Costa Rica Construction – Understanding EIFS Materials & Methods

My intention for writing this article is to share knowledge, experiences and solutions for new problems that have developed throughout Costa Rica since EIFS construction methods have begun to be used by general contractors in the last few years.

New exterior sheathing products have become affordable and locally available however these new wall systems and finishing plasters have specific installation methods that need to be understood by the professionals who specify them and the general contractors who are responsible for installing them correctly. Unfortunately, the construction specifications and blueprints don’t always detail the proper installation techniques that each products manufacturer specifies. This requires the builder to educate him or herself with new products compatibility and their proprietary installation techniques.

The builder will also need to share this newly acquired knowledge and train the construction tradesmen who will be installing the new products. Many of these old fashioned tradesmen have been installing traditional building materials according to ancient installation methods for many years and are usually not receptive to new products and installation techniques. This is why many new products fail, because they are not installed according to the manufacturer’s specifications.

Let’s begin learning about EIFS by describing this new Exterior Insulation and Finish System.

EIFS is a non-load bearing exterior wall system. The system’s primary function is to provide a weather barrier, thermal insulation and an attractive exterior finish. When properly installed and maintained, the system will provide many years of beauty and function.

The two basic types of EIFS are Barrier EIFS, which has been used for over three decades in the USA and Europe, and the newer Moisture Drainage EIFS. Most EIFS used on residences have been PB EIFS (Polymer Based). Both systems are a proprietary mix and require following the manufacturer’s installation details carefully.

Barrier EIFS:

a. EPS (Expanded Polystyrene) insulation properly attached to substrate or framing.

b. EPS properly prepared to receive basecoat.

c. Polymer Based basecoat applied to EPS.

d. Fiberglass mesh immediately embedded into fresh basecoat.

e. Finish coats according to the plaster manufacturers specifications need to be properly applied to the cured basecoat.

f· No PVC or metal Accessories; however, edges must be properly back-wrapped to protect the EPS and minimize damage.

The newer Moisture Drainage EIFS, is very similar to Barrier EIFS, but it requires a drainage plane and a moisture barrier on top of the moisture sensitive substrates.

Moisture Drainage EIFS:

a· EPS (Expanded Polystyrene) insulation properly attached to substrate or framing.

b· EPS properly prepared to receive basecoat.

c· Polymer Based basecoat applied to EPS.

d· Fiberglass mesh immediately embedded into fresh basecoat.

e· Finish coats according to the plaster manufacturers specifications need to be properly applied to the cured basecoat.

f· Flashings at roofs, decks, windows and doors, are required as part of waterproofing the system.

g· A sheet or liquid applied moisture barrier.

The significant difference, in addition to the Moisture Barrier, is the use of PVC Accessories.

a· PVC Weep Screeds at bottom of all walls and above windows, doors, decks or doors.

b· Horizontal Expansion Joints must allow for the drainage of moisture.

c· Flashings are required as part of weatherproofing the system.

Properly installed EIFS Moisture Drainage systems should also be resistant to cracking. The details are typically well developed and part of the manufacturer’s installation guidelines.

Once the desired wall structure system has been completed the plaster coating can be installed according to the following guidelines.

1. A Moisture Barrier is required on top of moisture sensitive substrates such as wood, gypsum, Styrofoam, EPS, etc.

2. Synthetic Stucco is applied in coats with a total thickness of 3/8″ to 1/2″. The application includes a base coat and at least two finish coats depending on the product and the desired texture.

3. Metal Accessories – Casing Beads or Stops or Grounds, Weep Screeds, Corner Aids, and Control Joints and Expansion joints at 144 square feet, window and door corners need to be installed per the manufacturer’s guidelines.

4. Flashings are required as part of weatherproofing the system.

5. When these synthetic plaster products are mixed and installed properly, the proprietary mixes are very effective at minimizing cracking and in the case of various high quality products are flexible and 100% waterproof. Some of which can be mixed with colored tints in order to avoid having to paint the finished stucco.

With over 25 years of construction experience in the USA and Costa Rica, the best and most cost effective plaster coating I’ve found to apply on exterior concrete or synthetic sheathing are the GrailCoat products.

These plastering products are modified with acrylic and polymer additives to augment there elasticity, making the structures on which they are applied 100% waterproof. Upon application of the GrailCoat coatings your finished surfaces are less likely to crack, peel or flake. They do not require extensive humidification with water and they provide optimum repellency in hot or cold climates. GrailCoat offers three coatings; DuraSurf, DuraFlex and SuperFlex.

For value and peace of mind GrailCoat is highly recommended. It blocks penetration of large water particles from the outside while allowing small vapor particles to escape from the inside. GrailCoat breathes, bends and waterproofs. It’s not only cost-effective in the short term, but in the long term, prevents costly maintenance expense caused by water, salt penetration and mold.

GrailCoat can be applied to exterior and interior concrete block, pre-cast concrete panels, Styrofoam, wood, particle board, steel and synthetic sheathing such as DensGlass. It has been manufactured to withstand the intense UV rays and seismic movements in Latin America and should not crack, peel, or flake if the recommended mixture and four step application process is used.

Most often, depending on the exterior sheathing product used, GrailCoat is troweled over polypropylene fiber mesh or expanded metal lath in three coats. The mesh and lath give strength and quality-control of application, and GrailCoat provides an aesthetically pleasing water proof barrier that won’t crack or de-laminate.

GrailCoat bonds to most substrates, repels mold growth and stands up to abrasion while at the same time prevents expansion, cracking and moisture intrusion which can all cause rebar and metal to rust. GrailCoat is a very effective plaster that protects structures from the elements year after year.

Written by Tom Rosenberger. With more than 25 years of homebuilding experience, 15 of which have been in Costa Rica, construction consultant Tom Rosenberger knows the ins and outs of building and remodeling a home in the Central Valley area of Costa Rica.

Andrew Makarik

to@welovecostarica.com

Andrew Makarik is the main editor of WeLoveCostaRica, a fan of this sunny country. He is also a loving husband and a has a lovely daughter. By being a devoted family man and the biggest Costa Rica fan, he wants to make more people feel at home there. WeLoveCostaRica unites people and helps them find new home or a new travel destination. This website is a friendly community where everyone can find not only information, but also new friends and travel pals. Andrew is also passionate about IT and programming, so he himself maintains a friendly atmosphere in this cozy environment of WeLoveCostaRica.com.