page_title: Purlin
hierarchical_section_title: Purlin
caption_attribution_description: English: This barn roof framing is of "common purlin" construction which is commonly found in old buildings in most of New England and some other regions. The wind braces between the principal rafters and the ridge beam are characteristic of a "five sided ridge" beam.
context_page_description: In architecture, structural engineering or building, a purlin is any longitudinal, horizontal, structural member in a roof except a type of framing with what is called a crown plate. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin, and common purlin.
context_section_description: In architecture, structural engineering or building, a purlin (or historically purline, purloyne, purling, perling) is any longitudinal, horizontal, structural member in a roof except a type of framing with what is called a crown plate. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin, and common purlin.
caption: A view of a roof using common purlin framing. This view is from the inside of the building, below the roof. The rafters are the beams of wood angled upward from the ground. They meet at the top of the gable at a ridge beam, which has extra bracing to attach it to the rafters.  The purlins are the large beams perpendicular to the rafters; from this shot, it appears that there are three purlins on either side of the roof. The sheathing boards are sometimes called the roof deck and are painted white.
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot G9", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2008:10:31 09:56:31", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "196", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "5108", "Thumbnail JPEGInterchangeFormatLength": "5465", "EXIF ExposureTime": "3/5", "EXIF FNumber": "9/2", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2008:10:31 09:56:31", "EXIF DateTimeDigitized": "2008:10:31 09:56:31", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "5", "EXIF ShutterSpeedValue": "3/4", "EXIF ApertureValue": "139/32", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "95/32", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "37/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "4000", "EXIF ExifImageLength": "3000", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "4000", "Interoperability RelatedImageLength": "3000", "EXIF InteroperabilityOffset": "3362", "EXIF FocalPlaneXResolution": "4000000/291", "EXIF FocalPlaneYResolution": "1000000/73", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}