Floor Joist Braces Ducts

Cross bracing and solid blocking.

Floor joist braces ducts.

While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. Finally if all else fails drop your pipes and ducts down below the joists and box them in with wood framed. Figure 4 2 x 4 installed below duct work table 1 provides the correct quantity of bridging relative to the span of the floor joist. But without proper support ducts can develops sags or kinks that reduce airflow 4a 4b.

Sometimes the best route for a flexible duct run is up and over an obstruction. To make matters worse the old metal ducts leak a ton or maybe two and there is a small sewage leak in the crawl located right under one of the pans. I did an audit on a house the other day and they have several of them. Although not as good as solid or cross bridging a 2 x 4 supporting the duct work as shown in figure 4 would provide more support and load sharing than a light piece of metal.

House is 1959 original floors. Floor joists are 2x10s the floor appears to be fullly nailed down solid 3 4 planks. Joist span and spacing is set by your local building code. Make sure not to install joists so they run parallel to and directly under walls where you intend to install ductwork.

When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. Duct work is mostly 8 round but going to get some oval. Walking on joists before all accessories and floor decking are installed i joists are unstable and can roll over if walked on leading to injuries. Bracing will stiffen a floor system prevent floor joists from twisting and increase overall stability however there are actually two types of floor joist bracing commonly used.

To prevent problems use saddles or straps to support at regular intervals 4c 4d follow the manufacturer s instructions but in case they get lost here is a list of best practices for. Don t allow your crew to walk on i joists or install subfloor sheathing until all hangers blocking panels and temporary safety bracing strapping are fully installed. Position bathroom vent fans so the ducts can run parallel to the joists right up to where they exit the house.