Attics are useful spaces to have for several reasons. They provide extra storage space, and in many cases, they can potentially be converted into a bedroom or other functional space.
How much weight can an attic hold?
On average, an attic that has not been designed specifically for storage or already converted into a habitable room can hold 10lbs per square foot. The maximum weight load of an attic can be increased by taking certain measures, such as layering wood across the joists to spread the weight.
Before storing items in the attic, it’s important to have a clear idea of how much weight it can hold.
If the attic is overloaded, this may cause the joists to break, potentially damaging the structure of your home.
There are many factors that contribute to the maximum weight an attic can handle. We’ll cover each of them in detail in this guide.
How Much Weight Can an Attic Hold?
Converting your attic into a functional room such as a study, home office, or spare bedroom is a great way to maximize the space you have available in your house.
Alternatively, you can utilize the attic as a storage space, keeping items that you rarely use out of sight to avoid clutter downstairs.
Whatever purpose you would like to use your attic for, you must consider the maximum weight it can hold to ensure you don’t cause any damage to the structure.
Attics vary in terms of layout, size, and design. The most important part of the attic when it comes to determining how much weight it can hold is the floor joists that make up the framing.
- If your attic has a floor structure that is composed entirely of 2×4 wooden joists, the chances are it will not be able to hold much weight. These joists are not particularly thick, and on their own are unsuitable for holding heavy items or building a room upon.
Walking around in an attic that has 2×4 wooden joists could be dangerous, and there’s a high risk that the ceiling could cave in. This type of attic, with no boards or other further reinforcement installed, is only suitable for storing lightweight items such as empty boxes.
An attic that has a floor structure that consists of 2×6 joists offers more robustness due to the increased thickness of the wood. If your attic falls into this category, you can use it for storing slightly heavier items, but again it will be unsuitable for being used as an area to walk around in or keep large, bulky items.
- The attics that can hold the most weight have a floor structure that is composed of 2×8 wooden joists. These joists can be used for a storage space that will be filled with a considerable weight load of items.
No two attics are the same, so it’s impossible to give an exact maximum weight that they can hold. However, based on averages, we can estimate that attics with the following joists can hold this much weight:
| Floor Joist Dimensions | Estimated max weight per square foot | Suitable purposes |
| 2×4 inches | 10lbs | Storing empty boxes |
| 2×6 inches | 14lbs | Storing lightweight items |
| 2×8 inches | 18lbs | Storing heavy items |
Can I Walk on My Attic Joists?
If your attic doesn’t have a floor installed, it may be tempting to walk around on the joists. While this may be safe in some cases, you should err on the side of caution and ensure that the joists are strong enough before walking on them.
If they are too weak, this could cause serious injury and damage to your property.
The first two things to consider are the size of the wood used for the joists in your attic and the weight of the person who is going to be walking on them.
2×4 joists will likely support someone who is under 150lbs, but a person who is heavier than that risks breaking them.
2×6 wooden joists will offer additional support and should be able to hold a person who weighs under 190lbs. If your attic is made from 2×8 wooden joists, the majority of people will be able to walk on them without any issues.
It’s important to note that other factors will determine whether or not you can walk on the joists in your attic. These include the quality of their installation, how they are laid out, and the age of the wood.
Take a look at this YouTube video on how to lay an attic floor.
If there is no floor laid out in your attic, you should be very careful when walking on the joists.
It’s advisable to avoid putting all of your weight on a single joist, but rather maintain contact with two joists at any time. This will spread your weight out across multiple joists and reduce the risk of one breaking.
It’s also important not to stay in one place for too long, whether you are standing, crouching, or kneeling.
Thankfully, there are simple steps you can take to strengthen the attic floor if you need to do some work in there which requires you to be stationary for a period of time, such as using a transfer board.
Can Attic Joists Support a Floor?
Adding flooring to your attic may seem like a simple task on the surface. However, there’s more to it than simply laying out floorboards across the joists and securing them.
The minimum joist size which is strong enough to support a floor is 2×8. Even this measurement is considered on the weak side, and you should use larger pieces of wood for the joists if you are to lay down a floor.
Unless you are highly experienced with building procedures and protocols, the only way to truly know whether the joists in your attic can support a floor installation is by seeking the opinion of a structural engineer.
Structural engineers are experts at gauging whether structures are strong enough for conversion or specific building work. If you have any doubts about the strength of your attic,
I’d highly recommend getting a professional opinion to avoid potentially damaging your property and leaving you with costly repairs.
Can You Lay Loft Boards Directly onto Joists?
Loft boards can be laid directly onto joists, providing they are strong enough to bear the weight.
To further strengthen the structure, it may be necessary to install additional supports which are attached to roof trusses or ceiling joists before laying down the boards.
These supports should be spaced around 1m from one another. This will increase the maximum weight that the floor joists can handle, in preparation for laying down the loft boards.
It’s important to lay down the loft boards across the joists while ensuring that the edges don’t hang over the joists. The boards should be cut to size so that they come to the middle point of the joists, which will make it possible to fix them securely.
Loft boards usually have tongue and groove connections, which strengthen the overall floor structure. Ensure that these connections are firmly made when you lay down the loft boards on the joists to ensure maximum weight capacity.
Can You Use Plywood for Attic Floor?
Plywood is perfectly suitable for an attic floor, but you must use sheets that are thick enough for this purpose.
Plywood is available in many sizes and thicknesses so it’s important to know what you’re looking for before purchasing it.
It’s advised that you use ¾ inch thick plywood for an attic floor. This is the standard thickness used by most builders, as it combines optimal weight with the robustness required to be used as a floor.
If your ceiling joists are on the weak side due to their thickness or spacing, you should consider using ½ inch thick plywood to avoid overloading them with the weight of the sheets.
The spacing between the joists will also impact the thickness of plywood which is most suitable for constructing your attic floor. If the joists are spaced 24 inches from one another, ½ inch thick plywood may bend so it would be better to use ¾ inch plywood in this scenario.
Related Questions
How much weight can you hang from a ceiling?
Hanging lights from a ceiling can be practical and aesthetically pleasing. However, most ceiling joists can handle a maximum weight of 20lbs, so it’s important not to overload them when hanging items.
Can you convert an attic into a room?
For an attic to be suitable for conversion into a living space, there are some requirements it must meet. Firstly, the attic must have a minimum vertical clearance of 7ft in the bulk of the space. It must also be accessible by a staircase.
Can you put plywood over insulation in an attic?
Plywood or other attic flooring materials can be placed over insulation, providing they would be securely positioned on the joists. The insulation must be tightly packed between the joists so that the plywood will not move when it is standing on.
