Concrete Blocks: Quality grade for face blockwork?

Created by Vicki Marshall, Modified on Mon, 07 Nov 2022 at 12:28 PM by Vicki Marshall

Region: All States

Assessor Question:

I designed a house specifying plain concrete blocks as face masonry. I have received conflicting advice as to whether the plain block can be used or I need to specify a higher quality block that is less hydroscopic

TechLink Response:

The descriptor of 'plain block' does not provide a clear and unequivocal specification of a specific modular masonry product for wall construction.
There may need to be clarification from the block manufacturer/supplier as to whether any of their products are unsuitable for specific applications.
That said, 'concrete blocks' would normally be anticipated as a suitable external wall fabric treatment as a veneer or as part of a cavity masonry load bearing structure.
Clay bricks and concrete blocks are all assumed to allow water to pass through pore space in the blocks and mortar jointing to the inside face of the wall.
That moisture drains down the inside face till it reaches a cavity flashing at the base of the wall where it is directed back to the outside via weep holes.