Tag Archives: EIFS tape

Synthetic Stucco – Why Weeping Holes Are Important

Posted by Admin on September 5, 2011 None comments

Synthetic Stucco (actually known as EIFS) is a popular cladding among both commercial buildings and residential homes in Northern climates because of it’s superior ability to insulate a wall and manage moisture. The moisture management comes primarily from 2 important components of EIFS:

  1. The weather barrier (typically trowel-applied) that acts as a back-up defense against any incidental moisture that gets past the outer barrier
  2. The drainage cavity created by geometrically defined insulation (read: insulation with grooves in the back) and strategically placed adhesive

There are a number of important details that need to be paid attention to, to ensure the system performs optimally. It’s important to note that the drainage system will work even if the details are screwed up to some degree, just not optimally. What we’ll focus on here is the weeping holes though.

Stucco Weeping Holes

Stucco Weeping Holes on a commercial building

Weeping holes are simply gaps in the caulking that is installed at the base of an EIFS wall. The EIFS can terminate 8″ above grade (per building code requirements), above another material (such as brick or stone) or at the joint between floors. EIFS should be terminated with a flashing that is tied into the weather barrier with the use of an EIFS tape, so that water is diverted away from the wall, out onto the exterior surface. Caulking is then installed between the flashing and the EIFS termination (the underside of the EIFS), with weeping holes every 24″ (or per manufacturer specifications).

The caulking prevents excessive wind-driven rain, and/or insects from entering into the EIF system from the bottom. The weeping holes provide adequate area for air flow and drainage of incidental water, while being small enough to act as a deterrent to insects. There’s actually a study floating around somewhere that concludes that the ventilation within an EIFS wall is enough to create an inhospitable environment for bugs to nest.

The lack of weeping holes when caulking is present is strangely common – whether by fault of the EIFS contractor being improperly trained (or maliciously lazy – is that an oxymoron?), a site supervisor lacking the knowledge, or inadequate inspection from the manufacturer. An EIFS wall without adequate drainage from the bottom may suffer from:

  • Precipitate buildup at the caulking
  • Inadequate air-flow for ventilation

Both of which will generally shorten the life of the EIFS wall itself. Will a general contractor who is on the job to ‘get it done and move onto the next’ care? Not likely. The EIFS wall probably won’t fail within the GC’s liability/warranty period, and they probably have backlash against the installer or supplier of the EIFS system regardless. It’s more about ensuring that EIFS countinue to be seen as a reliable, effective cladding for the sake of the future of the industry.

Oh, and the person who ends up owning or using the building. They’re important too.

Additional Components of the Weather Barrier

Posted by JamesCarnegie on November 5, 2008 None comments

An EIFS weather barrier is the same as putting building paper around your house, isn’t it? You can just slap it on and you’re safe, right? Yes… and no. Yes, it is a weather barrier which will keep moisture away from your substrate. No, it’s not the only component of a well constructed weather barrier. EIFS has gone through the fire of criticism and condemnation, and come out the other side stronger than any other cladding. It has undergone so much research and testing that it is now correcting faulty building methods in all other sidings as well as professionals’ understanding of their homes. A full weather barrier incorporates not only the weather barrier itself, but also caulking, flashing and window-tie ins in their respective location to keep water at bay.

Around any penetration in EIFS which may move (eg. hose bib, wiring, electrical meters) or openings which may expand and contract at different rates (eg. windows and doors) you will need caulking and a backer rod. Dissimilar materials expand and contract at different rates, causing rigid materials between them (such as a basecoat) to crack and leak water inside. Low-modulus caulking will expand and contract significantly before tearing, making it an ideal material for these gaps. However, caulking will only properly move when adhered to only 2 surfaces, therefore a closed-cell backer rod is required between the gap to provide a third surface, to which the caulking will not stick. It is recommended to caulk between the EIFS and other surface before applying the finish coat, as the caulking will not properly  stick to finish coat.

Low Modulus Sealant Adhered to 2 Surfaces and Backer Rod

Low Modulus Sealant Adhered to 2 Surfaces and Backer Rod

Look around at homes in your neighbourhood next time you’re out — how many windows have flashing over them? Water running behind claddings, then into the window frame is one of the most common causes of moisture problems in homes. Installing “kick out” flashing over a window will “kick out” any intruding water before it enters the window frame, preventing it from traveling any further down the substrate. Flashing needs to be installed starting behind the weather barrier, extending beyond the window frame, with a minimum 3/8″ drip edge (+ return) and sealant on the underside. It’s a good idea to get a color close to your stucco wall or trim (you likely won’t match it exactly) to blend in and minimize any aesthetic disturbance.

An additional step recommended by EIFS manufacturers (though rarely installed by applicators without proding) is window tie-ins using EIFS tape. EIFS tape covers from the outside weather barrier, across the window opening/framing and into the interior to completely seal the substrate, window frame and interior drywall from water intrusion. It is usually supplied as a peel-and-stick membrane (like duct tape), minimizing the time it takes to install and lower the chances of improperly installing it. It is worth asking who will do this as it is not normally within a stucco contractor’s scope of work.

Traditionally, it was uncommon to see flashing and window tie-ins on homes, and caulking (and the previous two) were never done by the EIFS applicator. More and more however, the burden is being placed on stucco applicators to completely seal the wall. Nobody likes asking for their cheque, then being told they’re expected to do more work that wasn’t included in their original scope and pricing. It’s perfectly reasonable to expect the applicators to take care of this step as part of their work — as long as it is clarified in advance so that they can include it in their price.