A opening width 2 b opening height 1 the rough opening would be 38 x 85 for a 3 0 x 7 0 door frame.
Masonry opening for 36 door.
Normally a shim space is allowed both vertically and horizontally to allow the installation of tapered shims to correctly position the window or door unit.
The example for this is if you want a 3070 36 x 84 door and frame in a cinderblock wall then the rough opening required is 36 4 x 84 2.
Rough opening overall frame width plus 1 2 and overall frame height plus 1 4.
The masonry opening will be calculated to allow the necessary additional room for the adjustment and correct installation of the window or the door.
For fire rated openings drywall must extend at least 1 2 into frame.
Getting the rough opening size right the first time will save you from frustration when installing your doors.
Rough opening overall frame width plus 1 2 and overall frame height plus 1 4.
This will give you room to space the door frame off of the sub floor.
When using masonry frames in cinderblock walls the rough opening must have 4 more in width and 2 more in height.
When the block is done set a rough buck of salt treated 2x4 using anchors or lead shields into the block.
Just add 2 to the width of the actual door size.
For a 3070 single door the frame s rough opening would be 40 1 2 x 86 1 4 wood stud walls.
You should add 2 1 2 to the height of the actual door.