By Gregory Havel
At times during the life of any building, temporary structures are erected over, around, or inside of it. These structures may be for cold weather protection during construction or remodeling, to protect the rest of the building from dust and other contaminants during remodeling or maintenance work, or to allow the building or parts of it to be fumigated to remove or prevent a pest problem.
These temporary structures have common features; they are usually made of a lightweight frame of wood or metal that supports a tent of sheet plastic. Hopefully, the sheet plastic is reinforced with threads and impregnated with a fire retardant.
Photo 1 shows the exterior of a heated temporary enclosure built on steel scaffolding; it is done this way so masonry work can continue during below-freezing temperatures.
(1) Photos by author.
Photo 2 shows the interior of the heated temporary enclosure with two propane-fired heaters. Fuel is stored in a 500-gallon horizontal tank outside the enclosure and brought to the heaters by flexible hoses rated for low pressure use. The reinforcing threads in the sheet plastic are visible on the right, above the flame-retardant-treated canvas that is used for the bottom of the enclosure. Note that the scaffold frames are linked together vertically and horizontally, that they stand on mud pads in contact with the soil, and that the screw jacks are used to ensure that the entire scaffold remains plumb and level.
Photo 3 shows a similar enclosure before construction of the masonry wall has begun.
Scaffolding without an enclosure lets the wind blow through and is safe for workers in winds of 30 miles per hour. Adding a sheet plastic enclosure creates the risk of the scaffold blowing over. To prevent this, the top of the enclosed scaffold is sometimes tied with cables to steel stakes driven into the ground. A more common practice is to load the scaffold with more pallets of concrete block or brick than will be used in the enclosure. The weight of the materials on the scaffold gives it stability that it would not otherwise have.
Temporary structures like the ones in these photos are of concern to firefighters because of the following:
- They can burn rapidly especially if they are not made of flame retardant-treated materials.
- Fires in these enclosures can be accelerated by fuels, especially if the fuel tanks or cylinders are not stored outside the enclosure.
- The presence of the temporary enclosure can interfere with firefighting or rescue operations in the building.
- Access to the interior of the temporary enclosure is often awkward and may require larger additional openings in the event of a medical emergency inside.
- Access to the location of the temporary enclosure is often difficult because of ground conditions like frozen ruts, snow piles, soft ground, and mud.
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MORE CONSTRUCTION CONCERNS
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- Construction Concerns: Plaster
- Fire Building Construction: Masonry Defects: Arches
- Fire Building Construction: Tall Buildings
- Firefighting Article: Construction Concerns: Infiltration
- Construction Concerns: Little Boxes on the Hillside
Gregory Havel is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 35-year veteran of the fire service. He is a Wisconsin-certified fire instructor II, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 35 years of experience in facilities management and building construction; and has presented classes at FDIC.