For large volume attics such as where roof slopes are greater than 8 12 designers.
Irc roof venting requirements.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
Drip edges shall be mechanically fastened to the roof deck at a maximum of 12 inches 305 mm o c.
As an example of what you can find in chapter 8 of the 2018 irc see.
Space irc 2012 limits the net free ventilation reduction from 1 150 to 1 300 for buildings in climate zones 6 7 and 8.
Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.
Vented attics shall have a minimum net free ventilation area at least 1 300 of the area of the vented space.
And this guideline you ll need a minimum of.
The requirements for vented and unvented attic space and enclosed rafter space shall be in accordance with this section.
Between half and two thirds of the provided ventilation shall be installed at the eaves.
2018 international residential code.
The following are the requirements taken directly from the irc.
Near ridge of the roof.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.
Pdf 2015 international residential code for attic ventilation 145 kb.
2018 international residential code.
With fasteners as specified in section r905 2 5.
The irc section r902 1 requires class a b or c fire resistant roofing only in jurisdictions designated by law or where the edge of the roof is less than 3 feet from the property line.
Jurisdictions in the us do not commonly require fire resistance classifications for roof coverings on one and two family residential dwellings.
Drip edges shall extend a minimum of 0 25 inch 6 4 mm below the roof sheathing and extend up the roof deck a minimum of 2 inches 51 mm.
Nrca guidelines regarding attic ventilation nrca recommends designers provide at least 1 square foot of nfva for every 150 square feet of attic space 1 150 ventilation ratio measured at the attic floor level ceiling.
Contains sections covering roof framing roof sheathing and roof ventilation.
On the upcodes website.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
