Today Was A Banner Day!

Today, I picked up my building permit! I had to sign a bunch of stuff acknowledging the responsibilities and liabilities of an owner-builder, but I had done some research, so I have a pretty good idea of what I was signing up for.

California law allows for an exemption for homeowners who want to build on their own property. Basically, they are exempt from the requirements of the California Business and Professions Code, meaning that you DON’T have to have a license to build on your own property. That being said, there are a number of restrictions, most of which have to do with who has liability. All good stuff to know because understanding these details will help you avoid unpleasant legal actions should something go wrong. While there is a lot of legal gobbledygook involved, it boils down to some simple stuff.

(1) If you do you your own work, then you are responsible for the quality of that work, and if you sell the property, the buyers could conceivably come back after you if your work was shoddy. Unlikely in my case because I will be working under approved plans which will be inspected by the building department. Plus, I don’t do shoddy work as I will have to live with it. AND I don’t plan on selling the house. It will likely be inherited by my children (and THEY will have to deal with it).

(2) If I hire work to be done, then the work must be done by a licensed contractor OR I assume the responsibility of acting as a business and therefore have to pay for all of the liability insurance and taxes. Simple solution: Only hire licensed contractors. (And check them out ahead of time.) Yes, it may cost a little more up front, but it’s pennies on the dollar compared with an undocumented immigrant falling off your roof and permanently injuring his back. The immigrant may not do anything, but you can bet that the health care system will track you down and make you pay! This happened to an acquaintance of mine, and I felt very bad for him. But that was a big lapse in judgment on his part.

(3) There are some restrictions on selling the property or working on many properties at once. This is to discourage flippers. You have to own the property for a period of time and you can’t do it to many properties at once. Again, pretty much N/A in my case as this is really my home and not some quick-turn investment get-rich-quick scheme.

The other thing that happened to me today was that my car turned over  100K on the odometer. So I got the extra digit on the screen. It happened moments after I drove out of the civic center parking lot after getting my building permit. Coincidence? Yes,but a happy one. At least it put me in a good mood!

Detailed Design — How To Design A Structure

After the architectural design was complete, the next step was to actually figure out how to construct it. My plans needed to be detailed enough for the city building department to approve them. At first blush, one might think that pushing out a bedroom by seven feet is no big deal. Throw together a few trusses, use the existing flooring, build some walls with holes in them for windows, and you’re done.

Well, not really. The short story is that building codes have advanced, and when you build an addition, you are actually going to build a carefully engineered structure. If you’re really not a die hard DIY and/or don’t have any background or training in structural engineering or construction, then your best bet is to hire a designer to do the work. They aren’t cheap (I got a quote for $7,500 minimum), but it may be worth it, depending on the complexity of your project. Having said that, you don NOT have to be a structural engineer to design an addition , or any other structure for that matter. All you have to do is follow the prescriptive  methods contained in the applicable codes. This is essentially a “cookbook” method of designing a structure that includes a number of safety factors such that a design using these methods will withstand loads and stresses (people, wind, earthquake, etc.) that are expected for a residential home in a specific location. Here is where you can benefit from my experience. DO NOT try to get all fancy and design something that is not clearly specified in the codes and deviates from the “cookbook recipe”, then you will have to get a sign-off by a licensed Professional Engineer (P.E.). Again, this is expensive, and probably not worth it for a smaller project. So if you’re willing to spend some study time (and maybe even learn something!), a DIY solution awaits!

The best place to start is the building code that is applicable to your jurisdiction. The California Residential Code is actually reasonably easy to follow, but I found the American Wood Council Wood Frame Construction Manual (WFCM) a better resource for my purposes. Since the California Residential Code allows it, that is what I used. What really made a difference and put it all together for me was the WFCM Workbook, which has an example home design that steps you through the process. You will also have to determine the environmental conditions that your structure will need to withstand. This includes maximum wind conditions, seismic design category, whether or not you’re in a flood zone, maximum and minimum temperatures, termite infestation likelihood, and other factors. These are usually spelled out in the code and it makes sense to put together a little table for yourself so that you can refer to it when bouncing back and forth between the various parts of the code to get your numbers.

The approach that I used, which was taken directly from the WFCM workbook, was to start at the top and work my way down from the roof to the foundation. At each step you not only have to specify the materials (trusses, roof underlayment, studs, joists, etc.), but you ALSO need to show how these elements are connected. The code gives a table of fasteners (mainly nails) for fastening framing and sheathing, but when it comes to connecting major assemblies to each other, you typically have to use engineered specialty connectors (for example, roof truss to wall top plate). You have to be able to show, step by step, that the loads from each element are transferred through successive elements all the way to the foundation. So, roof to wall, wall to floor, floor to wall, wall to foundation.

A quick word about fasteners. The common nail is a very nuanced component. There are many types of many materials, and it is IMPORTANT that you use the right nail for the right purpose. The tables in the code tell you what to do, but therein are requirements for not only nail type, but spacing, and orientation, e.g., toe nail vs. face nail. Bigger and more is not necessarily better because you risk splitting the underlying wood member. So follow the instructions! In general, nails are better than screws, especially for framing. This is because they have significantly higher shear strength, and have some ductility which means that they will “give” a bit in a storm or an earthquake whereas screws tend to be brittle. Not that screws are bad. Just don’t use them for framing or shear walls. An exception to this are structural wood screws (SWS). These are larger screws made of heat treated steels that have higher quality control than your run-of-the-mill screw. The manufacturers of these screws have data sheets which detail their application. I used them in some places, a ledger board for example, but in general, I stuck with nails when I could.

One thing that was scary for me at the last was trying to figure out how to retrofit concrete anchors to bring the addition into compliance with seismic requirements. Fortunately, the folks who make these connectors also provide a method of anchoring these connectors with special epoxy into existing concrete. The only “downside” is that I have to have a certified inspector sign off on the installation. Well, maybe not a downside as it really has to be right. Just additional expense.

Although I spent many months getting to this point, and went down a few “rabbit holes”, I can definitely say that the effort was worth it, especially as a DIY’er. The process of designing showed me how to build it with all of the right materials, methods, and references. It’s going to be really pro!

Here is a link to my detailed construction plans.

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