Clear scope. Clean execution.
Structural roof damage is the condition that changes a roofing project from a membrane repair to a full building engineering engagement. When deck sections are compromised by fire, long-term corrosion, or overloaded ponding water, the roofing repair cannot proceed until the structural element is addressed. Putting new membrane over damaged deck does not fix the deck - it buries the problem and adds a layer of liability.
I include a structural assessment component in every major inspection I conduct. I am not a structural engineer - I am a roofing contractor - and I do not perform structural engineering calculations. What I do is identify the visual and physical indicators of structural distress: deck deflection, deck corrosion through to the surface, parapet wall displacement, damaged framing at rooftop equipment curbs, and ponding patterns that indicate deck settlement. When I find those indicators, I flag them in the inspection report and recommend structural engineering review before the roofing scope is finalized.
San Antonio's commercial building stock includes a significant inventory of older metal deck buildings along the IH-35 South corridor, the 410 industrial ring, and the pre-2000 warehouse inventory near the Port of San Antonio on Kelly Field. Many of those buildings have not had a documented deck condition assessment in 20 years. The combination of San Antonio's summer heat cycling, periodic freeze events, and the occasional overloaded drainage event from Harvey-remnant or flash-flood rainfall creates deck degradation conditions that are invisible from the roof surface without probing.
Structural Damage Indicators We Identify During Roof Inspection
Metal deck corrosion and surface degradation: Surface corrosion on metal deck is common in older San Antonio commercial buildings, particularly in areas of chronic ponding or persistent roof leaks. We identify surface corrosion during core pulls and in areas where the membrane has been removed for inspection. Section loss - where the deck has corroded through the galvanizing and into the base metal - reduces the fastener pullout values for the new membrane attachment and may require deck replacement before re-roofing.
Deck deflection: Visible deck deflection between structural purlins indicates either overloaded live load, reduced section modulus from corrosion, or inadequate original design. We measure deflection with a straightedge across the bay span and document any deflection exceeding L/240 - the threshold at which most structural engineers would require a load capacity assessment before proceeding with additional dead load (new insulation and membrane).
Parapet wall displacement: Displaced or leaning parapet walls indicate either foundation movement - common in San Antonio's limestone karst terrain - or structural damage from storm events. Parapet displacement affects the flashing geometry and the attachment of the base flashing system. A parapet that is out of plumb cannot receive a standard base flashing installation without modification.
Equipment curb structural damage: Rooftop equipment curbs on older San Antonio buildings may have experienced the anchor degradation from freeze-thaw cycling, thermal expansion, and deferred maintenance. A curb that has separated from its structural anchor is a load transfer failure waiting to happen when the HVAC unit cycles under vibration load.
How We Handle Structural Findings in Our Inspection Reports
We document every structural indicator we find - deflection measurements, corrosion observations, displacement measurements, equipment anchor conditions - with photographs and written descriptions in the inspection report. We do not perform engineering calculations or make structural determinations. We provide the documented observations that a structural engineer needs to make those determinations efficiently.
Structural coordination: For buildings where our inspection identifies structural indicators that require engineering review, we recommend structural engineers with commercial building experience in San Antonio and can facilitate the coordination between the structural review and our roofing scope. The sequencing is: structural review first, roofing scope finalized after the structural findings are clear.
Scope hold: When structural indicators are present, we put the roofing scope on hold until the structural review is complete. We do not accept a contract for roofing work over a structurally compromised deck - the liability and the safety risk are both unacceptable. We will tell you this directly and explain why the hold is in the building owner's interest, not ours.
Frequently asked questions
How do I know if my San Antonio commercial building needs a structural roof assessment before re-roofing?
The indicators we look for during a standard inspection include: visible deck deflection between purlins that is noticeable when you walk across the roof, ponding water that has been persistent for more than 48 hours after a rain event (which indicates either drain inadequacy or deck settlement), evidence of prior or current roof leaks in the area above the deck, any fire event history, and building age over 30 years with no documented deck inspection. If your building has any of these conditions, a structural assessment component should be part of the re-roofing scope.
Does the structural assessment delay the roofing project?
It adds time - typically two to four weeks for a structural engineer's site visit, analysis, and report. That time is worth it. A roofing project that proceeds over a compromised deck creates a liability for the contractor and an unsafe condition for the building's occupants. We factor the structural review timeline into the project schedule at the beginning so there are no surprises mid-project.
Can the roofing repair and structural repair happen at the same time?
In most cases, structural repair and roofing work are sequenced, not concurrent. The structural work - deck replacement, parapet repair, curb reconstruction - is completed first, and then the roofing membrane is installed over the sound structural substrate. Running both simultaneously creates coordination conflicts and the risk that roofing work is installed over a structural repair that has not been inspected and approved.
Concerned about structural conditions on a San Antonio commercial roof?
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