Category Archives: Preservation Projects

Adobe Brick Making at El Presidio de Santa Bárbara State Historic Park

by Mike Imwalle

Josh Figueroa sifting dirt for adobe brick making. Photo by Mike Imwalle.

During the week before Christmas, SBTHP director and maestro adobero Tim Aguilar began preparing the Presidio site for making a large batch of adobe bricks for the reconstruction of the Northwest Corner defense wall. Crews immediately began sifting dirt  for the adobe mixture and grading the site flat for laying out the bricks. As soon as enough soil was prepared, crews began the process of mixing shovels of sifted dirt, water, straw, and a small amount of emulsified asphalt stabilizer.

The mixer crew adding shovels of dirt, water, and straw to the mixer. Photo by Mike Imwalle.

The site of the actual brick making is prepared in advance by laying out a series of wooden molds end to end and moistening them with water. The molds are constantly kept wet to prevent the thick mixture of mud and straw from sticking to the sides. Each mold has three rectangular reservoirs that will produce three 22 x 11 x 4-inch adobe blocks. The mud is delivered to the molds via wheelbarrows and dumped on to the surface of the molds.

SBTHP Director Tim Aguilar delivering a load of mud to the "punchers." Photo by Mike Imwalle.

The “punchers” scoop the excess mud out of the wheelbarrows and distribute it across the gang of three molds. Then, using their fists, they punch the mud deep down into the corners of the mold. This is a very important process to insure uniform size and good quality bricks with square corners. Once the mud is punched into the molds the excess mud is scraped even with the top of the mold and the surface of the brick is smoothed by hand. The mold is lifted off the bricks  and moved down to the end of the line to make another batch. Soon the site is covered with freshly made adobes ready to begin drying in the sun.

Punching and smoothing the adobe into the wooden molds. Photo by Mike Imwalle.

After laying flat for three or four days the bricks are tilted up on their side to maximize the amount of surfaces exposed to the air. This insures nice even drying and prevents cracking caused by the exterior of the brick drying faster than the center. After about a week of making bricks the entire site is covered, and we need to take a break to let them dry for about a month before we can stack them.

Lifting the molds off the adobe bricks. Photo by Mike Imwalle.

It is nice to have bricks all over site again. Brick making always generates excitement around the park and interest from the public.

Freshly made bricks spread across the front of the Presidio. Photo by Mike Imwalle.

I will be discussing more detailed aspects of adobe in future posts, including a closer look at the ingredients of adobe bricks, adobe construction, and the use of adobe bricks during construction of the original Presidio quadrangle.

Bricks tilted up on their sides to dry in the sun. Photo by Mike Imwalle.

Anyone interested in participating in an adobe brick making event please contact  Meredith Brockriede at to volunteer. If you are interested in supporting the Northwest Corner Reconstruction Project, visit the Buy-a-Brick campaign webpage here.

Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation. 

Northwest Corner Reconstruction Project: Rebuilding a Defense Wall, one brick at a time!

by Mike Imwalle

Northwest Corner rendering by Alex Eberle, Milford Wayne Donaldson Architects

After more than four years of intensive archaeological investigation, in 2003 SBTHP embarked on its most ambitious reconstruction effort since the organization’s founding almost fifty years ago. The Northwest Corner Project included the construction of new public restrooms, four adobe rooms to house a new Visitor’s Center, and more than 235 linear feet of outer defense wall. With completion of the restrooms in 2005 and the new Visitor’s Center in 2008 it was time to shift the focus of the fundraising and reconstruction efforts to the monumental task of the outer defense wall.

Reinforced concrete columns with sandstone foundations. Photo by Mike Imwalle.

In 2009 Channel Coast Corporation began the installation of 10-foot deep caissons to support 10-foot tall concrete columns. The columns would serve as the framework for the steel-reinforced bond beams that run the length of the 4-foot thick adobe wall.

Tait Masonry Crew laying adobe blocks on outer defense wall. Photo by Mike Imwalle.

With the concrete columns in place, David Tait Masonry began building a foundation of mortared sandstone to support the adobe walls. By October 2010 the foundation was completed, the first bond beam was poured, and we were ready to begin laying adobe bricks.

In January 2011 Tait Masonry laid a total of eight courses of adobe block on a 60-foot section of the wall closest to Canon Perdido Street and Channel Coast subsequently poured the second concrete bond beam. Work temporarily halted while additional funding was secured. In December 2011 thanks to generous contributions from the California Community Foundation, Williams-Corbett Foundation, Ann Jackson Family Foundation and the Ahmanson Foundation, construction of the wall has resumed.

Turning an adobe block for the "soldier" or "stretcher" course. Photo by Mike Imwalle.

Today the last bricks at the top of the 60-foot section of wall were laid. By the end of January Channel Coast Corporation hopes to have the upper bond beam and tile cap installed on this section and the adobe bricks laid and first bond beam poured for the next 60-foot section.

Exterior side of western outer defense wall. Photo by Mike Imwalle.

This wall takes an incredible amount of adobe block to reconstruct. So far we have laid almost 8,700 adobes in the Visitor’s Center buildings and another 3000 in the first 60 feet of defense wall. We still need more that 10,000 bricks to complete the project.

Top of adobe wall with concrete columns ready for bond beam and cap. Photo by Mike Imwalle.

Recently SBTHP director and presidio descendant Tim Aguilar and a crew made another 1,900 adobes.

Western outer defense wall at Canon Perdido Street sidewalk. Photo by Mike Imwalle.

Stay tuned next week for a post on adobe brick making and how you could become involved. If you would like to help support the making of 8,000 more adobe bricks to complete the project, please visit our buy-a-brick webpage.

Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.

