One Story Addition Structural Engineering
Professional structural engineering for single-story room additions, bump-outs, sunrooms, and family room additions throughout California. Our licensed engineers design safe connections between your new addition and existing home with PE-stamped plans ready for permit.
What is One Story Addition Engineering?
A one-story addition is one of the best ways to expand your living space without the complexity and cost of building up. Whether you need a new family room, expanded kitchen, sunroom, or extra bedroom, single-story additions require careful structural engineering to ensure the new structure connects safely to your existing home. Our engineers design foundations, framing, roof tie-ins, and lateral force-resisting systems that integrate seamlessly with your current structure while meeting all California Building Code requirements.
Why Choose Our One Story Addition Engineering Services
Seamless structural connection between new addition and existing home
Foundation design matched to existing conditions and soil type
Roof tie-in engineering for weathertight, code-compliant connections
PE-stamped plans accepted by all California jurisdictions
Cost-effective designs that avoid over-engineering
Fast 1-2 week turnaround for most single-story additions
Construction support and contractor coordination included
What We Provide
Comprehensive one story addition engineering services with complete documentation
Addition Foundation Design
New foundation design coordinated with your existing foundation type. We address differential settlement, soil conditions, and proper load transfer between old and new structures.
Framing Plans & Details
Complete wood-frame structural plans showing walls, headers, floor framing, ceiling joists, and rafters with all connection details for the new addition.
Roof Tie-In Engineering
Structural design for connecting the new roof to your existing roof system, ensuring proper load paths, drainage, and weatherproofing at the intersection.
Existing Wall Modifications
Engineering for removing or modifying existing exterior walls where the addition connects, including header beams and temporary shoring requirements.
Seismic Design
Lateral force-resisting system design for the addition that integrates with the existing home's seismic resistance, meeting California earthquake requirements.
PE-Stamped Permit Documents
Complete structural drawings, calculations, and PE stamp for building department submittal. Includes plan check correction response and permit support.
How It Works
Our streamlined process for one story addition engineering
Free Consultation
Discuss your addition plans, review architectural drawings or sketches, and provide preliminary guidance on structural approach and costs.
Proposal & Agreement
Detailed written proposal outlining scope, deliverables, fees, and timeline specific to your one-story addition project.
Existing Structure Review
Evaluate your existing home's structural system, foundation type, framing, and roof to determine the best connection strategy for the addition.
Structural Design
Engineering design of the addition's foundation, framing, roof, and connections to the existing home. All elements designed per California Building Code.
Drawing Production
Create detailed structural plans including foundation plan, framing plan, roof framing, connection details, and construction notes.
Calculations & PE Stamping
Prepare comprehensive structural calculations and apply Professional Engineer stamp to all drawings for permit submittal.
Plan Check Support
Respond to building department plan check corrections and coordinate with jurisdiction reviewers to obtain permit approval.
Construction Support
Available during construction for contractor questions, connection clarifications, and field adjustments to ensure proper structural installation.
Common Applications
We provide one story addition engineering for a wide range of projects
Cost Information
Transparent pricing for your project
Typical Range:
$2,500 - $6,000 for most single-story room additions
Factors Affecting Cost:
- Addition square footage and layout
- Foundation type and soil conditions
- Roof tie-in complexity
- Existing home construction type and age
- Number of existing walls being modified
- Beam spans and load requirements
One-story addition structural engineering fees depend on the size and complexity of the addition and existing home conditions.
Timeline
What to expect for your project
Design Phase
1-2 weeks for most single-story additions
Permitting
2-6 weeks depending on jurisdiction
Total Timeline
3-8 weeks from start to permit approval
Timelines vary based on project complexity, jurisdiction requirements, and information availability. We provide detailed schedules during consultation.
Frequently Asked Questions
Common questions about one story addition engineering
Do I need a structural engineer for a one-story addition?
Yes. California building departments require PE-stamped structural plans for room additions. A structural engineer designs the foundation, framing, roof tie-in, and connections to your existing home. This ensures safety, code compliance, and smooth permit approval. Skipping structural engineering leads to permit delays and potential safety issues.
How much does structural engineering cost for a room addition?
Most one-story addition engineering costs $2,500-$6,000 depending on size and complexity. Small bump-outs and sunrooms are typically $2,500-$3,500. Larger additions like family rooms or master suites run $3,500-$6,000. We provide free consultations with detailed quotes before starting work.
How do you connect the new addition to my existing home?
We engineer the connection at the foundation level (tying new footings to existing), at the wall framing (removing exterior wall sections with proper headers), and at the roof (designing roof tie-in framing and flashing details). Each connection is designed to transfer loads safely and meet seismic requirements.
Will my existing foundation support an addition?
Your existing foundation typically does not need to support the addition directly. We design a new foundation for the addition that works independently while connecting properly to your existing foundation. If we identify concerns with your existing foundation during evaluation, we address those in our design.
How long does the structural engineering process take?
Design and drawing production takes 1-2 weeks for most one-story additions. Building department plan review adds 2-6 weeks depending on your jurisdiction. Total timeline from start to approved permit is typically 3-8 weeks. We provide realistic timelines in our proposal.
Can I add a room on a hillside lot?
Yes, hillside additions require more complex foundation design (stepped footings, piers, or retaining walls) but are absolutely feasible. Engineering costs are higher due to the additional complexity, and geotechnical reports are typically required. We have extensive experience with hillside residential construction throughout Southern California.