What is EIFS, and how is it different from traditional stucco?

The short answer

Traditional stucco is cement plaster, applied in coats over metal lath, with no insulation. EIFS, which stands for Exterior Insulation and Finish System, is insulation board fixed to the wall, a thin reinforced base coat over it, and an acrylic finish coat on top. Both are trowelled finishes. One is a masonry skin; the other is an insulated, layered system.

Almost everything built or reclad in the GTA since the 1980s with a stucco look is EIFS. Houses from before that, and some custom work, may be traditional cement stucco.

Where EIFS came from

EIFS was developed in Europe after the Second World War to insulate and repair masonry buildings, and it arrived in North America in the 1960s. The most common type on houses is PB EIFS, polymer-based, where the coatings carry a high proportion of plastic resin that strengthens and seals them while keeping them flexible.

The layers of an EIFS wall

1. Substrate and weather barrier. The sheathing on the framing, and on modern drainage systems a membrane or coating over it that sends any water that gets in back out at the bottom.
2. Insulation board. Expanded polystyrene, usually one to four inches thick, adhered or mechanically fastened. This is where the insulation value comes from and why an EIFS house is warmer and quieter than the same house in siding.
3. Base coat with mesh. A polymer-modified cement coating with fibreglass mesh embedded in it. This thin layer is the strength of the wall. Corners and low walls that take knocks get extra layers.
4. Finish coat. An acrylic finish trowelled on in the texture and colour chosen. The colour runs through the coat, so it never needs painting.
5. Sealants and flashings. Every window, door, penetration and transition caulked and flashed so water runs out over the face. Not a layer of the wall, but the layer most failures are missing.

The layers of a traditional stucco wall

Building paper over the sheathing, metal lath fastened through it, then three coats of cement plaster: a scratch coat pressed into the lath, a brown coat to level, and a finish coat. The total is about an inch of cement. It is hard, heavy and breathable, and it cracks as the building moves, which is why traditional stucco walls are usually divided with control joints.

How they compare

Insulation

EIFS adds insulation outside the studs, which is the most effective place for it. Traditional stucco adds none. On a house that is being reclad, this is usually the deciding factor.

Cracking

Cement stucco cracks; it is in its nature, and small cracks are normal. EIFS coatings are flexible and reinforced, so a properly installed EIFS wall stays crack-free for decades. When EIFS does crack, something underneath is moving or wet.

Water

Traditional stucco lets water through and lets it dry out again. EIFS keeps water out, which means water that gets in behind it through a bad joint cannot escape. That is the origin of every EIFS horror story, and the reason sealing and flashing are not optional on an EIFS wall.

Weight and substrate

Traditional stucco is heavy and needs lath fastened into the structure. EIFS is light and goes onto sheathing, block, concrete or sound brick.

Repair

Both can be repaired. EIFS repairs are cut back to sound material and rebuilt layer by layer, and the finish is matched. Cement stucco repairs are chipped out and replastered, and matching old textures is harder.

Look

From the street, the same. Both take any texture from heavy to smooth. EIFS makes crisp modern smooth finishes and deep mouldings easier, because the profiles are cut from foam and meshed into the wall.

Which one do you have?

Tap the wall. EIFS sounds hollow and slightly soft; cement stucco sounds solid and hard. Look at a cut edge at a window or vent: EIFS shows white foam under a thin skin; cement stucco shows grey plaster an inch thick. Houses finished since the 1980s are almost always EIFS. If you are not sure, send us a photo of an edge and we will tell you.

Which one should you choose?

For a new house, an addition or a reclad in the GTA, we install EIFS: it insulates, it resists cracking, and done properly it lasts the life of the building. Traditional cement stucco still has its place on some heritage work and on garden walls, but for an insulated, long-lasting exterior the system is EIFS, installed as the manufacturer designed it and with every joint sealed.

If you want the layers on your own wall explained, book a free site visit. We open a small area if needed and tell you exactly what is there.