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Water Trails & Leak Tracing

Learn about the causes of water trails and the leak tracing process

In a previous blog article we discussed the susceptibility of brick and mortar to water damage. This discussion delved into the characteristics of hydration in masonry and the cause and effects of susceptibility in masonry building facades.   Water and moisture can debilitate a building, causing slow but insidious damage to masonry structures.

In the image below you can see a real life example of water damage.  Water leaked into the building from the outside, in this case, through the building facade.  This location is the ground level ceiling of a building in Capitol Hill. Typically when you first see water damage from a ceiling, you might expect that the source is a roof leak. In this case; however, there there are two levels of the building above this level, shown here, so it is likely not a roof leak related issue.   In this particular case water was entering from the masonry header around the window opening.

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In the image below you can see a collage of different types of exterior building facade water leak trails and symptoms associated with prolonged water entry into a building facade.


The image below shows a quintessential example of a water trail. The surface of the paint on the sheet metal architectural trim has degraded from exposure to ultraviolet rays.   This type of paint surface degradation is similar to surfactant leaching and cissing.   The main difference between this type of failure is that surfactant leaching and cissing are most often related to improper surface preparation. Here, over time as water has slowly dissolved the damaged paint, and therein has carried some of that paint away and allowed the paint to become deposited on the face of the brick, in the form of a water trail.

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In the image below you can see the same wall as shown in the photo above, but in this case the up close view shows a void in the prepend joint of the brick mortar at the prepend joint. As water is diverted to a concentrated wash over the masonry at this location, the void in the perpend joint is exposed to a significant amount of insidious water flow.

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Perpend joints are often the first joints to fail. This type of failure happens for two main reasons.

  1. The prepend joint is subject to an increased movement as the ratio of the head versus bed joint sizes are proportionately inverted.
  2. Additionally, the brickheads (the edge facing of a brick in the horizontal position), at the prepend joint or generally applied with less mortar. This is a shortcut that masons often take and can almost get away with, at first.   Some masons (such as IDS) require fully set head joints but many others will take a shortcut and just butter the edge of the brickhead. As you can see in the example above, taking the shortcut can lead to problems later.

The picture below shows a masonry void caused by a fastener installed to mount a security gate.

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When you look closely, into the recess created by fastening hardware of a past gate, now removed, but originally installed, mounted in the brick joint, you can see a deep void.  Voids like this and the alternative deterioration based voids create spots where water can enter.  The problems with voids in mortar, when at places of water runoff, from or outside of controlled diversion pathways, is that water is fast to enter but very slow to dissipate.   In fact, the water will saturate and spread within the masonry assembly.

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In the following image, you can see an example of an escape of liquid or leak from a half-round gutter on a historic brick building in Capitol Hill, DC.  This rear ell area of the building is built with a somewhat ornate wooden fascia board.

The leak, in this case is cause from two interrelated problems:

  1. Pinholes form in the partially deteriorated sheet metal of the gutter, more extensive at areas of water ponding, and
  2. There is a dip or ponding area in heavy precipitation events or when slightly clogged by tree debris.

These two issues compound one another in a viscous cycle.

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At a nearby location in the same building, you can see another area of deterioration.  In this case, the soldered elbow joint is too sharp of an angle for this small diameter downspout pipe.  We recommend downspouts of no less than 3″ diameter when allocated to a roof area over 2 squares per downspout. Also a graduated sweep could be used in lieu of a sharp elbow.

In this case because the pipe is small in diameter and has a sharp elbow which increases the difficulty for debris such as tree leaves, branches, or other types of building materials from flowing through the drain.     Other types of pipe configurations such as a graduated sweep could be used to allow debris and water to flow smoothly without increasing a potential for a clog. Debris running through a pipe, basically work to create a log jam (a backup) in the pipes with tight elbows or fittings.

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In the images above where water is not properly diverted through intended systems such as roof guttering and rain leaders, it leads to other problems. Residualy, at the majority of precipitation events, water will run down the masonry face.  That type of repeating event leads to specific damage at the area of exposure. In this case, the mortar has been overly hydrated and experienced alternating moisture and dry cycles which have led to dissolution of the binder material in the mortar. You can see the evidence of deteriorated joints at the face of the masonry wall. Essentially, the mortar joints are beyond their useful lifespan at this point already, but the acute area of additional water flow has increased deterioration to a more extensive depth in the brick joint and it should be pointed, but the other issue of rain diversion system malfunction should also be addressed and fixed even before brick restoration and brick pointing takes place.

