What Is a Rim Joist?
If you want to know what rim joists are then you should know about Joists first. In a house’s floor frame, there are many structural elements.
Some of these structural elements are primary structural elements. Joists are one of these primary structural elements of the house floor frame.
Joists are like ribs of the floor frame. They build up the structure of the frame of the floor and then the joists are covered with plywood.
The plywood subflooring completes the platform of the floor. On the outside ends of the joists, they are supported by the foundation structure or walls.
In an under-construction building, you can find rim joists. Along the bottom of each floor level, you could see a solid band of lumber running. These are rim joists. The main structural element of a ceiling or a floor frame is called the rim joists.
The joists that are used to make the ceiling and the joists that are used to make the floor are formulated by using lumber of different sizes. It can be either a different-sized 2x standard lamb or engineered lumber.
After the framing work is all done, using plywood subfloor material floor joists are covered, and then for finishing, flooring like wood, carpet, or tiles is used.
The space between the joists in the center is a minimum of 16 inches. A Rim joist is a structure that is made of wooden material.
The rim joists keep the floor frame wrapped from all sides. In an under-construction house when the floor frame is being prepared, you will see a band of permanent lumber that runs along the side of the floor frame. This lumber is called a rim joist.
Rim joists are made to give additional stability and strength to the other joists used in the floor frame. Both ends of a joist typically are nailed into somewhere in the rim joists.
It does not let the floor joists tip over to the side. Also, rim joists provide floor joist strength and keep the floor level and upright. After measuring and cutting the material, nails are driven into the floor joists from the rim joists.
Rim joists are placed on the top of the footing wall sill plate. If another wall has to be built then it can be built on top of the rim joist but before doing it, on the subfloor, the plywood must be installed.
A rim joist can be a load-bearing structure but it also may not be a load-bearing structure. It depends on whether something is built on top of it.
What Are Rim Joists For?
The most important purpose of rim joists is to deliver support to the other floor joists. To both ends of floor joists, rim joists are nailed. It creates a strong, upright, and leveled outer edge.
On the edge of the floor, joist wood is nailed. This helps the floor to stay stable and keeps the floor joists strong and level.
On the base of a house along the perimeter rim, joists run. In many cases, people built exterior walls on top of rim joists. Building External walls make the rim joist a load-bearing structure.
If you run any pipe through the basement of your house, you will have to drill through the rim joist to fetch it to the outside.
To keep a house strong and tie the floor framing and wall together, you will need some wood chunks where you will be able to put nails. Rim joists provide this chunk of wood.
In the case of decks, rim joists are not considered a weight-bearing structure because there is no wall built atop the deck. But still, rim joists are very important. Rim joists keep the floor upright and give strength.
Rim joists also can support stairs and for additional strength, railing posts can be bolted into the rim joist. Rim joists are also called by another name. They are also called band joists. They provide support laterally to the joists.
Rim joists protect the joists from leaning which is caused by the weight of load-bearing walls built on them. Another important feature of rim joists is that rim joists cover the joist cavity. The joist cavity is the space between two joists.
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Rim Joist Size and Materials
The material that rim joists are made of is not different from the materials that are used to make other joists.
It is the same material. If the frame is made of wood material then the rim joist would also be made of wood. If the frame is made of steel then rim joists made of will be used. In some cases, the rim joist used is made of different materials from the frame.
They use rim joists made of steel with frames made out of wood. The architect or the engineer desires the nature of the materials of the rim joist and frame used. It also depends on the desired strength of the frame.
The size of the rim joist is not different from the size of other joists. It is the same. So it keeps the rim joist level with the upper side and the lower side of the frame.
In some cases, the size of the rim joist and the size of other joists are different. If specifically said the rim joist is made smaller than other joists. In such cases, a hanger is used on the floor joists to secure the rim joist.
2x Framing lumber like the 2x 12 s, and 2x 10s is the most common material used to make rim joists. Joists can also be made of TJIs. It is a type of engineered wood and it is a very strong material. This lumber is bigger than standard lumber.
In many cases, traditional lumber and engineered lumber are used together. Most architects use TJI floor joists and traditional floor joists of standard size 2x 12 together.
In some specific cases, steel joists are also used as rim joists, and with the steel joists, traditional lumber and engineered lumber are used together. It depends on the design of the floor and the weight-bearing capacity.
Do I Need a Rim Joist?
Yes. Of course, you need a rim joist in the floor frame of your house or the deck. Rim joists close the open space created along the four outer sides while making the frame. To make a proper edge of the floor frame you will be needing rim joists.
It does not matter what type of floor framing you are creating, you have to attach rim joists. In the floor frame, assume that you are using standard 2x 10 joists.
