Seismic Retrofit Engineer and Wind Retrofit Design
A seismic retrofit engineer for bolting, cripple walls, soft stories and hurricane upgrades, with stamped plans for your existing building.
- Stamped by a PE licensed in your state
- Built to IBC, IRC and local amendments
- Plan-check comments answered
Strengthen the building you already have
Many existing buildings were built before modern codes required a continuous load path for earthquakes and high winds. Houses sit unbolted on their foundations, cripple walls have no sheathing, apartment buildings have open parking at ground level, and roofs are held on by toenails. A seismic retrofit engineer finds those weak links and designs targeted upgrades that make the building far more likely to stay standing and repairable after a major event.
PE Engineer designs earthquake retrofits for houses, apartments and commercial buildings, and wind and hurricane retrofits for homes and light commercial structures. We evaluate the existing building from your photos, drawings and measurements, identify the vulnerabilities that matter, and design upgrades sized to the hazard at your address. The plans are sealed by a PE licensed in the state where the building is located.
Retrofits work best when they are focused. We design what will make a real difference for the building, explain the options in plain language, and give your contractor clear details to install.
What you receive
- Existing building evaluation summary
- Retrofit plan with upgrade locations
- Anchor bolt and connection details
- Shear wall or frame design
- Roof-to-wall and uplift details
- PE stamped calculations and drawings
Retrofits we design
Each retrofit targets the specific weakness that causes damage in earthquakes or windstorms for that type of building.
Foundation bolting
Anchor bolts or retrofit plates that connect the wood sill plate to the concrete foundation, so the house cannot slide off its foundation during shaking.
Cripple wall bracing
Plywood or OSB sheathing with specified nailing on short crawlspace walls, turning a weak story under raised-floor homes into a braced one.
Soft-story retrofits
Steel moment frames, cantilever columns or new shear walls at open ground floors with parking or storefronts, where walls above sit on few supports below.
Roof-to-wall connections
Hurricane straps and clips that tie rafters and trusses to the walls, completing the uplift path from the roof down to the foundation.
Gable ends and openings
Gable end wall bracing, garage door reinforcement and coordination of opening protection, all common failure points in hurricanes and high winds.
Masonry and concrete buildings
Wall anchorage, parapet bracing and diaphragm upgrades for unreinforced masonry and concrete tilt-up buildings, where walls can separate from the roof.
Your Stamped, Permit-Ready Plans Start With One Upload
Send your drawings or describe the project. A licensed engineer reviews it and sends a clear, fixed-fee proposal, often within hours.
- Free and no obligation
- Reviewed by a licensed PE
- Secure file upload
What a seismic retrofit engineer looks for
Earthquake damage in wood buildings tends to follow a few predictable patterns, and a good retrofit addresses them in order of importance. When we evaluate a building, we look at:
- Foundation connection. Older homes were often not bolted to their foundations, or bolted with too few anchors. In strong shaking the house can slide off.
- Cripple walls. The short stud walls between the foundation and the first floor in raised-floor homes are often unsheathed and can collapse sideways.
- Soft and weak stories. Ground floors with garage doors, tuck-under parking or storefront glass have far less wall than the floors above, which concentrates damage at that level.
- Irregular and hillside buildings. Split levels, homes on stilts and buildings stepped down a slope have uneven stiffness that needs engineered solutions.
- Masonry elements. Unreinforced chimneys, parapets and masonry walls can crack and fall.
- Heavy equipment. Unanchored water heaters, boilers and rooftop units can tip and break gas or water lines.
We work from photos of the crawlspace, foundation, garage and exterior, plus any existing drawings and measurements. When the structure is hidden or conditions are unclear, a site visit can be arranged through a local licensed engineer. Our evaluation summary explains what we found and what we recommend, in priority order, so you can make informed decisions about scope and budget.
