Floods of Historic Proportions
What To Do When the Water Recedes
By Jennifer Farwell | Online Only | Mar. 21, 2008
Floodwaters flow through historic Black Rock Mill in Germantown, Md., after record rains in June 2006.
Credit: Aaron Skolnik, FEMA
Several years of history-making floods have wreaked havoc from the Gulf Coast to the Snoqualmie Valley in Washington; from El Paso, Tex., to New Hampshire and Massachusetts. Last year, record storms and rain from South Carolina to Maine damaged thousands of homes.
Mayors and city managers say the worst may be yet to come, as late spring snows melt, swelling rivers and streams beyond their banks. The Government Accountability Office recently released a report saying that the mounting evidence of global warming indicates that U.S. houses may suffer billions of dollars in additional damage due to flooding in upcoming years.
For the homeowner, a flood can be one of nature's cruelest acts, leaving a mass of sodden memories, mildewing furniture and carpet, and sometimes, structural damage. For historic properties, preservationists say the tragedy is compounded when owners don't take proper care to protect and restore their homes after a flood.
"Most homeowners of historic houses really want to preserve them, but so many erroneously think that much of their home's fabric can't be saved," says Patricia Gay, director of New Orleans' Preservation Resource Center. "They are confused by word of mouth and by uninformed contractors who just don't understand that most buildings—especially older ones—can be saved, even if they flooded."
For starters, the materials used in old houses offer intrinsic benefits particularly relevant to flooded buildings.
"Houses built in areas that are flood-prone were usually built with flood-resistant materials originally," says Rudy Christian, project development manager for the Preservation Trades Network, a professional organization of craftspeople involved in traditional building trades. Christian, who is helping educate homeowners along the Gulf Coast and in other badly flooded areas, says homeowners do not need to rip out plaster, original lathe, studs, and tongue-and-groove boards, nor do they need to remove windows, mantels, and other architectural details simply because they get wet.
By way of example, Christian, whose company, Christian and Sons, specializes in preserving and restoring wooden buildings, points out the differences between aged and modern woods.
"Old lumber was second or third growth, not the farmed, fertilized, and genetically engineered wood we see today. Modern lumber will be damaged by floodwaters because it contains more sapwood. It is not as dense, so it will absorb water and support fungal growth." Old wood is dense, and it was quarter sawn, not flat sawn, which makes it resistant to expansion and contraction, two added concerns when structures are submerged in water.
Remediation or removal of a few feet of mildewed plaster and a good clean-up may be all that is needed to prepare this flood-damaged historic house for restoration and repair.
Credit: Jennifer Farwell
Christian, Gay, and others, including representatives of the Alabama Historic Commission, Maryland's Ellicott City Restoration Foundation, and the National Trust for Historic Preservation, have developed a number of guides for owners of flooded buildings. Some of their recommendations include:
- If old wood becomes wet, don't replace it; just dry it out. That's true not only for exposed architectural details, but for studs and other framing wood. Prior to 1900, plaster contained lime, which has self-healing properties that make it a natural enemy of mold and fungus. If lime plaster becomes wet, allow it to fully dry again and it may be fine. After 1900, plaster was often finished with gypsum, which can grow mold. You may be able to treat the plaster and salvage it, but it's best to have a plaster professional check it for you. Another danger for plaster walls is disintegration of the "keys" (plaster material used during the first, or scratch, coat, which fills in between the lathe strips and provides structural integrity). If the keys are intact, the plaster is stable enough not to require replacement.
- Remove silt and flood debris as soon as floodwaters recede—preferably while it is still wet. Use fresh water to gently rinse away the muck. Avoid pressure washing, which can cause scour fine detailing and erode plaster. Rinse not only surfaces, but also interior cavities such as mechanical chases and electrical outlets.
- The best way to remove interior moisture is with the natural ventilation provided by windows and doors. Heaters and dehumidifiers can do permanent damage; introduce them slowly and in small quantities as drying progresses, if at all. Never use industrial-strength drying systems.
- Enclosed portions of buildings, such as wall cavities, can retain moisture for a long time, enabling additional deterioration. It may be necessary to open wall cavities for further ventilation, especially if insulation (which should be removed) is present.
- Houses submerged for a period of time will not necessarily sustain additional damage. Mold, which requires both oxygen and a damp (not submerged) environment, grows most readily where materials go through wet and dry cycles over a period of time. A primary concern with submerged homes is that the water has caused them to shift off their foundations or the lime used in foundation mortar has become unstable.
- If the lime in a foundation has crumbled due to prolonged exposure to water, replaced it with a traditional mortar made of lime and sand. "Quick" cements, like Portland Cement, do not expand and contract, are not self-healing; and grow salt crystals that displace the natural porous interiors of the masonry. "A basic principle of historic masonry is that the mortar must always be softer than the unit that it is binding," says Mike Logan the Operations Supervisor for Heritage Conservation and Community Projects with the Howard County (Maryland) Department of Recreation and Parks.
- If one area of your home is too severely damaged to repair, salvage as much of the usable materials as possible for use in another area of the home. If your home is historically significant or on the National Register of Historic Places, avoid using salvaged, historic materials from other sources, as their use confuses the historic record.
- Before hiring anyone to assist with debris removal or repairs, ensure they are familiar with appropriate procedures. If possible, use companies that specialize in historic preservation. Although their intentions are good, both volunteer and government-sponsored "gutting" groups have been responsible for a substantial amount of damage to historic buildings across the country. Likewise, contractors have unnecessarily destroyed historic details by recommending the materials they most commonly use rather than ones that suit the historic needs of the project.
Preservationists admit that sympathetic repair and restoration can be expensive, but say the result is a more valuable and well-built home. C. Elliott Perkins, acting executive director for New Orleans' Historic Districts Landmarks Commission, suggests there is a silver lining to the clouds that come with flooding rains. "Take this opportunity to go that extra mile," he says. "Once you have your contractor on the site, it's not significantly more expensive to fix those nagging problems you haven't gotten to in years."
Despite the fear and horror that floods generate, preservationists urge homeowners not to act in haste. "When unsympathetic gutting and repair occur," says Christian, "the result is an irreparable loss. Historic homes built before World War I use materials that cannot be manufactured any longer. Keep it, fix it, reuse it—but don't replace it."
Homeowner References
American Institute of Architects
Maintains a listing of and guidelines for selecting firms and companies that are trained in working on historic structures. Also offers preservation guides.
National Park Service
Preservation Briefs Series (www.cr.nps.gov/hps/tps/briefs/presbhom.htm) More than 40 guides on all aspects of restoring historic buildings. Online versions of these are available at www.oldhousejournal.com/notebook/npsbriefs/index.shtml.
National Trust for Historic Preservation
Resources for Returning Homeowners (www.preservationnation.org/hurricane/resources.html) Designed for returning victims of Katrina, the site offers PDF versions of several excellent flood-damage remediation and preservation guides.
Preservation Trades Network
"Brief Guide to Understanding Repairs to Historic Homes Damaged by Hurricane Katrina and Other Related Floods" (iptw.org/Repair_Handbook.htm) Detailed focus on repairing and preserving foundations and roofs with an excellent list of resources including lime companies (for mortar and plaster repair).
This article was originally published on Preservation Online in April 27, 2007.
Freelance writer Jennifer Farwell divides her time between Georgia and New Orleans.
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