How Much Does a New Deck Cost in Illinois?
A custom-built deck transforms your Illinois backyard into a three-season outdoor living space. In 2025, Illinois homeowners can expect to pay $12,000 to $60,000+ for a new deck, depending on size, materials, design complexity, and features like railings, stairs, lighting, and built-in amenities.
The average 300-square-foot composite deck in Illinois costs between $15,000 and $25,000 fully installed, including railing, stairs, and permits. PVC decking (like TimberTech Azek) runs approximately 15-25% more than composite (like Trex), but offers superior moisture resistance and longer warranty coverage.
Deck Cost by Material
Your choice of decking material is the primary driver of project cost and long-term performance. Here's what Illinois homeowners should know about each option:
- Composite (Trex, TimberTech): $30-$55 per sq ft installed. Made from recycled wood fiber and plastic, composite decking resists fading, staining, and scratching. 25-year limited warranty. The most popular choice for Illinois decks.
- PVC (TimberTech Azek, Wolf): $40-$70 per sq ft installed. Contains zero organic material for the ultimate moisture resistance. Won't rot, mold, or support insects. 50-year limited warranty. Premium choice for ground-level and pool decks.
- Pressure-Treated Wood: $15-$30 per sq ft installed. Lowest initial cost but requires annual staining/sealing, is prone to splitting and warping, and typically lasts 10-15 years in Illinois's climate.
- Cedar: $25-$45 per sq ft installed. Beautiful natural appearance and natural insect resistance, but requires annual maintenance and has a shorter lifespan than composite or PVC in Illinois.
Illinois-Specific Deck Building Considerations
Building a deck in Illinois requires special attention to several factors unique to our climate:
- Frost Depth: Illinois requires footings to extend 36 inches below grade (36-42 inches depending on location) to prevent frost heave. This adds significant excavation and concrete costs compared to warmer climates.
- Snow Load: Structural framing must be engineered for Illinois's snow load requirements, typically 40-50 pounds per square foot. This often requires larger beams and closer joist spacing than minimum code.
- Freeze-Thaw Cycles: Materials must handle 40+ freeze-thaw cycles per year without cracking, splitting, or delaminating. This is why we recommend composite or PVC over natural wood.
- UV Exposure: Illinois's intense summer sun can cause fading in lower-quality decking. TimberTech Azek and Trex Transcend feature UV-resistant cap layers that maintain color for decades.
Deck Design Options and Add-Ons
Beyond the basic deck structure, several features can enhance your outdoor living experience:
- Composite or aluminum railing: $50-$100 per linear foot installed
- Cable railing systems: $75-$150 per linear foot for a modern, unobstructed view
- Built-in LED lighting: $1,000-$3,000 for post caps, stair risers, and under-rail lighting
- Pergola or shade structure: $3,000-$15,000 depending on size and materials
- Screen enclosure: $8,000-$25,000 for a fully screened outdoor room
- Outdoor kitchen features: $5,000-$20,000+ for built-in grills, countertops, and storage
| Material | Cost per Sq Ft | Lifespan | Maintenance | Warranty |
|---|---|---|---|---|
| Pressure-Treated Wood | $15 – $30 | 10-15 years | Annual stain/seal | Limited structural |
| Cedar | $25 – $45 | 15-20 years | Annual stain/seal | None standard |
| Trex Transcend | $35 – $55 | 25+ years | Occasional wash | 25-year limited |
| TimberTech Azek | $45 – $70 | 50+ years | Occasional wash | 50-year limited |
| Wolf Serenity PVC | $40 – $65 | 30+ years | Occasional wash | Limited lifetime |