What is an EIFS?
Design
Application
Maintenance and Repair
Others

ANSWERS

Can water be added to the finish or basecoat?

Yes, but be consistent. Approximately 1 to 1.5 cups per pail. Adding too much water can dilute the colour.

When is an expansion joint necessary?

Expansion joints are necessary when they are required in the structure behind the EIF System. They are also required at every 3rd floor as a fire stop. Expansion joints must be carried through the exterior insulation. Movement joints are required to accommodate expansion and contraction of building materials due to thermal changes, moisture, wind, gravity, vibration and seismic activity. Expansion joint locations in the EIFS cladding shall be determined by a professional engineer/architect. The following situations, in particular, shall be considered:

at expansion joints that occur in the substrate,

at any abutment of the system with other materials,

where there is a change in substrate,

where structural movement is anticipated,

where deflections that might be in excess of L/240 are expected, and

at floor levels in wood frame construction (may not be required when using engineered wood beams).

Closed cell backer rods should be used at expansion joints so that the low-modulus sealant may be installed as per sealant manufacturer instructions.

Are control joints necessary?

Yes. Control joints are normally grooved in the system for aesthetic reasons but also to provide the tradesman applying the finish reasonable areas for completing his work without creating dry joints.

How do you repair smaller damaged areas of the EIFS?

Be sure to establish and correct the cause of the damaged area. Assuming the substrate is sound, proceed as follows:

1. Cut out and remove a rectangular section of the EIFS extending approximately 3" on each side of the damaged area to expose the substrate.

2. Grind off a band of acrylic finish at the perimeter of the hole to a minimum width of 2½" exposing the system's basecoat.

3. Apply adhesive to the back only of a tight filling piece of insulation and install where the damaged area has been removed, making sure that the substrate is clean and sound. Sand the edges of the board so that it is flush with the surrounding insulation.

4. Mask around the repair area and apply adhesive and reinforcing mesh so that the mesh overlaps the existing exposed basecoat 2½". Ensure that the mesh is completely embedded. Allow to cure for a minimum 24 hours.

5. Remask and apply the same colour and texture finish over the patch. Remove the mask and using a damp brush feather the perimeter of the patch into the existing finish.

Does the EPS board have to meet any requirements?

Yes, it has to be Wall Specification Grade (WSG) type 1 (1.0 pcf.) with a flame spread of less than 25. The EPS boards are 2 ft. X 4 ft. and the minimum thickness must be 3/4". The insulation is age cured and is manufactured to strict tolerances.

When is it necessary to backwrap the EPS board with the mesh?

This should be done wherever the EIF System is terminated, i.e. the bottom or top of a wall, around any opening in the system such as windows, doors, vents, etc. Ensure that the insulation is completely encapsulated with basecoat and mesh.

Can weather conditions during application affect the performance of EIFS coatings?

Yes, EIFS adhesives, basecoats, and topcoats can all be affected by the air temperature and humidity at the time of application. Long-term performance may suffer if coatings are applied when it's too cold or damp, or if uncured coatings are not protected during such weather.

What happens if it is too cold?

Polymer latexes used to make 100% acrylic coatings have what is called a minimum film formation temperature (MFFT). Above the MFFT, the latex will form a clear film with good-binding action. Below the MFFT however, the latex will dry to a white powder and no film will form.

What are some ways to avoid problems in cold weather?

Some general tips for applying EIFS in cold or damp weather are:

Protect coatings from freezing, and don't use one that has been frozen. Freezing causes polymers to clump together instead of dispersing evenly, resulting in more porous films.

Apply coatings when both air and surface temperatures are above manufacturers' recommended minimum application temperature (usually 40 degrees F.). Surfaces that are too cold can act as heat sinks and freeze coatings.

If low temperatures are expected after application, keep coatings tented and above 40 degrees F until they have thoroughly dried.

Don't apply coatings in the rain, or allow them to be exposed to rain before they have cured. This can prevent film formation and lead to wash-off.

Whatever the job or conditions, the best thing is to follow the specific storage, handling, and application instructions provided by the coating manufacturer. When applied under the proper conditions, 100% acrylic coatings have the strength and endurance to help make every EIFS application a lasting success.

Why is good film formation important?

The polymer film performs two vital functions in an EIFS coating: binding the filler particles together and adhering the coating to a substrate. If this process doesn't occur properly, the overall strength and durability of coatings and EIFS are substantially reduced.

What about excessive dampness or humidity?

High humidity or wet weather can also cause film formation problems. If the moisture in a coating is not allowed to evaporate after the coating is applied, the polymers are unable to form a proper film. As a result, the coating's performance can be adversely affected. Finishes, for example, can be susceptible to wash-off if it rains before they have dried.

What type of warranty is available with the Preswitt EIFS?

Preswitt offers a limited materials warranties depending on product selection and contract requirements. Preswitt's standard three year warranty is shown below.

Preswitt Manufacturing Ltd. warrant that materials manufactured by Preswitt Manufacturing Ltd. will meet performance specifications as described in the instructions, advertising, and other literature authorized by Preswitt Manufacturing Ltd., when applied in strict accordance with the manufacturer's specifications and application instructions.

