Quality Built, LLC - Tech Alert May 2016

By: Frank Yellico - Field Consultant, Level 4 

Best Practice Flashing Requirements forExterior Doors in Wood-framed Construction

In recent years, there has been a strong emphasis made in order to improve thequality of flashing around windows and doors in residential and commercialconstruction.  When it comes to some wood-framed exterior door installations, thereseems to be a double standard in regards to flashing requirements.  For example,some builders/installers have made comments such as:

“We don’t have flashing requirements for exterior doors.”“We don’t flash exterior doors because they are typically protected by a porchroof or roof overhang.”“We provide a metal drip cap flashing over the exterior doors forwaterproofing.”

Some contractors follow up such comments by stating:

“We have a flashing program for window installations that we adhere to in allcases.”

Although it is great that many builders are recognizing the need to  establish a

to realize, is that exterior doors posses a larger potential moisture intrusion area thanthe average window, and therefore, the presence of an exterior door flashingprogram is just as essential.

An abundance of issues with exterior doors have been observed in the field, whichhas proven that several builders have disregarded following an exterior door flashingprogram. In order to illustrate the importance of this, the following stand out as somesignificant examples:

Imagine a builder who does not flash a home’s front door entrance  assumingthat   that a  porch/roof overhang is sufficient enough  protection.   When the samebuilder installs a garage service door, the service door is not flashed other than witha typical secondary metal drip cap flashing, since this is the practice that has beenmimicked from the front door installation. The problem here, is that a garage servicedoor often has great exposure to moisture intrusion, since it generally has minimaloverhead roof protection.   Another example of where significant exposure tomoisture intrusion can be found, is at the exterior door of a multi-unit condominiumbuilding.   Often, the building plan lays out so that many of the doors arewell-protected, while other doors go unprotected.  Therefore, the tendency is not toflash the doors with anything other than a drip cap at the head.

Exhibit 1 shows a double standard when comparing an exterior door installation to awindow installation, where the door and window are installed in a protected area ofthe home’s exterior. As observed, the window is fully flashed, while the exterior doordoes not show any flashing. Please note that the weather barrier does not count asflashing, and because there is no flashing below the threshold of this door, a metaldrip cap will be installed above the door during siding installation.  

Additionally, the exterior door’s perimeter (where there is potential for leakage notrelated to flashing) is over twice that of the fully flashed window. This builder uses thesame exterior door installation technique on garage service doors, which are in an

EXHIBIT 1

service door in Exhibit 2.    

EXHIBIT 2

The weather resistive barrier in Exhibit 3 has not been properly extended over thehead flashing strip. 

EXHIBIT 3

Exhibit 4 shows an exterior door in a covered patio area that is not properly flashed. An edge of this doorway is only 12 inches from wind-driven precipitation.     Thispresents a problem because storm moisture can easily reach this improperly flasheddoorway jamb and threshold.

Quality Built recommends that builders and trade contractors adopt a consistent bestpractice program for the installation of exterior doors, and related items thatpenetrate the building envelope.  Consistently installing flashing in a best practicemethod on exterior doors will prevent an exterior door in a less protected locationfrom creating a water intrusion problem.  Exterior doors that are installed in more

EXHIBIT 4

occasional water intrusion, but minimize air infiltration and insect infiltration into thebuilding.  A third-party quality assurance program can help to verify the consistentinstallation of flashings, as required to create a complete weather-resistive buildingenvelope.

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A best practice flashing program should be adopted by all builders and trade contractors for the installation of exterior doors and all other items that penetrate the building envelope. This program should include mandatory flashing requirements for doors with pre-installed brick molding, or other pre-installed trim.  Typical AAMA, ASTM, NWWDA, WDMA, and manufacturer’s best practice flashing requirements should be met by this program. The steps for providing the best practice method of flashing installation at exterior doors will vary depending on the type of interface between the door and the flashing.  Many exterior doors do not have nailing flanges like windows, but instead have a brick mold or other trim that creates the transition to the flashing.  Quality Built's recommendation is that the following installation steps be followed:

1.

2.

3.

4.

5.

Install self-adhered, membrane flashing below the door threshold.  Installationof a sill pan below the door threshold is recommended. Jamb flashing should be installed on each side of the doorway.  A self-adheredmembrane flashing should be used.  The jamb flashing should extend over thethreshold flashing and extend a 6-inch minimum above the top of the doorwayopening on each side. The door should then be installed with compatible caulking below the doorthreshold, and continuously around the back of the brick molding or trim.  Appropriate manufacturer’s recommendations for door alignment andanchoring should be followed during installation. Angled metal drip cap flashing material extending over the door head trim andreturning at the ends should than be installed.A self-adhered head flashing strip should be installed across the top of thedoorway and over the drip cap vertical leg.   The head flashing strip shouldextend a 6-inch minimum over the top of the side jamb flashing material. The weather-resistive barrier (WRB) material should be installed over the topof the door head flashing material.

6.

Weather barrier material may be installed over the top of the doorway jamb flashingmaterial or below the doorway jamb flashing material, depending on the installationsequence. If a weather barrier is installed prior to the head flashing being installed,then the WRB should be cut back at 45 degree angles in each upper corner of thedoorway to allow the self-adhered membrane, and metal drip cap at the head of thedoor to be installed.  When the door head flashing has been installed, the WRB maybe pulled down over the flashing.  The seams in the WRB should then be taped witha tape that has been approved by the WRB manufacturer.    

Best practice exterior door installation procedures are provided in the

door installation, which include self-adhered flashing that can be installed directly onthe door frame/trim prior to the installation of the door in the wood-framedstructure.  A flashing product of this type is manufactured by Dupont™. 

Information on this Dupont™ flashingproduct (Dupont™ StraightFlash VF)can be obtained by clicking on the linkprovided below: http://www.dupont.com/products-and-services/construction-materials/building-envelope-systems/brands/flashing-products/products/straightflash-vf.html

Best practice installation methods forexterior doors manufactured byTherma-Tru™ Doors are provided byclicking on the link provided below:http://www.thermatru.com/customer-support/installation-instructions/index.asp

An exterior door installation, utilizing best practice recommendations is shown inExhibit 5. Please note that the weather barrier has been properly integrated over theself-adhered head flashing strip, and a sill pan has been installed below the doorthreshold. Compatible caulking has also been installed behind the door brick moldingabove and below the sill pan.

EXHIBIT 5

Consultant at Quality Built.

Frank  is  a  degreed  civil  engineer  with  over20  years’  experience  in  residen7al  landdevelopment  and  homebuilding.    Hisengineering  experience  includes  design,construc7on  inspec7on  and  construc7onmanagement.    Frank  establishes  a  rapportwith  his  clients  and  is  successful  incomple7ng  projects  on  7me  and  onbudget.    He  has  previously  operated  aprofitable  residen7al  building  corpora7onfor  over  15  years  and  has  received  over  20awards  for  excellence  in  building  andmarke7ng.

You can reach Frank at:fyellico@qualitybuilt.com

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Quality Built is committed to being a visionary leader in the insurance, financial andconstruction industry by providing reliable and innovative Third-party Quality AssuranceServices to our clients in the most professional and efficient manner utilizing cutting-edgetechnology, proprietary software and employees who maintain the highest level of integrityand expertise.

Contact Quality Built, LLC today at (800) 547-5125 or email: sales@qualitybuilt.com

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