Attaching EIFS – Adhesively Attached or Mechanically Fastened
Every day contractors call me to quote EIFS (exterior insulation and finishing system) materials or place an order for EIFS products. When I am trying to help a customer order enough materials for a project, one of the first questions I always ask is, “Is this project going to be mechanically fastened or adhesively attached?” I have come up with the phrase “glued or screwed” as when attaching EIFS, it can either be attached with basecoat adhesive (glued) or mechanically fastened (screwed). Most stucco contractors answer either way with a majority of systems being mechanically fastened.
But occasionally, when I ask if the system is to be adhesively attached or mechanically fastened (glued or screwed) I get the dead silence of confusion. Many old school contractors that have been doing stucco for years are very familiar with hard coat stucco applications but may be trying to install eifs for the first time.
Part of determining whether your system should be adhesively attached or mechanically fastened (glued or screwed) is determining what material the substrate in which the system is being attached. Although the layers of eps, basecoat adhesive, and finish are the same for an adhesively attached (glued) and mechanically fastened (screwed), there are a few slight differences in the application of the two systems.
In a mechanically fastened system (screwed), pre-assembled mechanical fasteners consisting of a galvanized steel screw and a 2” plastic stop washer are used to attach EPS foam board to the substrate. Mechanical fasteners are able to penetrate osb, plywood, chip board, and light metals. The screw length should be longer than the thickness of the eps foam board. A mechanically fastened system requires a stucco wrap, drainage mat, or rain screen between the substrate and the eps foam to prevent moisture from intruding into your system and damaging the substrate.
In an adhesively attached system (glued), EPS foam is secured to the substrate with the use of basecoat adhesive that is applied with a notched trowel forming a vertical drain plain.
Unlike the mechanically fastened system (screwed), the adhesively attached system (glued) requires a roll on secondary moisture vapor barrier, such as Tique AquaGuard. Tique AquaGuard can also be troweled on. The roll on barrier forms a membrane that protects the substrate from air and moisture intrusion. An adhesively attached (glued) system can be done over dens glass, osb, plywood, masonry, and other approved substrates.
Some contractors will used a combination of adhesive and mechanical fasteners in areas where there are high winds. Some contractors even use a combination of the two, using both adhesive and fasteners. This can be done but one must keep in mind that if one is using a roll on secondary moisture vapor barrier, such as Tique AquaGuard, that fasteners will penetrate the membrane that is designed to keep water and air from damaging your substrate. Click here for information about ordering Tique AquaGuard.
As always, follow the manufacturer’s recommendations and architectural specifications when installing EIFS. Choosing adhesively attached (glued) or mechanically fastened (screwed) applications does not affect the look of the finished product. EIFS is an attractive and cost efficient exterior choice. Exterior insulation is a great way to save money on heating and cooling costs and lowers your carbon footprint. The use of architectural shapes and different colors and textures makes every eifs installation unique. For a beautiful, customizable look that saves you money on heating and cooling choose and exterior insulation finishing system!
For more information on purchasing eifs materials for a screwed or glued system, call us today at 866.375.950. Our highly trained, friendly staff are here to help you.
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