Where to Put Joints
Over the years, I’ve compiled a list of where joints need to be used, or at least where one needs to consider using them. This list is summarized below, and is especially useful for passing on to whoever is responsible for designing and locating joints in EIFS-clad walls.
First, let’s clarify that the information below applies only to PB EIFS: The EIFS with thin, synthetic coatings and that normally use EPS insulation. This accounts for the vast majority of the market. PM EIFS, with its thicker, more stucco-like coatings, have their own joint issues, including control joints.
Second, this list is for “working joints,” ones that have sealant (“caulking”) in them. It does not apply to aesthetic reveals (“joints”) that are basically a groove, cut partially through the foam, and into which the EIFS lamina is applied.
Third, this list is not to say that you must use joints in these areas, but it sure does say that you should think about whether or not a joint is needed.
Fourth, keep in mind that joints need to be maintained. Caulking does not last forever, and replacing EIFS joints can be a major and expensive undertaking. That said, if, and the “if” is a big factor, one can properly get away without using a joint, it saves money now and in the future. The key is to use joints where they are needed and to try to not use them where they clearly are not needed. However, the clarity of where they are not needed is often really not so clear. The caveat and safe rule of thumb is: When in doubt, use a joint, otherwise a crack may appear, and possible resultant water entry and associated irate customers, etc. Also, remember if a “joint look” is wanted, it may not need to be a working joint. Rather, an aesthetic reveal might work. Aesthetic reveals are cheaper to install initially, and do not need periodic caulking replacement, since there isn’t any caulking.
Fifth, EIFS manufacturers’ requirements for joints vary. Since EIFS are proprietary products, in the end the proper design of joints in a specific EIFS wall depends on the building at hand, as well as what the EIFS manufacturer wants. It’s important to do what is required for the specific EIFS product, as the warranty, and not just the performance, could be affected. Expressed another way, this information is generic and does not supersede that of specific EIFS products.
Last, we do not need to belabor, in this month’s column, the fact that one needs to use a good sealant, and that the sealant needs to work well with whatever is on either side of the joint, and that the sealant should be acceptable to the EIFS manufacturer, and that it should be applied to the basecoat, and … this column is about where joints need to be considered to be used, not how to install or design them.
Joint locations listWhere EIFS abuts itself. Example: Floor line joints in wood frame buildings. One cannot simply abut one section of EIFS against another, i.e., two back wrapped EIFS terminations that simply touch each other. Touching does not constitute a weather tight seal in this case, nor does it allow for expansion. One also cannot simply splice together two adjacent EIFS areas, like some Rhode Scholars have attempted with EIFS panels, only to have a wall full of cracks before the third panel was hung. By the way, this condition also occurs where a barrier EIFS meets EIFS with drainage, especially if the two systems use different types of foam, or are fastened differently.
Where an EIFS abuts another material. The list is endless, but especially includes windows, wood, doors, beams, surface mounted projects, ducts, flashing and so on. Again, this is a case that simply bringing an EIFS into direct contact with, say, a window frame, is not a proper termination. The edge needs to be “wrapped” with the EIFS basecoat in some way, or terminated using trim. The number of times this shortcut has been attempted no doubt exceeds the number of grains of aggregate in a pail of EIFS finish. It is a widespread problem, and EIFS simply cannot be detailed like stucco.
Where the substrate changes. Obviously, various substrates can be used to attach an EIFS to. Each substrate type has different properties. This especially includes how much they move due to temperature change, moisture content change and under flexing conditions, such as wind. Where two different substrates meet, forces tend to be concentrated and tend to flow outward through the EIFS to the EIFS lamina. Such forces can overstress the lamina and cause cracks. A joint is needed at these locations to allow the movement to occur, rather than by futilely trying to resist it by hoping the EIFS lamina will hold the force in check. Of special concern are substrates that change from a material that is very stable and/or rigid, to one that is limber or whose properties can vary radically. An example could be wood framing used to close-off large openings in an existing solid concrete wall.
Where movement occurs in the substrate. This is a catchall description and a favorite of lawyers. What this basically means is that if there is a lot of movement of any kind, then a joint where the movement is concentrated is prudent. A couple of examples will help. When a poured concrete high-rise office frame abuts a poured concrete low-rise parking garage frame, a joint is needed where they meet. Even though the substrates are both concrete, it’s obvious that the two substrates will move differently. A similar situation can occur when the projecting EIFS-clad studs walls of a condo deck meet the main walls (that are also framed and sheathed the same way). Clearly, the movement of the deck slab will create a prying action at the deck wall-to-main wall interface, and hence a joint is needed at this location. A last example is where joints that do move, occur in the substrate. A classic case is tilt-up precast concrete panels. Even though clearly these panels are often less than 12-feet wide, they are often quite tall and do move independently from one another as discrete building elements. Hence, a joint is a good idea.
Where the EIFS stops, but the EIFS lamina continues, without the foam, onto the substrate. This can occur when an EIFS wall terminates in the middle of a block wall. It’s not uncommon to want to retain the EIFS appearance on the concrete. However, one cannot normally continue on with the EIFS lamina from the EIFS to the block. A joint is needed at this location. A practical example of this is where EIFS finish is used over stucco at the curbside at a bus stop, and the upper walls are EIFS.
Sometimes, one can get away without using a joint. I’m not advocating this but sometimes it works. Usually, such attempts are most successful in areas where the climate is stable. Places like southern California, which basically does not have any real weather, can get away with funky EIFS joint details better than, say, the Appalachian area, with its full, four-season climate and freeze-thaws. It also helps if one tries to make the substrate more monolithic. For example, filling-in a window opening in an existing brick wall with concrete block, instead of wood framing, is more likely to stay crack free. Also, not having a joint in the foam, where it crosses the joint, helps a whole lot. So does using a more stable type of wood substrate, such as plywood, in lieu of materials like OSB.
To make life easier for the EIFS contractorOn large wall areas, it’s sometimes a problem to try to do the whole wall in one pass. This especially includes applying the finish. Breaking up large wall areas into more manageable, smaller areas, is a sensible approach, I think. For one, it helps avoid building up high EIFS lamina stresses over large areas but it also allows the contractor to stop and start at reasonable intervals. This is not to say that in some cases that an aesthetic reveal will not solve the stop-start problem, but such joints do not allow for movement. And allowing the wall to move a bit on its own is a good principle.
Be careful when putting joints in EIFS with drainage walls. Keep in mind that the water needs to be able to get out of EIFS with drainage walls, and sealing the lower horizontal edge of such wall area can hold the water. Consider, for instance, the condition at a horizontal floor line expansion joint in a wood frame house. A joint is needed there, but should the water be let out at that point, or have it keep trickling downward? Published details show many variations on how to deal with this condition.
Caulking the hell out of every lineal inch of some sealant joint is sometimes not a bright idea. This especially is an issue on long runs of horizontal joints (such as at window sills), where the leak water, if any, needs to be able to get out. If the entire length of the joint is sealed, the water can back-up behind the sealant. Thus, putting a weep hole in the sealant bead at regular intervals makes sense. This is especially true when pan flashings are used, so that the water that inevitably runs to the ends of the flashing can get out at that point.