Ponding water
Low spots, sagging decks or blocked drains leave water sitting on the roof. Standing water speeds up membrane wear and finds any weak seam.
GLENDALE, CA · COMMERCIAL ROOFING
Commercial Roofing in Glendale, CA
Based in Glendale, Citium provides roof repair, installation and replacement for residential and commercial properties. Most commercial roofs here are low-slope, so this page covers TPO, torch-down and what owners should plan for.
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Commercial roofing from a Glendale-based contractor
Citium Roofing Solutions is based at 401 N Brand Blvd in Glendale and provides roof repair, installation and replacement for residential and commercial properties. On commercial buildings that usually means a low-slope roof: 60-mil TPO or a modified bitumen (torch-down) assembly.
Every job starts the same way. Citium assesses the roof to confirm measurements, condition and pricing, and the visit ends in a written scope that names the assembly. The price follows that visit, not a phone guess by the square foot.
The rest of this page is general guidance for owners and property managers in Glendale: how low-slope roofs fail, when a repair is enough, how permits work in the city, what maintenance keeps a flat roof working, and what to have ready when you ask for an estimate.
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Low-slope roof systems on commercial buildings
TPO membrane
Citium installs 60-mil TPO over specified insulation and cover board, mechanically attached or fully adhered. The seams are joined with heat welding, and the white or light gray surface reflects sun instead of soaking it up.
TPO roofingModified bitumen (torch-down)
A three-layer torch-down assembly is a base sheet, a ply sheet and a mineral cap sheet. Torch application is one method, not a default for every property, and it needs fire precautions around parapets, wood and rooftop equipment.
Modified bitumen and torch-down roofingOlder built-up and layered roofs
Many older Glendale buildings carry several layers of past roofing, sometimes gravel-surfaced built-up roofing. Knowing what is up there, and how many layers, comes before any repair-or-replace decision, because it affects weight, drainage and whether another layer is allowed.
Buildings that mix flat and pitched roofs
Mixed-use and multifamily buildings often pair a flat main roof with pitched sections, mansards or tile accents. The transition between the two is a common leak point and belongs in the same scope as the membrane.
Flat roof repair03 /
Where commercial roofs leak
Seams
Seams are the joints of a membrane roof. As a roof ages, open or poorly bonded seams become one of the most frequent leak sources.
Equipment curbs and penetrations
HVAC units, vents, conduit and pipes each need flashing that stays sealed, even after the equipment is serviced or replaced.
Parapets and wall flashing
Where the roof turns up a wall, flashing and terminations loosen with movement and age, and water gets behind them.
Drains and scuppers
Leaves, dust and debris collect through the dry season and block drains right before the first winter storm.
Foot traffic
Service technicians walking the roof puncture and scuff membranes, especially around equipment and along the usual path to it.
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TPO or modified bitumen?
| TPO | Modified bitumen | |
|---|---|---|
| Construction | Single-ply membrane | Multiple layers (base, ply, cap) |
| Seams | Heat-welded | Lapped and bonded per the application method |
| Surface | Smooth white or light gray | Granule-surfaced cap sheet |
| Heat | Light surface reflects sun | Depends on the cap sheet color |
| Install considerations | Attachment depends on the deck and insulation | Torch method needs fire precautions |
| Repairs | Heat-welded patches on clean membrane | Compatible cap sheet patches |
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Repair or replace a commercial roof?
Some localized issues can be repaired. A split seam, a failed flashing at a curb, or a punctured area on a membrane that is otherwise sound is usually a repair, and it should be priced and described as one.
Replacement comes up when the problems are spread across the roof: wet insulation in many areas, a membrane that has turned brittle or pulled away from the edges, repeated leaks in different spots, or existing layers that rule out another overlay.
Either way, the written scope should say which it is and why, and list the drains, flashing and details it covers so you can compare bids line by line.
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What a commercial reroof usually involves
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Assessment
The roof surface, drains, parapets and rooftop equipment are checked, along with the existing layers and insulation. Citium assesses the roof to confirm measurements, condition and pricing.
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Written scope
The proposal names the system, attachment method, insulation, flashing details and drainage work, and how unexpected findings such as wet insulation or a damaged deck are handled and priced.
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Permit
In the City of Glendale, re-roofs are applied for online through the GlendalePermits portal. A change of roofing material, or a building identified as historic, needs a Design Review Exemption approved before the building permit application. Citium includes permit and inspection steps in the project plan.
