Best Roof Expansion Joint Design?
With factory-fabricated downturn transitions married to a RoofJoint Wall Closure, the roof to wall expansion joint interface is properly sealed.
What’s the best roof expansion joint design? Our Chicagoland rep, recently asked some good questions:
“What is preferred: all pre-compressed foam joints for roof and walls or RoofJoint with foam for verticals? What are the criteria for specifying one over the other?”
The answer to the first question is, “both.”
The best roof design–where the desire in today’s world of LEED certification and advancing building science is for a totally sealed, best insulated building envelope–is to install the RoofJoint over Horizontal Colorseal (or Emshield DFR if a fire rating is required) in the roof and Seismic Colorseal (or Emshield WFR if fire rating required) in the walls and connect the walls to the RoofJoint with the Seismic Colorseal RoofJoint Closures.
For both cavity wall and solid wall construction, the best roof expansion joint designs incorporate factory-fabricated roof to wall transitions with precompressed foam joints as secondary sealants and insulation and look like this:
Best Roof Expansion Joint Design Solid-Wall Construction:
Best Roof Expansion Joint Design -- Cavity Wall Construction:
Next-Best Roof Expansion Joint Design
IF, the designer chooses not to specify the Best system, the next best is to use RoofJoint on the roof and Seismic Colorseal with Closures in the walls.
Why? Because, like with our FP systems for plaza decks, the RoofJoint flanges ensure a static, positive integration of the expansion joint to the roof membrane.
This is better than putting Horizontal Colorseal in a curb and terminating the roof membrane on the curb because that approach lacks a positive roof membrane integration.
The next-best roof expansion joint solutions for cavity and solid wall construction look like this:
Next-Best Roof Expansion Joint Design - Solid Wall Construction:
Next-Best Roof Expansion Joint Design - Cavity Wall Construction:
Sometimes in a horizontal roof condition the roofing membrane does not run all the way to the joint edge. If there is a parapet condition where the membrane is terminated into the coping then Horizontal Colorseal between the backs of each parapet would be used as you cannot tie directly into the membrane. If the membrane runs to the edge of the joint then the RoofJoint can be used to tie directly into the membrane
SJS System with a lighter cover plate on roofs is sometimes an option where joints are larger than 4-inches. SJS-FP with side sheets is the best option as it too integrates with the roof membrane.
Fire Compartmentation
Fire rating of building facades, building additions at elevation changes, and fire compartmentation is increasingly driving building envelop design.
In all of the above scenarios, fire-rated and watertight Emshield precompressed foam joints can be substituted as follows: