Weather conditions in the Pacific Northwest vary from mild, though often wet, to freezing temperatures with ice and snow for long lengths of time. Weather conditions must be considered when evaluating construction projects in terms of the safety of workers, work sequencing and the time needed to complete tasks. Today we will be reviewing some challenges that come with winter weather, and strategies to minimize them. Issues may include the need to protect building elements as well as creating safety hazards for onsite workers. Best practice is to develop plans to mitigate these concerns before the wet weather occurs. Let’s take a closer look at the challenges that winter weather might bring.
Protecting Building Materials
Many building materials cannot be exposed to significant amounts of moisture or even humidity. This limitation restricts project schedules and can dictate the order of installations for work. Examples include:
As we discussed in this article titled the Art and Science of Concrete, weather conditions can significantly impact concrete. If exposed to the elements, installers must take care to protect the surface from rain, and to ensure that the concrete doesn’t get too hot or too cold. A delay in the concrete pour may be necessary if temporary protection measures can’t be installed.
These materials are extremely sensitive to moisture. For instance, drywall compound cannot be finished if the temperature is too cold or humidity levels are too high. Methods of solving these challenges include:
- Waiting to install these items until the building is enclosed and heated.
- Adding temporary heat to the space.
- Installing ventilation such as fans, as well as dehumidifiers to lower the moisture in the building.
- Completing moisture testing of the existing framing prior to installing finish materials.
- Installing temporary barriers to enclose the space, such as plastic or plywood infill at glass openings.
Like drywall, paint cannot be installed on wet surfaces or in wet conditions. Without proper temperatures, paint may not adhere or dry appropriately.
Warranties for flooring materials could be voided if the moisture content in the floor slab is too high.
Finished Carpentry and Wood
Unsealed wood products can stain and warp if exposed to water. It is possible to trap moisture in wood framing if it’s covered up while the moisture content is too high, leading to mold growth. Temporary protection and/or moisture testing prior to installing finishes are best practices for avoiding these issues.
Protecting these materials from the weather are critical to avoid damage or long-term issues such as delamination, deterioration, or mold growth. Managing schedules, temporary protection and heating and cooling are all key to preventing problems.
When winter weather stops work tasks, it is justifiable to delay a project schedule per contractual agreements between owners and contractors. Tasks, such as large concrete pours, cannot occur during rain or freezing events. Similarly, remodels that involve opening areas of existing roofing may need to be delayed in inclement weather. Critical to schedule delays, the contractor must communicate and document these delays with the ownership team. A failure to do so could contribute to fees in the form of liquidated damages.
What are liquidated damages? According to the American Bar Association, they are:
“…provisions specify(ing) a predetermined amount of money that must be paid as damages if one party does not meet certain contractual requirements. 1) In construction contracts, this typically manifests as a fee per unit of time (the “Liquidated Amount”) in case of a missed schedule milestone such as Substantial Completion. 2) The Liquidated Amount is usually expressed as dollars per day. 3) Liquidated damages may also be tied to performance metrics, such as efficiency, output or availability of a project or facility.”
Essentially, liquidated damage clauses set pre-agreed upon dollar amounts to be paid to the owner if a contractor fails to meet their obligations. Therefore, if delays due to weather are necessary, proper documentation is critical. Other options for minimizing the effects of winter weather might include adjusting schedules forward, or taking a construction break during the worst seasons of the year. Prioritizing site work and wet weather site preparations ahead of the wet weather season leads to efficiencies and cost savings, as well as the minimization of safety risks and penalties.
Earthwork Risks, Erosion Control & Dewatering
One of the largest risks to cost and schedule on a given construction project is the site work. Unknown conditions or weather delays can extend the time it takes to build, increase the modifications required to stabilize the site, and more. In the Pacific Northwest, regulating bodies in Oregon and Washington require a Certified Erosion & Sediment Control Lead (CECSL) inspector be onsite to maintain records related to erosion & sediment control. Temporary and permanent dewatering systems must be installed to manage the runoff from a given site.
What is dewatering?
As we discussed in an earlier article, dewatering is the process of removing surface or ground water from a particular location. Most construction work cannot occur in areas with significant water ponding. Techniques have been designed to move water out of each area for the duration of construction. The process typically involves sloping the areas of work to drain water away, pumping surface water to another location, or drilling a series of well-points into the ground around the area of work and pumping it to another location to artificially lower the water table while work is occurring.
Some form of pumping is typically used for all deep foundation work, pipe zones, utility trenches, and manhole structures, as these items are placed beneath the surrounding ground level. Maintaining proper dewatering systems and preparing jobsites for winter weather conditions protect the owner and contractor from delays and additional costs.
Wet weather comes with various site safety challenges for crew members. These include:
- Increased risk of slips, trips and falls due to frozen, muddy or wet surfaces.
- Decreased visibility if safety glasses are wet, or the environment is dark, foggy, or saturated with rain.
- Equipment and vehicle windshields or mirrors can become fogged or distorted, making safely operating them an added concern. It’s critical that workers stop their actions to clean or clear windows and mirrors before proceeding with their work.
- Clogging tools, such as saws becoming clogged with wet sawdust, etc.
- Excessive weight of materials due to ponding water or saturation.
- Employee visibility – wet and foggy conditions can lead to poor visibility for employees operating machinery, heavy equipment, or passenger vehicles. It is recommended for workers to wear a Class II high visibility garment.
- Slippery tools or materials – working from heights with wet, slippery tools or materials increases the likelihood of these hazards striking workers below. Using the correct glove type, using tool lanyards, and establishing a drop zone are important considerations.
- Electrical Hazards – Power tools, including temporary power distribution boxes and extension cords, have the potential for electrical shock when operated when wet.
- In addition to these safety concerns, crew members working in wet or freezing conditions without proper protective equipment and waterproof gear are at risk of hypothermia. Workers should dress in layers and have access to a warm, dry, environment for break periods.
Proper planning to implement safety measures during winter weather is critical to keeping workers safe and the project underway.
In addition to weather conditions, winter can bring challenges related to labor availability and delivery schedules. Freezing and/or snowy conditions can shut down roads and prevent access for workers and deliveries in the Portland Metro area. This can affect supply chains and labor forces. Floods and power outages during winter storms can also cause delays as workers must tend to their homes and families, or sites must shut down due to a lack of power.
Winter weather presents multiple challenges for construction sites, but with proper planning, documentation and a little flexibility, plans can be put in place to minimize the impacts to the project schedule and cost.