Chapter 9. ROOF EDGE DETAILS - UCANR

chapter 9. ROOF EDGE DETAILS9.1 GENERALOf all exterior building components, roofsprobably have the greatest exposure toenvironmental and physical abuse. Theymust be carefully designed and installed toprovide the appropriate performance andlife expectancy. Because of the widevariation in detailing, this section will notattempt a thorough coverage of roof design,but instead will set forth some basicconsiderations regarding roof edge detailingthat we believe are critical to qualityperformance.9.2 SHINGLE, SHAKE, AND TILEROOFINGThese systems are similar in basic concept;they are composed of small units that relyon overlaps and underlayment to achievequality performance. In fact, the primarypurposes of the top surface are to providea water shedding surface and sun and abuseprotection for the actual membrane. Accordingly, the underlayment is extremely important in any of these systems. The materialmust have all the performance requirementsof a membrane discussed in Chapter 3 andmust be installed in a manner thatmaintains its integrity. Table 9-1 sets forthmembrane recommendations for these roofsystems for various slopes.In all cases it is important to properlydetail and install the edge conditions.Always try to carry membrane felts over,or up and over, and down to ensure theroof membrane will always drain free andclear of any adjacent system. Also, try toensure that the membrane does not rely onadhered or embedded sheet metal for waterproofing. The following conceptual details(Figures 9-1 to 9-6) show some of thetypical conditions commonly encountered.9.3 BUILT-UP ROOFINGBecause this is a wood-detailing manual,this section will only attempt to highlightsome basic edge conditions that oftenadversely affect adjacent wood construction.Not only is no attempt made to cover theassembly of built-up roofs, but also theissue of single plys or elastomerics will notbe mentioned except to state that some ofthe basic concepts of good edge conditionsare similar to those for built-up roofconditions. Discussion of either of theseunbroken membrane-type roofs could easilytake a chapter, if not a whole book.To the authors, a single concept is criticalto these roofs and adjacent wood construction: the membrane proper must be kept inan unbroached condition with all edgeconditions either above scupper or drainheight until water runoff is complete.Figures 9-7 and 9-8 show some conditionscommonly encountered.

chapter 9 - 2WOOD: DETAILING FOR PERFORMANCETable 9-1Felt Underlayment RecommendationsRoof Slope4:12 up3:12-4:12Less than 3:12Wood ShinglesSolid backing (pressure treated)Spaced stripsAsphalt ShinglesSolid SheathingSpaced stripsWood ShakesSolid sheathing (pressure mated)Spaced stripsTile, Cement, or ClaySolid sheathingSpaced strips* NR - This application not recommended.NR*NR

WOOD: DETAILING FOR PERFORMANCEchapter G-3RoofingFeltRoof sheathingFelt split sheet.Note: For "A" dimensionsee Table 3- 1ROOF DETAILEAVE OVERHANGFigure 9- 1

-chapter 9 4ROOF DETAILCLIPPED EAVEFigure 9-2WOOD: DETAILING FOR PERFORMANCE

WOOD: DETAILING FOR PERFORMANCEchapter 9. :C-5Siding-FeltEXTERIOR"Z" counterflashingBacking for membraneTurn up membrane- - - - - - - - - - - - - - - -Note: For "A" dimensionsee Table 3- 1ROOF DETAILRAKE AT WALLFigure 9-3

chapter 9 - 6WOOD: DETAILING FOR PERFORMANCEEXTERIOR"Z" counterflashingBacking for membraneTurn up membraneROOF DETAILSLOPED EAVEFigure 9-4

WOOD: DETAILING FOR PERFORMANCEchapter 9 - 7Underlayment membraneNote: For "A" dimensionsee Table 3- 1ROOF DETAILRIDGEFigure 9-5

chapter 9-8WOOD: DETAILING FOR PERFORMANCEFull felt sheet under metalIROOF DETAILVALLEYFigure 9-6Note: For "A" dimensionsee Table 3-1I

WOOD: DETAILING FOR PERFORMANCEBuilt-up membraneRedwood or treated fasciMetal flashing (option)BUILT-UP ROOF DETAILEAVEFigure 9-7

chapter 9-10WOOD: DETAILING FOR PERFORMANCEEXTERIORBUILT-UP ROOF DETAILRAKE AT WALLFigure 9-8

Roof Slope 4:12 up 3:12-4:12 Less than 3:12 Wood Shingles Solid backing (pressure treated) Spaced strips Asphalt Shingles Solid Sheathing Spaced strips Wood Shakes Solid sheathing (pressure mated) Spaced strips Tile, Cement, or Clay Solid sheathing Spaced strips NR* NR * NR - This application not recommended.