How Big Will Duplexes And Triplexes Be, Under RIP?
February 9, 2017
We've heard some say that RIP's "2,500 square foot" limit will prevent McMansions and that that duplexes and triplexes won't be built because they can't fit on typical lots.
In fact, RIP's "size and height rules" will allow 4,500 square foot duplexes and triplex that are three-and-one-half stories and 35 feet high, and these huge structures, along with ADUs, can be fitted onto every Laurelhurst lot (after the existing house is demolished).
Here's how it works.
RIP Permits Duplexes and Triplexes Up to 4,500 Square Feet
RIP has been advertised as a way to reduce the scale of infill houses, to sizes proportional to the neighborhood. For a 5,000 square foot lot, RIP will supposedly limit building size as follows:
Duplex or triplex: 2,500 square foot
House: 2,000 square foot
These advertised size limits are misleading. Here is how RIP actually allows duplexes and triplexes as large as 4,500 square foot:
RIP’s size limits don’t include basements or attics
Basements can be half above ground, i.e. “daylight” basements
Attics can use dormers to be habitable space
See the city's RIP concept paper - note b)
Thus, in reality, developers can build this:
Second floor 1,250 square feet
First floor 1,250 square feet
Finished basement - half daylight, 1,250 square feet of living area
Finished attic - with dormers, a 1,250 square foot attic can easily have 650 square feet of living area
Total 4,500 square feet
To encourage duplexes/triplexes and discourage single family houses, RIP advertises a smaller, 2,000 square foot size for houses. But that still means a RIP single family house can be about 3,500 square foot. In Laurelhurst, a infill new house of that size is usually called a “McMansion”.
Detached Accessory Dwelling Unit (ADU) Can Be 750 Square Feet
RIP also allows a detached ADU of 750 square foot (0.15 x 5,000 square foot lot).
ADUs can have a pitched roof, 20 feet high at the peak, and the attic can be expanded to standing height with dormers.
Three and a Half Stories and Over 35 Feet Tall
RIP also advertises itself as a way to prevent infill buildings that are much taller than neighboring houses. However, RIP measures height at the midpoint of a pitched roof, so the actual infill building can be over three-and-a-half stories and 35 feet tall.
Here is what a 4,500 square foot, three-and-a-half story duplex and a 700 square foot ADU on a 5,000 square foot lot can look like.
This duplex, which is 35 feet tall at the peak of the roof, will be permitted on every Laurelhurst lot under RIP.
There is even space for a garage, if RIP requires off-street parking for duplexes and triplexes (it isn't clear, from the city's concept report, if it does or doesn't).
This Can All Be Built On A 5,000 Square Foot Laurelhurst Lot
This super-sized duplex (or triplex) can fit on the typical Laurelhurst lot.
Here are the city’s basic setback and lot coverage rules for lots in Laurelhurst.
General setback: front 20 feet, side 5 feet, rear 5 feet.
Garage front setback: 18 feet.
Outdoor area: at least 250 sq ft, including a open space of at least 12 feet x 12 feet
Maximum lot coverage: on a 5,000+ square foot lot, buildings may cover at most 2250 square foot of land, plus 15% of the lot size over 5000 square feet.
As shown in the drawings above, these rules allow a 4,500 square foot duplex plus 700 square foot ADU plus garage to all sit on a 5,000 square foot lot.
Here's the city's drawing showing the same thing - but the edit in red ink is ours (we took the liberty of including the real square footage of the house).
How out-of-scale will these towering duplexes and triplexes look, next to existing historic Laurelhurst houses? Here's an example - this is the McMansion recently built by Everett Custom Homes at 1109 42nd St. This replaced an original house, nearly a century old, that was in harmony and in scale with its neighbors.
The McMansion above is not a duplex, and is "only" 3,400 square feet. What can a RIP-sized duplex be like? Here are some duplexes in other close-in East Portland neighborhoods, that illustrate what infill developers will be able to replace Laurelhurst's historic houses with.
3916 N Gantenbein.
120 NE 28th St.
If the neighborhood isn't protected by Historic District, these pictures show the Laurelhurst of the future.