The rim joist is a critical structural component of your home’s floor system, running along the perimeter of the foundation and supporting the ends of the floor joists. Over time, due to moisture, rot, or termite damage, this essential piece of framing can deteriorate, compromising the structural integrity of your house. Replacing a damaged rim joist is a major repair that involves temporarily supporting the weight of the house. This is a project that strikes fear into the hearts of many homeowners.
While this task is serious and requires extreme caution, understanding how to jack up a house to replace rim joist is possible for a very experienced and confident DIYer. It is a process that demands careful planning, the right equipment, and a slow, methodical approach. This guide will provide a detailed, step-by-step overview of the process, emphasizing the safety and precision required for this advanced structural repair.
Why This Structural Repair Is So Important
A rotted or damaged rim joist is a serious structural problem that cannot be ignored. It directly supports the weight of your exterior walls and the ends of your floor joists. A compromised rim joist can lead to sagging floors, cracked drywall, and doors that no longer close properly. If left unaddressed, the damage can worsen, threatening the stability of your entire home. Properly jacking the house to perform this joist replacement restores the foundation support, halts further damage, and ensures the long-term safety and structural integrity of your property.
8 Step-by-Step Guide: How to Jack Up a House to Replace Rim Joist
Step 1: Assess the Damage and Plan the Repair
Before you even think about lifting a house, you must conduct a thorough assessment of the damage. Identify the full extent of the rot or decay in the rim joist and the adjacent floor joists. You need to determine exactly how many feet of the rim joist need to be replaced. This assessment will dictate the number of jacks you need and the length of your temporary support beam. Plan to replace a section slightly larger than the visibly damaged area to ensure you are tying into solid, healthy wood. Meticulous planning is the most important part of this entire operation.
Step 2: Gather Heavy-Duty Tools and Materials
This is not a typical DIY project; it requires specialized, heavy-duty equipment. You will need several hydraulic bottle jacks, typically in the 12- to 20-ton capacity range. You will also need temporary support posts (4x4s or steel screw posts) and a long, strong temporary beam, often made from laminated veneer lumber (LVL) or multiple 2x10s nailed together. You’ll also need pressure-treated lumber for the new rim joist, a reciprocating saw, a circular saw, a pry bar, a sledgehammer, and all necessary safety gear, including safety glasses and heavy-duty gloves.
Step 3: Build a Solid Foundation for the Jacks
You can never place a jack directly on a basement floor or on bare ground, as the immense pressure will crack the concrete or sink into the dirt. You must build a solid, temporary foundation for each jack. This is typically done by creating a cribbing base out of stacked 4×4 or 6×6 lumber pieces, or by placing the jack on a solid concrete block with a thick piece of steel and plywood on top to distribute the load. This solid footing is absolutely essential for stability and safety during the lifting process.
Step 4: Position the Temporary Support Beam and Jacks
With your jack foundations in place, position the long temporary beam parallel to the rim joist you are replacing. This beam should be placed directly under the floor joists, about two to three feet away from the foundation wall. Now, place your hydraulic jacks and support posts under this temporary beam, spacing them approximately every four to six feet. The goal is to create a new, temporary support system that will carry the entire load of the floor and walls above once you begin the lift. This setup is the core of how to jack up a house to replace rim joist.
Step 5: Begin the Lifting Process Slowly and Evenly
This is the most critical and dangerous part of the job. Using your hydraulic jacks, begin to lift the house ever so slightly. The key is to work slowly and evenly across all the jacks. Go from jack to jack, giving each one just a quarter-turn or a single pump at a time. You are only aiming to lift the house by about 1/8 to 1/4 of an inch—just enough to take the weight off the damaged rim joist. Listen for any cracking or popping sounds and watch for any signs of distress in the structure above.
