Winter pool construction: Tips for builders when working in sub-zero temperatures

by Samantha Ashenhurst | September 5, 2018 9:05 am

By Michael Willis

[1]

Canadians are fortunate to have terrific summer weather with comfortable temperatures. In fact, in many regions, the heat—at times—is comparable to what is experienced in the southern United States. For many pool owners, nothing compares to lounging poolside while sipping a beverage and watching their children splash in the water on a hot summer’s day. Swimming pools and outdoor living go hand-in-hand.

It is seldom to see an extravagant backyard oasis that does not have some type of water element incorporated into the design—whether it is a pool, hot tub, pond, or water feature. When the weather is co-operative, it is an easy sell for most homeowners to invest their hard-earned money in creating these types of spaces. Keep in mind, the key word is ‘when’ the weather is co-operative.

Pool sales during the spring and summer remain relatively consistent from year-to-year; however, when the temperature is lower than average, or heavy amounts of precipitation are experienced, sales will surely suffer. Even with the uncertainty of Mother Nature, the pool and hot tub industry cannot escape the fact Canada has a rather short swimming season. This is not only reserved for those who use their pools, but also for those who are building them.

Most pool builders scramble to sell and install as many projects as possible in a compressed season with the goal of having sufficient funds to carry the business through the winter until the warm weather returns. This cycle continues each spring, with builders anxiously awaiting the onslaught of phone calls requesting new pool installations and service work.

In Canada, pool building is referred to as a seasonal profession. The same can be said for most outdoor living industries. Most pools, hot tubs, and water features go through some sort of winterization or seasonal shutdown. By late fall, most waterscapes are closed for the winter, water levels are lowered to accommodate winter precipitation, plumbing lines are drained to prevent freezing, and covers are secured to keep debris out and protect the pool’s interior.

Most pool builders end their construction season in the fall and lay off employees over the course of the winter. Some take on snow clearing contracts, mainly to cover operating costs and to keep staff employed. That said, snow clearing is equally as unpredictable as pool building, as the amount of work available is reliant upon the weather.

Outside of the pool industry, most construction trades continue working year-round—even during the harshest winter weather. They have adapted their techniques and building practices to eliminate seasonal shutdowns, keeping workers employed, productive, and profitable. The same can be true for the pool industry. With the correct design and construction considerations, it is feasible to continue building pools year-round, even in colder climates.

Although these practices may not be feasible for every pool builder, with the right project and planning, it is an ideal way to soften the workload during the busy spring months. Many factors can contribute to whether or not a project should be constructed during the winter; however, such as scope of work, budget, location, schedule, and type of project.

Scope of work

[2]

The scope of work is an important factor to consider when building pools year-round. When thinking about this type of construction schedule, the following should be considered:

Is the project large enough in terms of the work to be completed as well as complexity? For instance, a small-scale project spanning one month of work may not prove cost effective for winter construction; however, a large-scale project spanning six months would be.

What tasks can be performed in inclement weather, and what precautions should be taken?

Budget

The reality is, winter construction costs more and these expenses are typically taken on by the builder. Therefore, mitigating expenses is important, but it can be tricky to perfect. Pool builders should not expect their first winter construction project to go according to plan or on budget. Further, they should not expect the homeowner to be on board with paying the additional fees either.

Laying out the costs up front, in the project bid or contract, could potentially sway them. So can listing how much time can be saved and the benefit to the client of not having to look out their window on a hot summer’s day and seeing their pool under construction.

Some homeowners undertaking large-scale projects will be willing to pay a premium to have their pool constructed over the winter. This allows them to have complete use of their outdoor space once summer arrives. When budgeting for winter construction the following factors should be considered:

• Temporary construction tenting (e.g. rental units, custom site fabricated units, lighting, etc.).
• Heating (e.g. heater rental, fuel, and maintenance).
• Site preparation (e.g. insulated blankets or tarpaulins, hydronic heaters, frost removal by excavation).
• Special winter products (e.g. winter concrete mixes, admixtures).
• Snow removal (e.g. machine rental, snow hauling, de-icing salt).
• Material storage (e.g. tenting and heating of materials).
• Overtime labour and reduced productivity costs.