Residential earthquake retrofit: bolting, cripple walls and soft stories
For many single-family homes, a retrofit focuses on two upgrades: bolting the sill plate to the foundation and bracing the cripple walls with structural panels. These upgrades are relatively affordable and address the most common causes of serious damage to raised-floor homes.
Some jurisdictions accept prescriptive retrofit standards for simple houses, such as the cripple wall and sill anchorage provisions in the International Existing Building Code appendix, or plan sets based on FEMA P-1100. Those approaches work well when a house fits their limits. When it does not, because the cripple walls are too tall, the house is on a slope, the foundation is deteriorated or the layout is irregular, an engineered design is required. We provide both paths: we confirm when a prescriptive approach applies and design an engineered retrofit when it does not.
Soft-story buildings need more. Apartment buildings with tuck-under parking and homes over garages typically need a steel moment frame, cantilever columns or new plywood shear walls at the open level, along with new foundations to carry the overturning forces. Several cities in high-seismic areas, including many in California, have mandatory soft-story retrofit programs with their own deadlines and design criteria, and we design to those local requirements.
Every retrofit drawing shows the anchor type and spacing, sheathing and nailing, hardware, and any new footings, so the contractor knows exactly what to install and the inspector knows exactly what to check.
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- Free and no obligation
- Reviewed by a licensed PE
- Secure file upload
Wind and hurricane retrofit for existing homes
In hurricanes and severe windstorms, homes usually fail from the top down. Wind pressure lifts roof covering and sheathing, water pours in, and if the roof structure itself is not tied down, it can lift off the walls. A wind retrofit strengthens that chain of connections.
Typical wind retrofit measures we design include:
- Roof deck attachment. Re-nailing roof sheathing with closer spacing and ring-shank nails when the roof covering is replaced.
- Roof-to-wall connections. Hurricane straps or clips at each rafter or truss, connected to the wall top plates and continued down the wall.
- Gable end bracing. Bracing for tall gable end walls, which can be pushed in or pulled out by wind if they are not braced back to the ceiling or roof framing.
- Garage doors. Reinforcement or replacement with a wind-rated door. A failed garage door lets wind pressurize the house from inside.
- Opening protection. Coordination of shutters or impact-rated windows and doors, with attachment details where needed.
Programs such as the IBHS FORTIFIED Home standard describe recognized levels of wind retrofit, and in some states documented retrofits may help with insurance premiums. In Florida and other coastal states, the work must also meet the local code for existing buildings. We design to the wind speed and exposure at your address and provide the stamped documentation your building department and insurer may ask for.
Commercial and multifamily retrofits
Larger existing buildings have their own retrofit needs. Concrete tilt-up warehouses and older masonry buildings can lose the connection between heavy walls and a flexible wood roof in an earthquake, letting walls fall outward. Retrofits add wall-to-roof anchors, continuity ties across the roof diaphragm, and parapet bracing. Unreinforced masonry buildings may need wall anchorage, new shear walls or frames, and diaphragm strengthening.
For engineered evaluations of these buildings we follow ASCE 41, Seismic Evaluation and Retrofit of Existing Buildings, which sets out performance objectives and methods for checking existing components. Where a city has adopted a mandatory retrofit ordinance, we use the design criteria that ordinance specifies.
Retrofits are also triggered by other projects. A change of use, a large addition or significant alterations may require the existing structure to be evaluated and upgraded under the existing building code your jurisdiction has adopted. We can tell you whether your project triggers that requirement and design the work in the same set.
Nonstructural components matter too. Rooftop mechanical units, tanks, generators and storage racks can fail even when the building does not. Our equipment anchorage design covers those items. For property owners who first need to know the condition of the building, our structural inspection letters provide an engineer’s assessment before deciding on the retrofit scope.
You likely need this if
- Your house is not bolted to the foundation
- You have a raised floor with cripple walls
- Your building has tuck-under parking
- Your city issued a retrofit order
- You live in a hurricane or high wind area
- You are altering or changing the use of a building
How it works, start to finish
From your first message to stamped drawings, you work directly with the engineering team.
