Based on the provided home addition planning guide for the Denver area, the specific total cost for a 500-square-foot home addition is not listed as a flat dollar amount. However, the guide provides a detailed framework for estimating costs based on several variables:

Cost Allocation Breakdown To estimate your budget, you can allocate your total investment according to these typical percentages:

• Interior Finishes: 20-30% (Flooring, cabinets, fixtures)
• Foundation: 10-20% (Varies significantly based on soil type and whether you use helical piers or concrete footings)
• Framing and Structure: 15-20% (Lumber, steel, and labor)
• Plumbing and Electrical: 15-20% (Upgrades to existing systems)
• Design and Engineering: 10-15% (Fees for architects and structural engineers)
• Landscaping and Exterior: 5-10% (Site work and restoration)
• Permits and Fees: 2-5% (Denver-specific permit costs)

Major Cost Drivers

• Build Up vs. Build Out: Building upward (adding a second story) typically results in a higher cost per square foot because it requires significant structural reinforcement of the existing foundation. Building outward (expanding the footprint) generally has a lower cost per square foot.
• Soil Conditions: In Denver, expansive clay soils often require specialized solutions like helical piers, which can increase initial foundation costs but are installed up to 66% faster than traditional footings.
• Contingency: It is recommended to allocate an additional 10-15% contingency fund to cover unforeseen conditions discovered during construction.

• Home Addition Planning Guide: Essential Steps for Colorado