Searching for a Structural Engineer

Wed, Mar 21, 2018

Now that we have decided to draft our own architectural plans, we need to find a structural engineer who will do all the structural analysis, and provide structural plans for us.

Finding a structural engineer for an Owner/Builder residential project is hard. I started out with a google search and calling various firms, but what I was finding is that only the bigger firms had websites that were coming up on Google, and they weren’t interested in doing a residential project.

I came across the Structural Engineers Association of Washington website. This gave me a directory of all the members in the state.

I started calling and emailing everyone that was within about an hour drive from my primary residence. Every time we solicit a service from someone, I type up a brief PDF document outlining what I am looking for. This includes a description of the project, the requirements I have for the contractor, desired timeline, etc. By having this template drafted up ahead of time, it makes it easy to ensure everyone you are talking to is dealing with the same information.

I contacted maybe 20 firms and about half got back to me. Most of those responses were simply stating they either did not have time to take the project on, or were not currently interested in residential. But I had three firms that seemed interested in the project, and that is about as many as I was hoping for.

From various conversations, I’ve learned we will be facing a few challenges with the house as it is envisioned now…

Snow Load

We want exposed timber trusses in the main floor. These have to be custom designed a structural engineer, which we knew going out into this, but the first question they all asked is what our snow load requirement was. After a call to the county, we found out our ground snow load was 194 psf (pounds per square foot). The snow load on a heated roof was reduced to 174 psf.

These numbers are incredibly high. Snow weighs about 20 pounds per cubic foot, which means the roof is designed to support 9 feet of snow! One of our engineers commented that he had designed single vehicle bridges with a live load requirement of only 250 psf! Our roof is supporting almost as much weight as a bridge that cars were driving on!

Having a few exposed trusses, with large open spans between them, is out of the picture. The engineer could design exposed trusses, but they would have to be much closer together, and likely thicker, which is going to drive up the material and installation cost. Ultimately, we can always build faux trusses later to achieve the look we want.

Balcony off the Master Bedrooms

We want a balcony that juts straight out of the master bedrooms. In the architectural plans, I have not accounted for putting any kind of bracing below this balcony. It is 100% cantilevered (e.g., floating), and we really want it to remain that way. When you walk out of the master bedroom, we want it to feel like you’re floating on a platform in the sky. The master bedrooms will be about 15 feet off the ground as it is, but with the balcony projecting out over a small cliff, you will actually be about 40 feet off the ground.

Balcony profile

Since this balcony also has a covered roof, and that roof is supported by posts on the outside edge of this balcony, the balcony must be able to carry the load of the roof, plus itself, and any live loads. The more the balcony projects out, the more extreme these numbers become.

Deck

Finally, we want a covered deck to the north of the house. This deck has a shed underneath it, so the deck will serve as roof/ceiling for that. In other words, the decking must be waterproof, and because of our snow load, this deck must be concrete!

We have been playing to do the concrete ourselves, using ICF, but a suspended concrete deck is going to be more technical than I want to do myself.

By the end of these discussions, one of the engineers had dropped out, and we received bids from just two firms. Both were fairly reasonable, and we ended up going with a small firm called SideSway Engineering. We liked that the firm was small, and Chris, the owner, who we had been talking to already, would be personally working on the project. He had completed a number of cabins in the Cascades and seemed to be pretty enthusiastic about what we were trying to build.

If you are venturing down this same path I am, another thing to negotiate with your engineer is to get time with him during the actual build. Challenges will arise during the build, and in our case of not being experts, we may just need to ‘phone a friend’ at some point. Chris seemed very open to this, and his time would be covered at a standard rate. A bigger firm may have been able to get our plans returned to us faster, but may not have been as willing to spend 20 minutes on the phone next year when we are in the middle of the actual construction. Having someone on our team we could trust and rely on was worth waiting a bit longer.

Schedule Update

Our schedule is being pushed out again. SideSway cannot start work until May and expect to take 6-8 weeks to do their work, and then the county wants 6-8 weeks to issue a build permit. We may have a build permit by the end of Summer. I’ve been thinking that our new plan should be to get our concrete work done this fall, and be ready to frame in early spring. That maximizes our time to waterproof the building too.

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