How to Limit Water-Induced Damage to Buildings during Construction?

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The damage to a building due to water/moisture is a significant factor that either shortens its useful life or necessitates costly repairs. 

The types of damages a building suffers due to moisture are listed below:

1. Decay of wood-based materials
2. Spalling of masonry caused by freeze-thaw cycles
3. Damage to gypsum plasters by dissolution
4. Corrosion of metals
5. Damage due to expansion of components or materials
6. Spalling and degradation caused by salt migration
7. Failure of finishes and creep deformation
8. Reduction in strength or stiffness.

Water-induced damage prevention must be considered at all phases of the construction process, including design, construction, and building commissioning. The moisture sources and moisture migration, design evaluation tools, and design methods used to limit the water-induced damage are discussed in this article: How to Limit Water-Induced Damage to Buildings in the Design Stage?

This article discusses the methods used to limit the water-induced damage to the building during construction and a checklist.

Methods to Limit Water-Induced Damage during Construction

The various steps that can be considered during the construction of a building to limit water-induced damage are listed below:

1. Inappropriate Building Positioning- Construction of buildings should be avoided in areas prone to floods and having high water table. Efforts to avoid moisture buildup owing to rainwater leakage, air movement, or vapor diffusion will be futile if the structure is destroyed or severely damaged by floods.
2. Inadequate Flashings and Curbs- Flashings and curbs of inadequate height should be avoided. Consideration should be given to peak rainfall, runoff, and wind velocities when selecting the height of the vertical leg of flashings.
3. Integration with cladding or roofing systems- Failure to properly integrate flashings with roofing or cladding systems is a fairly common error and must be avoided.
4. Entrapments- Rainwater leakage or condensation may cause substantial degradation of building components unless the water is dissipated. The use of vapor retarders and inappropriate use of coating, paints, and sealants can reduce the dampness in the building components during and after construction. 
5. High Thermal-Conductance Paths: High thermal conductance paths may cause condensation within assemblies or constructions. These may occur at junctions of walls and ceilings, walls and roofs, walls or roof openings, and perimeters of slabs on the ground. The methods for preventing condensation occurrence are-
   • Reduce indoor humidity
   • Select units that contain thermal breaks or that are made from low conductance materials
   • Consider double or triple glazing, insulating glass units with low emittance glass, low conductance gas fills, or low conductance edge spacers.
6. Ice damming is caused by the melting of snow cover at higher portions of the roof and subsequent refreezing at lower portions of the roof. Prevention measures may be broadly classified as-
   • Limiting heat loss from the conditioned space to the roof space.
   • Cooling the bottom of the roof deck by ventilation.
7. Incompatible materials- Consideration must be given to the compatibility of adjacent materials. An example of compatibility is that of sealants with substrates. Another example is the compatibility of mortars with masonry units.

Suggested Field Check Lists

The below-given checklist can be considered during and after construction. The list is intended for use after the building design has been completed.

During Construction

1. Assure that the builder understands design intent with regard to moisture management. This most commonly concerns installation details that concern the management of rainwater. When details given by the designer are not practically executable, resolve problems via communication with the designer.
2. Check that components meet specifications and design intent. If they do not, consult with the designer. Either do not use these components or modify their installation to meet the intended design.
3. Check the moisture content of materials during construction. Do not use wet materials in locations where the design will not permit rapid dissipation of moisture. Alternatively, modify the construction schedule or on-site practices to allow drying.
4. Check workmanship: below-grade drainage (where specified), capillary breaks, vapor retarders, air retarders, flashing, window installation, ductwork.

At Commissioning

1. Check for precipitation management: proper grading at foundation, proper pitch of guttering and termination of downspouts, an inspection of flashings, and sealant applications.
2. Check for pressure balancing of air handling systems.
3. Determine that building operation for the first year of occupancy is adequately planned. This may be necessary for the dissipation of moisture from wet building materials.

In Service

1. Promptly note any unexpected performance. This includes but is not limited to leaks, window fogging, and indoor mold growth. Improper drafting of combustion appliances requires immediate attention; it is a potential life-safety hazard and a potential source of moisture problems.
2. Note carefully any treatments for problems and the date of treatment.
3. Note any changes in occupancy characteristics.
4. Keep note of maintenance performed on the building, including painting and sealant maintenance.
5. Keep note of renovations or modifications made to the building or changes in landscaping. Landscaping changes, including those on adjacent properties, may affect site drainage.
6. Periodically (seasonally) note and record indoor humidity.
7. Keep note of the use of unvented combustion appliances.
8. Keep used of such appliances within usual and customary limits.
9. Check the condition of windows and caulk seals annually.
10. Check gutters and downspouts and clear blockages as needed. The needed frequency will depend upon the proximity of trees to the building. Do not overlook the possibility of bird nests causing blockages.
11. Where the roof space is accessible, check for roof leaks yearly, especially at roof penetrations.
12. Check for plumbing leaks twice a year. In particular, look for leaks associated with sinks, shower enclosures, and bathtubs.
13. Keep note of the use of landscaping irrigation. Do not allow irrigation spray to contact the building unless designed and built to accommodate such wetting.

FAQs

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