Preswitt Manufacturing Ltd. will replace materials if the products originally supplied are proven to have been defective, and provided not more than three years have elapsed since time of delivery. No other warrantees are expressed or implied.

Click here to view an article entitled "Warrantees: Expectations and Reality" by Gregg Lowes of the Northwest Wall and Ceiling Bureau.

Is mechanical attachment of EIFS recommended to resist high wind loads?

In general, adhesive attachment of EIFS to sound supporting construction provides superior wind load resistance in comparison to mechanical attachment. It is important in an adhesively attached system that the supporting construction is sound - free of surface damage, defects or contamination - and, in the case of sheathing substrates, that they are attached with fasteners.

Fastener spacing must be capable of resisting wind loads. Preswitt recommends that mechanical fastening of the insulation to the substrate only be considered where adhesive attachment cannot be used. Should code requirements or designer preference dictate, Preswitt will approve the use of mechanical fasteners.

What type of maintenance is required for an EIFS?

1. Immediate correction of any deficiencies, defective caulking or flashing.

2. Mandatory annual inspection of the wall by a qualified, recognized third party inspection agency, with particular attention to those locations where the system interfaces with other materials.

3. Periodic cleaning of the wall surface to prolong life of the coating, and maintain its original appearance.

Cleaning of Acrylic Finish

• Acrylic finish can be cleaned with a combination of household bleach and T.S.P. (Trisodium Phosphate) in water. A 10%-15% bleach solution with water can be spray applied, or used in conjunction with a soft-bristled scrub brush.
• Light pressure washing can also be used, this method works well for regular dirt. Always pre-rinse the wall surface prior to applying cleaning solutions, this will remove light surface dirt, as well as inhibit absorption of dirt laden moisture.
• If graffiti is involved, regular paint solvent (mineral spirits) can be tried. This will not attack the acrylic, but may take off the graffiti.
• Acetone, Lacquer Solvent, Xylol, and Paint Remover will attack the acrylic and should be avoided.
  

Mechanical scraping with a matched touch up of paint can be good approach for a small area .

Patching: Any patching of acrylic finish or EIF Systems should be done by a qualified plastering contractor. If required, contact Preswitt for a list of current qualified applicators.

Rainscreen Vents: Drainage vents occur in various locations in the Rainscreen EIF System. These vents typically are located at the base of the EIFS walls, as well as at floor line expansion joints. If moisture is observed draining from these vents, please contact your building manager. Inspect all penetrations and caulked joints in the vicinity of the drainage vent.

What materials can I use to recoat my EIFS?

Preswitt offers a number of acrylic finishes that can be used for this purpose, including both standard acrylic and elastomeric coatings. A top quality acrylic latex paint is also acceptable.

What type of sealants are recommended for use with EIFS?

In general low modulus sealants that maintain their properties with exposure to UV (ultra-violet) light are recommended. In addition the sealant should comply with EIMA Test Method 300.01. Preswitt approves of the following sealants.

• Tremco "DYmeric" with Primer #1
• Pecora "Dynatrol II" with Primer P75
• Tremco "Tundra Foam" Backer Rod
• Dow Corning 790/795 Silicone Building Sealant
• Dow Corning "Firestop System"
  a) Fire Stop Foam
  b) Fire Stop Sealant (DC2000)
  c) Firebarrier Mineral fibre joint filler
  

What type of textures are available?

90% of the Acrylic Finish sold by Preswitt is Medium texture. The popularity of this texture can be attributed to the following;

• Additional coating thickness.
• Ability to cover minor ridges or defects in the substrate.
• Longer open time and workability compared to the thinner coatings.

For the above reasons, Preswitt Manufacturing recommends the use of the Medium texture finish over Portland Cement Plaster (Stucco) substrates, particularly in larger wall areas. The fine finish is more suitable for small areas and detail work over stucco, or on smooth planer surfaces.

Is flashing required with EIFS?

For the wall to resist water penetration, particularly at transition areas such as decks or roof/wall intersections, flashing must be installed to divert water beyond the cladding, not into or behind it. Similarly, if windows are expected to leak, sill flashing beneath them is important to divert water away from and not into the wall assembly.

Prepare the wallboard surface as you would for painting. Prime the surface with primer. Preswitt finish following normal application procedures. The primer should be tinted to match the finish.

Is the Preswitt finish an elastomeric?

Preswitt's standard Quality Finish like many acrylic coatings has a certain amount of elastomeric properties. Preswitt's Flexsil finish is the company's silicone enhanced finish with the greatest amount of elastomeric flexibility.

How much do the different systems cost? How much extra is it for heavy duty mesh?

This is probably the most often asked question and the most difficult to answer. The cost of the materials FOB our plant is constant however there is such a variation in the labour element, the site costs, location, time of year, degree of difficulty, availability of the work force and size of project, that it is impossible to give a reasonably accurate unit cost estimate without this information. We have a number of experienced applicators that can furnish reasonable cost estimates to the design authorities, on request, given sufficient project information. The heavy duty mesh adds approximately $1.50/sf to the material cost of Preswitt's standard EIFS.

How does Preswitt approve of contractors/applicators?