Step 6: Remove the Damaged Rim Joist
Once you have successfully taken the load off the old rim joist, you can begin the removal process. If the sill plate beneath the rim joist is also damaged, you will need to remove both. Use a reciprocating saw to cut the nails connecting the floor joists to the rim joist. You may also need to cut the rim joist into smaller, more manageable sections to pry it out. This can be tough work requiring a pry bar and sledgehammer. Be careful not to damage the surrounding floor joists during removal.
Step 7: Cut and Install the New Rim Joist
Measure the space precisely and cut your new, pressure-treated rim joist to fit snugly into the opening. You may need to use a sledgehammer to gently tap the new board into its final position. If you are replacing a long section, you may need to use multiple pieces, ensuring the joints are staggered and well-supported. Once the new rim joist is in place, secure it by driving galvanized nails through the floor joists and into the new rim joist, a process known as end-nailing. This is a crucial step in learning how to jack up a house to replace rim joist.
Step 8: Slowly Lower the House
With the new rim joist securely installed, you can begin the process of lowering the house back down onto its new support. Just like the lifting process, this must be done very slowly and evenly. Go from jack to jack, releasing the pressure in tiny increments. A sudden drop can shock the structure and cause significant damage. Continue this gradual process until the full weight of the house is resting firmly on the newly replaced rim joist and the foundation’s sill plate.
Key Safety Precautions
- Work Evenly and Gradually – Always raise or lower the house in small, equal increments across all jacks to prevent structural stress or damage.
- Inspect Equipment – Ensure all jacks and supports are in good working condition and rated for the required weight before starting.
- Secure the Structure – Make certain the house is properly stabilized to avoid unexpected shifts during the process.
- Monitor Surroundings – Keep a safe zone around the working area and ensure no one stands under the house during lifting or lowering.
- Avoid Sudden Movements – Take care not to release pressure or adjust jacks too quickly, as this can cause abrupt shifts or drops.
Frequently Asked Questions
How Much Does It Cost to Replace a Rim Joist?
The cost can vary dramatically. If you are an experienced DIYer tackling the job yourself, your main costs will be for tool rental (heavy-duty jacks) and materials, which could be several hundred dollars. If you hire a professional foundation repair company, the cost can range from $2,000 to $10,000 or more, depending on the extent of the damage and the complexity of the job.
What Causes Rim Joist Damage?
The most common cause of rim joist damage is moisture. Water splashing up from the ground, leaking gutters, or improper exterior grading can saturate the wood, leading to rot. This area is also a prime target for termites and other wood-boring insects. Inadequate flashing around decks attached to the house is another frequent source of water intrusion.
How Do I Know If My Rim Joist Is Damaged?
You need to perform a visual inspection from your basement or crawlspace. Look for wood that is dark, discolored, soft, or crumbly. Probe the wood with a screwdriver; if it sinks in easily, you have rot. Other signs include a musty smell, visible mold or fungus, or evidence of termite tunnels.
Should a Rim Joist Be Pressure-Treated?
Yes, absolutely. Because the rim joist sits directly on top of the foundation, it is highly susceptible to moisture. Any replacement rim joist lumber should always be pressure-treated to resist rot, decay, and insect damage, ensuring a long-lasting and durable repair.
Is This a DIY Project or Should I Hire a Pro?
This is an advanced structural repair that carries significant risks. While it is technically possible for a very experienced DIYer with a deep understanding of house framing and safety procedures, it is strongly recommended that most homeowners hire a professional foundation repair contractor. The potential for catastrophic failure is high if the job is done incorrectly.
Conclusion
The procedure for how to jack up a house to replace rim joist is one of the most serious structural repairs a homeowner can face, but it is essential for maintaining the safety and stability of your home. It is a project where precision, patience, and an unwavering commitment to safety are paramount. From building a solid base for the jacks to the slow, methodical process of lifting and lowering, every step must be executed perfectly.
While this guide provides a detailed overview, the inherent risks of this job cannot be overstated. For most, the wisest course of action is to entrust this critical task to a qualified professional. However, understanding the process gives you the knowledge to oversee the project intelligently and appreciate the complexity of your home’s structure.