Translations:Adventist Youth Honors Answer Book/Vocational/Masonry/59/en

Build Up the Corners

The fourth step is to build up the corners of the wall, usually four or five courses high. This is also called laying up a lead. Step back each course one-half block. For the horizontal joints, apply mortar only to the tops of the blocks already laid. For the vertical joints, you can apply mortar either to the ends of the new block or the end of the block previously laid, or both, to ensure well-filled joints (figure 15). As you lay each course at the corner, check the course with a level for alignment (figure 16, view 1), for level (view 2), and for plumb (view 3). Carefully check each block with a level or straightedge to make sure that all the block faces are in the same plane. This ensures true, straight walls.

Figure 17: Using a story or course pole.

Figure 18: Checking the Horizontal Spacing.

Figure 19: Filling in the wall between corners.

A story or course pole, which is a board with markings 8 inches apart (figure 17), helps accurately place each masonry course. Also check the horizontal block spacing by placing a level diagonally across the corners of the blocks (figure 18). When filling in the wall between the corners, first stretch a mason’s line along the extensor block edges from corner to corner for each course. Then lay the top outside edge of each new block to this line (figure 19). How you grip a block before laying is important. First, tip it slightly toward you so that you can see the edge of the course below. Then place the lower edge of the new block directly on the edges of the block below (figure 19). Make all position adjustments while the mortar is soft and plastic. Any adjustments you make after the mortar stiffens will break the mortar bond and allow water to penetrate. Level each block and align it to the mason’s line by tapping it lightly with a trowel handle.