Contractors are approved based on their experience and familiarity with Preswitt products. Preswitt has identified preferred contractors through association with them in the BC market over the past twenty years. Factory training is available to experienced plaster and stucco tradesmen.

How does the insulation value of the Rainscreen system compare to the Standard system?

Preswitt tested the Rainscreen system in accordance with the CCMC standard for durability under climatic changes. The test chamber was then modified to allow for both static cyclic wind pressures and a steady state dynamic component. The interior side of the exterior sheathing was maintained at a constant temperature of 30°C and the exterior temperature at -10°C. Temperatures were measured within the drainage cavity at incremental distances from the drainage hole under a variety of wind pressure regimes.

The thermal performance tests indicate that in general, a Preswitt Rainscreen wall should perform similarly to a non-vented EIFS walls. Some localized cooling does take place in the direct vicinity of the vent, but this area is small compared to the size of the wall. This test showed that to a significant extent the Rainscreen system preserves the insulation value of the standard system.

Who inspects Preswitt systems as they are installed?

Independent third party inspectors are generally required by regulatory agencies, or the design authority, to monitor the installation and insure that the Preswitt system is applied in accordance with the specifications and Preswitt's written instructions.

Does Preswitt provide shop drawings?

Preswitt does not manufacture factory units that require shop drawings. We do publish a number of detail drawings showing our recommendations as to how our materials should be installed and how they relate to and interface with other construction materials. Preswitt respects the designer's authority regarding decisions on details and welcomes the opportunity to be involved in the preliminary design process including, when requested, the submission of detail drawings for consideration.

Our experience shows that most problems can be resolved proactively by attending to significant details early in the design process. Where a number of identical details are required on a particular project, we recommend that a full sized mock-up of the feature be constructed on site with all associated parties in attendance (i.e. sub and general contractors, architect, building envelope professional, inspectors, windows contractor, caulking contractor, etc.).

What standards apply to the Preswitt systems?

Today's standards vary somewhat by geographical location. The City of Vancouver holds the most stringent requirements for the approval of EIFS systems in Canada. Vancouver requires that all EIFS used in high-rise construction be fully rain-screened pressure equalized systems, approved by the Canadian Construction Materials Center. Preswitt has met this standard. To view or download the CCMC evaluation report for Preswitt's Rainscreen EIFS, click here (you will need Adobe Acrobat reader to view this document. Click here to download the free reader from the Adobe website).

Preswitt is also listed by other regulatory and testing agencies (for more information click here).

How does the Preswitt Rainscreen system drain?

First, a water penetration barrier (Preswitt's MP Flexcoat) is trowelled over the exterior sheathing to provide a primary layer of protection. Then the insulation board adhesive is applied in vertical strips to create drainage channels behind the insulation. At the bottom of the wall section, a starter strip of insulation board is installed which restricts further vertical drainage and directs any moisture to the exterior of the compartment via a vent hole. Moisture should never come out of this hole, but if it does, it is an early warning sign that there is a problem in the wall area in the immediate vicinity of the hole that should be rectified without delay. Click here for a more detailed description.

What is pressure equalization, and who designs it?

Pressure equalization is the speed at which the pressure within the wall cavity equalizes with the pressure on the outer surface of the wall under varying pressure (wind) scenarios. Pressure equalization is important in that when the pressures are not equal, a pressure gradient can be created which can drive moisture into the wall through cracks in the wall surface. At this time there are no standards to clearly define a required level of pressure equalization.

Building elevations are subjected to differing pressures over the face of the wall over time. For example the pressure exerted by the wind on the face of a building gets stronger as you get closer to the corner of the building. To adjust to these areas of differing pressure, the wall is divided into compartments of varying sizes. Smaller compartments equalize faster. Locating and sizing these compartments is the responsibility of the design authority. The following guidelines are submitted for the designer when considering the use of the Preswitt EIFS Rainscreen System:

• 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 per compartment, sized to suit the compartment area.
  
• Vent size based on 0.25 sq. in. per 60-sq. ft. of wall area.
  

What makes Preswitt's air/vapor/water penetration barrier (MP Flexcoat) better than others?

Preswitt's MP Flexcoat is a top of the line water penetration barrier, and vapor retarder that meets todays most stringent code requirements. To view a detailed description of the Flexcoat and the strength and materials test data results click here.

If cracks appear, will Preswitt's Rainscreen EIFS take care of it?

Yes, Preswitt's Rainscreen system has a drainage cavity behind the insulation board that will direct any moisture out to the exterior of the wall assembly. Moisture should never get into the drainage cavity. If it does, it will drain out of the vent hole. Moisture coming out of the vent hole is an early warning sign that there is a problem in that particular compartment of the wall that should be rectified without delay. Click here for a more detailed description of how the system drains.

Can insects be a problem?

In our 20 years of experience, no insect problems have been reported with Preswitt systems. Screening to prevent insects from getting into the drainage cavity via the vent holes can be added at the discretion of the building designer.

What additional resources are available regarding EIF systems?

There is a great deal of information about EIF systems on the internet. See our Links page for links to web sites that provide additional resource information. If you require specific information, please contact us.