Brick and Mortar Preservation Update from Rosewell!

written by Kenneth Tappan, Preservation Program Coordinator for the Fairfield Foundation

As stabilization efforts continue at Rosewell, we wanted to highlight one of the repairs
from last summer. At the southeast corner of Rosewell, the ruin had extensive damage and
needed attention to prevent further masonry loss. We chose this location as one of our first
repairs because of accessibility and the fact that there would be no archaeology needed while
our staff archaeologists were busy working at other sites all over the Middle Peninsula.

Rosewell’s southeast corner, showing bricks missing before preservation work. Note the vertical slits indicating the joist pockets for the first floor framing.

This section of the ruin had many of the facing bricks missing, which in turn was accelerating
damage to the underfired/salmon bricks which were used on the interior of the walls because of their softness and porosity. The loss of facing bricks in this area exposed the narrow pockets where wooden joists had been fitted into the wall during construction and mortared into place. The impression of wood grain from some of these joists could be seen on the mortar. These openings help us understand how the building was built, but they also allow additional access for moisture and vegetation that is detrimental to the ruin’s stability.

Underfired brick is always part of the equation when it comes to historic masonry. The logistics of moving hundreds of thousands of bricks for the construction of buildings like Rosewell meant that it was easier and cheaper to mold and fire the bricks for a project right on the construction site. By doing this there was no permanent kiln. Instead they would construct one or more single-use kilns called clamps out of the bricks that were molded that summer. The outermost layers of brick that were furthest away from the fire would not reach the ideal temperature (1,800 degrees F), resulting in more porous, light red brick. These bricks, if used responsibly, can certainly last, but that is only possible if the underfired brick is away from the elements and protected from freeze and thaw cycles.

The south side of the ruin also has its unique challenges. It takes the brunt of the sun
during our hot Virginia summers. Keep in mind, brick is considered a soft material – water can
and does travel through it. In fact, the rising damp can be seen quite dramatically on the south
side of the ruin and it shows itself in the extensive mortar failure that starts around four feet above
grade and rises to around 10 feet. This mortar failure shows how high that rising damp goes before
it evaporates. The reason the mortar has degraded and not the brick is because lime is hygroscopic, meaning the lime will pull in water from the brick and the evaporation of water occurs in
the mortar joint. Judging by old photos, this mortar decay has been ongoing for many decades.
In fact, the mortar failed around 4 to 5 inches into the wall. In certain areas when removing the
powder, bricks would simply fall out and had to be re-laid, but in most areas simple tuck pointing
was needed to strengthen the wall. It is always easier to remove failed mortar and tuck point
with an appropriate lime mortar than it is to replace original brick. While undertaking this repair we were able to use a combination of original Rosewell bricks that were gathered by the Fairfield crew over the winter months for exterior use, as well as modern, hand-molded bricks for areas of less visibility. We are also utilizing an appropriate lime mortar that will continue to provide the masonry with a way of releasing moisture that the ruin pulls up from the ground.

Preservation Intern Ty Martin (The College of William and Mary) repoints a section of wall at Rosewell.

During the repair to the south wall and at two other locations at the site last summer, the details of the Rosewell mansion really came into focus. The level of craftsmanship and detail applied to the exterior of the building is really quite exquisite. One detail that highlights this is the size of the mortar joint for the exterior of the wall. The mortar joint for Rosewell is around ¼ inch, whereas other contemporary buildings have joints ranging usually from ⅜ to ½ inch. Although this may not seem like a huge difference, it really shows the level of expertise in the construction of the house. Hand-molded brick are not precisely uniform; they have curves and missing corners, and sometimes the brick face isn’t flat. It is the job of the bricklayer to make an imperfect material appear more perfect than it is. By having a bigger mortar joint it gives the bricklayer more play and more space to navigate this problem. The thinness of Rosewell’s mortar joints indicates that the bricklayers had to work with precision and also spend extra time molding bricks to create more uniformity. This might only take an extra 10 seconds while molding a brick, but that time adds up when constructing a building of Rosewell’s scale. This detail really resonated with me last summer, and I’m looking forward to discovering more of the intricate details of the ruin – the ones that really make you stop and appreciate the grandeur of Rosewell.

Newly repaired section of the southeast corner of the Rosewell mansion. Note that the decorative water table treatment has not yet been restored. Future work will include bringing back some of these details.

As we move into the 2026 season at Rosewell, we are excited to continue work on the ruin, turning our attention to the interior and the re-installation of the fireplace arches which will provide much needed support for the chimney stacks and will stop further masonry loss. This repair will also be exciting because of the return of archaeological work inside of the ruin to reveal a solid surface to build off of for the various arch rebuilds at the base of the chimney stacks.