There is approximately 16 inches distance between two joists. You will have to attach a ledger at the back of each joist. This gets bolted to the house. The ledger is the rim joist of the back.
Whether it is a house or a building, a shed, or a deck, whatever it is, if it has a floor frame then you will need rim joists. In some special conditions, the rim is structural. Rim joists give support to the floor sheathing as The rims sit on top of the frame.
For this reason, the rim joists must be strong enough. So the rim is secured to the floor frame. Another reason you need to attach rim joists is that rim joists help to hold the rail posts.
If you are building a deck, then most likely, you will attach rail posts. For this, you can bolt or nail through the rim joists. Rim joists are also a great place to secure a stair stringer.
Can You Drill Through a Rim Joist?
Yes. You definitely can drill through a rim joist. If you run a pipe, wire, or vent through your basement, then you will have to drill through the rim joist.
One thing should be kept in mind while drilling a hole through a rim joist. If the hole gets bigger, then it will decrease the strength of the floor frame. You can drill a hole through a rim joist, but the hole should not be very big.
After the installation process is over, make sure to insulate the hole with something. To see gaps and small cracks, use foam. Spray it over the area, and you will notice if any crack is there. Foam not only works as a great insulator but also keeps pests away from your house.
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What Is the Difference Between a Band Joist and a Rim Joist?
As mentioned earlier, the band joist and rim joist are the same things. There is no difference between these two terms.
Rim joists are attached to the frame joists perpendicularly. Rim joists cap off the open ends of a floor frame thus providing lateral support. This part can be called by both the terms a rim joist and band joist. Both the terms indicate the same thing.
Can Rim Joists Be Replaced?
Many folks seem to be confused about the replacement of rim joists. Whether replacing it is possible or not. Well yes, it is. Rim joists can be damaged by many things like rain and insects. So if a rim joist is damaged you will have to replace it with a good one.
Cut out the damaged part from the rim joist. Replace it with perfect measurements. This process is done from the outside of the house. At first, the removal process of the damaged part begins with removing the sliding and sheathing parts that expose the rim joist.
Some strappings, bolts, and hangers also needed to be removed. If any piping, wiring, or vents are there then remove them before cutting out the damaged part. After the completion of the entire process reinstall the waiting, piping, or vents.
If the floor frame is too old and not in very good condition then it is better to use some support while removing the damaged section. So before you start the removal process check everything carefully and then initiate.
After you have done the inspection, take proper measurements of the damaged section. Cut the damaged section as per the measurements. Replace this section with new material. Reinstall the wiring, piping, vent hanger, sheathing, straps, and hangers. And now the floor is all set.
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How to Install Rim Joists?
Rim joists run in a specific direction. This direction is determined by the architect and engineer. But commonly in a rectangular house rims run from the front to the back of the house. Running the rim joists this way requires the least amount of material.
Architects or engineers want to use as least material as possible. Because short joists prevent flexing, they try to prevent the structure from flexing. The joists need to be as long as the span is.
Each of the rim joists runs parallel to the longer side of the house if it is rectangular. For this reason, rim joists take a perpendicular position to other joists.
The floor joist of the outermost side is called the end joist. They are not to be mistaken as rim joists. Rim joists are always fixed in a perpendicular position. Spotting rim joists is very easy as they look like the letter T if seen from above.
Rim joists are fixed either on the upper-level walls or the foundation walls. The upper-level walls mean the top palate and the foundation walls mean the sill palate. Then framing nails are used to frame them into the palate.
To reinforce the connection metal straps can be used. These metal straps are called tie downs. You can look for these straps at any lowes or home depot.
Strapping gives additional support to the rim joists so they do not get separated in high winds and earthquakes. The straps keep the structure tied. From the outside edge of the rim joists, joist nails are driven through into the butt of the joists.
Thus rim joists are nailed to each joist. This connection is extremely strong and it keeps the floor joist stiff and level. If traditional lumbar rim joists are used with engineered floor joists then hangers will be needed.
Should You Insulate Rim Joists?
Experts say that the more insulation you can get it is better for your house. Insulation means less heat will pass through the walls.
It helps to keep the house warm in winter as well as cool in summer. By insulating, you can maintain a consistent temperature when you turn on the AC or heater. This way you could save a lot of energy and money. The insulation process of the rim joist is very easy.
If you are building a new house then you can get a rigid foam insulation board and install it in a way that the foam covers the rim joists. Or in an old house, you can cover the inside of a rim joist with insulation.
It can be done from the basement. To insulate the rim joist you should use air impermeable insulation because the rim joist is prone to drafts. It includes rigid foam, batt, or spray. While spraying the foam, seal the edges carefully so no gap remains there. It will keep air and moisture away.
