Mixing traditional siding with some other alternative cladding—manufactured brick, stone veneer, or horizontal siding—is a popular way to add character to home exteriors. But unless builders are careful, this accent can quickly become an eyesore that leads to costly remediation and liability issues.

That’s because too many builders don’t properly flash the transition between sidings and sometimes even stop their water management entirely where the alternative cladding begins. Since some alternative cladding, such as manufactured stone, is already prone to water absorption, this lack of moisture protection creates a haven for mold and other water intrusion problems.

Here are four of the most common water barrier mistakes builders make when transitioning between traditional and alternative claddings.

  1. Poor flashing details at the edge of windows. Typical vinyl windows require an insert that’s available from manufacturers that fills the J-channel. Backer rod and sealant should be installed between the window insert and the cladding. Using a vinyl casing bead rather than backer rod is an even more foolproof way to create a proper sealant channel.
  2. Failure to use through-wall flashing above the alternative cladding. To create proper through-wall flashing, the wall needs a continuous drainage plane behind the traditional siding that’s allowed to drain out of the wall via a through-wall flashing above the alternative cladding. For a more refined look use a fabricated metal coated steel or aluminum flashing that blends with the cladding. Remember to extend the water resistant barrier at least 6” above the transition point of the flashing and provide blocking if necessary.
  3. Inadequate water resistant barrier behind the alternative cladding. Alternative cladding may need more careful water management than traditional vinyl siding. Use a rainscreen mat over the housewrap, or at least one to two layers of black paper over the housewrap as required by code. Another option is using a woven polypropylene flashing that’s mechanically fastened with staples or cap nails. These are designed to be easily integrated with existing weather resistant barriers.
  4. Lack of a foundation wall base. For proper moisture management, the wrap and rainscreen should lap over the foundation sill and terminate at the bottom of the wall at a weep screed that’s positioned at least 4 inches above grade.

For more on cladding transitions and water resistive barrier options, go to http://www.tamlyn.com.