It is sometimes necessary to attach floor joists to existing concrete walls as part of a home’s floor structure. Installing a ledger board that matches the joist size is the most common method of securing floor joists to concrete walls. A typical two by 8-floor joist construction method ensures proper support for the floor joists. It is also possible to modify the installation procedure according to the size of the floor joists.
The Proper Way to Attach Floor Joists to an Existing Wall
It is possible to connect floor joists to existing walls. Knowing the tricks and tips will help you get the job done. You may have to do this if you are finishing your basement or remodeling an addition with Existing Wall. In any case, this is not an impossible task, but it will require the right tools.
Here Are Some Things You Will Need
- Tape measure
- Chalk line
- Framing square
- Level
- Power drill
- 9/16-inch wood drill bit
- 5/8-inch masonry bit
- 2/8 pressure-treated lumber
- 1/2-inch by 3-inch concrete anchors
- Epoxy cement (optional)
- 1/2-inch diameter by 4-inch steel bolts
- 1/2-inch flat washers
- 2/8 joist hangers
Think about Your Options
You have a few options when you connect floor joists to concrete walls. The cheapest way to do this is to purchase masonry nails. Using them to connect concrete with wood works well. Also, you might want to try masonry screws. Hardware stores usually call masonry screws blue screws or “Tapcons.” A masonry screw must be able to penetrate the concrete wall when you choose it. Using screws measuring 1 3/4 inches or 1 inch in diameter is usually sufficient.
Masonry Nail
It would help if you drove the nail between the mortar blocks. Masonry nails are most commonly screwed into the actual blocks themselves. When you push them into concrete blocks, masonry Nails will hold much better, and the blocks won’t break as easily.
Masonry Screws
Predrilling the holes into which masonry screws will go is the first step in using them. Ideally, the diameter of the holes should range from 1/16 inch to 1/32 inch. Drill the holes into the concrete block wall; you will attach the wood when predrilling. Moving slowly and with patience when using a hammer drill is essential. Make sure you are not doing all the work since drilling a concrete block. Apply enough pressure, so you are backing up the predrill as it does its job.
Project Step-by-Step
Step 1
Make a mark at both ends of the concrete block wall at the level of the top surface of the floor joists. Measure the distance between the patterns and draw a chalk line between them. Check the chalk line with a level after establishing a guideline. Ledger boards will have this guideline defining their top edge.
Step 2
To cut 2/8 pressure-treated lumber to the specified length, measure the horizontal length of the concrete block wall. We will make the ledger board(s) using the cut boards. If your construction plans call for a different joist dimension, you must cut the appropriate lumber size for ledger boards.
Step 3
Make a note of the locations of anchor bolts. Measure the entire length of the ledger board(s) and place 30-inch interval marks over the whole length. Mark each ledger panel separately if it consists of more than one piece. Using a framing square, extend each pattern across the width of the board(s).
Step 4
On your ledger board, mark every other line 3 inches in from the edge. Using this method, you will draw the centers of anchor holes on one edge of the ledger board.
Step 5
Repeat Step 4 at the opposite board edge for the anchor bolt positions to create a zig-zagged pattern.
Step 6
Each ledger board should have an additional anchor bolt centered in width, 3 inches from each end.
Step 7
At each anchor bolt center point marked on the boards, drill a 9/16-inch hole.
Step 8
Mark each drilled anchor bolt hole on the wall with the ledger board(s) next to the chalked guideline. If you want to mark the concrete, insert a nail set and tap it with a hammer into each hole. Following the marking of anchor holes on the concrete wall, set aside the ledger board(s).
Step 9
Using a power drill and a 5/8-inch masonry bit, drill a horizontal hole in each anchor bolt location on the concrete block wall. For about 2 1/2 inches of anchor lengths, dig the spot at a depth matching that length. Blow or brush away the concrete dust when you have completed each hole.
Step 10
Use concrete anchors to secure any holes drilled in the concrete block wall.
Step 11
Orient the ledger board’s top edge with the chalked guideline by repositioning it against the wall. Install a bolt into each anchor location after sliding a washer onto a 1/2-inch by 4-inch steel bolt. Secure the ledger to the concrete block wall by tightening each bolt with an adjustable socket wrench.
Step 12
If additional ledger boards are required, repeat Step 11.
Step 13
Utilizing a framing square, mark the layout of the floor joists along the ledger boards installed previously.
Step 14
Using standard framing practices, install one joist hanger at each floor joist location.
Helpful Tips
It is easier to mark the anchor bolt locations for the ledger boards and install them with assistance. It is possible to strengthen the anchors’ attachment to concrete block walls by coating them with epoxy cement during installation. Ensure the epoxy does not get into the anchor threads and prevent the bolts from being installed properly.
However, it is possible to use concrete anchors for floor joists that run parallel to concrete block walls. And this may require pressure-treated floor joists against the block wall.
Precautions
It is always important to keep safety in mind when working on such a project. Safety glasses are a necessity. You should wear safety glasses when pre-drilling the holes for the masonry screws. A severe injury could result if safety precautions are not taken. This task should only be accomplished using masonry screws and nails.
Warning
It is possible to attach wood framing to block walls using a variety of concrete wall anchors. Before selecting the wall anchor for this project, consult your local building department for information regarding local code requirements. All wood installed directly with concrete or another masonry must be pressure-treated to resist mold and rotting.
Frequently Asked Questions
Can I Use Joist Hangers for Floor Joists?
In addition to simplifying framing, joist hangers strengthen your deck or floor. Use joist hangers when hanging floor joists for more straightforward floor deck construction. On a 16-inch center line, place hangers every 16 inches. Position each hanger using the tab to hold it in place.
Is a Joist Hanger Stronger Than Nailing?
It is more accurate to place joists using joist hangers. Moreover, they support the joist’s underside and allow for toenailing. The hanger is, therefore, more durable than a toenail. Despite their expense, joist hangers offer greater strength and ease of use.
Conclusion
Floor joists are an essential component of a building’s structure. They help keep the house solid and durable for a long time because they run horizontally across the span of the house. Besides providing a foundation for the subfloor, floor joists also support the subfloor. In a room, floor joists hold up the floor and whatever else is inside.
Choose the proper Room floor joists (materials, sizes.) for your specific needs. A structural engineer must calculate joist requirements following the building’s engineering and local building codes, even though span tables and calculators help determine the required joist specifications.
