# What Does Masonry Opening (Mo) Mean In Construction?

Masonry Opening (MO) is a term used in construction that describes the measurement of an opening from the masonry header to the subfloor.

The MO measurement is typically taken before laying in any bricks or blocks, and it is important to have this exact measurement as any errors may cause serious problems with the finished product.

Generally, when dealing with brickwork, this measurement may include mortar joints between each brick or block and will usually measure up to roughly 6 inches in height.

Although measurements vary depending on the individual job, this generalized opening size has become a standardized go-to for many construction jobs.

## What Size Is The Masonry Opening?

The general size of a masonry opening for a door should be 2 or 4 inches (51 or 102 mm) greater than the height of the door itself – this accommodates both the door framing and ensures that a standard-sized door can be used.

It is important to keep these measurements consistent to make sure that your doorway looks aesthetically pleasing, as well as in accordance with local regulations.

## What Is The Difference Between A Rough Opening And A Brick Opening?

A Rough Opening is the wall opening size that must be cut to fit a door system, and it typically includes a 2-inch space for shimming and slight adjustments.

The Brick Opening is the size of the actual space within your wall through which the door will pass, including any brick moulding on either side. Frame Width is used to refer to the width of only the door frame itself, not including any additional brick molding.

Finally, Nominal Door Size is used to refer to the nominal dimension of the door width opening when referenced in terms of its standard measurements rather than its exact installed dimensions.

## How Do You Calculate Masonry Opening?

When calculating the width of masonry openings, it is important to measure from face-of-masonry to face-of-masonry in order to allow for an even number of mortar joints as well as masonry units.

To do this, you must use the 4” module plus 3/8” since that will provide one more mortar joint than the number of masonry units spanned by the opening.

Doing this will ensure that the opening is properly measured and provides a reliable framework for any work that needs to follow.

## What Is The Rough Opening For Masonry?

The rough opening for masonry is an opening in a wall or other surface that frames the door or window so that it can be properly mounted and sealed.

For existing masonry walls, the rough opening needs to be the overall frame width plus 1/2 inch and overall frame height plus 1/4 inch; whereas for wood stud walls, it must also have an overall frame width of plus 1/2 inch and overall frame height of plus 1/4 inch.

This ensures that there is enough space for all of the framing components when installing a door or window, as well as allowing proper room for flashing and caulking to seal out moisture.

#### Related Posts

error: Content is protected !!
0