Construction Practices – Foundations


After the footing concrete cures we are ready to start with the cmu foundation block for a home with a crawlspace. Make sure that the footing concrete is clean and all of the 5/8 "all threads are upright. The first course of cmu block should run straight and level and be started at the lowest" step down. "Once the low point terminates into a step then the second course of block should be run. The second course on the lowest step down will, if footing correct, run right in line with the next height of feet for its first course.

This process repeats until all of the step downs are filled and the block has a level run around the perimeter of the structure meaning that all of the blocks are consistently level around the perimeter. Determine the venting necessary for the crawlspace and install sideways block to allow airflow or use bricks laid in a soldier course (vertical) with gaps between them. Proper venting is usually measured as 1 sqin per 1 sqft. Once the cmu blocks are laid in a level position around the perimeter – a crawlspace height should be determined.

A crawlspace height should usually be a consistent 24-36 "from ground to bottom of low horizontal framing member. This practice typically ends up preventing the proper amount of air flow in the crawlspace. Keep this in mind when determining the height of the perimeter block. Construct the cmu piers to a height equal to or below the level height of the perimeter block. A structural engineer or state licensed architect will determine this with the floor layout and girder placement. (dropped girder or inline girder). Piers are generally, by code, supposedly to be filled solid with concrete as well as the cells containing the 5/8 "all threads around the perimeter.