Waterproofing Historic Buildings

Posted on Posted in Waterproofing

Controlling excess water or moisture has always been a major issue in construction; whether it’s a residential or commercial structure, it is a source of concern for both new and historic buildings. Unwanted water over a period of time can cause damage to a building’s structural integrity as well as its aesthetics; not to mention the financial and labor havoc it can wreak. Maintaining moisture control on historic buildings presents additional challenges as most modern waterproofing or damp proofing methods may not work effectively.

These days, buildings are constructed with keeping water out in mind by way of using relatively air-tight design methods and waterproof or water resistant materials. Building construction before the industrial era used materials that are “breathable” in contrast to the modern day’s method of near total water-tightness. The reason for this was the unavailability of resources at the time such as hard dense bricks, cement based mortars and renders, modern masonry paints and external sealants. To keep dampness at bay, regular evaporation of moisture was a necessity.

In pre-industrial times, buildings were designed and constructed to shed majority of rain water. Porous construction materials in the exterior of a building are naturally dried by wind and the sun; while interior moisture evaporated by air movement through windows, roof coverings, and open fireplaces. Walls and floors would have been in a constant cycle of wetting and drying.

With that said, waterproofing historic buildings is not as simple as applying modern-day membranes or sealants. Doing so without careful consideration and understanding of the materials used at the time to construct the building may cause more damage rather than repairing or eliminating a problem. Of course, to preserve the beauty or historic buildings and maintain or prolong their structural integrity, excess water still need to be controlled, if not eliminated.

The main causes of excess moisture in old buildings are:

Air moisture condensation – comes from modern day energy-saving measures that reduce ventilation and increase humidity such as double-glazed windows. Humidity is also raised by modern lifestyles that generate large quantities of water vapor, from bathing, cooking and washing.

Penetrating damp – roofs, chimneys, parapets and other exposed parts of a building are most at risk to rain penetration, especially where access for maintenance is difficult.

Internal spillage – comes from overflowing baths or showers, gradual breakdown of old pipes resulting to leaks.

Below ground damp – results from the inhibition of moisture evaporation from below because of impervious coverings such as vinyl sheets or rubber-backed carpets.

It is also worthwhile to take into consideration the variety of simultaneously existing conditions that contribute to excess moisture when planning to waterproof or damp proof historic buildings. It may be necessary for the owner or the professional waterproofing contractor to address the following:

  • Types of building materials and construction systems
  • Type and condition of roof and site drainage systems and their rates of discharge
  • Type of soil, moisture content, and surface /subsurface water flow adjacent to building
  • Building usage and moisture generated by occupancy
  • Condition and absorption rates of materials
  • Type, operation, and condition of heating, ventilating, cooling, humidification/ dehumidification, and plumbing system
  • Daily and seasonal changes in sun, prevailing winds, rain, temperature, and relative humidity (inside and outside), as well as seasonal or tidal variations in groundwater levels
  • Unusual site conditions or irregularities of construction
  • Conditions in affected wall cavities, temperature and relative humidity, and dewpoints
  • Amount of air infiltration present in a building
  • Adjacent landscape and planting materials

Common signs of moisture problems which may be visible or hidden are:

  • Presence of standing water, mold, fungus, or mildew
  • Wet stains, eroding surfaces, or efflorescence (salt deposits) on interior and exterior surfaces
  • Flaking paint and plaster, peeling wallpaper, or moisture blisters on finished surfaces
  • Dank, musty smells in areas of high humidity or poorly ventilated spaces
  • Rust and corrosion stains on metal elements, such as anchorage systems and protruding roof nails in the attic
  • Cupped, warped, cracked, or rotted wood
  • Spalled, cracked masonry or eroded mortar joints
  • Faulty roofs and gutters including missing roofing slates, tiles, or shingles and poor condition of flashing or gutters
  • Condensation on window and wall surfaces
  • Ice dams in gutters, on roofs, or moisture in attics

Before starting on any waterproofing or rehabilitation work, it is imperative that the building be thoroughly surveyed and inspected. It cannot be reiterated enough that aside from assessing causes of excess moisture, it is vital to take the building materials in consideration when planning for waterproofing work in order to choose the best method. An accurate diagnosis will provide for an effective solution.

The first remedy may just involve basic maintenance such as clearing a blocked rainwater gully, improving drainage or changing washing or cooking habits, for instance. The next step would be to control air moisture condensation, penetrating damp, and below ground damp.  Cyclical maintenance procedures can help eliminate or minimize excess moisture. This would include regularly inspecting and repairing minor defects in the roof, gutters, walls, windows, crawl space, pipes, mechanical equipment, ventilation, and landscaping.

After initial remedies have been undertaken and there are still water issues, there may be a chronic damp issue and you may need a professional to resolve that. In Southern California, Westside Company is a reliable waterproofing contractor. For two decades we have used a variety of waterproofing methods depending on our client’s needs. No two jobs are the same and we will make a careful assessment of your moisture issue to determine the best way to resolve it whether it’s a residential or a commercial building. To schedule an inspection, please call us at 310 994 4626 or e-mail us at westsidewaterproofing@gmail.com. We serve most of the Los Angeles area including Angelino Heights and Beverly Hills where there are a number of historic or old buildings. We also provide waterproofing maintenance services. Contact us now and keep your historic home or building safe and moisture-free.

(Photo from www.laconservancy.org)
(Photo from www.laconservancy.org)