This measurement will help you.
Installing an attic tent.
Use plastic roof cement to smooth the vent base and then place the base over the hole.
Slip the top end of the flashing above the shingles directly over your hole allowing it to lap over the area below the hole.
Installation of this type of attic ventilation involves leaving a gap in the sheathing along the ridge and covering it with a perforated vent.
Next measure the access way you will need the inside width and length of rough frame.
Installation of an attic tent is relatively simple.
Using roofing nails secure the base and seal the nails with roof cement source.
Installation process for a stair attic tent measure the distance and the height of the attic stairs start from above the frame.
Measure the inside width and length of the rough frame then pick the attic tent closest in size.
Do it yourself.
Static vents often protrude from roofline thanks to.
Due to their flexibility you have about a 2 3 margin of error.