Post on 17-Dec-2015
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Learning ObjectivesLearning ObjectivesTapered Insulation PresentationTapered 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
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Tapered InsulationTapered 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
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Why use a tapered Why use a tapered insulation system?insulation system?
Main Goal Eliminate the
amount of ponding/standing water on the membrane when the roof deck does not provide adequate slope
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Ponding may void the roofing warranty
Why is it Important?Why is it Important?
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Prevents the potential for roof collapse from excess weight
Why is it Important?Why is it Important?
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Prevents growth of vegetation, fungi, and bacteria.
Why is it Important?Why is it Important?
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Why is it Important?Why is it Important?
Extends the overall life of a roofing system.
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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
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Tapered Insulation DesignsTapered 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
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One Way Slope to GutterOne Way Slope to Gutter
Most basic design Simple installation
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Two Way Slope to GutterTwo Way Slope to Gutter
Second most basic design
Roof is cut in half which reduces the maximum thickness
Simple installation
Ridge
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Valley and Cricket to DrainValley 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
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Modified 4-Way Slope to Modified 4-Way Slope to DrainsDrains
Second most effective drainage
Used when no overflow drains exists
If one drain is clogged the water can flow over to other drain
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4-Way Slope Design4-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
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Common Attempt to Show a Common Attempt to Show a 4-Way Slope Design4-Way Slope Design
Randomly drawn valley lines at no specific angles
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Correct Way to Show a Correct Way to Show a 4-Way Slope Design4-Way Slope Design
Zoom Window
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4-Way Slope Design4-Way Slope Design
Zoom Window
Valley Lines should be drawn at a 45 degree angle
out of each drain
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Reasons to Alter Reasons to Alter 4-Way Design4-Way Design
Complex existing drain locations
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Reasons to Alter Reasons to Alter 4-Way Design4-Way Design
Constant perimeter height is required
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Reasons to Alter Reasons to Alter 4-Way Design4-Way Design
Multiple drains at low point with no overflow drains
Overflow drains added
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Reasons to Alter Reasons to Alter 4-Way Design4-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
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Reasons to Alter Reasons to Alter 4-Way Design4-Way Design
Multiple roof top units prevent layout from draining
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Tapered Cricket
Tapered CricketsTapered Crickets
Used on both: Full tapered systems Structurally sloped decks
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Tapered Cricket
Tapered CricketsTapered Crickets
Also called: Saddles Hog Backs
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Tapered CricketsTapered Crickets
Secondary application of insulation used to divert water from roof top curbs, valleys, and low points to drains or scuppers
Tapered Crickets
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SLOPE OF TAPER
SLOPE OF TAPER
SL
OP
E O
F C
RIC
KE
T
SLOPE OF CRICKET
Secondary application of insulation used to divert
water from roof top curbs, valleys, and low points to
drains or scuppers
RA
IN
Tapered CricketsTapered Crickets
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Incorrectly drawn crickets
Correctly drawn crickets
Tapered CricketsTapered Crickets
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4x4 Tapered panel
Portion of tapered panel that is field trimmed as waste
Crickets are created in the field by field trimming tapered panels as shown
Tapered CricketsTapered Crickets
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Tapered CricketsTapered Crickets
Full Diamond Cricket
Installed 4x4 Tapered Panels
Full Diamond Cricket Uninstalled Portion
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Parts of a Tapered CricketParts of a Tapered Cricket
Cricket Width (Points 4 to 5)
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Parts of a Tapered CricketParts of a Tapered Cricket
Cricket Length (Points 1 to 2)
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Parts of a Tapered CricketParts of a Tapered Cricket
The slope that is created by the structural deck, tapered insulation or a combination of the two.
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Parts of a Tapered CricketParts 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.
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Parts of a Tapered CricketParts 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.
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Tapered Cricket
Tapered CricketsTapered Crickets
Caution! If not designed properly crickets can pond
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Three Main Contributors to the Three Main Contributors to the Working Effectiveness of a CricketWorking Effectiveness of a Cricket
Cricket Valley Slope
Cricket Surface Slope
Cricket Width
Cricket Valley Slope
Roof Surface Slope
1. Roof Surface Slope
Crickets divert water, so the greater the Roof Surface Slope
the better they will perform!
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Three Main Contributors to the Three Main Contributors to the Working Effectiveness of a CricketWorking Effectiveness of a Cricket
Cricket Valley Slope
Cricket Surface Slope
Cricket Width
Cricket Valley Slope
Roof Surface Slope
2. Cricket Surface Slope
The Cricket Surface Slope pushes the water into the
Cricket Valley. Therefore it should be at least twice the
Roof Surface Slope!
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Three Main Contributors to the Three Main Contributors to the Working Effectiveness of a CricketWorking Effectiveness of a Cricket
Cricket Valley Slope
Cricket Surface Slope
Cricket Width
Cricket Valley Slope
Roof Surface Slope
3. Cricket Width!!
A WIDER CRICKET IS
BETTER!
The most important factor in cricket performance! The
wider the cricket is made the better the resulting Cricket
Valley Slope.
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Calculating Cricket Valley SlopeCalculating Cricket Valley Slope
Step #1
Step #2
Step #3Step #4
Step #5
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Getting an Accurate and Getting an Accurate and Functional Tapered DesignFunctional Tapered Design
Be clear and concise so that “guessing” by the tapered designer and contractor is eliminated!
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General Required General Required Information to Insure Information to Insure
Accurate DesignsAccurate Designs
Dimensions of building perimeter
Number and location of drains
Mechanical unit, skylight and roof penetration locations
Expansion and control joint locations
Existing height restrictions
Existing unique field conditions
Provide accurate information about:
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What Else Can You Do?What Else Can You Do?
Add charts to the roof plan page to clearly designate what insulation should be provided for each roof area.
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What Else Can You Do?What Else Can You Do?
Use a Roof Legend to clearly label existing conditions and to call out what is needed and where.
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What Else Can You Do?What Else Can You Do?
Specify whether slope arrow is designating a required tapered slope or an existing structural slope.
Note desired minimum and maximum thickness.
Note all components that are included in thickness shown.
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What Else Can You Do?What Else Can You Do?
Note desired cricket widths on roof plan.
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Locating Roof DrainsLocating Roof Drains
Locate as close to the low point as possible
Locate them symmetrically and in line with each other
Space drains using 2’ or 4’ increments due to modular sizes of tapered panels
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Locating Roof DrainsLocating Roof Drains
One drain for every 5000 square feet of roof area
75 feet maximum distance between drains
Sizes are determined by roof area and average rainfall data
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Locating Roof DrainsLocating Roof Drains
Provide overflow drain no more than 2” above primary
Avoid having roof top units or penetrations near drains
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SummarySummary
The goal is to drain water from the roof! Several tapered designs possible Use 4-way slope design as often as possible Draw lines at 45 degree angles from drains Crickets divert water 3 main factors to cricket performance: roof
surface slope, cricket valley slope, and cricket width
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SummarySummary
Be clear and concise on drawings and specifications
Provide as much information as possible Locate drains symmetrically and in line
as often as possible Never space drains more than 75 feet
apart Always have a backup drain
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SummarySummary
You are in control of the project Make sure submitted shop drawings reflect the
tapered design that you want Reject Non 4-way layouts if that is what you
showed in your bid documents Reject layouts that shrink the cricket widths
shown in your bid documents You have the power to make sure the most
EFFECTIVE tapered design is submitted and installed
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QUESTIONS?QUESTIONS?
This concludes the American Institute of Architects Continuing Education Systems Program
Firestone Building Products