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Residential Building Height HandoutDEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT 1 \\RVFPS-02\Depts\PW\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Residential Building Height Handout.docx Rev. 1/2016 CITY OF RENTON RULES FOR RESIDENTIAL BUILDING HEIGHT Planning Division 1055 South Grady Way-Renton, WA 98057 Phone: 425-430-7200 | www.rentonwa.gov This handout addresses the most commonly asked questions and provides general information about the allowed height of residential buildings (buildings located in the RC, R-1, R-4, R-6, R-8, R-10, R-14, and RMF zones). Please refer to Renton Municipal Code (RMC) for more information, specifically Section 4-2-110 for development regulations and Chapter 4-11 RMC for definitions. How is residential building height measured in the City of Renton? Height is measured from the grade plane (i.e., average grade) to the wall plates, and then from the wall plates to the top of the building or other attached structures (e.g., a rooftop deck). What is a wall plate? A wall plate is a horizontal member (e.g., lumbar, brace, etc.), built into or laid along the top of a wall, that distributes and supports the pressure from joists, rafters, etc. How is a grade plane determined? The grade plane is the average of multiple finished grade (after construction) ground elevations. Depending on site characteristics there are three ways to determine grade plane: If the ground level within 6’ of exterior walls is generally level (only slopes slightly to provide drainage): 1. The grade plane is the averaged elevations at the corners of the building. If the ground slopes away from exterior walls, and the lot line(s) are MORE THAN 6’ AWAY: 2. The grade plane is the averaged elevations of the lowest points located 6’ away from the exterior walls. If the ground slopes away from exterior walls, and the lot line(s) are LESS THAN 6’ AWAY: 3. The grade plane is the averaged elevations of the lowest points between the exterior walls and lot lines. Where the slope is inconsistent or retaining walls are utilized, or where the building footprint is complex, the determination of grade plane can be more complicated. In such cases, a more exacting method for calculating the grade plane must be utilized. 2 \\RVFPS-02\Depts\PW\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Residential Building Height Handout.docx Rev. 1/2016 Is there a limit to the number of stories? Yes, the number of allowed stories depends on the zone. The definition of a “story” may qualify the first level of a house to be a basement instead of a story. The first floor may qualify as a basement if the finished floor directly above is: 1. No more than 6’ above grade for at least 50% of the building’s perimeter; and 2. No more than 12’ above grade at any point. How high can my roof extend from my wall plates? Roofs that are pitched at a slope of 4:12 or greater may extend up to 6’ above the maximum wall plate height. If the wall plates are lower than the maximum height allowed, the roof may project higher to compensate for the difference. For example, if the maximum wall plate height is 24’ yet the wall plates of a house are no higher than 20’ from the grade plane, the roof may extend up to 10’ from the wall plates (24’–20’=4’; 4’+6’=10’ roof height). Roofs pitched less than 4:12 may only extend above the maximum wall plate height if the roof is “stepped back” 1.5’ from each minimum building setback line for each 1’ above the maximum wall plate height. The maximum height of the stepped back projection is 6’ from the maximum wall plate height. This exception also applies to features such as decks. In the illustration below, the deck extends 6’ from the maximum wall plate height and is stepped back 9’ (1.5’x6’=9’) from each minimum building setback line. The east side of the building is setback 9’ beyond the minimum required setback line, which allows that side of the deck to be flush with the façade. Common rooftop features, such as chimneys, may project an additional four (4) vertical feet from a roof surface. 3 \\RVFPS-02\Depts\PW\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Residential Building Height Handout.docx Rev. 1/2016 Are there exceptions? Yes, there are two exceptions: 1. If a shed roof is the primary roof surface, wall plates may be higher than the maximum allowed as long as the average height of wall plates is equal or less than the maximum allowed. In the example below of a house located in a zone with a maximum wall plate height of 24,’ the wall plates supporting the high side of the roof are 28’ above the grade plane, and the lower wall plates are only 20’ above grade plane, which results in an average wall plate height of 24’. 2. If a roof surface only covers a modulated portion of a façade, the wall plates supporting that roof surface may extend above the maximum allowed but must not extend above the ridgeline of the primary roof. Such qualifying façade modulations are limited to be no wider than ten feet (10’) or twenty-five percent (25%) of the building elevation, whichever is greater.