If you want to insulate the rim joist by using fiberglass, then it may let moisture and air in. This moisture and air can lead to mold problems. So you should spray foam along the edges of the wood. It will create a better seal.
Frequently Asked Questions:
Rim Joist Size
The standard sizes for rim board products certified by APA are 25 to 32 mm (1 to 1-1/4 inches) in thickness, 241 to 610 mm (9-1/2 to 24 inches) in depth, and 2.4 to 7.3 m (8 to 24 feet) in length.
Deck Rim Joist Size
Joist boards come in a variety of sizes, ranging from 2-by-4 to 2-by-12. You can choose the size that works best with your overall deck design and dimensions. The bigger your deck is, the larger joists you need. Commonly used joist sizes are 2-by-6, 2-by-8, and 2-by-10.
Lsl Rim Board Sizes
Rim Board (Not all sizes may be stocked locally)
|1 1̷8” TJ®-Rim Board||9.5″ to 16″|
|1 ¼” 1.3E TimberStrand® LSL||9.5″ to 24″|
|1 ½” 1.3E TimberStrand® LSL||9.5″ to 24″|
Rim Joist Material
Rim joists are usually made of the same material as the other joists. If your framing is wood then they’re generally wood. If they’re steel then the rim is typically also steel. However, in some cases, we’ve built a rim out of steel with wood inside joists.
Is Rim Joist Structural
Conclusion. Rim joists are a main structural component in a house’s floor system. They close the cavities between floor joists, preventing twisting or other movements.
Rim Joist Vs Band Joist
The wood that butts up to floor joists and wraps around the perimeter of the floor framing is called a rim joist. They are also referred to as band joists. If you look at a house from the outside as it’s being framed, you’ll notice a band of solid lumber running along the side of the floor frame.
Band Board Vs Rim Joist
Rim joists are the perimeter joists of a deck. The two outside parallel joists, plus those that run perpendicular to all the joists, form the rim of the deck or a band that ties the structure together. Hence, they are known collectively as band boards and rim boards.
Rim Joist Installation
Measure and cut the rim joists to length. Set one edge of a rim joist on the beam with the top edge of the other end flush with the ledger. Fasten the boards with two 3-inch deck screws. Fasten the other rim joist the same way.
What Is a Rim Joist on a House?
Rim joists are located at the top of your basement walls. They usually look like wooden squares going around the perimeter of your basement. The main purpose of a rim joist is to support the weight of the floor resting on the joists.
What Is a Rim Joist on a Deck?
In the framing of a deck or floor system, a rim joist is attached perpendicular to the joists and provides lateral support for the ends of the joists while capping off the end of the floor or deck system.
What Is the Best Way to Insulate Rim Joists?
Commercially applied spray foam is considered to be the best way to seal the rim joist area. The spray foam easily fills in and seals all the cracks and openings in the rim joist or band joist area. It is generally installed by a professional insulation contractor with the necessary mixing equipment.
Do I Need a Double Rim Joist Deck?
Doubling the rim joist is an alternative method to splicing. The layers strengthen the joint between planks by staggering the seams of each layer by 4-feet. Butt joints are commonly used when boards are doubled. Building Codes require blocking between joist ends or a rim joist to prevent twisting and install blocking.
Do You Need a Double Rim Joist on a Deck?
It is advisable to increase the rigidity and strength of your deck’s rim or perimeter in order to reduce bounce and provide a solid foundation for your rail system. This can be accomplished in a couple of ways. You may want to install double rim joists across long sections to respond to the flexibility of the material.
Joist Notch Reinforcement
You can reinforce a notched joist that has not cracked by cutting two pieces of 3/4-inch plywood as wide as the joist depth and as long as the plywood sheet. Screwing a piece to the joist on each side offers moderate reinforcement. Stronger reinforcement is in order if the joist is sagging or has cracked.
Where Should You Not Drill Holes in Joists?
For the engineered I-Joists shown in Fig 1, some of the limitations are: Do not notch or drill holes through the top or bottom ﬂange. It is generally permissible to drill up to 38mm holes anywhere on the web.
Rim Joist Replacement Cost
Rim joist replacement will run you $10 to $67 per square foot. A full repair job will cost between $1,000 and $10,000, depending on the extent of the damage and the square footage of the area.
Can You Drill Through Rim Joist?
Since the rim joist is continuously supported by the walls or foundation it rests on, the strict notching and hole-boring rules don’t apply. Just don’t create a large hole or notch directly under a group of studs that support the end of a beam, or a window or door header above.
Should You Insulate Rim Joists?
In just a couple of hours, you can seal and insulate your rim joists, which are major sources of heat loss in many homes. This project will help lower your heating costs and save you money. Insulating the rim joists is one of the best things you can do to make your home more energy efficient.
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