- 1Share your projectSend the address, scope and any drawings, photos or plan-check comments. Two minutes is enough.
- 2Receive a fixed-fee proposalAn engineer reviews the scope and replies with a firm price and delivery date for your seismic & wind retrofit drawings.
- 3Engineering and draftingWe run the calculations and prepare drawings to the codes your jurisdiction enforces, checked before sealing.
- 4Stamped set deliveredYou receive a sealed PDF set ready to submit, and we answer any plan-check comments within scope.
Codes and standards for retrofit design
Retrofit designs follow the existing building code your jurisdiction has adopted, local retrofit ordinances and recognized national standards:
- International Existing Building Code (IEBC), including its seismic strengthening appendix chapters
- ASCE 41, Seismic Evaluation and Retrofit of Existing Buildings
- ASCE 7 for seismic and wind loads
- FEMA P-1100 for seismic retrofit of one- and two-family dwellings
- AWC Special Design Provisions for Wind and Seismic (SDPWS)
- State codes such as the California Existing Building Code and the Florida Building Code, Existing Building
How licensing works. Engineering drawings must be sealed by a Professional Engineer licensed in the state where your project is located. PE Engineer works with a network of state-licensed PEs, so every set is reviewed and stamped by an engineer with an active license in the state where your project is located. Their name and license number appear on the seal, exactly as your building department requires.
Related services
Structural Inspections & LettersSealed structural inspection reports and engineer letters for foundations, cracks, framing, damage, unpermitted work and existing buildings, written for the people who requested them.Explore More
Foundation DesignFootings, slabs, stem walls, piers and pile foundations designed and PE stamped for your soil, loads and local code.Explore More
Equipment AnchorageSeismic and wind anchorage calculations for machinery, tanks, generators, electrical gear and rooftop units, designed to ASCE 7 and ACI 318 and PE stamped.Explore MoreFrequently asked questions
Does my house need a seismic retrofit?
If you live in an earthquake-prone area and your home was built before modern anchorage requirements, has a raised floor with cripple walls, or has living space over a garage, a retrofit is worth considering. Send photos of the crawlspace, foundation and garage, and we will tell you which upgrades would make a real difference.
What is a soft-story retrofit?
A soft story is a ground floor that is much weaker or more flexible than the floors above, usually because of garage openings or storefront glass. A soft-story retrofit adds steel frames, columns or shear walls at that level, along with new foundations, so the building does not lean or collapse at the ground floor.
Do I need a permit for a seismic or wind retrofit?
Generally, yes. Retrofits are structural work and most building departments require a permit. Some accept prescriptive plan sets for simple bolting and bracing, while others require engineered plans. Either way, a permit gives you inspected, documented work, which matters for resale and insurance.
Is a prescriptive retrofit enough, or do I need an engineer?
Prescriptive standards cover many simple houses on level lots with short cripple walls. Houses on slopes, with tall cripple walls, deteriorated foundations, irregular plans or soft stories need an engineered design. We can confirm which path fits your house before any work starts.
Can a wind retrofit lower my insurance premium?
In some states and with some insurers, documented wind mitigation features such as roof-to-wall straps, enhanced roof deck attachment and opening protection may qualify for premium credits. Requirements vary by insurer and state, so check with your agent. We provide the engineered design and documentation the work is based on.
What do you need to quote a retrofit?
The address, the year the building was built if known, photos of the foundation, crawlspace or garage and exterior, any existing drawings, and any city retrofit notice you received. We send a fixed-fee quote, usually the same day, and explain which upgrades we recommend.
Get your free seismic & wind retrofit proposal
Tell us where the project is and what you need. Attach any drawings, photos or plan-check comments. A licensed engineer reviews every request.
- Upload your filesPlans, sketches, photos or comments
- Get a fixed-fee proposalUsually the same day
- Receive stamped drawingsSealed by a PE licensed in your state