RAINSCREEN EIF SYSTEM
APPLICATION INSTRUCTIONS

General Description

This Preswitt System utilizes the Standard System with modifications over a primary lamina that has been trowelled over an approved substrate. The primary lamina acts as an air barrier and secondary against water ingress into the building. Preswitt’s M.P. Flexcoat mixed 50/50 by weight with Portland cement is the preferred trowelled on membrane.
 

Reinforcing mesh is required in this membrane. Peel and stick strips are applied at expansion joints, window flanges and as required to create a complete sealed airtight and weather resistant envelope. Careful inspection of the envelope for leaks and necessary repairs is essential before proceeding with the installation of the EIFS.

In order for the System to provide drainage for incidental water intrusion and air pressure equalization the following modifications to the EPS insulation and its installation were introduced.

1. Standard EPS Panels: A ½" x ½" bevel is cut in the EPS at the top edge as indicated to facilitate the direction of water flow to the proper drainage trough. Adhesive, minimum 3/8" thick is applied in vertical strips to the back of the insulation panels in the pattern indicated and applied to the wall. Installed in this manner drainage channels approximately 8" wide and 3/16" deep are formed. Uniformity of the depth of the channel can be maintained with the use of elementary gauges. Deeper channels are possible by cutting channels in the EPS board to suit.

2. Starter Strips: These are the first pieces of insulation installed in any section. Slots are cut to size on site to satisfy the requirements for drainage and air pressure equalization.

 

Installation of the starter strips is of primary importance to the functioning of the System. It is imperative that the following points are strictly observed:

a) Butter the back of the starter strip with adhesive to ensure 100% contact with the air/vapour barrier.
b) Carefully level strips to ensure proper drainage and provide correct starting course for the remainder of the insulation.
c) Apply Dow 790 or 795 or Tremco Spectrum 3 to the bottom of the drainage channel to effect maximum seal.

It is recommended that sections of the work be periodically tested as the work proceeds to ensure that drainage is being effective. After installation of the insulation the application of the reinforced Basecoat and Quality Finish is the same as for the Standard EIF System.

Rainscreen Compartmentalization

Every building elevation at various times is subjected to differing pressures over the wall face. At this time there are no standards to clearly define a required level of pressure equalization. To localize these areas of differing pressure the wall is divided into compartments and the sizing, location and appropriate vents will be calculated by the design authority.

The following guidelines are submitted for the architect/engineer’s consideration:

  • Smaller compartments equalize at a faster rate.
  • Compartmental requirements are greatest at the perimeter of the wall.
  • Horizontal division shall be spaced not more than 30 ft. apart.
  • Compartment sizes should not exceed 300 sq. ft.
  • One vent sized to suit compartment area.
  • Vent size based on 0.25 sq. in. per 60-sq. ft. of wall area.