Location

A project’s physical location may determine whether it lends itself well to winter construction. Erecting temporary construction tenting requires a significant amount of space. Storing construction materials and equipment on-site can also be challenging, as space is usually at a premium. Even simply plowing, moving, and stockpiling snow and ice on-site requires significant real estate.

Schedule

Projects with a construction period of four to eight months are especially suited for winter construction. These projects ultimately require a significant amount of time between commencement and completion.

[3]

Keep in mind, a project being built in the summer may require three months to finish, while the same pool constructed during colder months may require double the amount of time. Scheduling certain project components over the winter will aid in alleviating the potential backlog than can be experienced in the spring from unexpected delays and inclement weather.

Tasks should be scheduled in a manner as to not jeopardize the quality of the end product. Some examples include:

• Site excavations can take place providing the ground is not frozen.
• Concrete can be formed and placed with the proper preparation and curing techniques.
• Finishing details can be performed such as tiling and stonework, but should only be attempted if a suitable temporary heated structure is in place. Most adhesive manufacturers recommend their products should not be applied in temperatures below 10 C (50 F), with a minimum cure time before subject to freezing temperatures.

Builders should expect every task to take longer than it would if it was completed during the warmer months; therefore, allocating additional time to each task serves to mitigate risk.

Type of project

In colder climates, pool builders are incorporating features that were thought to be only possible in regions with warmer weather where the limitations are fewer. Backyard landscapes have evolved far beyond the simple pool, landscaped patio, and garden. Extravagant water features have become the norm, and are fully equipped with all the bells and whistles.

That said, certain types of projects are ideal for winter construction— especially indoor pools. Ideally, the main structure of the pool area is completed in the fall, with possibly some aspects of the pool also complete. When winter arrives, a roof may already be overhead allowing work to be completed in a heated structure without requiring the use of temporary construction tenting.

A home that is constructed in tandem with a pool/landscape is also ideal, as most trades will be working year-round anyways, so much of the infrastructure will already be in place. One of the main benefits in these scenarios is the fact the homeowner does not live on-site, so the added pressure of hastily completing the project may not be present to the same extent as it would during the summer.

Erecting temporary construction tenting

[4]

Temporary tenting or hoarding is commonplace for any type of construction being completed during the colder months. These structures need to be built to handle all types of weather conditions, such as rain, snow, ice, and wind. The tenting should also allow workers to perform their tasks in comfort to ensure maximum quality and productivity.

Many temporary tenting variations are available for use. Determining what type of tent to use will depend on the specific work that is being completed. For instance, inflatable tents, which are inflated by large blower fans, are ideal for temporary work that can be completed quickly. Pre-fabricated truss structures with light gauge steel or aluminum trusses are well-suited for long-term construction often spanning several months. These structures are covered with plastic or tarpaulins that can be heated.

On-site fabricated structures, using dimensional lumber, is also a cost-effective form of tenting and can be customized to a project’s unique requirements. Tenting not only benefits a builder by sheltering work areas and crew members from the elements, but also allows a builder to essentially create their own weather. Temperature and humidity can be set to ideal levels, which allows for the proper curing of products such as concrete.

Concrete in the winter

Attempting to complete certain construction tasks during the winter can be more difficult to perform than if they were done during the summer. Pouring concrete is one of these tasks; however, by following the proper guidelines and taking the appropriate precautions, concrete can still be placed in the coldest of temperatures.

To successfully pour concrete to form the pool structure, proper site preparation must take place beforehand. Any area where the concrete is being placed should be thawed and free of ice or snow. It should never be poured onto frozen ground, as settlement may occur once it thaws. It may take several days to warm the ground to the appropriate temperature. However, this can be achieved using hydronic surface heaters. These heaters are the ideal method to make sure the ground is free of ice and is warmed to the appropriate temperature.

These heaters use diesel, propane, or natural gas and are capable of thawing and heating 232 to 557 m² (2500 to 6000 sf) of ground up to 0.3 m (1 ft) in depth per day. These systems comprise a boiler unit which heats fluid passing through a heat exchanger. Lines run from the heating unit along the surface of the ground which is then covered by lightweight, flexible insulated blankets or tarpaulins, which lay flat in sub-zero temperatures.

