Attic Wieght Limit
Modern standards call for around 12 to 16 inches of insulation in the attic and your long term utility bills would probably appreciate it.
Attic wieght limit. So if your ceiling is unfinished you have some excess carrying capacity up there. To simplify you can place 20 pounds of dead load per square foot on your subfloor as long it s supported mid span. Observing the weight rating. If you want to use your attic on a regular basis or to store large items you may need to enlarge the access opening and install an access ladder or drop down stairs.
It is vital to observe the weight rating and make sure that you comply with it at all times. Increasing the total weight on the floor to 4 480 pounds however results in a live load of 40 psf which is beyond the floor s load capacity. Most trusses are designed for only 10 lbs psf live load for storage unless they are attic trusses like drooplug mentioned. As larry said don t overdo it.
You ve added about 300 lbs already when you put 6 sheets of plywood up there. If you care about this you will need to add a second layer of floor joists over the originals perpendicular is best to limit thermal bridging insulate then lay floor over that. Access to attic storage. Your allowed weight and span for a 2 x8 x12 2btr hem fir based on the info you have provided is 20 psf of dead load and 30 psf of live load with minimum bearing length of 0 68.
If the attic has the potential to become a regular living space talk with a contractor about adding a fixed stairway. Of stuff on it. Scrap of plywood over the chords and set about 40 lbs. Is a safe estimate.
This is because the ladder is simply not strong enough to support any more weight and you are putting unreasonable pressure on the attic access ladders every time you break the weight limit. Make sure items are spaced so that the weight is evenly distributed over the chords. A typical load is 5 and 10 pounds per square foot. If the total weight exceeds the load limit of the truss then the truss is compromised.
With an evenly distributed live load of 30 psf which the tables show the floor is able to support the total weight on the floor would be about 3 360 pounds.