DADUs, ADUs & Backyard Cottages

South Seattle Shipping Container Office

January 10, 2018

 

Two shipping containers are getting a new life in Georgetown – as a backyard office for our busy client!

This project has been a long time coming, but it didn’t originally start out as a container structure. We first studied it as a garage remodel, but seismically unstable soil conditions prevented following through on this approach. We needed something that was intrinsically sound.

This project is driven by material reuse, living small, and building green. There exists a backyard garage/shed original to the 1928 house that the “remodel” scheme originally looked at building over with a timber “exo-skeleton”, and a “new” scheme replaced it entirely. But we needed to find a more economical, resourceful, geotechnically-stable, and environmentally-friendly option, and shipping containers hit the mark! Without the need for siding, roofing, or structure, this project saves three large budget numbers right off the bat; it even comes with flooring if you purchase a container in decent condition. We chose “one-trip” containers for this project so they weren’t new off the shelf, but haven’t been damaged by countless trips across the sea.

Having justified our choice of “material”, the most difficult part of the project began: research. Shipping container building isn’t taught in a classroom or in a textbook, and it is still scarcely available online. We relied on the help of a few local experts to get us started. Cantilevering the containers turned out to be much simpler than we anticipated; we were presented with only a few sheets of engineering plans and a handful of details for the entire project. The shipping container supplier will complete all steel modifications on site, i.e. window openings, steel strengthening, etc. before the containers are delivered, and the interiors can even be pre-fabricated so that once on site, only assembly is required!

A particular aspect of this property did indeed make the planning more difficult, yet provided its own solution. Seattle’s Georgetown neighborhood is entirely within a liquefaction zone, meaning that during a seismic event the ground will liquefy and structures can be seriously compromised (Think: cars and homes halfway submerged in the ground after the soils re-solidify). All parties, including the city, wanted to make sure that life safety was guaranteed. The structural and geotechnical engineers designed a 18″ thick concrete mat slab that will effectively allow the structure to float relatively intact during any seismic activity. The fact that the shipping containers might once again “float” was not lost on us!

Complete with a green roof, this backyard office will be a respite away from the working world, while also fitting in with the industrial aesthetics of the Georgetown neighborhood. In the lower container, a side door leads to a bathroom with a shower and a kitchenette with a view of the green urban jungle that our owner meticulously maintains in his backyard! The south side of the container will be an unheated storage space accessed by using the actual container doors. The upper container is accessed by an exterior stair and small deck. From the deck you can either climb to the upper roof deck to tend the gardens or enter the upper container: a full-length office space, surrounded by warm-toned birch ply walls.

Not surprisingly, not every project has the need, desire, or property available to build a 2-story cantilevered shipping container in their backyard; we’re quite excited to see the final product! Stay tuned for photos as the project takes shape in the real world. Construction is expected to start February 2018.

 

DADUs, Backyard Cottages and Small Living in Seattle: Can you DADU too?

August 15, 2016

The greater Seattle area is growing! Are you up to date on what you’re able to build in your backyard?

This “DADU” is being built to be a music studio and garage for our clients. The benefit is that, at any moment, our client can rent this out as a fully-equipped home!

We’ve had a lot of interest lately in small buildings from clients and several that we’d like to discuss. These have been garages, studios, and Detached Accessory Dwelling Units (DADUs), sometimes called backyard cottages. In each municipality and in single-family zones, there are specific rules governing these structures, as they are on the same lot as the principal structure (usually a single-family residence).

The benefit of an additional occupancy unit is three-fold: for homeowners who rent out these units to another family, it’s extra income every month. It’s also a place for elderly family members to stay and retire, as size requirements can make DADUs great for aging-in-place. And beyond rental benefits, having a DADU can significantly increase the value of your home and the investment can provide generous tax benefits depending on your personal finances (consult your tax advisor). For Seattle residents, see this guide for more info: Guide to Building a Backyard Cottage.

For DADUs, the rules cover such things as minimum lot size, lot coverage limits, impermeable surface percentage maximums, parking requirements, size and height limits, and, of course, occupancy rules. In the case of Seattle, where there is a push by the mayor and the city council to dramatically increase density, the restrictions on these structures have loosened to make it easier to grow, and we could expect that they might loosen even further.

Currently in Seattle, any home in Single Family 5000, 7200, and 9600-zoned lots can build a DADU or accessory structure if they meet the design prerequisites:

  • Your lot is at least 4,000 square feet
  • Min. 70′ deep and 25′ wide
  • Your total lot coverage does not exceed 1000 sq ft + 15% of your lot size (for lots less than 5000 sq ft) or 35% of your lot size (for lots over 5000 sq ft), including the main home.

All other requirements depend on the design of your DADU. See a few examples below:


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Our first example is a true DADU. The owners of this property are looking to build a quaint studio above a garage to rent out to a student or young couple. It includes a murphy bed, kitchenette, 3/4 bath, and a spacious 1-car garage with workspace in the back.

Larsen 1Larsen 12 Larsen 123

 

This backyard office is a second story addition – but it’s not as simple as it seems. This home resides in a liquefaction area of Seattle and therefore requires heavy duty engineering to pass city inspection. We designed two schemes around this fact: the first includes building an exoskeleton around the existing shed to support the new second story (see the upper photos). Our second scheme rebuilds the structure anew to better account for earthquake forces (see lower photo) by “floating” the structure on a large, structurally reinforced concrete slab.

The lower floor of both plans will be split between a bathroom and kitchenette, and a fully separate gardening area. The upper floor will be a bright and airy office space for our client’s busy schedule, and will double as a guest room on occasion. The bathroom and kitchenette will allow for this to be a certified-DADU in the future!

For further reading, the Guide mentioned above is a trove of helpful information, and we highly advise you consult it when considering if you, too, can DADU!