Typically ceiling joists are 2 6 or 2 8.
Putting ceiling joists in the attic l.
That s a big size and strength difference between the two types of attic joists even if the joist spacing is the same.
Instead you should place the cutout opening inline with the ceiling joists rafter ties.
Purchase rolls or packages of insulation that will fit in the spaces between the ceiling joists.
How to vault a ceiling.
Work from the perimeter of the attic toward the door or hatch so that you don t trample all over the insulation you just put in.
You also need to ensure that the joist spacing is adequate.
Standard joist spacing for the installation of attic flooring materials is 16 inches on center oc meaning the distance from the center of one joist to the center of the next joist is 16 inches.
Always cover the tops of the ceiling joists to make sure the insulation is deep enough to reach your target r value and to prevent thermal bridging the heat loss that occurs through the wood framing.
Now let s read about the steps for properly finishing the attic walls and ceiling.
First head to the attic.
The standard width for joists is 24 inches.
Once we look to make the attic livable space the existing ceiling joists usually will not meet the structural requirement for a floor.
In the first step a knee wall is installed.
If the attic were designed as living space those ceiling joists would become floor joists and be much bigger.
Attic joists for live loads.
The location of the top of the knee is marked and after checking the level long boards are attached to the ceiling joists.
Joist dimensions are only part of the equation.
This way you only need to cut one of them to make the room for the rough framing opening.
You potentially compromise too many of the rafter cross ties by doing that.
Step 1 framing of the top and sides of the knee wall.
More times than not the floor structure of an existing attic is actually a ceiling joist.
The subfloor installation is easy.
I would not put the attic stairs ladder assembly opening at right angles to the ceiling joists.
Use of joists in attic flooring.
But if it s framed traditionally with big lumber rafters the roof can stay in place.
Ceiling joists are typically 2 8 lumber floor joists are usually 2 10 or 2x 12 lumber.
Set up a stepladder tall enough to work comfortably from.
They are designed to carry only the weight of the drywall or plaster depending on the age of your home.
You ll have to remove the entire roof structure to vault the ceilings.
Precise measurement is the most difficult as you need to consider all underlying obstructions carefully before proceeding with your plans.