[5]

These blankets are typically orange and have two layers of tarpaulin material covering an inner layer of closed-cell foam insulation. The ground below the blankets is thawed and remains warm until concrete is ready to be poured. Special measures should be taken when placing concrete at temperatures below 5 C (41 F). When below-freezing temperatures are expected, it is essential to protect concrete during its placement and curing stage. Concrete suppliers prepare special ‘winter condition’ blends by adjusting the concrete mix to the expected weather conditions.

If the concrete is being poured outside, or in a controlled environment, transporting it to the site in cold weather also requires the concrete supply company to take additional steps. The concrete mix comprising coarse (stone) and fine (sand) aggregates, cement powder, and water should be heated and free of any frozen materials.

Special additives or admixes such as setting accelerators may be added to aid in the chemical reaction of the setting concrete and to increase the rate of early strength development. This essentially speeds up the concrete’s curing process. Water reducing admixes are also commonly added to the concrete so it remains workable (in a fluid state). By using a reduced amount of water in the mix, the cured concrete will have a higher strength.

Before leaving the concrete plant, the temperature of the mix should be adjusted taking into account the time needed for loading the truck, transportation to the site, unloading and placement, and the time it will take before the concrete is finished and protected. If concrete is being placed using a line pump or standard boom pump, pre-heating the lines will also be required.

Pouring concrete is far easier in a tented enclosure, as the temperature and humidity levels can be controlled. This can actually lead to a higher strength and quality of concrete than what may be poured in the summer. Concrete should always be protected in the initial curing stage until it reaches at least 3447 kPa (500 psi). Once it has gained the sufficient strength, the concrete should still be heated and protected from freezing for a few days. Afterwards, the enclosure’s heat can be gradually decreased. Sudden cooling should be avoided to mitigate the possibility of thermal cracking of the concrete. Pouring pool components in the winter will allow ample curing time for the structure. This eliminates the crew from sitting idle as they wait for concrete to cure when the weather is warmer and more co-operative.

Heating

[6]

There are many types of heaters that can be used on a construction site. When selecting one, consider the size of the enclosure, the type of work being performed, and what type of fuel source is required. One heater may work well on one site, but it may not be suitable for another.

Electric heaters

Electric heaters are sufficient for smaller areas between 12 and 42 m² (130 to 450 sf) with heating capacities of 5000 to 18,000 British thermal units (Btus) per hour. Smaller electric heaters can be plugged into a regular 120-volt receptacle, while some larger units will require a 240-volt receptacle. When using the latter, a licensed electrician may be required to connect it to a power source.

Forced air heaters

Forced air heaters fuelled by diesel, propane, or natural gas are ideal for medium- to large-tented areas. These heaters are equipped with a fan that sits behind an ignited burner which expels the hot air. Forced air heaters can warm an area between 88 and 929 m² (950 and 10,000 sf) with heating capacities of 30,000 to 400,000 Btus per hour.

These heaters are primarily used in situations where workers are not present in the area for extended periods, as they exhaust directly into the tented area and produce significant amounts of carbon monoxide, which can be deadly to workers.

Indirect air heaters

Indirect-fired air heaters also use diesel, propane, or natural gas and are ideal for the largest tented structures. These heaters operate in similar fashion to a traditional furnace to produce clean, dry heat without the use of a flame. Exhaust air is expelled through a chimney, while heated air is returned through a flexible hose to the tented area. Indirect-fired air heaters can have heating capacities in excess of 900,000 Btus per hour.

Extreme caution should be taken when using any type of heating source on a construction site. Common hazards may include fire and explosions, asphyxiation, carbon monoxide, and burns. The location of the heaters should remain free of site materials and equipment. Proper ventilation and airflow should be maintained to any tented area where heating is present.

Workers who handle or connect propane-fuelled heaters must have a Record of Training (ROT) certificate which must be renewed every three years. There are legal requirements for the approval of equipment, the use of gas-fired equipment, and the storage and transportation of gas cylinders. The rules and regulations can be found in the Occupational Health and Safety Act, Transportation of Dangerous Goods Act, Technical Standards and Safety Act, which are overseen by the Technical Standards and Safety Authority (TSSA).

