Ask an Expert: The Adobe Guy

October 2, 2016 raguirre

Adobe Guy Pat Taylor

Meet Pat Taylor, the go-to contractor for historical adobe restorations. He fills us in on the fascinating work of nursing our oldest buildings back to health.

Adobe Guy Pat TaylorHow did you get involved in this particular niche?
I’m a carpenter by trade and then became a mason. I gravitated towards fixing up old places because I grew up in an old adobe here in Mesilla. I worked with Cornerstones Community Partnerships, a nonprofit that works with communities to restore structures, for 20 years, plus I’ve contracted on my own, so I’ve been in and around the industry for about 38 years.

Preservation. Restoration. There’s a lot of different terminology. What’s the difference?
The National Park Service has four treatments for historical structures: preservation, restoration, rehabilitation, and reconstruction. Preservation is maintaining and protecting the structure. Restoration projects restore it to a specific time period. Rehabilitation involves upgrading, usually utilities, and often some elements of preservation and/or restoration. With reconstruction, you’re actually replicating something that was once there, but isn’t anymore. Those projects are very far and few between because they have a very high standard. You can’t invent something; you have to follow what was there and that really involves supporting documentation. A lot of times that just isn’t available.

What do you look for when assessing a building?
We’ve done a lot of seismic retrofit on the West Coast and in Chile, but here, the problems are almost always moisture related. Yes, believe it or not, we do have humidity here.

When these old buildings were originally made, they were either mud plastered, lime plastered, or they weren’t plastered. About the turn of the century, cement became widely available through the railroad system. Cement doesn’t allow the walls to breathe; it retards the natural evaporation process. Salts also come along with moisture and humidity. If you visit Mesilla in the early morning, you can see a white stain on the bottom of the walls because the humidity picks up the soluble salts and draws them up, just like when you put a roll of paper towels in a bowl of water. You can watch that moisture climb all the way up. Adobes do the same thing. Water becomes a vehicle for the salts and, as they migrate to the surface, they start to crystalize and expand. They expand with 800 pounds per square inch, and that can wreck infrastructure, bridges, and roads. Adobe is easy prey because they are much softer than concrete systems.

We open up a section of the wall, take off the concrete color and the cement plaster, and identify the damage. We do moisture tests and, generally find the moisture content to be between four and 11 percent, which is moderate.
Anything above 11 starts sending up flags. At 13 or above, you have some serious issues.

We also identify what materials were originally used. We always try to do what is historically correct to the building.

How do you counteract the damage?
Adobe Guy Pat Taylor When builders started using cement 100 years ago, they thought, “We’re done. We’ll never have to plaster again.” They were doing it under the pretext of keeping the moisture from getting in, when in reality what needs to happen is that the moisture needs to get out. They failed to realize that the salt crystallization would happen inside the walls instead of on the outside. You end up with degradation of the adobe structure instead of just the plaster surface. It wasn’t even that long ago that we had dirt streets and dirt floors and mud walls. Sure, there were problems with the building structures, but not the magnitude we have today. With asphalt streets, concrete sidewalks, and concrete floors, the only things picking up the moisture are the walls. If they can’t breathe and expel that moisture, it causes damage.

What we try to do is reintroduce the dynamic of how the walls originally functioned. After our assessment, we’ll do our adobe repair and get it back to the natural wet/dry balance, and then we put lime plaster on. Now, as the moisture comes up with those salts, the salts migrate to the outside surface of the wall and that crystallization happens on the plaster surface instead of inside the wall.

Does that mean it won’t ever get damaged again?
Adobe Guy Pat TaylorAn adobe is like a marriage, you have to maintain it or you will have problems. Every few years or so, you’ll need to lime wash the outside of the building. Lime wash is just another layer of permeable material on the outside of the building that will take that hit of moisture first before it hits even the lime plaster. It helps ensure the salts crystalize on the outermost layer.

When you’re working on old buildings, how do you protect the historical elements?
I sat on a committee about 15 years ago that did a historic amendment to the NM adobe building codes. Often times, going by contemporary building codes will conflict with the materials and repair process necessary for an adobe and could damage it. We introduced a process so building inspectors would feel comfortable signing off on a building that’s going to need to be addressed differently than what modern codes dictate.

Some of the things we identify during an assessment are what the National Park Service calls “character defining features.” It could be anything from a porch to a material. We evaluate if there’s enough to either save, conserve, or replicate. In our case, we’re often reintroducing a material, like lime, that’s been lost to the ages.

Pat Taylor Inc.
575-526-7995 | pattaylorinc.com

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