To assess your attic's weight capacity, examine the attic joists and trusses. Measure joist specifications, identify truss designs, check material quality, and consider the structure's age.
The only way to know for sure is to find a manufactures tag and call them and have them look it up in their records. The look to be a attic truss so a few hundred pounds should be no issue.
If you have an attic with joists measuring over 16 inches or reaching 24 inches OC, this is not ideal for the installation of flooring or converting your attic into a livable space. However, if you hire a contractor, they can offer advice on how to increase the structural support to get it there.
Take careful precautions in an unfinished attic
Some of the warning signs include: An attic “floor” that lacks floorboards and floor joists (make sure to walk only on the joists, which requires stable balance) There is obvious evidence of water damage, mold, or mildew growth.
Look in the attic.
In unfinished attics where the frame of the house is exposed, it's easier to see where the beams connect. Follow the wall stud into the attic and see if it aligns with the joist. If the vertical stud runs perpendicular to the horizontal joist, there's a good chance it's load bearing.
Uninhabitable attics without storage can typically support 10 pounds per square foot, while those with storage can handle around 20 pounds per square foot.
First of all, converting your attic into a living space must meet local building codes and regulations. This means you may need to hire an engineer to ensure the structural integrity of the space. You may also need to work on your home's electrical and HVAC infrastructure.
To assess if your attic can support a finished space, you should consult a structural engineer, especially if your home is older and may require reinforcement. A structural engineer will evaluate the foundation, walls, and floors to determine if your attic is a good fit for conversion.
Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.
To find out if you have enough attic insulation, measure the thickness of the insulation. If it is less than an equivalent of R-30 (about 10 to 13 inches), you could probably benefit by adding more. Before insulating, seal any air leaks and make roof and other necessary repairs.
Install a reliable access ladder or stairs for easy entry and retrieval, ensuring safety by adding handrails. Organize the attic by categorizing similar items and using labeled boxes, storage bins, or shelves. Maximize vertical space with hooks or racks for tools, clothing, or sports equipment.
Safety concerns: Attics may not be designed to support heavy loads, raising safety concerns about overloading the attic with too many or too heavy items, potentially compromising the home's structural integrity.
How much weight ceiling joists hold depends on their size and spacing and what they're made of. Wooden joists can support 50 to 100 pounds per square foot. Steel joists are more common in commercial buildings and can handle higher loads. Joists are spaced at regular intervals of 16 or 24 inches apart.
To summarise, and to be on the safe side, unless you know that your joists are stronger, we recommend loading your loft flooring with no more than 25kg of stored items per square metre, plus the weight of one person accessing them.
This rule means, at least half of your attic space must be 7 feet high by 7 feet wide, with a total of 70 square feet. Keep in mind, codes vary from place to place, but for using the attic as an actual room, this rule typically applies.
Reach out to your local municipality to see if you need a permit for your attic remodel. A permit is usually only needed if: You are adding electrical wiring or ventilation. You plan to change the structure of your home in the process, such as knocking down an existing wall or adding a dormer.
An attic can make a perfectly good bedroom as long as it meets ceiling height requirements and has an acceptable window. A former living room or den is also often a good candidate for a bedroom, since it likely has methods of egress and meets other requirements already.
Roof Weight Standards
A minimum requirement is for roofs to be able to support a concentrated weight of 300lbs. Concentrated weight means that this load is placed directly on a single area on the roof.
Inspect for Framework Damage
Another way to determine how much weight your attic can hold is to determine how much framework damage it has. Even if you seem to have a strong attic by outward appearance, unseen damage could still be weakening it just below the surface.
How far can an attic truss span? Attic trusses can span up to around 90ft, it's worth considering that long spanned trusses are more challenging to deliver, erect, brace and install efficiently.