Dry Stack foundation walls?

[dicksewerrat]

Has anyone had any experience with the "DRY STACK" method of constructing basements?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[concretemasonry]

It has been attempted for many years (over 40)and still keeps popping up periodically.

It is advertised a stronger (using surface bonding), but that is misleading. It is never as strong as a partially reinforced wall using conventional construction.

You can find tests that show it has slightly greater flexural/tensile resistance. You will never find a test that shows it has greater compressive strength because of the point contact between the masonry units.

It is generally used as an uncontrolled system because the interest by amateurs that only look at free labor and a lack of skill.

Because it is dry stacked the strength and properties are highly variable, because the allowable block tolerances are much too liberal. Usually the lower level of producers promote the system because they can get a higher price for the units from real contractors that pay for the labor savings of quality units. Better producers manufacturers make the stock unit heights slightly low, but within tolerance because of the contractors preferences where joint reinforcement may be used. Specially surface or ground units are not economically viable and shimming or an intermediate mortar joint may be required in addition to the bed joint on the footing may still be needed.

Because the system has not been widely accepted, the block length generally are modular and not full length. As in all construction some head joints or very accurate cutting may be required to make the over-all dimensions fit.

The surface bonding coatings can be very touchy when used by an amateur. Over-mixing and under-mixing are common and you cannot temper it like you can temper mortar according to ASTM C270.

The coatings are very effective in reducing water penetration though a wall, but still require additional coatings and obviously drain tile (interior, exterior or both)below the footing bottom for a true waterproofing system.

Dick

 

[concretemasonry]

Correction -

In error - Usually the lower level of producers promote the system because they can get a higher price for the units from real contractors that pay for the labor savings of quality units.

Correction - Usually the lower level of producers promote the system because they have a different cost-oriented market. The better producers can get a higher price for the units from real contractors that pay for the labor savings of quality units. It does not cost more to make an accurate unit using any modern equipment.

Being involved in the manufacturing of CMUs for 30+ years, generally, good residential basement contractors will pay a higher price for good units than commercial contractors will. It may have something to do with egos and perceived importance. Generals and builders that do not do their own masonry work are very often price shoppers because of lack of knowledge of masonry construction. They also get higher "comp" bids from real masonry contractors because they buy job-by-job and not on an annual or overall basis.