What is the best exterior covering for Structural Insulated Panels?

Asked By: scangigi on Thursday, April 30, 2009
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Answer The home is being built in Lake Havasu, AZ. We used SIPs for the roof, walls and a roof top deck floor. The panels are OSB exteriors with a ESP core. In regards to choosing a covering for the SIPs in my homesite area, what should I be most concern with ... water proofing, mold resistant/prevention, moisture rot, and/or other? We choose a Coolerado (100% fresh, filtered, cooled air added humidity)coolng system and a traditional furnance heating system. I'd like a product that is maintenance free, promotes minimal surface flaws(bubbling, cracking, peeling), and color is mixed in. I'd appreciate your direction. Thanks. Gigi

Thanks for your question Gigi. One of the best things about using Structural Insulated Panels is that they will accept most any type of siding. There are a few things to take into consideration. First of all you would want to make sure that the exterior wall covering you install on the house fits in with other homes in your development. Since you can use, vinyl, aluminum, stucco, stone and most other types of wall coverings, this should not be a problem.

SIP Cross Section

From an energy standpoint, because Structural Insulated Panels are virtually air penetration proof, you would not have to worry too much about the insulation value or air penetration properties of the wall coverings you install. However, you still want to make sure that any siding you have installed is installed in accordance with the manufactures specs and according to your local building codes.

Having said that, because you live in a very warm climate, it would be best to install an exterior wall covering that help keep the house cool and not be subject to warping or any other problems that could occur from moisture or the constant amount of sun light in your area.

As far as mold or other moisture issues, you might need to be concerned about using vinyl siding. Unlike wood and masonry, vinyl siding presents its own breed of maintenance worries. Moisture trapped beneath the vinyl siding will accelerate rot, promote mold and mildew, and invite insect infestations. To avoid hidden decay, you will want frequently re-caulk joints between the vinyl siding and adjacent trim. 

From a cost standpoint, vinyl siding has a definite advantage over most other choices, so if you do decide to go with this type of siding, make sure you have your contractor takes all the necessary precautions to help avoid moisture problems. Vinyl siding can also withstand years of sunlight without fading but I have seen some warping issues if not installed correctly.

Brick is nice, but because is is porous, it can absorb moisture. There could be problems with brick veneer when it comes to moisture problems and here is the reason why. When it rains, water can be absorbed into the brick veneer. Water vapor can then penetrate through the exterior sheathing into the exterior wall cavities by a process called vapor diffusion. This water vapor condenses on the cavity side of the interior polyethylene vapor barrier. When sufficient moisture condenses on the surface of the polyethylene vapor barrier, it is possible to run down the surface of the polyethylene under the action of gravity where it can accumulate on the bottom plate of the wall. If enough water accumulates at the bottom plate, mold growth can occur with the possibility of causing wood rot.

Having said that, the Structural Insulated Panels should be less prone to having this occur then with standard stick construction.

Stucco also can have some problems when it come to moisture. The insudstry estimates that about 80% to 90% of stucco homes, will have some degree of moisture issues. This includes sythetic stucco that installed over foam and hardcoat stucco as well. The problem is caused by moisture that can get trapped behind the stucco walls and if left untreated, can cause damge similar to that mentioned above with vinyl siding.

Natural or Veneer Stone, Cement Board Siding would be great choices in your area. Whether you choose natural stone siding, stone veneer, or simulated stone veneer, these products are water resistant, aren't phased by impacts, are impervious to insects, and you can expect them to last for decades, if not lifetimes, depending on the product you choose.

So, based on all your concerns, I think stone products or cement board siding, would be your best choice. However, the cost of any of these choices will be considerably higher then vinyl siding. 

Keep in mind that all of these types of exterior wall coverings can work nicely for many homes in various locations with different types of climate conditions. I have installed many of these on homes in my area without problems. Preparation and proper installation as well as taking all the necessary precautions with any type of exterior wall covering, can help it to be problem free, and last for many years.

For amore detailed information about Structural Insulated Panels click on the following link. SIPs

I hope this helps. Rick

Rick Maselli is Founder and Editor of Showroom411.com


User Comments

Rick, Thanks for your reply. In my research I came across a flexible waterproof modified cement coating product by Grailcoat (www.grailcoat.com). In regards to it fitting my project's concerns(noted in my 1st post)... 1. What comments might you have about the product material? 2. What additional suggestions would you add in the area of the product's application instructions. My sincere appreciation, Gigi
Commented by scangigi - 5/1/2009
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