Pico Adobe Roof Project

by Mike Imwalle

Tile plaque on the adobe wall enclosing the Pico Adobe. Photo by Mike Imwalle.

The Buenaventura Pico adobe is a hidden gem within El Presidio de Santa Bárbara State Historic Park.  The Mexican-period adobe is unique in that it was designed with a relatively steep-pitched shingle roof rather than the typical low-pitched tile roof popular in the Spanish period adobes that preceded it. Despite the fact that for years you could see the sun shine through the plank sheathing from the inside, it had never leaked. Nevertheless, the 30-year old cedar shingle roof had to be replaced, and in September 2010 SBTHP‘s Restoration Committee made a priority of seeking funds to make it happen. The adobe is a City of Santa Barbara Landmark and is frequently used for SBTHP Board meetings, staff meetings, receptions, and occasionally by other community organizations. In July of this year one of those organizations, the Pearl Chase Society, generously got the fundraising ball rolling with a gift of $5,000 towards the new roof.

Upper left: Previous condition of Pico Adobe roof, November 2011. Lower left: close-up of weathered cedar shingles. Upper right: Casa Roofing crew stripping old shingles. Lower right: existing sheathing. Photo by Mike Imwalle.

Additional donations from David and Louise Borgatello, Mary Louise Days, Michael and Nancy Gifford,and Montecito Bank & Trust completed the fundraising effort and I began seeking bids from roofing contractors. Casa Roofing was selected as the successful bidder and after completing the California Environmental Quality Act (CEQA) review through State Parks, the project of replacing the cedar shingles was scheduled to begin in November of this year.

Upper left: installation of new plywood sheathing. Upper right: felt cap ready for new pressure treated shingles. Lower right: first row of shingles being installed on porch roof. Lower right: shingles on front side of the adobe. Photo by Mike Imwalle.

On November 15th the crew from Casa Roofing began carefully stripping the weathered shingles. The underlying paper was nearly disintegrated but the sheathing was in remarkably good condition. After doing some minor dry rot repair on a porch roof rafter and some fascia boards, the adobe was ready for the new roof.  After a short weather delay and minor permitting issue was resolved, they quickly nailed on a layer of 1/2-inch plywood and covered it with a fiberglass cap. New pressure-treated cedar shingles were finally delivered on December 14th and the crew began installing them the next day. A large debt of gratitude is owed to the donors that made this possible, to SBTHP Director Don Sharpe for his assistance with the permitting process, and to Richard, Lorraine, and the crew from Casa Roofing for making this possible. Hopefully this roof will provide shelter for the adobe for another thirty years and it will continue to serve the community as a meeting place for generations to come!

Upper left: last row of shingles on front side of roof. Upper right: last ridge shingle being nailed. Bottom center: completed roof! Photo by Mike Imwalle.

Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.

Adobes just need a little (ok, A LOT of) TLC.

by Michael H. Imwalle

Eduardo Vallin Garcia, maintenance supervisor for the Santa Barbara Trust for Historic Preservation can often be seen around SBTHP-managed properties performing the duties of carpenter, blacksmith, plumber, electrician, gardener, groundskeeper, adobe brick maker, and when we are lucky, master griller and bartender. More often than not however, Ed is working hard to maintain the thousands of square feet of adobe wall surfaces by making sure they are protected from the elements. Ed, with the occasional help of volunteers, maintains the twelve-room, 4,400-square foot Casa de la Guerra, thirty rooms and 8,000 square feet of adobe buildings at El Presidio de Santa Barbara SHP, and the Pico adobe.

Clockwise from upper left: 1. Damaged defense wall section with bricks exposed. 2. Water damage repaired with new mud plaster. 3. Eduardo applying a final coat of whitewash. 4. Completed repair (November 2011). Photos by Mike Imwalle.

The term adobe refers to a sun-dried earthen block or buildings made from adobe blocks. Water is the biggest enemy of adobes. When moisture is re-introduced to the earthen blocks it breaks the bond that cements the particles together to form the blocks and they can fail with catastrophic results. The most important element of an adobe building is the roof. The typical adobe roof is low-pitched with large eaves or overhangs to shed water away from the adobe walls. The second most important measure of protection for an adobe building is its shell, or protective layer of mud plaster and whitewash. While a good roof may protect the tops of the walls and interior spaces for decades, maintenance of the protective layer of plaster and whitewash is considered part of the annual upkeep of an adobe.

Clockwise from upper left: 1. Removing damaged exterior plaster from Northeast Corner defense wall. 2. Applying the first coat of adobe plaster. 3. Eduardo applying the finish coat of adobe plaster. 4. Completed repair (November 2011).

In addition to the thousands of square feet of buildings, there are other adobe features that periodically require special treatments. Two examples would be the adobe porch surface at the Casa and the outer defense walls at the Presidio. While maintenance of the adobe porch usually consists of repairs due to wear and tear of the adobe surface, repairs to the defense wall are usually required as result of exposure of the relatively unprotected walls to the elements. While the Northeast Corner defense wall does incorporate a tile or adobe cap for protection from rain, the bulk of the water that hits the cap runs down the surface of the walls. This leads to erosion of the walls surfaces and requires chinking deep recesses in the wall surfaces with chunks of tile or adobe. After the damage is patched, it is plastered with mud and whitewashed. As Eduardo can tell you, this work never ends. As soon as one section is repaired it is time to move to another building and repeat the process.

Clockwise from upper left: 1. Water-damaged adobe along rampart. 2. Eduardo chinking deeply damaged areas with small pieces of tejas, or roof tiles. 3. Preparing for the final coat of whitewash. 4. Completed repair (November 2011).

¡Qué es la vida de un adobero!

Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.  Eduardo Vallin Garcia is the maintenance supervisor. Together, they are an unbeatable adobe restoration and repair team.