Is A DPC Set-Back Approximately 10mm A Common Practice?

[PSE]

On our property, at DPC height there was no evidence of a DPC fitted.  The builder Bellway, didn't think this was an issue and said that there would definitely be one fitted even though it was not visible.  In the NHBC Standards 2013 6.1 S4, it states that a DPC should not be set back from the edge of the masonry, be of the correct width, and on the image, it shows and states slight projection.

I used the NHBC Resolution Service with regards to this and at the Resolution Meeting, a brick was removed below the DPC height to reveal that there was a DPC fitted but was set-back approximately 10mm from the masonry edge.

In the NHBC Resolution Report I received, it states

"On the date of inspection the builder removed a brick from the side wall of the property below the dpc. The edge of the dpc became visible as soon as the mortar was removed. The edge of the dpc was later measured as being recessed into the brickwork by not more than10mm.

It is common practice to recess the dpc so that the joint can be properly trowelled to a smooth finish. In this instance there is no negative impact of doing so, as it is linked to a radon gas barrier and a cavity tray which cross the cavity to the perimeter of the building. The dpc is achieving its primary function, to prevent rising dampness in the outer leaf brickwork."

[New Home Expert]

If the dpc does not extend the full width of the brick, then water can be soaked upwards by capillary attraction. The NHBC will know this. Its commonly known as rising damp.

The DPC that is set back, is allowing a clear path for this as there barrier is not full width of the outer skin.
To then say that it is common to keep the DPC back (more than 25mm in this case) for "trowelling pointing" is ridiculous. It is just a smokescreen excuse to pull the wool over homeowners eyes in an attempt to avoid doing anything about it.  One thing for sure, is it is most definitely NOT "common practice" at all!

In most cases the a DPC width is 100mm - exactly the same as a standard brick!
DPC details from Visqueen.

In your case the mortar is so weak that the brickwork will need to be taken down and rebuilt so the DPC width is a moot point as it could be sorted anyway.