For years, off-street parking requirements were the single biggest barrier to ADU construction in Washington State. Many properties simply didn't have room for both an ADU and additional parking. That changed dramatically with House Bill 1337, which eliminated parking requirements for ADUs near transit — and in Bellingham, that covers the vast majority of residential neighborhoods.
This guide explains the current parking rules, who qualifies for the transit exemption, and what this means for popular ADU types including garage conversions.
Not sure if your property qualifies? Our free feasibility study checks transit proximity as part of the analysis.
Bellingham: No Off-Street Parking Required (Most Areas)
Under HB 1337, no off-street parking is required for ADUs located within half a mile of a major transit stop. Because Whatcom Transportation Authority (WTA) operates fixed-route bus service throughout Bellingham, the vast majority of residential properties fall within this exemption radius.
In practical terms: if you live in most Bellingham neighborhoods, you do not need to add any parking for your ADU. Your existing driveway and on-street parking are sufficient. This is a massive change from the pre-2024 rules, which often required one or two dedicated off-street spaces per ADU.
Whatcom County Rules
For properties in unincorporated Whatcom County (outside Bellingham city limits), parking rules are different. The county has been updating its ADU regulations to comply with state mandates, but rural properties typically have more lenient parking requirements anyway — because lots are larger and most properties already have ample driveway and on-site parking.
Properties in smaller incorporated cities within Whatcom County (Ferndale, Lynden, etc.) follow their own municipal codes, which are also being updated to comply with HB 1337. The transit exemption applies anywhere a fixed-route bus service operates within half a mile.
For the specific rules affecting your property, see our comparison of Bellingham vs Whatcom County ADU regulations.
Transit Proximity Exemptions
The key question is whether your property is within half a mile of a major transit stop. Here's how most Bellingham neighborhoods stack up:
| Neighborhood | Parking Status | Transit Details |
|---|---|---|
| Sunnyland | Exempt | Multiple WTA routes along Holly/Meridian |
| Birchwood | Exempt | WTA routes along Northwest/Meridian |
| Columbia | Exempt | Near WWU transit hub |
| Fairhaven | Exempt | Fairhaven transit center, multiple routes |
| Lettered Streets | Exempt | Downtown transit center proximity |
| Roosevelt | Exempt | Central location, multiple routes |
| Happy Valley | Exempt | Near WWU transit routes |
| Samish | Exempt | Samish Way corridor routes |
| Cordata | Mostly Exempt | Most areas within transit radius |
| South Hill / Edgemoor | Check | Some areas may be outside transit radius |
*Transit exemption based on half-mile radius from WTA fixed-route bus stops. Verify your specific property with our feasibility study.
What Counts as “Parking”?
Even for properties outside the transit exemption zone, the parking requirements are less onerous than you might think. Here's what typically satisfies the requirement:
Typically Counts
- Existing driveway space (even gravel or compacted surfaces)
- Tandem parking (cars parked one behind another)
- Carport or covered area (doesn't need to be an enclosed garage)
- Pervious paving or permeable surfaces
Good to Know
- On-street parking is NOT counted toward off-street requirements
- Standard stall size: 8.5' x 18' minimum
- ADA accessible spaces only required for commercial, not residential ADUs
Garage Conversion Parking Implications
One of the most common concerns we hear: “If I convert my garage to an ADU, do I need to replace the parking I'm losing?” Under the old rules, the answer was usually yes — which made many garage conversions impractical because there was nowhere to put the replacement parking.
Under HB 1337, the answer for most Bellingham properties is no. The transit proximity exemption means you don't need to replace the garage parking. Your existing driveway (in front of where the garage was) and on-street parking are sufficient.
This change alone has made garage conversions one of the most cost-effective ADU options in Bellingham. You're working with an existing structure, reducing construction costs, and you don't need to budget for building a replacement parking area.
Important note: Even though you don't legally need parking, consider your household's actual parking needs. If you have three cars and a single-car driveway, losing the garage means two cars on the street. Practically, most homeowners find that driveway parking plus on-street works fine.
Frequently Asked Questions
Do I need to add parking to build an ADU in Bellingham?
In most cases, no. Under HB 1337, cities cannot require off-street parking for ADUs within half a mile of a major transit stop. Since most Bellingham neighborhoods are within this distance of a WTA bus route, the vast majority of properties are exempt from any ADU parking requirement.
If I convert my garage to an ADU, do I need to replace the parking?
Under HB 1337, the loss of parking from a garage conversion does not need to be replaced if your property qualifies for the transit proximity exemption. Since most Bellingham properties do qualify, you can convert your garage without adding new parking spaces. Check our feasibility study to confirm your specific property.
What counts as a "major transit stop" for the parking exemption?
Washington State defines this broadly. It includes stops served by fixed-route transit (bus routes with regular schedules). In Bellingham, WTA operates extensive fixed-route bus service throughout the city, which means the half-mile radius covers most residential neighborhoods. The exemption does not require high-frequency service — just a fixed route.
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