The Rainscreen System

Rainscreen façade systems work by pulling the exterior cladding of a building (the “first line of defense”) away from the rest of the wall assembly, creating an open air space between the two that allows for water drainage and ventilation. Any number of durable materials can be used for this type of exterior cladding, including ceramic tiles, fiber-cement panels, composite boards, and weather resistant exterior woods. Cladding is installed with small gaps between the individual panels, allowing the system to ‘breathe,’ and minimizing the capillary forces that would typically pull or wick water toward the building’s interior. Any water that does make its way through this open-jointed exterior cladding, due to wind or gravity, will either evaporate in the ventilated air space, or run as droplets down the back of the cladding and away from the building. The building’s interior and insulation are protected from this moisture by a water resistant air barrier.

This layered approach to wall construction eliminates many of the problems associated with water damage, wall cavity condensation, and mold. It can also improve the performance of the building and the comfort of its occupants by dissipating radiant heat in the ventilated air space, limiting thermal bridging, improving the wall’s insular properties and minimizing temperature fluctuation. From a design perspective the system also adds a great deal of visual interest to the façade, creating dramatic open reveals and shadow lines.

For information on rainscreen technology:

Rainscreen Cladding (wiki)
Rain Screen Designs for Absorptive Claddings (National Association of Home Builders)
Rain Screens Eliminate Moisture, Improve Efficiency (Ecohome Magazine)
NBS Building Regulations

The drawings above map out the approach that we’ve taken to rainscreen design on the front façade of the Carpenter St. project.  Our wall construction includes high density fiber-cement rainscreen panels, a self-adhering, vapor permeable building wrap by Henry, called Blueskin, and Henry Permax closed-cell spray foam insulation (installed by Northend Barriers).  Thanks to Peter Taylor at PPSI, LLC (Preserving and Protecting Structures’ Integrity) our building envelope consultant, for his help throughout the design process.

Check out the links below for information on any of the products that make up our wall assembly:

USG (US Gypsum) – recycled content from a local plant

Henry (Permax Insulation)

FSC (Forest Stewardship Council) – third-party certification

CBF (Cement Board Fabricators)

Henry (Blueskin building wrap)

Northend Barriers (insulation installers)

All in all it’s going pretty smooth but is taking longer than we thought. You have to be very patient when cutting and pre-drilling the panels, taking time to measure and re-measure, along with being careful not to damage the panels before they go up.  They are very durable after they are installed but need to be handled with care prior. The panels are not cheap, running about $350 a panel (or $8/sf) and take a few weeks to get, so do not want to make any mistakes.  As you can see the client chose an “Olive Green” color which is a nice accent against the slate-gray colored windows and the mill-finish metal panels. Regarding the fasteners, they are ‘star head’ Stainless Steel screws and you have a choice of either a clear Stainless Steel or a color-matched fastener. I ordered a few of either kind and put them both up for the mock-up. In the end we chose the stainless, which looks great with the metal panels.

The fiber cement panels come in 4′x8′ and 4′x10′ sheets. We actually had the factory rip the panels down to the size we needed, which is 3′x6′. The reason we went with this size is two-fold: one, the 3×6 proportion worked well with the overall scale of the facade. 4×8 seemed too big but 2×4 was too small (or ‘busy’). The other reason was maximizing the waste factor.  By cutting the panels down to this size we are actually able to cover the facade using a fewer number of panels than if we went with 4×8.  This is mostly due to how the 2-story bay affects the panel layout. As an aside…I recommend that, if you are looking to use these panels on a project, you do NOT have the factory cut the panels down. Ironically, the edges cut by the factory are actually not as clean as the edges we cut on-site with our circular saw (with a new diamond blade).

We are using a 1/2″ thick x 3″wide composite material for the trim around the entire perimeter of the window. This strip will be placed perpendicular to the facade and create a sharp ‘frame’ around the window, leaving a 1/4″ reveal but covering the cut edges of the fiber-cement panels.

We will also be installing an wood rainscreen section (using IPE, or Brazil Walnut) at the interior portion of the metal bay. This work will begin next week.

One of the advantages  of not working in a traditional office environment is that you get to use scrap plywood & nails instead of post-it notes…

SBN’s annual member directory is a great resource for discovering local business owners that are committed to Philadelphia and to preserving our city’s future. Connect with local merchants that value personal relationships, invest their resources back into our communities & neighborhoods, and seek out ways to minimize their own   environmental footprint. Whether you’re looking for fair-trade coffee, an accountant, massage therapy, or a custom-made table, make the SBN directory your first stop. An online listing of SBN members is also available- search by company name or service type.

Shameless plug…

SOLIBS is listed under Shelter–> Architects,  Contractors, and Building Supplies on pg.80.

Bench Dog Design, is included under Retail –> Furniture/Housewares on pg. 69.

Contact us at info@southernliberties.com if you’d like your own (free) copy of the SBN directory. Get in touch with Ben Kincaid, Membership Coordinator at SBN if you’d like to distribute copies of the directory in your own neighborhood.

Learn more about the Sustainable Business Network of Greater Philadelphia and the Buy Local Philly campaign.

August- September 2009: deconstruction of existing (poorly rebuilt) facade, new framing begins

October-November 2009: Third floor framing begins and plywood sheathing is completed

Another great product from Cincopa Send Large Files. Also read how to Add video to your website.

Montrose Green is an award-winning,  innovative green rowhouse renovation in the Graduate Hospital neighborhood of Philadelphia, just south of Center City.  The  3 story house is approximately 1800 SF with 3 bedrooms, 2.5 baths, and a study.  It features a 15′x10′ private rear yard and green roof with skyline views.  The house has a spacious, open floor plan with a gourmet kitchen, bar, and ample natural light from 3 sides. Custom millwork, reclaimed wood paneling, and an open riser steel stair are just a few of the innovative features that make this house stand out from the crowd.  Eco-friendly materials  and both energy and water saving features are integrated throughout the home. Utility bills are expected to be 30-50% less than a conventional home.  Full unfinished basement for storage or future expansion.  Landscape features include a stormwater planter with native plants & grasses along the front, as well as a stainless steel rain barrel, trellis system, and planter at the rear. The house is registered Platinum with the USGBC’s LEED for Homes program.  Certification is pending, summer 2010.  Architectural design & construction management by SOLIBS, LLC.  Custom furniture & woodwork by Bench Dog Design.

To learn more about this project, please visit the Montrose Green blog which documents the demolition, construction, and design process from start to finish.

Rendering of Front Elevation

To learn more about the proposed design, click here.

Please contact us at info[at]solibs.com  if you’re interested in discussing an upcoming project or collaboration.