Roof Connection Details Eave Rake Details u Definition

Roof Connection Details

Eave & Rake Details u. Definition: Architectural details that incorporates the roof to the wall assembly u Common members included in details: – fascia and fascia trim – soffit and soffit vents – lookout or outrigger – slope/pitch – rafter and ceiling joist – double top plate

Terms to Know--Rake Detail u Definition: Detail taken at the sloped edge of roof or at the gable end of the building, usually this detail is perpendicular to Eave Details

Terms to Know--Fascia u Finished member secured to end of rafters u Some construction include a sub-fascia in preparation to receiving a finished fascia.

Terms to Know--Soffit u Enclosed/boxed-in area or open area below rafters on the overhang of a roof Soffit Area

Terms to Know--Eave Detail u The projecting portion of the roof parallel to the slope. Sometimes called the cornice detail u To draw eave detail, architect needs to know – roof material--wood vs. composition shingles – rafter size & spacing – roof/eave overhang – roof slope/pitch – roof sheathing – exterior wall sheathing – eave design Eave Detail

Roof Pitch u Pitch – Rise over Span – Always reduced to the smallest fraction

Roof Slope u Slope – Slope is stated as a ratio of rise over run with run, run is 1/2 of span but is always expressed as a base of 12 – Slope is placed on a detail as a upside down triangle with 12 (run) horizontal line and rise by the vertical line

Drafting Slope in a Detail the slope is 6: 12 as shown below u All is necessary is to determine hypotenuse of a triangle having a base of 12 units and the leg of 6 units u Draft a line 12” long using the scale of your drawing u Then a vertical line 6” long with the same scale u The diagonal is the slope for this problem r o f E G N I IL A ET D IN L E P O L S 12” BASE LINE 6” LEG LINE u Assume

Calculations for Slope u Problem: Span of a building is 30’, Rise is 5’, what is the slope? u Run = 1/2 Span =. 5 x 30 = 15 u Slope = Rise/Run = 5/15 = x/12 (Convert) 15 x = 5 x 12 u x(new rise) = (5 x 12)/15 u x(new rise) = 4 SLOPE = 4: 12

Eave Designs

1) Exposed Tail Rafters u An exposed wood member that is spliced to the common rafters u Usually thicker than common rafter with the spacing further apart

Boxed Cornice--Soffit Styles u 1) Boxed Horizontal u 2) Boxed Parallel to rafter, sloped u 3) Either styles can be Open or Enclosed

2) Boxed (Enclosed) verses Open Soffit u Boxed Horizontal or Boxed Parallel to rafter and sloped Boxed Horizontal Soffit Open Soffit Slopped Open Soffit

Soffit Design Considerations u 1) Must make provision for ventilation – eave soffit (intake) and attic (exhaust) u 2) Determine area of ventilation – Attic area (x) 1/150 = total area of ventilation req’d (net free area) u 3) Determine location of ventilation – eaves-- soffit contiuous vs. soffit cutout – gable ends--square, rectangle, round or triangle shape – ridge --continuous along roof ridge – roof --various types projecting out of the roof

Ventilation Products/Suppliers Ventilation Types: 1) Roof Louvers 2) Gable Louvers 3) Ridgeline Vents 4) Gravity Turbines 5) Power Vents

3) Fascia Styles and Designs u vertical vs perpendicular Fascia perpendicular to rafter Fascia vertical to rafter

Drafting the Eave Detail u It is recommended to complete the eave detail design before drafting other roof details u Common eave/cornice detail scale sizes:

Rake Detail u Rake - assembly along sloping edge of roof u Usually different overhang from eave u No need to “notch” for rafters

Detail Example Eave Detail Notes Scale: 1 1/2” = 1’-0” u u u u 5 -Ply built-up roof w/ 50# building felt@ edge 3/4” CDX plywood 5/8” GB (Interior finish) 38 R fiberglass batt insulation(12”)(ceiling) 2 x 8 CLG Joist @24”OC Pre-fab trusses optional 1 x 6 T&G siding over 1/2” OSB 15# felt between (Match previous details) Add 1 x 3 trim at fascia Full fiberglass batt insulation in wall

Detail Notes Continued Scale: 1 1/2” = 1’-0” u Attic insulation R 38 - 12” foil faced fiberglass batt u 2 x 8 rafter and ceiling joist @ 24” OC (or prefab wd truss) u 1/2” AC exterior plywood soffit u 7/8” stucco exterior finish w/ 1 x 2 redwood ground at top next to soffit u 24” overhang (from stucco to fascia) u 2 x 4 lookout @ 24” OC u R 11 -3 1/2” craft faced fiberglass batt in (2 x 4 studs @ 16” OC