The ins and outs of EIFS joint placement

Joints serve as an interface between components and are used in Exterior Insulation Finishing Systems between EIFS where it is laid adjacent to more EIFS, as well as where EIFS meets other materials.

Joint purposes

A joint’s main purpose is to allow for shifting in the building’s structure without subsequent damage to the EIFS. In essence, these joints allow the building envelope to remain flexible enough to stretch with the building as it shifts. There are various elements that all share the “joint” name, and while many are quite essentially the same, joints like aesthetic reveal joints are not.

Cold joint: a separation of two materials that are liquid-applied, like EIFS, that allows for one material to cure before applying the other side.

Joint issues

Because joints must be maintained in order to keep them functioning properly and effectively, it is wise to only use joints where they are necessary, saving time and further costs. If the look of a joint is all that is desired in one area, using an aesthetic reveal, which does not act as a working joint, can be used as it does not require the same maintenance.

Joint placement may not always be up to the contractor or the installer, as joint installation recommendations may be already specified in the manufacturer’s instructions, which as always should be followed. Not doing so might void any warranties and cause significant problems further down the road.

Special considerations should also be taken in acknowledging the fact that if water is going to infiltrate the EIFS, the joints themselves are a likely starting point.

Where joints should be placed

• When the finish of the EIFS is continued onto the substrate for a continuous look, but without the incorporation of the insulating expanded polystyrene (EPS) foam. This is a prime location for a joint as obviously the thicker original EIFS will not flow right into simple lamina only over the substrate.
• Because all substrates retain unique properties and will shift or flex at different rates, the EIFS branching from one type of substrate to another will need to be separated by a joint to allow for the extreme movement differentials and prevent cracking due to excess stress on the lamina.
• Even when substrates are the same, there are applications where movement may still occur depending on how they’re situated. If there is the likelihood of shifting between the two materials, even if they’re of the same composition and share the same properties, a joint is necessary.
• When EIFS is laid adjacent to any other material, not utilizing joints at these meeting points is a leading contributer of water intrusion, and the EIFS must also be properly terminated.
• When EIFS is laid adjacent to more EIFS, a joint is necessary as the simple placement of each piece next to one another is not an adequate seal in any way, especially if both are backwrapped. A joint must be placed between the abutment of EIFS for proper sealing.
• On large wall faces, joints are optimal even though the larger the overall wall, the easier it is to complete as one solid piece. However, this will put stress on the lamina and incorporating a series of joints will lessen this stress, and further allow the wall to remain flexible and reduce cracking.

Joints and drainage

Joints used with drainage EIFS must be placed in such a way that water is able to still drain out properly. Over-caulking horizontal joints can also impede proper drainage, and water will not be able to escape. Incorporating drainage into the joint seal itself will rectify this.

When a joint may not be necessary

Having a relatively seamless substrate made of wood-based materials can work with less joints, and using concrete instead of wood framing around openings may also result in less cracks without the use of joints.

The main purpose of a joint is to facilitate the shifting of a building without destroying the EIFS. Obviously, buildings and homes shift and creak due to temperature and humidity, the result of significant changes in these variables. If a particular climate is relatively consistent and doesn’t fluctuate in temperature or humidity, one may be able to get away with using less or no joints, although this is not generally endorsed.

Ontario receives a healthy dose of all four seasons as well as extreme, rapid freezing and thawing, so this method doesn’t work here.