Designing a Rainscreen System: Special Considerations

In this three-part series we’ll be covering everything you need to know about rain screen systems, including what they are, why they’re important, and why composite cladding is a better choice than wood as the outermost rain screen component.

For part 2, we spoke with Bill Ross, Director, Strategic Partners at Fiberon and resident cladding expert, to determine specific considerations when designing a rain screen system.

Missed part 1? Check it out to learn the basics of rain screens and moisture management.

Moisture management: the MOST important consideration

There are two types of moisture that can affect the building envelope: vapor exfiltration from the inside and water infiltration from the outside. Effective management of this moisture is essential for maintaining the integrity of the building materials, and thus, the building envelope itself. Rain screen systems (also known as Rear-Ventilated Façade Systems) are the solution. The trick, of course, is ensuring that appropriate materials are specified and best practices for material installation are followed.


How to choose the ideal cladding material

Cladding is the outermost component of a rain screen system, and there are a number of considerations when it comes to material selection. Many materials can serve well as cladding and each has its strengths and weaknesses.  How do you make the best choice for your project?  Prioritizing material benefits is a good place is to start.

For example, how important are:

  • Design and Layout – What is the look you desire? What do you want it to look like 10 or even 20 years after installation?
  • Installation and Costs – Are you looking for a product with simple, straightforward installation that can be done by installers with common tradecraft at reasonable costs? Or are you budgeting for a highly engineered system requiring trained technicians and specialized installers? Is upfront price to purchase more important than higher, longer term cost of ownership?  Many products can double or triple in price over their lifetime due to maintenance requirements.
  • Eco-friendliness – Some options contain recycled material, while others use products that are particularly unfriendly to the environment. Some products promote their greenness, but their routine upkeep requires regular application of high volumes of toxic chemicals, which can eventually migrate out of the product and into the environment.
  • Safety, Testing, and Code Compliance – Some products are safer than others. Testing by third-party agencies to ensure regulatory compliance will provide confidence that the manufacturer’s claims are objectively verified.
  • Maintenance and Warranty– What is warranted? When does the warranty expire? Or, if a warranty isn’t offered, is that a deal breaker?
Design and layout

Cladding

Cladding is the first line of defense against water infiltration.  It is also likely the only part you will ever see, so your choices are important on a number of levels.

Board orientation is something to consider.  Fiberon composite cladding is versatile and can be installed horizontally, vertically, or diagonally.  This is not true of all manufactured sidings. One popular siding manufacturer is designed specifically to be installed parallel to the framing.

Aesthetics also come into play when deciding on specific design features. For the same natural, random color variations seen in hardwoods, without the maintenance that comes with them, composite cladding can be a great choice. The amount of variance you want depends on personal preference and the product line you choose.  Some products will make more of a statement, like Fiberon Horizon composite cladding, which is multi-chromatic with bold graining and a lot of variation.  Conversely, our Symmetry cladding is subtly realistic with muted color variation and realistic embossing.  Numerous color options exist across the market, and some buyers do opt to mix and match colors for dramatic effect.

Especially when mixing two different colors, we recommend laying out boards in advance to see what the finished pattern will look like and make adjustments to achieve just the look you want.

Furring

Where you will place the furring materials behind the cladding will also make a difference in the finished installation.  Because the fasteners that attach the cladding are, in turn, attached to the underlying furring, where you locate the furring will determine where fasteners are placed on the face of the cladding. A little bit of advance planning will result in the optimal appearance of your long-lasting rain screen system.

Fasteners

If they are bright stainless steel, fasteners can be an architectural element. Or, if color matched, merely a means of fastening; either highly visible or nearly invisible. Either way, fasteners can be just a functional necessity or a consideration that affects the look of the final project and allows for a personalized aesthetic.


Choosing an alternative cladding orientation, like these vertical composite cladding boards, can add a striking visual element to your structure. Shown here: Horizon composite cladding in Ipe
Installation and Costs

Installation of cladding can be very straightforward and accomplished by reasonably experienced professionals or advanced DIYers, as is the case when choosing wood or Fiberon composite cladding. No special crews are required and it’s not a multi-step process, saving time and labor costs.

With other materials like fiber cement and metal cladding, installation can be somewhat to very technical.  The degree of difficulty and specialization will affect cost but, when done well, has little to no effect on project longevity.

Eco-friendliness

A lot of building products promote their greenness.  Some are environmentally inoffensive when manufactured, but their routine upkeep requires regular application of high volumes of toxic chemicals which can eventually seep from the product into the environment.  Do you ever wonder where all that stain and sealer went that you applied a few years ago?

Safety, Testing and Code Compliance

Product safety varies widely, and safety can be a concern for different reasons.  Here are a few examples:

  • During the installation process, fiber-cement products can release particulates that have been associated with pulmonary problems. Special care and gear are needed when working with these materials.
  • Wood and foam-insulated panels are not fire rated.
  • Areas prone to hurricanes or typhoons often require materials rated for high-velocity winds. Not all cladding materials have such designations.
  • Code Compliance is another important factor to consider when choosing materials as it may affect the ability to get building permits or meeting local zoning requirements.
  • Due to specific molecular structure, some materials are better to cut and work with to eliminate fine particulate contamination, including Fiberon composite cladding.
  • Third party testing is something that designers and building owners should also consider. Not all products go through the expense to provide customers with these third-party verifications of claims.  Flame Spread Index (FSI) will be important for many applications, especially residential.
Maintenance and Warranty

Maintenance is a reality for all cladding options. The difference is the frequency, cost, and difficulty of the maintenance required.  The more maintenance required, and the frequency of that maintenance, the more the ownership costs increase. The cost of re-painting or restaining, for example, is a big part of the equation.

Warranty performance over time is another consideration.  How long will it last?  Will it rot?  Is it affected by fungal growth?  Can it be damaged by termites or carpenter ants? Is the color warranted against fade?

Considering composite cladding? Check out our Composite Cladding FAQS, and stay tuned for the third and final part of our cladding series where we’ll be comparing a number of composite cladding material options.

Comments
Close