Repairing EIFS Sealant Joints
Repairing the sealant joints that weatherproof the gap between adjacent wall materials is one of the more common maintenance chores for virtually all types of walls. EIFS walls need this type of care too, yet EIFS has its own peculiarities in terms of doing it right.
This month's column gives some insight to how to repair EIFS sealant joints. It'll also give you some ammo when trying to explain to a building owner why EIFS sealant replacement projects can get a bit pricey.
First, to work properly, the sealant needs to be well bonded to the EIFS. This means more than being in contact; it means being glued to it. To achieve a good bond, the surface of the EIFS must be clean. Compared to many traditional building materials, EIFS is not particularly "robust"; EIFS is a lightweight material. This means that rough physical force should not be used to remove the old sealant nor to clean the surface of an EIFS. Doing so can damage the EIFS to the point that the EIFS itself, not just the sealant, needs to be repaired. In the case of repairing sealant joints, the need for gentle repair techniques has several implications.
Repairing EIFS sealant joints usually means removing the old sealant and replacing it with new sealant. Although it is sometimes possible to overlay some type of sealant over the old one, this article concerns the more common practice of removing the old sealant and replacing it with another sealant in the same basic joint configuration as the original.
In terms of removing the old sealant, sometimes the sealant has lost its bond to the EIFS and can be pulled out without difficulty. However, normally removing the sealant is not particularly easy. Often, there are areas that are loose as well as areas that are still very well attached. If you try to yank a well-attached sealant bead from the EIFS, you'll probably take some of the EIFS with it. This means that the EIFS itself must then be repaired.
Bring out the oldThe usual way to get out the old sealant is to slit along its length right next to the EIFS surface (often with a thin-bladed knife), and then pull it out of the joint. However, simply removing a big gob of sealant is not enough; all of the sealant must be removed. Usually, it is very difficult to get the sealant to detach itself completely from the EIFS, so sealant residue is normally left on the EIFS. In particular, the sealant residue gets into the nooks and crannies of the EIFS coating, and is hard to get loose. Sealant joint cavities are also frequently so narrow that it's hard to get tools into the sealant joint to even get at the surface that needs to be cleaned. Since properly applying a new sealant requires a clean surface, somehow the old residue must also be removed. Herein lies the problem: how to get a clean surface to apply to the new sealant.
Keep in mind that EIFS contains synthetic plastic resins, both within the EIFS finish and basecoat, and within the foam insulation itself. Although these materials are well suited to their purpose of being part of an EIFS, they are sensitive to some manmade chemicals. This means that using harsh chemicals and solvents to dissolve the sealant residue is risky. Harsh chemicals may not only attack the resins in the EIFS lamina, but may also leach through the lamina and attack the foam. Clearly, this would reduce the ability of the new sealant to properly bond to the old EIFS. Luckily, special cleaners are available that are intended for use with EIFS; manufacturers of these products advertise in Walls & Ceilings. These cleaners will help remove many types of residue from EIFS surfaces without affecting the EIFS. Unfortunately, even easy-to-use liquid cleaners often cannot get rid of all the residue. When the old sealant is really stubborn and is lodged in the texture of the EIFS surface, sometimes the only method that works is the "Controlled Rambo Approach."
The Controlled Rambo Approach means using controlled physical force. If you use chisels and scrapers in the normal macho manner to remove sealant residue, you may damage the EIFS lamina. If the lamina is damaged, then it too will need to be repaired before the new sealant can even be installed. Obviously, this compounds the sealant joint repair problem and helps explain why replacing EIFS sealant joints can get expensive.
Control is needed of the physical process of removing the residue. One way to achieve this is to use a grinder. The trick is to not dig down into the basecoat and not to cut into the reinforcing mesh. One also needs to keep an eye on the grinder disk itself, as it tends to get clogged with gummy sealant residue. This grinding process requires skill and is time consuming. In the end, what one is looking for is a virgin basecoat surface to which the new sealant can be adhered.
Often, it is necessary to apply a skim coat of basecoat adhesive to the ground away area to produce a smooth, uniform surface. Cementless basecoats work well for this application as the Portland cement mixing process is avoided. If the reinforcing mesh is damaged by the cleaning process then this too will have to be replaced. This can be difficult as the mesh is often wrapped back onto the studs or tucked behind the insulation. Worse yet, the mesh also continues onto the outside surface of the EIFS.
