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COMMERCIAL ROOFING. Tapered Insulation Systems. Learning Objectives Tapered Insulation Presentation. Tapered insulation – what is it? Why do we use it? Various designs from good to best Crickets function and design Specifying a good design. What, Why, and How?. Tapered Insulation Systems.
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COMMERCIAL ROOFING Tapered Insulation Systems
Learning ObjectivesTapered Insulation Presentation • Tapered insulation – what is it? • Why do we use it? • Various designs from good to best • Crickets function and design • Specifying a good design
What, Why, and How? Tapered Insulation Systems
Tapered Insulation • Rigid roof insulation • Made from various materials • Polyiso • Extruded & Expanded Polystyrene • Perlite • Typically 2x4 or 4x4 panels • Provides r-value and slope • Typical slopes available • 1/8”/ft., ¼”/ft., ½”/ft. • Arranged by a designer into a tapered system to promote positive drainage
Why use a tapered insulation system? • Main Goal • Eliminate the amount of ponding/standing water on the membrane when the roof deck does not provide adequate slope
Why is it Important? Ponding may void the roofing warranty
Why is it Important? Prevents the potential for roof collapse from excess weight
Why is it Important? Prevents growth of vegetation, fungi, and bacteria.
Extends the overall life of a roofing system. Why is it Important?
Why is it Important? • National Agencies & Code Groups require a minimum slope • ¼”/ft. minimum in most cases • Provided by structure or a tapered insulation system • Ponds existing after 48 hours not acceptable to any of the major code bodies
Tapered Insulation Designs • Numerous possible designs even for the simplest roof • Individual job parameters determine which design is the best option 4-way slope Modified 4-way slope with cricket Valley & Cricket
One Way Slope to Gutter • Most basic design • Simple installation
Ridge Two Way Slope to Gutter • Second most basic design • Roof is cut in half which reduces the maximum thickness • Simple installation
Valley and Cricket to Drain • Commonly used design with drains • Cheapest material cost in most cases (versus 4-way slope design) • Potential small ponding along cricket edges (typical) • Not the most effective drainage design Potential ponding area
Modified 4-Way Slope to Drains • Second most effective drainage • Used when no overflow drains exists • If one drain is clogged the water can flow over to other drain
4-Way Slope Design • Most effective drainage design (any compromise will effect performance) • Every tapered system should start with this design • Next step is to identify justifiable reasons to alter this layout
Common Attempt to Show a 4-Way Slope Design Randomly drawn valley lines at no specific angles
Zoom Window Correct Way to Show a 4-Way Slope Design
Zoom Window 4-Way Slope Design Valley Lines should be drawn at a 45 degree angle out of each drain
45 Degree Valley Miter 45 degree angle
4-Way Slope Design WHAT ARE VALID REASONS TO NOT USE A 4-WAY SLOPE DESIGN?
Reasons to Alter 4-Way Design Complex existing drain locations
Reasons to Alter 4-Way Design Constant perimeter height is required
Reasons to Alter 4-Way Design Multiple drains at low point with no overflow drains Overflow drains added
Reasons to Alter 4-Way Design When cost is a bigger issue than performance 4-Way Design -Most effective drainage -Higher material cost Valley & Cricket Design -Least effective drainage -Lower material cost
Reasons to Alter 4-Way Design Multiple roof top units prevent layout from draining
Tapered Crickets • Used on both: • Full tapered systems • Structurally sloped decks Tapered Cricket
Tapered Cricket Tapered Crickets • Also called: • Saddles • Hog Backs
Tapered Crickets • Secondary application of insulation used to divert water from roof top curbs, valleys, and low points to drains or scuppers Tapered Crickets
SLOPE OF CRICKET SLOPE OF CRICKET SLOPE OF TAPER RAIN SLOPE OF TAPER Tapered Crickets Secondary application of insulation used to divertwater from roof top curbs, valleys, and low points to drains or scuppers
Types of Crickets ½ - Diamond Cricket
Tapered Crickets Incorrectly drawn crickets Correctly drawn crickets
Tapered Crickets Portion of tapered panel that is field trimmed as waste 4x4 Tapered panel Crickets are created in the field by field trimming tapered panels as shown
Full Diamond Cricket Full Diamond Cricket Uninstalled Portion Installed 4x4 Tapered Panels Tapered Crickets
Tapered Crickets RTU
Parts of a Tapered Cricket Cricket Width (Points 4 to 5)
Parts of a Tapered Cricket Cricket Length (Points 1 to 2)
Parts of a Tapered Cricket The slope that is created by the structural deck, tapered insulation or a combination of the two.
Parts of a Tapered Cricket The slope of the cricket panels. Recommended to be at least twice the net Roof Surface Slope that exists. This ensures that the water is directed into the cricket valley.
Parts of a Tapered Cricket The net slope created along the edges of the cricket. (Points 4 to 1, 4 to 2, 5 to 2, & 5 to 1) This directs the water to the drains.
Tapered Crickets • Caution! • If not designed properly crickets can pond Tapered Cricket
Cricket Valley Slope Cricket Surface Slope Cricket Width Roof Surface Slope Cricket Valley Slope Three Main Contributors to the Working Effectiveness of a Cricket 1. Roof Surface Slope Crickets divert water, so the greater the Roof Surface Slope the better they will perform!