Types of Floor Truss Systems

Worker Spraying Blown Fiberglass Insulation between Attic Trusses
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There are many types of floor truss systems, some of which have been used extensively for hundreds of years. Trusses serve to make a floor stronger by combining the materials in an appropriate fashion. Trusses support the floor, ceiling, or roof above them and can last a very long time with minimal maintenance under normal conditions. One of the most popular floor truss systems is the standard parallel truss, but there are various others that are quite popular as well. Different styles provide their own advantages and disadvantages, and some are more suitable than others in certain applications.

1. Parallel Trusses

Parallel trusses are amongst the most common, as they are relatively uncomplicated and do not require quite so much wood to build. Parallel trusses, as the name suggests, consist of parallel beams to provide support for the roof above. When built to a quality specification using high quality materials, parallel trusses are more than adequate for the majority of uses. In spite of this, they do not provide as much stability as certain other floor truss systems, such as the Pratt truss system. They are less appropriate for supporting a floor upon which there will be a great deal of weight, especially if that weight is not evenly distributed across the floor.

2. Pratt Trusses

exposed floor joists

One of the older and most popular methods of providing support to a floor is the Pratt truss system. When constructing this type of floor truss, the first stages of it are very similar to the parallel system. However, for additional support and stability, diagonal beams will also be added between the two parallel lengths of wood. This provides far more stability than the standard parallel floor or roof truss system, but it also uses at least 50 percent more material, therefore making it considerably more expensive and time consuming to build. Pratt truss systems also make a floor less likely to creak when walking over the floorboards. This is because there is less give in the floorboards due to the diagonal beams that they lie upon in addition to the main parallel beams.

3. Wood Materials

Most floor truss systems, especially those used in houses, are made entirely from wood. For most utilities, using a truss system made entirely from wood is perfectly adequate. In spite of this, an appropriate form of wood should be used. Hardwoods are ideal. Oak is often used for supporting trusses in older houses, as it lasts for an extremely long time, requires little maintenance, and is more than strong enough for the job.

4. Wood and Steel Hybrid Systems

For buildings with multiple floors and a great deal of support required for the extra weight, a hybrid system is often used. This system uses steel bracers in addition to the wooden beams to provide extra support. With the addition of steel, trusses are much stronger, making them essential for certain applications. Due to the larger number of materials required, hybrid systems are more expensive.