American Architectural Manufacturers Association<\/a>, intended for use when manufacturer instructions are absent or incomplete, provides basic step- by-step installation instructions for 19 different ways to integrate various roofing materials, underlayment, flashing and skylight-mounting configurations to preserve the drainage plane. This must be the overriding intent of any installation protocols.<\/p>\nNote that some roofing contractors warrant their work against leakage, and skylight installation should not compromise or void such warranties. When in doubt, independent installers should confer with the roofing contractor.<\/p>\n
INSTALLATION SUPPLIES<\/h4>\n Proper installation begins with selection and use of the proper supplies\u2014notably sealants, fasteners and flashing.<\/p>\n
SEALANT SELECTION<\/strong> \nIf sealants are recommended by the manufacturer, follow the manufacturer\u2019s specifications. When the manufacturer is silent about the use of sealants and the installation guidelines dictate their use, the following recommendations should be observed:<\/p>\n\nCompatibility\u2014The sealant must not adversely react with or weaken the material it contacts.<\/li>\n Adhesion\u2014The sealant must have good long-term adhesion. Surface preparation, cleaning procedures and, in some cases, primers are recommended by the sealant manufacturer.<\/li>\n Service Temperature\u2014If the installation location involves elevated ambient temperatures, the sealant should exhibit corresponding service temperature performance.<\/li>\n Durability\u2014The sealant must be capable of maintaining the required flexibility and integrity over time.<\/li>\n Application\u2014Proper bead size and other application details should be followed to ensure a well-performing joint. Improper use of sealants can dam water pathways, so an important rule of thumb is not to block any weep holes that may be in the skylight system.<\/li>\n<\/ul>\nTypically, sealant or roofing cement is applied around the perimeter of the rough opening (deck mount) or the flange of self-flashing units or the top edge of a mounting frame. However, some skylights are designed with integral flashing flanges to be installed without the need for sealants.<\/p>\n
It is also possible to utilize rolled roofing membranes as a substitute for sealants or plastic roofing cement. \n \nFASTENERS AND ANCHORS<\/strong> \nWhen not specified or supplied by the manufacturer, selection of fasteners must take into account corrosion resistance and compatibility with the substrate and other materials they may contact.<\/p>\nFLASHING<\/strong> \nFlashing is critical to preserving the drainage plane, so flashing and seal- ant must be integrated with the roofing material and underlayment. There are several types and configurations of flashing applicable to different skylight mounts and roofing materials.<\/p>\nStep flashing, often used with skylights, is a system in which metal shingles or plates are used in a stair-step pattern under regular shingles and stepped up the vertical surface of a curb. The sequence for step flashing is to apply the sill first at the down-slope edge of the skylight or curb, resting it on top of the lower course of shingles. Step flashing is applied sequentially up the sides of the curb. Finally, the head flashing (saddle) is set in place.
A car dealership makes good use of a vaulted commercial skylight. PHOTO: Skyco Skylights<\/p><\/div><\/p>\n
Counterflashing (or cap flashing) is often used to protect and waterproof (by overlapping) terminated top edges at curb or base flashing. Formed metal or elastomeric sheeting is secured onto a curb to cover and protect the upper edge of a base flashing and its associated fasteners.<\/p>\n
Flashing for use with tile or corrugated metal roofing typically includes a bottom collar with a seamed-in corrugated conformable apron designed to fit over the top surface contour of the roofing.<\/p>\n
In metal roofs, roofing material can act as the flashing, especially along the sides of a curb mount. Separate flashing collars are used at the top and bottom of the curb, bent into shape to attach to the sides.<\/p>\n
WORKPLACE SAFETY<\/h4>\n Of equal or greater importance than doing the job right is doing the job safely. Every year, several construction and maintenance workers are injured or killed by falling through skylight rough openings or installed units that were never intended to bear the associated point load. Codes are generally mum on the topic. Accordingly, roofing safety is an important aspect of skylight installation.<\/p>\n
The responsibility for fall protection must be shared among the many parties involved with the design, construction and maintenance of roofs. Recommended safety procedures for minimizing risk require attention to the following basic safety practices:<\/p>\n
\nOnly construction and building maintenance professionals should ever be on a roof.<\/li>\n Applicable OSHA safety regulations should be complied with at all times.<\/li>\n All individuals allowed to be on a roof must be fully trained on roof safety and should have the competence and sense of personal responsibility to follow recommended practices.<\/li>\n Warning signage should be posted at each access point onto the roof.<\/li>\n<\/ul>\nIn some cases, the use of railings, grids, external or internal screens, or specially designed products meeting a fall-protection standard may be employed. \n \n
