If the uneven floor is due to floor joists that have warped or twisted over time or were incorrectly installed the only way to level the floor is to remove the subflooring and shim the joists.
Best floor joists for second floor.
Typically the second story floor joists will not only run the same direction as the first floor joists they will also be directly over them.
In my experience manufactured floor joists are the best alternative in most cases.
When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started.
Though joists may be any size that you desire using typical floor joist and beam specifications ensures that you can find hardware to fit the joists and that the floor provides adequate support for furniture and other items in a room.
Joist span and spacing is set by your local building code.
Live load is weight of furniture wind snow and more.
Floor trusses can span farther between bearing points than i joists allowing for larger open rooms.
First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs.
And the supplier typically will provide the layout at no extra charge if you buy from them.
This also reduces the need and cost for extra bearing posts beams and footings.
Floor trusses have built in openings which can be used to install hvac ductwork plumbing lines and electrical wiring.
Wood i joists with dimension lumber top and bottom chords and osb web.
An inaccessible attic space on the other hand might have a live load of only 20 psf.
Other than the floor stiffness i would not recommend going more than 16 o c.
Two types of engineered joists are most frequently used in floor systems today.
This is because they are.
1 psf lb f ft 2 47 88 n m 2.
Second floor construction techniques follow a standard process.
I joists have major advantages in high volume construction with standard layouts.
2 grade of douglas fir are indicated below.
1 ft 0 3048 m.
Floor joist spacing for i joist and 19 2 spacing for open web because the floor plywood tends to get bouncy.
Floor joists or beams provide the below surface support for the wood subfloor of a room.
While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length.
Open web trusses with wood webbing held together with metal plates.
Framers construct the second story floor system to match the layout of the main floor system.
Most rough carpenters now have experience installing these.
Dead load weight of structure and fixed loads 10 lbs ft 2.
A room used solely for sleeping might need to carry only 30 psf whereas a garage floor over a basement would need 50 psf or higher.