There's a lot of confusion about whether or not your house plan needs any engineering before being approved by your building department for construction permits.
In this post we'll walk you through different types of requirements, codes and engineering as well as potential costs and turn around times that you can expect.
Unlike some others, we don't shy away from saying it - all online house plans should be reviewed by a structural engineer to comply with local loads and site conditions. Every site has different soil conditions, topography, wind loads, snow loads, seismic loads and weathering conditions. Online house designs can typically be built anywhere but they do need to have their structural design optimized for the site itself. While much of structural design can be as prescribed by the building code, there are many facets of the design that can benefit from an experienced engineer.
Types of House Plan Engineering:
In the US, Engineers are licensed at the state level. When required, structural engineers can review our plans, develop overlay plans of their own and stamp those drawings to certify that they meet the required code in your jurisdiction. Note, while we provide typical cost ranges for each service these numbers can vary widely for different jurisdictions, site conditions and house designs. We provide cost ranges as a rough reference point but you should secure multiple bids to ensure that you're getting a fair price.Structural ($1,000-4,000 typical range):
Structural Engineering is by far the most common type of engineering for house plans. A Structural Engineer will design your foundation, floor framing, roof framing, load paths and window/door headers. They'll put together a structural framing plan with all of this information, as well as typical construction details like stepped foundations and nailing patterns.Truss Engineering ($ = Included in Truss Bid):
Almost universally, truss engineering is provided by the truss manufacturer so it's not something to worry too much about as an owner. When the time comes for bidding trusses, you (or your General Contractor) will simply provide the house plans to the truss manufacturer and they will develop engineered truss shop drawings for you as part of their bid. It's a highly automated computerized process which makes it very affordable to include in the truss package.Geotechnical ($1,000-2,000 typical range):
Geotechnical Engineering is much less common but occasionally required for sites with abnormal soil conditions. When necessary, a Geotechnical Engineer will go out to your site and dig test pits, test the bearing capacity and composition of the soil (before and after excavation). Their findings will be transferred to the structural engineer to be fed into the foundation design. Most houses do not require Geotechnical Engineering, but if the lot is significantly sloped or has challenging soil or possible flood conditions then you might want to budget for a Geotechnical Engineer. Your Structural Engineer or local Building Department can advise.Civil ($1,000-3,000 typical range):
Many jurisdictions require site plans but most do not require them to be stamped by an Engineer. In some rare cases, a Civil Engineer will have to be brought in to develop a site plan but this is usually only for large developments or land subdivisions. The site plan will transpose the House Plan on top of the lot survey and then the Civil Engineer will layer in grading and drainage structures, hardscaping (driveways, walkways), temporary erosion control structures, utilities, landscape screening and more. They may need to perform impervious surface and drainage calculations to meet local codes.Mechanical / Electrical / Plumbing (MEP) Engineering ($2,000-3,000 typical range):
An MEP Engineer is a type of Mechanical Engineer. MEP Engineers are very rarely needed in single-family residential projects but can be useful if you are trying to design a very complicated HVAC, electrical or plumbing system. Building Departments almost never require MEP Engineers to stamp plans so typically what happens is that each MEP subcontractor will put together a quick sketch of the system they're installing to meet the permit requirements (if needed).
How to Find an Engineer:
If you've contacted your Building Department and they told you that you need your plans Engineered. There's a number of places you can look to easily and quickly get that done. As a rule of thumb, it's best to find an Engineer who is local to the building site since they will know how to work efficiently with your Building Department which reduces the risk of getting your plans rejected for resubmittal and delaying your construction process. Remember to get multiple bids!
Call your building department and ask for local references.
Call local contractors and ask for local references.
How Long Does Engineering Take?
Typically it can take around a month depending on the individual consultant, but most of that is just waiting time - the actual engineering will typically only take a few days. We recommend contracting your engineer as early as possible so that you can get in the queue.
Building code is administered at the local level. As part of your Lot Evaluation process, you should determine which building department has jurisdiction over your lot and what building code they've adopted (if any). Yes, believe it or not some remote jurisdictions have no building code!
We design all of our house plans to the International Residential Code (IRC) which is the most commonly adopted code by local building departments across the US and many other countries. The code covers foundation design, floor construction, wall construction, roof construction, energy efficiency, and more. Some jurisdictions develop their own code or sometimes add a supplement to the IRC to account for local conditions.