In order to replace damaged mesh on the surface of an EIFS that is exposed to the elements, new mesh must be added to that surface, too. This means that the exposed EIFS finish must be ground away and a new basecoat and finish applied. Another way is to create a thin, deep groove between the basecoat and the foam and then slip the new mesh, with basecoat adhesive, into the groove. It?s obvious that both these methods can be time consuming, and hence reinforces the need to be careful when removing the old sealant. In fact, splicing in a new lamina at the edge of a sealant joint is such a pain that some contractors find it easier to saw away a strip of EIFS (including the foam) around the sealant joint and replace the entire EIFS.
Out of the wayOnce the old sealant is completely out of the way, then is a good time to peer into the joint and assess the condition of the wall that supports the EIFS. Often, the reasons why the old sealant is being replaced is that water may be getting in. It?s possible that the water has affected the studs and sheathing. If so, now is a good time to fix them. Removing and replacing EIFS, framing and substrates is a subject unto itself. However, the key point is that the scope-of-work of a simple sealant replacement project may expand into a major project. The good news is that often, water damage is limited to the area immediately adjacent to the leak, so the amount of wall area needing replacement is limited. Either way, it's better to fix the problem properly now than later.
If the EIFS itself is being removed as part of the sealant replacement process, it's also a good time to consider the width of the sealant joint. Sealant joints tend to be undersized, i.e., the width is narrower than optimum. Narrow sealant joints put extra stress on the sealant and its bond to the EIFS. Hence, allowing an extra 1/4 inch or so to the joint width can help the sealant perform better, so long as aesthetically sensitive on-lookers can withstand the horror of a slightly wider sealant joint.
When replacing sealant joints, it's also a good idea to consider what type of sealant to use. EIFS manufacturers and sealant manufacturers maintain lists of sealants or and specifications for sealants, that work with their products. It's prudent to use such "approved" sealants as it can affect warranty coverage as well as the performance of the sealant joint.
Sometimes the reason the old sealant failed is that it wasn't up to the task. In other words, the quality of the sealant itself was inadequate for the demands of the building. There are a number of high-performance sealants on the market that perform well with EIFS, notably silicones, urethanes and polysulfides. For the modest additional cost of a premium sealant, the new replacement sealant should last much longer than the original. Hence, the long-term cost of maintaining the sealant joints for the building is reduced.
Many sealants require the application of a primer to the surface of the EIFS prior to applying the sealant. A primer is a liquid-applied coating that is applied to the EIFS prior to the sealant. The use of a primer can significantly improve the bond of the sealant to the EIFS, and hence the performance of the joint. Thus when recommended for use, primers should be used. Primers take the form of a specialty coating obtained from sealant manufacturers, or from EIFS manufacturers. Some primers do not "weather" well and create stains on the exposed surface of the EIFS, so be careful when applying them to the sealant-to-EIFS bond area. Hence, care is needed in applying some primers. Once the primer is in place, the sealant is applied as usual.
Many EIFS sealant joint configurations also require a backer rod or other means of limiting the depth of the sealant bead and giving the sealant bead the proper shape. Make sure to use a type of backer rod that does not absorb moisture. Actually, using a backer rod can save money because it helps avoid the tendency of pumping too much sealant into the joint; sealants are expensive, and performance-wise, less often works better then a lot. A properly proportioned sealant bead also helps the sealant stretch properly because thick sealant beads are stiffer and don't elongate as easily.
Most EIFS manufacturers want the sealant applied to the basecoat and not to the finish. This is because EIFS coatings tend to soften a bit when exposed to moisture for long periods. When softened, the EIFS materials lose some of their strength and hence, anything bonded to it, like a sealant, cannot get as good a grip. I can hear you saying now that masking off the bond-line is a hassle, and it's really much easier to go directly onto the finish. But if you decide that you want to go onto the finish instead of the basecoat, be sure to check with the EIFS manufacturer first to be sure it will stand behind it.
It's interesting to note that the problem of replacing sealants is not unique to North America. In Europe, where modern EIFS originated, sealants are used all the time but in a different way. In Europe, metal trim is often embedded into the perimeter of the EIFS. This improves the damage resistance of vulnerable corners, but also give a hard surface to which to attach sealant. It also gives the sealant good initial bond, and allows more aggressive cleaning techniques to be used when the sealant needs to be replaced. Interestingly, some of the new drainage-type EIFS used in North America also use embedded trim at the edge of the EIFS, which should help in the ongoing matter of the maintenance of EIFS sealant joints.
Lastly, make sure that the maintenance people for your EIFS buildings are aware of the above concerns. Most of the maintenance people that I have come across don't realize what EIFS is (they think it's stucco or concrete, and act accordingly). Once they realize what is entailed with doing EIFS sealant joint repairs, they may want to have your firm do the work, or a sealant specialist.