To meet all three goals insulating your finished attic ventilating the roof and maximizing headroom use a combination of dense batt insulation rigid foam sheeting and air chutes.
Finish out attic separate loft.
Use screws to attach sheets of birch plywood to the angled ceiling over the insulation making sure to drive the screws into the ceiling joists.
Follow the rule of 7s.
For a finished attic to be to code it must satisfy the same living requirements of other rooms sometimes called the rule of sevens any living space in a home needs to have at least 7 feet 2 1 m of clearance from the floor to the ceiling and there needs to be at least 70 square feet of space available at least 7 feet 2 1 m in each direction.
At least 50 step 2 make sure the attic has a full size staircase.
Enlarging an existing stairway or adding a new one will affect spaces below.
That s measured after you finish the ceiling.
A stair designed with an intermediate landing and two runs needs about 8 feet on the lower level.
Need more headroom in the basement.
Building codes vary by location but most require at least a 7 foot clearance for attic expansions.
Run the plywood down to the top of the knee wall.
Step 1 check the ceiling height.
Enforcement varies but codes typically say that at least half of a finished attic must be at least 7 feet high and that this area must be a minimum of 7 feet wide and 70 square feet.
A contractor or a local building official can help you assess how the rule will apply to your attic and how modifications like dormers can resolve height shortcomings.
If you don t have enough height you ll have to raise the roof line and that adds a lot to your construction costs.
The plywood will create a smooth strong ceiling without having to apply drywall tape and mud to the ceiling.
A straight run stair will chew up 10 to 14 feet of floor space.
If you re finishing your attic insulating it to the proper r value can cause a dramatic loss of headroom if you limit yourself to fiberglass batts.