Buildings & Structural

Home Addition Engineering

Engineering for room additions and second stories: foundations, framing, beams and site impacts, stamped for your permit. Typical US fees run $2,000 to $8,500, and most projects take 2 to 6 weeks for design. Our drawings, calculations and reports are sealed by a Professional Engineer (PE) licensed in the state where your project is located, ready for permit submission.

Typical US fee$2,000 to $8,500

Typical timeline2 to 6 weeks for design

Permit drawingsSealed by a PE

What the work involves

For an addition, an engineer checks whether the existing foundation and framing can carry new loads, designs new footings, beams, headers and connections, and stamps the structural sheets in the permit set. A second-story addition often needs the existing foundation evaluated and sometimes reinforced. A civil engineer may also be needed when the addition changes impervious area, grading, drainage or setbacks, or sits on a septic system or slope. The architect or designer typically leads, with the engineer providing the stamped structural design.

When you need it

Adding a second story or building over a garage
Adding a room that ties into existing roof or floor framing
Building department requires stamped structural calculations
Addition on a slope, fill or expansive soil
Addition increases impervious area enough to trigger a drainage or grading review

What you receive

Structural calculations
Stamped foundation and framing plans
Beam and header sizing
Connection and hold-down details
Grading or drainage plan if required

What drives the cost

HomeAdvisor lists basic residential structural engineering at $2,000 to $8,500 per project and drawings at $500 to $5,000 per sheet. Second-story work that requires foundation evaluation, or sites needing a drainage plan, tend toward the upper end.

Related calculators

Roof Pitch CalculatorConvert roof pitch (rise per 12 in of run) to angle and percent, and calculate rafter length and the pitch multiplier.Footing Size Calculator (Bearing Area)Estimate the required plan area and side length of a square spread footing from column load and allowable soil bearing pressure.Point Load on Beam CalculatorFind support reactions, maximum moment and deflection under a single point load anywhere on a simply supported beam.Simple Beam Deflection Calculator (Uniform Load)Calculate maximum moment, shear, bending stress and midspan deflection for a simply supported beam under a uniform load.

Frequently asked questions

How much does home Addition Engineering cost?

Across the US, home Addition Engineering usually costs $2,000 to $8,500. HomeAdvisor lists basic residential structural engineering at $2,000 to $8,500 per project and drawings at $500 to $5,000 per sheet. Second-story work that requires foundation evaluation, or sites needing a drainage plan, tend toward the upper end.

How long does home Addition Engineering take?

Plan on 2 to 6 weeks for design from signed proposal to stamped deliverables, longer if a site visit, soil testing or a permit review cycle is involved.

Do I need a licensed PE for home Addition Engineering?

In most US jurisdictions, yes. When the work needs a permit, the plans, calculations or report usually must be sealed by a Professional Engineer licensed in the state where the project is located. Every deliverable we issue for permit is sealed that way.

Will I also need a structural engineer?

Sometimes. Depending on the site, home Addition Engineering can also involve a structural engineer, architect, geotechnical engineer or land surveyor. We tell you up front which other professionals your project needs and coordinate with them so the drawings agree.

Who do you provide home Addition Engineering for?

Most of our clients for this service are homeowners, contractors and architects. Describe your project and one of our engineers will reply with scope, fee and schedule.

Do I need an engineer or an architect for an addition?

Often both. An architect or designer lays out the space, and a licensed engineer designs and stamps the structural elements. Some jurisdictions accept prescriptive framing for simple one-story additions without an engineer, but second stories and nonstandard spans usually need one.

Can my existing foundation support a second story?

Only an evaluation can say. The engineer checks footing size, soil conditions and the condition of the existing foundation, and may recommend underpinning or new footings.

Will an addition require a new survey?

Many jurisdictions require a site plan showing setbacks, and some require a boundary or topographic survey prepared by a licensed land surveyor, especially near property lines. An existing survey may be accepted if it is recent and shows current improvements.

What drives the engineering fee?

The number of new structural elements, whether the existing structure must be analyzed, steel or long-span beams, and whether site drainage or grading plans are also required. Getting a fixed-fee proposal with a defined scope makes quotes easier to compare.