Case Study: Tiny Home Becomes Permanent Detached Accessory Dwelling Unit in Lynnwood, Wa.
Guest Post From Kurt Galley With Carriage Houses NW, LLC.
Carriage Houses NW has a really exciting development we want to share regarding backyard cottages. The city of Lynnwood recently approved the placement of one of our Park Model tiny homes on wheels onto a permanent foundation as a backyard cottage, also known as a detached accessory dwelling unit (DADU). Our tiny houses are licensed in Washington State as Park Model RVs, which means they conform to a different set of build requirements prescribed for park models and travel trailers, rather than modular homes.
Met All Requirements Through Wa. Labor And Industries
They go through a rigorous approval process which includes structural engineering and systems inspections for framing, insulation, electrical wiring and plumbing. They leave our factory with an L&I insignia that they meet or exceed all requirements.
When our customer, Randy Thompson, approached the city of Lynnwood to see if they would allow a certified tiny house as a DADU, they approved it on the condition that it be attached to a permanent foundation. And this brings us to second exciting part of the story! A typical stem wall foundation requires significant soil excavation, time and expense.
Engineered Diamond Pier Alternative Foundation
We submitted a request to the city to allow us to use something called diamond piers as an alternative foundation. Diamond piers are small, engineered cement blocks that are dug into the ground and then steel posts are run through them until they hit bearing soil. It’s much less invasive, quicker to install and often costs less than a traditional cement foundation. The city approved the request and we had the house installed and attached to the diamond piers with very little excavation or disruption of the natural landscape, in less than two days’ work.
This application of a tiny house permitted to be attached to residential property represents a revolutionary development as the Pacific Northwest faces a housing crisis that is projected to last for years to come. Carriage Houses Northwest is excited to have been part of this innovative approach which provides home owners more flexibility and options for adding living space to their property.
About Carriage Houses NW, LLC
Kurt and Frannie Galley are the founders of Carriage Houses NW LLC in Marysville, Wa. Carriage House NW LLC is licensed as a Factory Assembled Structure Manufacturer of tiny homes certified as RVs and Park Models. Their models are structurally engineered and meet rigorous safety and building standards. They leave the facility with the Washington State Department of Labor and Industry’s RV Insignia. Additionally, all tiny homes are certified by Pacific West Associates, a Nationally recognized RV inspection and Certification agency.
How Is A Park Model Considered A Tiny Home? Example In Los Angeles
Los Angeles just gave the green light to allow movable tiny homes as ADUs, following the lead of Fresno and San Luis Obispo. They are required to be certified and built to RV, NFPA 1192 standards or Park Model, ANSI 119.5 standards.
”Tiny Home” builders usually always voluntarily build beyond the required minimum standards, addressing snow loads when applicable, with higher insulation ratings, 2 X 6 construction, 25 year roof warranties and superior materials.
Note: Photo Credit: Carriage Houses NW, LLC
Featured home is Not actual home in Lynnwood, more photos coming
Photos of the Diamond pier foundation from the actual site