Planning a new deck or modifying an existing one? A structural engineer needs specific information about the deck, property, loads, and site conditions to design a safe structure and prepare accurate structural calculations and drawings.
Providing the right information at the beginning can make the engineering process faster, reduce revisions, and help determine the appropriate structural system for your deck.
1. Deck Dimensions
The engineer will typically need the basic dimensions of the proposed deck, including:
- Overall deck length and width
- Deck height above grade
- Number of levels
- Cantilevers and overhangs
- Stair locations and dimensions
- Areas for future additions or special features
A simple sketch with dimensions can be very helpful.
2. Deck Location
The project location is important because building codes, design loads, frost depth, wind requirements, snow loads, and other conditions vary by location.
Provide the:
- Property address or project location
- City and state
- Local jurisdiction, if known
- Existing house relationship to the deck
The engineer can then determine which codes and design criteria apply.
3. Site and Property Information
Site conditions can affect the deck's foundation and structural design.
Useful information includes:
- Property survey, if available
- Site plan
- Existing grades
- Location of property lines
- Existing retaining walls
- Drainage conditions
- Soil information, if available
- Location of underground utilities
Photos of the proposed deck area can also help the engineer understand existing conditions.
4. Deck Height and Elevation
The height of the deck is particularly important for designing posts, beams, stairs, bracing, and foundations.
Provide measurements from the ground to:
- Deck surface
- Bottom of beams
- Existing foundation
- Door or house connection points
For an existing deck, photographs showing the entire structure and support system are extremely useful.
5. Proposed Deck Framing
If known, provide the desired framing configuration, such as:
- Joist size
- Joist spacing
- Joist span
- Beam size and location
- Beam spans
- Post size and spacing
- Ledger location
- Rim joists
- Blocking and bracing
If you don't know these dimensions, the engineer can determine appropriate framing based on the design requirements.
6. Foundation and Footing Information
The engineer needs to understand how the deck will transfer its loads to the ground.
Provide information about:
- Existing footing locations
- Footing dimensions
- Footing depth
- Pier or post locations
- Soil conditions
- Frost depth requirements
- Existing foundation problems
For a new deck, the engineer can design the appropriate footing and support configuration based on the applicable site and loading conditions.
7. Connection to the House
For an attached deck, the engineer needs information about how the deck will connect to the house.
Important information may include:
- Ledger location
- Exterior wall construction
- Rim joist or structural framing behind the ledger
- Existing fasteners
- House foundation configuration
- Door locations
- Siding and exterior finishes
The connection between the deck and house is an important part of the overall structural load path.
8. Deck Materials
Tell the engineer what materials you plan to use.
For example:
- Pressure-treated wood
- Cedar
- Composite decking
- PVC decking
- Steel framing
- Aluminum components
Material properties and member dimensions can affect the structural design.
9. Special Loads and Features
A structural engineer needs to know about anything unusually heavy or structurally significant that will be placed on the deck.
Examples include:
- Hot tubs
- Outdoor kitchens
- Fireplaces
- Large planters
- Pergolas
- Deck roofs
- Enclosures
- Heavy masonry
- Pool equipment
- Large storage areas
A hot tub, for example, can add several thousand pounds of concentrated load and may require special structural consideration.
10. Photos of an Existing Deck
For an existing deck evaluation or renovation, clear photographs can save considerable time.
Useful photos include:
- Full deck overview
- Joists
- Beams
- Posts
- Footings
- Ledger connection
- Fasteners and connectors
- Stairs
- Railings
- Areas showing rot or damage
- Connection to the house
Close-up photographs combined with overall views provide the engineer with valuable information before an inspection.
What Does a Structural Engineer Actually Design?
Based on the project requirements, the engineer may determine:
- Joist sizes and spacing
- Beam sizes and spans
- Post sizes and spacing
- Footing sizes and locations
- Ledger connections
- Structural connectors
- Bracing requirements
- Guard and stair structural requirements
- Load paths
- Design loads
- Required reinforcement
The engineer may then prepare structural drawings and calculations suitable for construction and, where required, permitting.
Do You Need a Survey or Architectural Drawings?
Not always.
A simple residential deck may be engineered from a dimensioned sketch, photographs, property information, and measurements. More complicated projects may require a survey, architectural plans, site plan, or other documentation.
The exact requirements depend on the project and local permitting requirements.
How to Make the Deck Engineering Process Faster
Before contacting a structural engineer, gather:
✓ Deck dimensions
✓ Deck height
✓ Property location
✓ Photos
✓ Proposed framing layout
✓ House connection details
✓ Foundation information
✓ Material preferences
✓ Special loads
✓ Existing drawings or plans
✓ Survey/site plan, if available
The more accurate information you provide, the easier it is for the engineer to evaluate the project and develop an appropriate structural design.
Final Takeaway
A structural engineer needs more than just the length and width of a deck. The design depends on the deck's location, height, framing, foundation, house connection, materials, loads, and site conditions.
Providing accurate project information and photographs at the beginning can help your engineer develop safe, code-compliant deck structural designs, calculations, and drawings efficiently.
Need Deck Structural Engineering?
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Have your deck information ready? Contact DeckStructuralEngineer.com to discuss your project and determine what engineering services you need.