Courses are available to provide workers with the necessary training to safely connect, activate, and disconnect propane-powered equipment, as well as the safe handling, storing, and transportation of dangerous goods.

Working safely in the cold

[7]

Performing tasks in inclement weather and uncomfortable conditions is difficult. Although it is possible for workers to perform in these conditions, the reality is productivity will be less than what would be accomplished in warmer weather. Days are also shorter, coupled with the need for more breaks to rehydrate and warmup.

Therefore, being prepared is important. This begins by wearing the appropriate clothing and equipment. Workers should consider dressing in layers with clothing suited to the forecasted weather and temperature. By wearing layers, workers can remove clothing as they exert themselves, and replace them when they are cold.

Proper winter footwear, gloves, or mittens should be worn to protect feet and hands, as these extremities are generally the first to suffer from the cold. Monitoring for conditions such as frostbite, dehydration, and hypothermia are important, as well as recognizing their signs and symptoms. Frostbite occurs as skin tissue begins to freeze and, when left untreated, it can lead to permanent skin damage, infection, nerve damage, and potentially the loss of limbs. The signs and symptoms of frostbite may include:

• Cold, tingling sensations of the skin;
• Numbness of the area;
• Red, white, blue-grey coloured skin; and
• Hard, waxy skin appearance.

Workers should visually inspect each other for frostbite of the face and neck, as it tends to go unnoticed by those who are affected. Preventing frostbite is quite simple; therefore, workers should dress accordingly and go inside or to a heated area when experiencing symptoms or feel cold.

Dehydration can occur as the body conserves heat to stay warm. When the body is cold, blood vessels constrict to maintain the body’s core temperature. When this happens, workers can be fooled into thinking they are properly hydrated. With a diminished response to replenish liquids and an increase in urine production, workers can be equally as prone to dehydration in cold weather as they would be in warm weather. The signs and symptoms of dehydration may include:

• Fatigue;
• Dizziness;
• A state of confusion; and
• Dark coloured urine.

Mild to moderate dehydration can be reversed quickly by drinking more fluids and maintaining a steady intake throughout the day.

Hypothermia (when one’s body temperature falls below 35 C [95 F]) occurs when the body loses heat faster than it can produce it. When one’s body temperature drops to this level their internal organs, respiratory system, and nervous system cease to function normally. When left untreated, these systems begin to shutdown causing severe health issues and possibly death. The signs and symptoms of hypothermia may include:

• Shivering;
• Slow shallow breathing;
• Slurred speech;
• Low and weak pulse;
• Clumsiness or poor co-ordination;
• Low energy and fatigue; and
• A state of confusion or memory loss.

Preventing hypothermia is simple; workers should dress accordingly and be mindful of the signs and symptoms. They should also constantly warm up when they feel cold.

Having an organized and clean construction site is also important to worker safety. Debris and materials may become buried during a snowfall, which may pose a tripping hazard. Accumulation of snow and ice is also hazardous to workers—from slipping to falling from overhead structures.

It should be routine to remove snow and ice from the construction site by means of plowing or blowing.

With the ever-growing ingenuity and scale of projects being undertaken in colder climates, it only makes sense that an increasing number of builders will see the benefits of constructing pools year-round. Some may say building pools during the winter is wrong, while others may say those who do are a little crazy; however, this author enjoys the shear satisfaction of telling clients his company builds backyard retreats in the dead of winter.

[8]Michael Willis is an aquatic designer and partner at Roger Willis Contracting Ltd., an Ottawa-based pool builder specializing in unique, custom aquatic projects. He works in various fields—from project design to completion—and builds throughout eastern Ontario and the Caribbean. Willis is a member of the Master Pools Guild, Pool & Hot Tub Council of Canada (PHTCC), and Landscape Ontario Horticulture Trades Association. He can be reached via e-mail at michael@rogerwilliscontracting.com[9].

Source URL: https://www.poolspamarketing.com/trade/features/tips-for-builders-when-working-in-sub-zero-temperatures/

---