Source: City of Glendale, Permit Application Guidance (Re-Roof)
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Access and occupants
Roof access, material staging, any hoist or crane, parking and noise are planned around tenants and the building's schedule.
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Rooftop equipment
HVAC units, conduit and other equipment may need to be disconnected, raised or reflashed, which means coordinating with the trades that service them.
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Work in sections
Large roofs are usually done one section at a time, so the building is closed in and watertight at the end of each workday.
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Final inspection and records
The city's final inspection closes the permit. Workmanship and product warranties are stated in the contract for a specific job, so keep the contract, product data and permit record with the building's documents.
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Maintenance that keeps a low-slope roof working
Low-slope roofs hold debris and water longer than pitched roofs, so small problems grow faster when nobody looks. A simple plan is a walk-through before the rainy season, another after a major storm or wind event, and a check whenever another trade has worked on the roof.
On each walk-through, clear drains, scuppers and downspouts; look for water that is still standing a couple of days after rain; check seams, wall flashing, curbs and pipe penetrations; note new punctures or scuffs near equipment; and look at ceilings below for new stains.
Keep a roof log with dates, photos, leaks and repairs. It helps whoever works on the roof next, and it turns a surprise replacement into one you can budget for.
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What to have ready for a commercial estimate
Property basics
The address, building type and use (retail, office, multifamily, mixed-use or industrial), number of stories, and the approximate roof area if you know it.
Roof history
Approximate roof age, known layers, past repairs, and any drawings, earlier proposals or product records you have on file.
Leak details
Where leaks show up inside, when they started, and whether they follow rain, wind or HVAC use. Photos taken safely from inside or from the ground help.
Roof access
How the roof is reached (interior hatch, fixed ladder or exterior access), who holds keys, and any areas with restricted access.
Rooftop equipment
HVAC units, solar arrays, antennas or signs on the roof, and the companies that service them.
Occupants and schedule
Tenants, noise-sensitive uses, parking limits, and the times when work can or can't happen on site.
Decision and budget
Who approves the work, and whether you are planning a repair now or a replacement later. Citium offers financing; ask about current options.
Financing options09 /
Energy code on commercial reroofs
California's Title 24, Part 6 energy code sets cool roof requirements for many nonresidential reroofs. Which ones apply depends on the building, the roof's slope and the climate zone, and replacing most of a roof is what usually triggers them.
A light TPO membrane or a cool-rated cap sheet is the usual way to meet them. Citium confirms the CRRC values for the specified product against what your address requires.
Source: California Energy Commission, 2025 Building Energy Efficiency Standards (Title 24, Part 6)
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Commercial roofing questions
Which is better for a commercial flat roof, TPO or modified bitumen?
Neither is better for every building. TPO is a single-ply membrane with heat-welded seams and a light, reflective surface. Modified bitumen is a multi-layer assembly with a granule-surfaced cap. The deck, insulation, rooftop traffic, drainage and budget decide which fits.
Can a commercial roof be repaired instead of replaced?
Often, when the damage is limited to seams, flashing or a small area and the membrane is still sound. Widespread wet insulation, a brittle or shrinking membrane, or repeated leaks across the roof point to replacement.
Why does water pond on my flat roof?
Ponding comes from blocked drains or scuppers, low spots in the deck, sagging structure, or a roof built without enough slope. Clearing drains fixes some cases; others need tapered insulation or structural work.
Can roof work happen while the building stays open?
Often, yes. Low-slope roofs are usually worked in sections, and access, staging and noise are planned around tenants. The scope should say how the roof is closed in at the end of each day.
Does a commercial reroof in Glendale need a permit?
Yes. Re-roofs in the City of Glendale are applied for through the GlendalePermits portal, and a change of roofing material or a historic building needs a Design Review Exemption first. Citium includes permit and inspection steps in the project plan.
Source: City of Glendale, Permit Application Guidance (Re-Roof)
How often should a commercial roof be checked?
Check drains, seams and flashing before each rainy season, after major storms, and after any trade works on the roof, such as an HVAC replacement or a new vent. Low-slope roofs hold debris and water longer than pitched roofs, so small problems grow faster if nobody looks.
GET STARTEDCitium Roofing Solutions 401 N Brand Blvd, Unit L106B, Glendale, CA 91203818-531-1277citiuminc@gmail.com
Talk to Citium about your commercial roof
Call 818-531-1277, email citiuminc@gmail.com, or request a free estimate online. Tell us the building type, the roof system if you know it, and what you're seeing. Citium Roofing Solutions is at 401 N Brand Blvd, Unit L106B, Glendale, CA 91203.