I Find It Inspection - What is a rainscreen building in Vancouver

   Homes across Vancouver and the Fraser Valley are exposed to wet conditions almost all year round which can cause many problems without proper rainscreening.  When buildings have tall walls, such as condominiums, they are at a greater risk of experiencing problems which is why Vancouver has a 'leaky condo' issue.  To prevent these issues, exterior siding on buildings must be properly 'rainscreened' or 'face sealed'.  Though both of these methods are effective, their upkeep needs and costs are much different.

Rainscreen Systems

A rainscreen system is made up of three protective layers:

-A water resistant liner installed on the  outside of the home's sheeting

-An air gap

-A tough exterior surface which combats mechanical damage and offers primary water control

    The most simple part of these layers, the air gap, is surprisingly the real science behind how a rainscreen works.  Vancouver not only experiences rain, but the wind that comes with it.  When this wind pushes against the outside of a building, the lower pressure found inside that building will want to 'suck' exterior water in.  When there is a proper air gap in a rainscreen system, it will act as a neutral pressure gap between the exterior and interior of the home.  Water that does manage to enter the gap due to wind will lose its momentum, fall to the bottom, and safely leave the building without causing damage.  The gap in the rainscreen also encourages circulation which aids in keeping building materials dry.

    'Z' flashing is often found in taller raincreened buildings such as condominiums.  'Z' flashing creates separate water control 'zones' by separating each story of the exterior.  By creating these 'zones', water flow is diverted into different areas rather than all the accumulated water flowing to the bottom of the building.  When one section of this type of rainscreen system fails, only that one section is compromised which reduces any repair costs. Materials that are commonly used in a rainscreen system include:

-Veneer Brick or Masonry

-Fiber Cement Boards (Hardie Board)

-Some installations of EIFS and Stucco

Face Sealed Systems

    A Face Sealed Exterior system put simply is a building with siding that is water tight and sealed top to bottom.  Face sealed systems should have no joints that water may be able to penetrate.  Ifany water does manage to enter the building, it can cause very serious and expensive damage that is hidden and can easily go unnoticed.  Unlike a rainscreen system, a face sealed system does not have an air gap to manage any moisture that may enter.  Because of this, any failure in a sealed system will cause rot and mold which will compromise the structure of the building.

    Face sealing a tall building like a condominium can present many challenges.  The large amount of doors, windows, balconies, vent holes and other protrusions make properly face sealing extremely difficult.  To prevent further 'leaky condo' problems, face sealed buildings must be diligently maintained with painting, caulking and weather proofing.

Materials that are commonly used in a Face Sealed system include:

-Concrete or Masonry 'Mass' Walls

-Traditional Stucco

-Exterior Insulated Finish System(EIFS)

Vented Cladding

   Though Vented Cladding is not necessarily a rainscreen system, it can offer some 'rainscreen like' benefits.  Products used in vented cladding such as vinyl have a built in air gap when installed.  This air gap lies behind the face of the vented material which allows for drainage and circulation.  Because of the inherent 'rainscreen like' qualities, vented cladding can perform similarly to a proper rainscreen system and be used as an acceptable alternative.  

Materials that are commonly used as Vented Cladding:

-Vinyl Siding

-Lapped Wood

-Shingles

Is your building Rainscreened?

    To spot if a building is properly rainscreened, you must be able to identify building materials and how they were installed.  A proper home inspection will tell you if you are going to have any problems due to improper rainscreening.  A few things a home inspector may look for include the following:

-Proper drainage holes at the base of a brick veneer as well as under the roof overhang or flashing

-Cement board is nailed in only a horizontal direction on vertical wood strips to create a proper air gap

-Flashing at the top and bottom of Stucco to create ventilation for the air gap

-Buildings over two stories have uniform horizontal lines separating each story into their own 'zones'

    A proper home inspection will identify if a building is rainscreened or face sealed, and also caution a buyer of  the diligent maintenance required of a face sealed building to prevent water damage.  A home inspector will also make sure proper materials were used and installed professionally, as well as inform a buyer of any upcoming repairs that will be needed.  In wet climates such as Vancouver's, buyers should be encouraged to purchase a home that has been built with rainscreening methods over one that has employed face screening methods.

To Conclude

   A building's rainscreen is extremely important in areas in and around Vancouver such as Surrey.  A diligent home inspection will provide you with useful information on a building's rainscreen system and could save you a great deal of money not only on the biggest purchase of your life, but also possible repair and maintenance costs further down the road.  Don't find yourself trapped in a 'leaky condo'.  Always have a home inspection completed before buying a house, townhome, or condo!