Swift ADU
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Our Role
Design and Build
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Year
2022
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Location
Boise, ID
Details
This project was to design and build an ADU on a lot near BSU that already had an existing home and detached garage on the property. This property was already used as a rental property for students going to BSU. The client wanted to maintain the existing footprints of both the existing home and detached garage while adding the additional unit so that it did not interfere with the existing tenants. The client had a daughter that would be going to BSU and wanted to create a new unit where she could live while attending college. Since this project was starting to be discussed for design in November the client wanted the project completed prior to the following fall semester beginning. Design was completed and the permit process began in early January, permits were received in early April and construction was completed the first week of August a month ahead of the requested completion date.
Project Brief
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Location
Boise, ID
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scope
New ADU
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timeline
2 Months Design, 4 Months Build
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client goal
New ADU for college student rental.
The Challenge
There were two main challenges in this project.
1. How to best utilize the available space on the property without removing the existing detached garage or driveway parking. There were nuances to the dynamics of how tenants of the main house used the property and the detached garage that had to be accounted for in the final layout. The main parking areas for the whole property would end up right in front of the new ADU. This property is roughly 3 blocks from BSU so during the school days students park along the road all over this neighborhood.
2. The sewer line on the existing home would back up every winter and create issues in the basement. Since this sewer line was tied into the house at the basement it was roughly 8′ deep where it entered the house and met the City sewer main. The path of the existing sewer line ran directly under where we wanted to place the ADU. We decided that the best thing to do would be to run a scope in the sewer line so we could inspect the inside of the sewer pipe as well as check depth along the way. We were able to identify several bellies in the pipe and check overall fall from the house to the sewer main. The total fall was only 1″ over 60′ or 0.14%. Code minimum on a 4″ sewer line is 1% fall but ideally we should have 2% with this basement system.
Our Solution
1. To find a layout that would fit the property and allow the existing detached garage to remain on the property took several rounds of revisions. Once the final layout was done it accommodated an ways flow from the main house to the detached garage and driveway with strategically placed gates int he fence line but also allowed for privacy between the two units with the wood fence. We were also able to remove the existing driveway and spot property lines and setbacks which allowed us to extend the driveway towards the adjacent alleyway just far enough to allow a third car worth of width. A strategic placement of the ADU also created a fourth parking space between the detached garage and the new ADU.
2. DSC suggested installing a basin and lift station of the back of the existing house so that we could get additional fall from the house as well as a basin for any potential backflow during the winter from the city sewer line. Once this was in place we could pump from the basin high enough to give us the 2% fall to the city sewer. The client agreed and this system was installed and quality control checked repeatedly. Once installed we were able to reroute the sewer line around the footprint of the new ADU. We removed the native soil that was excavated out from under the footprint of the ADU and replaced it with structural fill and compacted. This allowed for a stable base to place the foundation for the ADU. Once this new system was installed we have had no additional backflow issues from the city sewer.
Project Images
Customer Review
Bryan
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