Fabric Covered Structures for the Cold Housing of Livestock
Fabric-covered buildings have been around for a long time. They have become an accepted alternative for machinery storage, hay storage, and livestock housing (Figure 1). They can provide a low cost cold housing alternative to conventional housing provided producers are aware of the differences and prepared to work with them.
Many producers consider fabric-covered buildings as an alternative to conventional housing, because they feel that they are a lower cost option, bright, airy and well-ventilated. These things can be true if designed and managed properly, but producers need to understand what the limitations are and how to work with them.
Probably the number one reason why producers consider fabric-covered buildings is because they believe they are a lower cost alternative to conventional post frame buildings. If you are considering one based on cost make sure you do an "apples to apples" comparison. A fabric-covered building is not the same as post frame or stud frame building. When calculating the cost of a fabric-covered building make sure the cost includes the complete structural package including, end walls, doorways, and ventilation options. End walls and doorways are sometimes missing from a quotation. Other things like site preparation, foundation, and setting up the structure need to be considered, but that should be part of the costing for either structure.
The other item that can be quite different when comparing the two structures is insulation. Producers often overlook the fact that fabric-covered buildings are NOT insulated. They are a cold environment barn. It is very easy to add a minimal amount of insulation under the roof steel of a conventional building to reduce condensation, at a nominal cost. Fabric-covered buildings are not insulated, therefore they will drip. On a cold clear night frost will form on the underside of the fabric, and when the sun comes out in the morning, the frost will melt and drip on whatever is below. This usually only lasts for 20 to 30 minutes, but if you can't put up with this annoyance don't consider an uninsulated building.
Bright and Airy
Producers like the fact that fabric-covered buildings are bright and airy. The light and openness of the buildings have the appeal of being in the "great outdoors". The most common colour of fabric used today is white. Clear fabric lets more light in, which is nice during cold weather, but then the building heats up too much in the summer. The white fabric allows ample light in both winter and summer, without the building heating up too much during hot weather.
A building can be open without being well-ventilated. Because of their shape, fabric-covered buildings have lots of air volume, which does help with ventilation, but in order to be ventilated properly they need air inlets and air exhaust opening, just like any other livestock structure. If a fabric-covered building is to be used to house livestock it will need adjustable openings on both sides, usually in the form of curtain walls, and exhaust openings in the peak, usually taking the form of chimneys, or possibly an open ridge. The only exception would be a smaller fabric-covered structure that is less than 100 ft long. A shorter fabric-covered structure can be ventilated successfully end to end using end opening doors for hot weather and shade cloth in the gable ends during the cold months of the year. Shade cloth breaks the force of the wind and allows air to filter through. It is a good idea to cover the shade cloth in the gable ends with an adjustable curtain to control the amount of opening.
The fabric-covered structures are often installed on posts, so that the straight wall of the posts can be used to provide the adjustable curtain inlets. The chimneys should be sized to provide about ½ ft2 of chimney opening for every 100 ft2 of floor area for exhausting stale air (Figure 2).
Producers are concerned that the fabric will wear out over time and need to be replaced. This is not much different than a painted steel roof that will need repainting down the road. However, it is important to keep the fabric taut. The roof material is held in place with belt tighteners. It is important to keep the fabric under tension, so that it doesn't move and wear on the support frame. It is also important to repair any mechanical damage as soon as it happens. If the fabric is ever punctured or torn by a front end loader or something else, it is important to repair the hole or tear with special tape so that it doesn't get worse. Wind can cause a small tear to increase rapidly.
Due to their size and shape, fabric-covered buildings are subject to wind loads, especially uplift. It is important to have the support posts anchored properly, and the frame bolted to the post properly so that the post does not lift from the ground, or the frame from the post.
It is also important to clear away the snow that slides off the roof away from the sidewalls. If the snow is allowed to accumulate too high on the sidewalls it may cause extra lateral loading that the structure was not designed for. Snow along the sides may also block ventilation.
Fabric-covered buildings can provide a low cost alternative for livestock that can be housed in a cold environment, provided the producer knows the limitations and how to work with them. Properly designed, they provide a bright airy well ventilated environment that can be a pleasure to work in.
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|Author:||Harold House - Agricultural Engineer, Beef Structures/OMAFRA|
|Creation Date:||30 October 2013|
|Last Reviewed:||30 October 2013|