You may be working on building a house and have gotten to the point when the ceiling joists are constructed. However, you are presented with the option of installing spliced ceiling joists, but when is the appropriate time to use them?
Ceiling joists should be spliced if a very long interior joist is required, the joists crack or split during transport or construction, or if parts of the joist have been removed during previous renovations.
In this article, you will learn how to splice ceiling joists, when you shouldn’t splice ceiling joists, whether or not ceiling joists abide by building codes, as well as how to strengthen ceiling joists.
How Do You Splice Ceiling Joists?
Before splicing ceiling joists, measure the length needed for the full joist and mark on each two by four where they will be joined together. On the sections that will connect the two joists, spread construction adhesive, preferably of a waterproof variety, and put the joists together. If you are splicing due to breaks or cracks, make sure these areas are included in the splice.
Use four inch screws to secure the board connection on each end and stagger screws throughout the joist to hold the splice together. Make sure that the screws go through both joists but do not go all the way through to the other end. If you can see the tip of the screw, you’ve driven it too far and need to back it out a bit.
Splicing ceiling joists will give you the length and stability you need for interior ceiling support as long as you join the two by fours properly. Failure to secure the splice could result in major structural damage and building code violations.
When Can You Not Splice Ceiling Joists?
Spliced ceiling joists only strengthen the integrity of the ceiling; however, they are unnecessary if the length between exterior supporting walls is short enough to accommodate a single two by four beam. Splicing the joists together unnecessarily can add weight to the structure of the ceiling which may introduce the increased possibility of collapse later on.
Ceiling joists should not be spliced without the use of the proper construction materials. Splices that are constructed without an adhesive are more likely to split over time since they are only held together with nails or screws. Likewise, if spliced joists are only screwed together on the ends and applied with adhesive but have no interior support screws, they are vulnerable to splitting.
Although cracked joists can be reinforced by splicing, completely compromised wood that is rotted or has multiple fissures should not be used at all for ceiling joists. Splicing a good two by four to a weak board will sacrifice the structural integrity of both boards and could result in the collapse of the joist.
Are Spliced Ceiling Joists Up to Code?
Spliced ceiling joists are approved by building codes and, in fact, required for certain cases especially when the spanning length of the ceiling needs extra reinforcement. Building inspectors often pay close attention to spliced ceiling joists since there are commonly used to support load bearing walls.
Inspectors will make sure that the beams are properly spliced by checking the number of supportive screws and ensuring that there is a proper length overlap and the beams are flush with each other. Spliced ceiling joists are often preferred over continuous joists in the event that exterior walls are spaced far apart.
The length of the overlapping beams needs to be equal on either side of the load bearing wall which the spliced ceiling joists support. Failure to comply with proper building codes when it comes to spliced ceiling joists could result in a failed building inspection. If this occurs, the inspector will advise you on how to proceed.
You may be required to fix the splice by correcting the existing issues or adding another two by four to the splice. Alternatively, the ceiling joists may need to be taken down and reinstalled entirely. Always make sure you read, understand, and abide by building codes before installing spliced ceiling joists.
How Do You Strengthen Spliced Ceiling Joists?
Spliced ceiling joists, if constructed correctly, provide great support, especially for load bearing walls. There are several ways to further strengthen the capability of spliced ceiling joists. The more screws or nails you add to the combined joists, the stronger the hold will be. Stagger the application of nails and screws evenly among the boards for the best result.
Additionally, using the correct construction adhesive will only enhance the structural support of the joists. There is a minimum overlap length you should adhere to when creating a spliced ceiling joist; however, increasing this length will give more support to your ceiling.
If you are renovating and a spliced ceiling joist needs reinforcement, adding another two by four will increase the structural support of the beam without having to remove and reinstall the spliced joist.
The best way to ensure the strongest spliced ceiling joists is to use the most optimal materials including wood, fasteners, and adhesive. Taking the time to measure out the required lengths and following the best practices according to building codes will also ensure that you construct a joist that will remain structurally sound.
Conclusion
Spliced ceiling joists are commonly used when the span of exterior walls is greater than the length of a continuous beam. They can also be used to reinforce cracked wood and lend support to load bearing walls. Spliced ceiling joists are approved and recommended for use by building codes to ensure the structural integrity of the ceiling.
Adding beams and more fasteners to the spliced joist will increase its strength. Spliced ceiling joists should always be constructed with both adhesive and fasteners. The length of overlap should be equal on either side of the wall they support. Always inspect your materials before use and measure out your beams to ensure the best possible construction of your joists.