Low to Moderate. While some aspects can be DIY, critical skills in membrane welding, precise flashing, and proper substrate preparation are often beyond typical homeowner capabilities. Professional installation ensures code compliance and warranty validity.
Professional installation is recommended due to critical details in membrane welding, flashing, and proper drainage slope, all of which are essential for long-term weatherproofing and code compliance in DuPage County's climate.
Project Guidelines & Rules
General Administration & Permits
3 Rules
Permit Application & Plan Review
IRC R105.1, R106.1, and your local municipality's building ordinances.
Required Inspections (e.g., Pre-Roof, Final)
IRC R109.1 and your local building department's inspection requirements.
Contractor Licensing & Insurance
State of Illinois and local municipal licensing board requirements for contractors.
Building Envelope & Structural Considerations
4 Rules
Structural Deck Integrity & Condition
IRC R502, R506, R802; Deck must be sound, free of defects, and capable of supporting loads.
Roof Slope for Positive Drainage
IRC R905.1, Minimum 1/4 inch per foot (2%) for flat roofs.
Wind Load Design (DuPage County)
IRC R301.2.1, ASCE 7-22 (as referenced by IRC); Basic wind speed typically 115-120 mph (3-second gust exposure category B or C).
Snow Load Design (DuPage County)
IRC R301.2.3, ASCE 7-22; Ground snow load typically 25 psf for DuPage County.
Materials & Assemblies
4 Rules
TPO Membrane Specifications
IRC R905.15, ASTM D6878; Listed for intended use, minimum 45 mil thickness (60 mil or 90 mil commonly specified).
Insulation Board Type & R-Value
IRC Chapter 15 (Energy Efficiency), R806.4, R905.15.2; Polyisocyanurate or other approved insulation to meet Climate Zone 5 (DuPage County) requirements.
Fasteners, Adhesives, & Sealants
IRC R905.15.4, R905.15.5; Must be compatible with all components, listed for roof applications, and resist specified wind uplift.
Underlayment/Cover Board (if required)
IRC R905.15.2, R905.15.3; Used to provide a smooth, stable surface over insulation or deck.
Installation Procedures
7 Rules
Substrate Preparation
Manufacturer's installation instructions, IRC R905.15; Clean, dry, smooth, and free of protrusions.
Vapor Retarders (if required)
IRC R806.3, R905.15; Placement determined by climate and building conditions to prevent condensation.
Insulation Attachment
IRC R905.15.2; Mechanically fastened or adhered to the deck/vapor barrier per manufacturer's specifications and wind uplift requirements.
TPO Membrane Fastening
IRC R905.15.4; Mechanically fastened at seams or fully adhered system as per design and wind uplift calculations.
Seam Welding
IRC R905.15.3; Hot-air welded seams, tested for integrity and must be watertight.
Flashing & Detailing (Parapets, Penetrations, Drains)
IRC R905.15.5; All penetrations, parapet walls, and scuppers must be properly flashed using TPO accessories or compatible materials, min 8" above membrane.
Edge Termination & Securement
IRC R905.15.5; Drip edges, metal coping, or termination bars securely fastened and sealed at all roof edges.
Drainage & Water Management
3 Rules
Positive Drainage
IRC R905.1; Roof must drain within 48 hours of a rain event.
Scuppers & Internal Drains
Illinois Plumbing Code 1101.4, 1101.9; Sized per tributary area and rainfall intensity. Emergency overflow drains required for primary drains.
Gutters & Downspouts
IRC R801.3; Sized and installed to accommodate roof runoff, preventing water damage to foundations.
Electrical Considerations (Roof-Mounted Equipment)
3 Rules
Wiring Methods for Roof-Mounted Equipment (e.g., HVAC)
NEC 300.5 (Protection Against Physical Damage), NEC 225.10 (Wiring on Buildings); Raceways must be secured and supported above the roof membrane.
Support for Electrical Conduit
NEC 300.11; Conduit and wiring systems must be adequately supported to prevent damage and allow water drainage.
Disconnecting Means for Equipment
NEC 440.14 (HVAC Disconnect); Readily accessible disconnect within sight of the equipment.
Plumbing Considerations (Roof Penetrations)
2 Rules
Vent Stack Penetrations
Illinois Plumbing Code 903.1, 904.1; Vent stack flashing must be watertight and extend a minimum of 6 inches above the finished roof surface.
Roof Drain Connections
Illinois Plumbing Code 1101.4, 1101.8; Connections to roof drains must be watertight and allow for thermal expansion and contraction of piping.
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