is $329.26, while on DSA work the gate sits earlier, since fabrication may not begin until the submittal is approved.
30 business days MINIMUM BETWEEN THE EXTERIOR ENVELOPE SUBMITTAL AND SETTING GLASS, SAN DIEGO IB 188 10 feet LONGEST SPAN THE STATE ARCHITECT'S REVIEW EXEMPTION ALLOWS ON AN EXTERIOR WINDOW WALL SYSTEM $329.26 SAN DIEGO'S DEFERRED SUBMITTAL PROCESSING FEE
The architect or engineer of record lists the deferral with the building official's prior approval, then states in writing that the documents have been "reviewed and found to be in general conformance to the design of the building," a statement that lands after the permit has issued and not less than 30 business days before the glass goes up.
The 2025 California Building Standards Code has been in force since January 1, 2026 and attaches to a project by application date rather than by issuance, and San Diego reviews a deferred submittal against the building codes the structure was permitted under, so a building that got its permit on the 2022 code has its 2026 glazing submittal read to the 2022 code.
Somewhere in the design meeting before any of that, with the floor-to-floor dimension fixed and the elevation drawn, somebody put the vertical member either into the slab or past it. The anchorage, the fire containment assembly, the second subcontractor and the delegated calculations all arrived with that line.
PermitFeed reads every SoCal filing nightly and scores it for glass and glazing contractors. The Trade Sheet shows the live numbers for your territory.