EIFS – Synthetic Stucco Siding
EIFS siding, or synthetic stucco, is a siding that offers clear advantages when properly installed but can be very problematic when installation errors occur. It is different to traditional stucco.
WHAT IS EIFS SIDING,
What is synthetic stucco? The EIFS acronym stands for Exterior Insulation and Finish Systems. EIFS stucco construction includes:
- A drainage layer to channel incidental moisture to the ground and away from the home’s sheathing
- A layer of polystyrene or similar insulation (the Exterior Insulation)
- A base coat that might be a Portland cement mix or synthetic product reinforced with fiber mesh
- A top coat of synthetic stucco (the Finish Systems)
Leading manufacturers DryVit, BASF Senergy and Sto Corp design EIFS systems for different applications. They all feature the same general layers outlined above. A wide spectrum of base coats and finish coats are used to create systems specifically engineered for each type of installation or the finish preference of the homeowner. The synthetic stucco system as a whole creates a moisture barrier.
INSTALLING AN EIFS SYSTEM
At the site, installation proceeds as follows:
- The mesh or grid drainage layer is adhered to the home’s siding
- The foam insulation panels are glued or fastened on, and seams are staggered
- The seams are caulked
- The base coat is applied by hand or spray
- Fiber mesh is installed for strength and to accept the finish coat
- The top coat is applied by hand or spray
EIFS VS STUCCO
When considering synthetic stucco vs traditional stucco, EIFS siding has two advantages. First, it includes a layer of insulation. Secondly, it offers even more finish options than stucco.
Traditional stucco is not prone to the moisture problems discussed below.
PROS AND CONS OF EIFS SIDING
EIFS siding advantages:
- Insulation that boosts the home’s energy efficiency and indoor comfort
- A range of attractive finishes that mimic stucco, brick and metallic siding
- The durability of stucco
- Lighter than stucco or brick
- Better control of moisture than stucco, brick or fiber cement, but only when properly installed
EIFS siding disadvantages
- Potential water damage resulting from improper installation
- Lack of certified and experienced EIFS installers
- The need for annual and thorough EIFS inspection to look for potential moisture intrusion
EIFS PROBLEMS WITH MOISTURE
Concerning EIFS and moisture, everything depends upon installation. The EIFS industry often quotes a 2006 study from the prestigious Oak Ridge National Laboratory funded in part by the US Department of Energy. The study concluded that “EIFS was the best performing cladding in relation to thermal and moisture control when compared to brick, stucco and cementitious fiberboard [fiber cement board] siding.”
When properly installed and maintained, EIFS siding does indeed create a very protective envelope around the home. The problem is the immense difficulty in making a home completely watertight.
When the moisture barrier, drainage plane or flashing around windows, doors and mechanical vents is installed improperly or is damaged after installation, perhaps as the home settles, water can get into the sheathing and framing of the home.
The problem is made worse because EIFS siding doesn’t breathe well. In other words, water that gets in won’t easily evaporate. Rot and mold, both of which lead to very expensive repairs, will result.
Synthetic stucco problems are hard to resolve. The issues can be so bad and occur with such frequency that many home inspectors steer potential buyers away from EIFS-sided homes. Some insurers either won’t provide EIFS insurance or charge very high premiums to do so.
EIFS REPAIR COSTS
The problems with moisture have been spelled out. An additional concern is that synthetic stucco repair is very difficult and a skill few siding contractors have mastered. In other words, tearing out some of the siding and replacing it can lead to the same type of water infiltration and resulting damage but on a larger scale.
In terms of the cost of repairs, expect to pay $150-$500 to repair flashing issues around doors and windows. If EIFS siding needs to be replaced on part of the home, the cost might be as high as $16 per square foot depending on many factors including the location of the repair and the type of EIFS finish originally applied.