When remodeling a home, you may find that a floor joist needs to be replaced. Finding damaged joists in older homes is a common occurrence. A damaged floor joist can cause the floor to be weakened and fail if it isn't remedied. Before replacing a floor joist, you need to know what damaged it. The two common culprits of damaged wood are water and termites. Each type of damage requires a solution before a replacement joist can be installed. As a homeowner, you want to lower your risk for future problems. A leak or hungry termites will damage new wood in a recurring cycle.
Things You'll Need
- Tape measure
- 16d nails
- Circular saw
- Joist hangers
- Hydraulic jack
- Wood glue
- Cinder blocks
Enter the basement or crawl space to evaluate the extent of the damage to the floor joists. When a termite problem is present, it is likely that other joists are damaged. Check for cracks in the crawl space perimeter or above a floor joist that shows water damage. Fix these problems before proceeding.
Measure the length and width of the old joist. Joists come in standard sizes of 2-by-8 inches, 2-by-10 inches and 2-by-12 inches. Depending on the construction method used, a particular joist might have a block brace under it.
Take your measurements to the hardware store. Buy two boards the same width and length as your old joist, and four joist hangers to fit them.
Rip the new boards with a circular saw to get a custom fit; the new lumber may be a slightly different size than the old joist. Cut 3/8 inch off the bottom corner on one side of the new joist, using the circular saw set at a 45-degree angle. Cut 3/8 inch off the top corner on the other side of the new joist in the same way. This will give you some wiggle room when installing the joist.
Line up the new joist next to the old joist. Lift it into position. Make sure the replacement joist sits firmly on the sill plate. Tap the joist gently into place with the hammer. Slip a joist hanger on each end of the new joist.
Attach the joist hanger to the replacement joist and the sill plate by hammering 16d nails into each hole in the joist hanger.
Insert the second replacement joist on the other side of the old joist. The old joist will now be sandwiched between new wood. The new wood will be attached to the old wood after the old wood is braced.
Lay a scrap piece of lumber across the jack plate of a hydraulic jack. Position the jack and the scrap wood under the break in the joist. Jack up the joist slowly, repositioning it as you go. You want to fit the joist back in its old spot to be mended.
Apply wood glue to the replacement joist to minimize the squeak of new wood and create a tighter bond. Nail the second replacement joist to the original joist. Offset the nails mending the two joists together. Toenail -- hammer nails in at an angle -- any brittle wood to prevent splitting.
Place new braces under the replacement joists if the original joist had them. Insert scrap pieces of wood -- such as two-by-fours or plywood squares -- as shims on top of the brace if you can see gaps between the brace and the joist.
- Fine Homebuilding: 6 Ways to Stiffen a Bouncy Floor
- "What Your Contractor Can't Tell You: The Essential Guide to Building and Renovating”; Amy Johnston; 2008
- “Renovating Old Houses: Bringing New Life to Vintage Homes”; George Nash; 2003
- Photo Credit Hemera Technologies/AbleStock.com/Getty Images
How to Replace Rotted Floor Beams
Rotted floor joists may be caused by a variety of reasons. Although strong, joists can be damaged by extensive exposure to water...
How to Replace the Rotted Floor Joist of a Garden Shed
Strong wooden beams help add stability to the floor of a garden shed or any other structure. Unfortunately, excessive moisture, termites and...
How to Install Floor Joists
A nice, solid floor is a must in any home and installing floor joists is something you can do yourself.
How to Replace a Rotten Floor
Rotten flooring can damage more than just the floor of a house. It can make wall construction weak where it meets the...
How to Repair a Ceiling Joist
A damaged, broken, or cracked ceiling joist can cause a ceiling to sag and should be repaired as soon as possible. If...
How to Repair Termite Damage to a Floor Joist
If termites have eaten through part of a joist under your floor, the first issue is to stop the infestation, by hiring...
How to Install a Rim Joist
A rim joist is found in the subfloor of a house. It is the end piece around the room that completes the...
Repair Techniques for Floor Joists
Floor joists are the large beams that support the floors in your home. When they are spaced too far apart to handle...