Roof Problems Leading to Siding Rot Part II

Earlier this week, we looked at a modified bitumen membrane which had a a cementitious siding facade at the exterior of the building below, which was being damaged by problems that traced all the way back and all the way up to the main low slope flat roof.  Today, we take a look at the damage caused to that siding, from the missing flashing at the top of the wall.

Although this particular roof system happens to be modified bitumen, the exact same principles, in this area of flashings, apply to other types of roofs such as TPO. EPDM and other synthetic, polymer, or thermoset membranes.

Here, in the next picture, you can see the lower portion of the exterior side of the wall, where it has been exposed to excessive hydration for an extended time. The wall has had water run all the way down behind the between sanwhiched portions of the siding and the vapor barrier all the way to the base of the wall.

lower portion of exterior side

In addition to this critical problem of the missing flashing cover at the parapet, there’s another nuisance type problem that is also closely related. The original developer and low quality contractors install a wood trim board at the exterior side of the building facade. Unfortunately to save money, this type of cheap alternative is commonly used in Washington DC areas where houses are being flipped, especially at the rear additions the Washington DC row homes.

missing flashing cover

This type of wood happens to rot very quickly because of it is a fast growth softwood joined with fingerjoints at the linear run.  There are 7 different types of alternative materials that can be used for installation of trimbors at cemetery fold, one of the best types to be used is a 70. She’s trimboring. This particular type of materi. It’s very expensive and very heavy to work with, but it’s comparable to the citing itself and has one of the longest longevities and durabilities.

installation of trimborns

If you look close at the pictures that you can see then the material types selected is not the only problem, this work was also installed with very low quality workmanship.  Here, instead of using a scarf joint in a launch tutorial run of trim boards, they just used a square. But joint to join the board edges. That’s not correct.

sqaure joint

Signs of the poor workmanship are evident throughout the building exterior shell, not just at the siding.  At the roof itself, for example, several installation defects are evident from one close up picture alone:

  1. The new modified bitumen membrane was installed at least 3 months before completion of the renovation, so a coating should have been applied. This is apparent just from deduction, in a basic understanding of the assembly and the steps needed in the overall renovation.  It would have required more time than the minimum window would have excused.
  2. The lack of a protective coating has allowed UV rays to cause cracking and alligatoring in the surface of the membrane.
  3. The termination welds are delaminating which will lead to fishmouthing.

poor workmanship

Upkeep, Care and Maintenance of Washington DC Roofs

This case study is a perfect example of why a professional roofer should be used for all types of roof installation, even things that seem as simple as a balcony.  Consulting with a roofing professional, like Dupont Roofing, familiar with the specific climate conditions and the building science of roofing in Washington DC is advisable to ensure the roof assembly is appropriately designed and constructed to manage the flow of water, ice damming, capillary action and condensation effectively.

The upkeep, maintenance, and general care of flat and mansard roof systems should be driven by an understanding and passion for historical methodologies, waterproofing principles, engineering and building science. Washington DC, a city built with both vintage charm and contemporary modernities, residential and commercial buildings of substantial value. 

The roofs of these buildings are their defensive shield from the harsh elements of nature. To our clients, as well as all readers of this article and our blog, we emphasize the importance of quality construction and active building maintenance.  Our website includes informative resources you can use to understand and learn about best practices on preservation of your building.  If you are in need of further guidance on the roof and its associated systems for your Washington DC property, we are here to assist, where we can. Simply contact us or complete the webform below and drop us a line and we’ll respond if we can help.

On Key

Related Posts

what damages metal roof paint

Terne Metal Roof Paint Deterioration

Terne-coated metal roofs are an element of historic architecture, somewhat common in Capitol Hill and other historic neighborhoods of Washington, DC. However, the terne coating