Sloped glass in a commercial setting allows for natural lighting. PHOTO: Wasco Skylights<\/p><\/div><\/p>\n
INSTALLATION GUIDELINES<\/h4>\n The skylight industry installation guidelines published by AAMA are organized into two major groupings: skylight installations on steep-slope roofs (3:12 pitch or greater, about 15 degrees from horizontal up to 75 degrees or 15 degrees from vertical) and installations on low-slope or flat roofs (less than 3:12 pitch).<\/p>\n
Installations on steep roofs with asphalt shingles, wood shake or slate, tile or metal are covered; in the case of low-slope or flat roofs, built-up, modified bitumen and single-ply roofing systems are discussed. In general, skylights are usually installed on steep-slope roofs after the roof is finished. For low-slope or flat roofs, the skylight typically is installed before the roof is finished.<\/p>\n
Most installations are deck mount, in which the skylight attaches directly to the roof deck, or curb mount, in which the skylight utilizes a curb consisting of 2- by 4-inch or 2- by 6-inch nominal lumber or prefabricated metal. The curb is anchored to the roof deck or framing into the structural supporting rafters to become a permanent part of the roof structure, raising the skylight above the roof deck surface and reducing its exposure to water and snow accumulation.<\/p>\n
Sometimes a separate roof curb is used, providing a means of flashing the roof penetration created by a skylight by integrating it with the roofing system. Roof curbs can also be used to modify the slope of the skylight relative to the roof. Curb installation must be verified as level and square.<\/p>\n
Roof curbs can be constructed on the job site or prefabricated\u2014often by the skylight manufacturer as an accessory. Steep-slope roofs generally warrant lower roof curbs. Low-slope and flat roofs sometimes require higher roof curbs as water levels on the roof surface increase.<\/p>\n
Some unit skylights will have an integral flashing flange that contains and directs water that runs off the slate shingles\/wood shakes. Sealant prevents water from traveling beneath the roofing material and underlayment and the top surface of the flange onto the roof deck. Some designs include a specially configured flange that provides this function and eliminates the requirement for sealants.<\/p>\n
GENERAL INSTALLATION CONSIDERATIONS<\/h4>\n
Skylight installation guidelines, published by AAMA, are grouped via steep-slope and low-slope roofs.<\/p><\/div> \nThe rough opening must first be cut into the roof deck and checked that it is properly sized, level and square.<\/p>\n
When a skylight is to be installed in an existing roof and roof trusses or raf- ters need to be cut to accommodate the position and size of the unit, it may be necessary to temporarily support those sections. Additional structural framing must redistribute transmitted loads to adjacent structural members. In some cases, this will require additional members or reinforcement to bolster load-bearing capacity.<\/p>\n
The underlayment or felt is cut back around the perimeter of the opening. For deck mounting, replace the underlayment and bring it up to the edge of the rough opening. For curb mounting, bring it to the base of a curb and up the sides of the curb. A cant strip, which is a beveled support, is often used at the intersection of the roof deck with vertical surfaces so that bends in the roofing membrane to form base flashings can be made without breaking the felt. Using separate pieces of underlayment around the skylight saves the hassle of trying to cut full rolls around the skylight and makes for a more watertight installation.<\/p>\n
Adhesive-based underlayment can be more effective in many cases, and some skylight manufacturers require this. Wrapping the skylight with an ice and water membrane instead of the standard underlayment is a good idea and may be required in some areas.<\/p>\n
Good skylight design follows the principles of good watertight design. Proper installation essentially means doing it right the first time to ensure the integrity of the roof\u2019s water-resistive barrier.<\/p>\n
A home uses operable skylights, which open to allow ventilation and daylighting. PHOTO: VELUX<\/p><\/div>\n
Learn More<\/h3>\n The following guidelines and other publications are available through the Publication Store<\/a>:<\/p>\n\nAAMA 1607-14, \u201cInstallation Guidelines for Unit Skylights\u201d<\/p>\n
AAMA 501.2, \u201cQuality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls and Sloped Glazing Systems\u201d<\/p>\n
AAMA 503, \u201cVoluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls and Sloped Glazing Systems\u201d\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
As trendy as they are for green building and demonstrably beneficial for energy savings through daylighting, skylights are sometimes viewed with a certain trepidation by…<\/p>\n","protected":false},"author":123,"featured_media":5725,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"Avoid Problems with Skylights through Proper Installation","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[25],"tags":[1651,215,6730,6731,6729,509],"jetpack_publicize_connections":[],"yoast_head":"\n
Avoid Problems with Skylights through Proper Installation - Roofing<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n \n \n\t \n\t \n\t \n