EIFS Minimum Requirement For EPS Foam Thickness

Did you know there is a EIFS minimum requirement for EPS Foam thickness?

You may be under the EIFS minimum requirement for EPS Foam thickness because of an industry shift from 1 1/2″ foam to a 1″ foam standard. With the rising cost of material we have found that many Synthetic Stucco contractors are pushing 1″ foam. In years past the norm was an 1 1/2″ of foam. The problem with using one inch foam is that the minimum requirement for the EPS Foam is 3/4″ which one inch would seem fine then, but after sanding the foam it is getting close to the 3/4″ in troubled areas that need a little extra sanding, but that is not the real problem. The problem is that in many cases the design calls for aesthetic reveals or v-grooves, which are cut into the foam with a hot knife. These aesthetic reveals are anywhere from a 1/2″ to 3/4″ deep when using one inch foam. If you use one inch foam you are limited on your design because you cannot use the aesthetic reveals. The use of aesthetic reveals are great for stopping points when applying the EIFS finish coat so the entire area does not have to be done at once. Also, the aesthetic reveals allow for easy and cheaper repairs if the Synthetic Stucco becomes damaged down the road. Exterior Insulation and Finish System needs to re-finished from coast-to-coast to look brand new, otherwise you will be looking at a patch in the middle of a huge wall. Aesthetic reveals can add to the beautiful design of Synthetic Stucco, help the applicator when applying the finish coat, save costs on repairs. The cost savings of using 1″ foam is not worth the disadvantages and usually these savings are not passed down to the customer. Another disadvantage of using the thinner foam is the r-value you are losing. Your EPS Foam will be a 1/3 thinner so you will be decreasing your r-value of the Exterior Insulation and Finish System by that much. You will still be virtually  eliminating thermal bridging but for my buck I want to keep my r-value as high as possible. The technical term for what I have been calling ‘foam’ or ‘EPS Foam’ is expanded polystyrene (EPS).

There are places where you would use one inch Styrofoam. Window returns come to mind off the top of my head. Typically, the clearance around the window is much lower than the field wall. Door clearances have the same clearance issues. Also, one inch Styrofoam can be used in decorative trim applications


EIFS minimum requirement for EPS Foam thickness

OMG, I can see ever piece of Foam on the wall

OMG, I can see ever piece of Foam on the wall

If you can see every piece of foam on the wall the applicator has missed a crucial step

The other day a came across an EIFS house that I could see every piece of foam on. I have seen some EIFS applications where in the right sunlight you could see a few pieces of foam, but this was the worst you could literally see every piece of foam. The home owner naturally asked me how this could have happened. Apparently the contractor told him that is just how it looks. I can tell you that, that is not true. There is a few reasons that could have happened and in this case it was probably all of the above. If the foam is not rasped or rasped correctly you will be able to see the foam pieces after the job is done. Also, the adhesive used to adhere the foam to the wall can get in between the pieces, and cause gaps. The gaps will dry at a different rate due to moisture and heat flow, and that will cause them to be seen. I have purchased foam that was not all exactly the same thickness, which if not rasped down will cause the pieces to be seen, but this is very rare I have only seen this a couple times in my 23 years in the industry.

In the case I just seen I am sure they did not rasp the foam at all, and when sticking the foam they did not make sure the pieces where applied tightly together, which caused the finished product to look like that. To fix the wall it now needs to coated with two layers of base coat. The first layer to fill in all the seams to even them out. The second layer is a complete coat over the entire wall to blend everything together. This process to repair the wall takes a highly skilled plasterer. Short of that you would have to re-stick the entire wall, essentially redoing the wall over the existing EIFS.

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OMG, I can see ever piece of Foam on the wall