The video below shows a stone masonry wall capped with an aluminum flashing lacking a drip edge bent into the metal.  Without a formed drip edge, the water runs down the face of the stone masonry wall.

The issue in the photo below looks similar but is actually caused by a different problem, nonetheless still related to improper diversion.  In this case the metal flashing was field cut, at the bottom edge without a bent metal drip edge.


As a result, water freely runs down the face of the wall.

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A close up shows an even better view of this issue.

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When you look closely at the photo below, you can see that the granite stone sill has no protruding drip edge and no reglet or raggle cut into the underside of the front stone nosing or leading exterior edge.

In this case the water droplets roll back to the brick wall.  As in the other examples, this causes multiple problems such as increased hydration at the face of the wall which leads to accelerated deterioration of the mortar joints, face spalling during freeze-thaw cycles, efflorescence and binder dissolution at residual hydration cycles.

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The picture below shows at totally different style of sill, yet with a similar condition.   This sill is a rowlock brick course, with water from precipitation forced to run down the face of the brick sill nosing, and then back down the wall of the brick.

An important characteristics of water is that H2O molecules will form a light bond in a capillary action.   This capillary action will allow water to pull itself upwards in defiance of gravity, to some extent, and between tight spaces with openings in membranes between spaces with pressure differentials, water can actually be pulled upwards and in directions that deny gravity.

In the case of the sill in the images both above and below, the water running over the face of the sill drips back to the face of the masonry wall, and then wicks into the masonry joints, causing unnecessary excess hydration.

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The video below shows a stone wall under a horizontal concrete deck slab.  Without a raggle or reglet, the water runs down the face of the stone masonry wall.

The photo below shows the area in the video above, but the photograph below allows a closer view of the details at the mortar joints.  You can see the mildew or lichen plant growth on the mortar joints.  Once plant or complex growth begins on mortar joints, root and anchoring growth further deteriorates mortar joints at increasing rates.

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The brick wall in the picture below is covered with white chalky water trails.  Like the many photos and videos above, this shows another masonry assembly which has not been sufficiently protected from passive water exposure through water diversion.  As water washes down this wall at most precipitation events, water is entering the deteriorated mortar brick joints.  As the water enters and saturates the joints, and therein dissolves binder materials.

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In the image below, you can see the efflorescence caused by dissolution of mortar subcomponents.  In this case the efflorescence occurs under the face of the wall paint.  That paint is actually largely separated and delaminated from the surface of the brick.  Meanwhile the mortar is disintegrating.

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The picture below shows the same wall from a different angle.  The lower area of the wall is wet and darker in color at the bottom 3 to 4 courses of brick as a result of rain splash back, another manner in which masonry building assemblies are affected by rain and precipitation.

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From a conservation and preservation perspective, several approaches can be taken to improve conditions related to deteriorated historic brick masonry. Primarily, lime mortar brick joints and low temperature fired soft red clay bricks should be inspected and checked on a routine maintenance schedule, either seasonally or at least annually.   If brick masonry is kept in good condition, the life of embedded wood elements can be significantly extended.  Hire a professional contractor which specializes, understands and appreciates historic construction elements and buildings.


In this article we talked about the following terminology and  concepts, follow the links below for more related information from the IDS website:

  • Facades
  • Roof keaks
  • Masonry opening headers
  • water trail
  • Sheet metal
  • Ultraviolet rays.
  • Surfactant leaching
  • Cissing.
  • Surface preparation.
  • Bed joints
  • Brickheads
  • Controlled diversion pathways
  • Water dissipation
  • Escape of liquid
  • Half-round gutter
  • Rear ell
  • Escape of liquid
  • Half-round gutter
  • Rear ell
  • Fascia board
  • Pinholes
  • water ponding
  • Tree debris
  • Viscous cycle.
  • Alternating moisture and dry cycles
  • Useful lifespan (Service life)
  • Brick restoration and brick pointing
  • Stone masonry wall
  • Aluminum flashing
  • Drip edge
  • reglet or raggle
  • accelerated deterioration
  • Face spalling
  • Freeze-thaw cycles
  • Efflorescence
  • Binder dissolution
  • Residual hydration cycles
  • Door and window sills
  • Rowlock brick course
  • Capilarry action
  • Pressure differentials
  • Mildew or lichen plant growth
  • Materials delamination
  • Rain splash back

These concepts are part of the fundamentals of historic masonry restoration, tuckpointing, and brick repair.

The links in the list above will take you to other articles with more information on defects, failures, preservation and repair of historic masonry.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the historic masonry of your building in Washington DC, fill out the webform below and drop us a line.  We will be in touch if we can help.