One of the most important design concerns for earth covered structures are waterproofing and damp proofing. Care should be taken for proper arch erection, including correct fastening of the bolts and application of caulking as per the Erection Manual. Satisfactory waterproofing materials for earth covered Wonder Building Shelters should possess the following characteristics:

1. Durability and Permanence for the local soil conditions
2. Flexibility sufficient to withstand any building movement due to expansion or contraction, soil settling or shifting and vehicular traffic in the vicinity.
3. Ease of application during construction weather conditions.
4. Safety to the applicator during application
5. Uniformity of product quality during application
6. Stability to prevent seepage of coating into buildings or off of inclined building surfaces.

Coal pitch tar is the basic material suggested for underground waterproofing because it can best provide durability and permanence under the widest variety of soil conditions. In spite of much experimentation with other materials, coal tar pitch remains a widely accepted product for under- ground protection.

The decision to use a solid coal tar pitch requiring heat during application or a liquefied form of coal tar pitch for cold application should depend upon their ability to provide the foregoing listed charac-teristics.

Both hot and cold application of coal tar pitch offer durability, permanence, and flexibility. How-ever, the cold application products offer distinct advantages in the remaining characteristics includ-ing ease of application. Cold products can be painted on the steel. See the products’ directions for application procedures on steel products.

The design of the earth covered structure should also include a barrier such as visquine or other barrier material. Again, this material should be chosen for its durability, permanence and flexibility and the other characteristics discussed above. This barrier should be installed within the dirt and extend from one end of the earth slope to the other. The design of the earth covering needs to include adequate drainage. At the base of the barrier membrane, drainage tubes, tiles, or other drainage should be installed. This entire drainage system should be designed to keep the water away from the arch structure.

OTHER IMPORTANT DAMP PROOFING CONSIDERATIONS

All metal buildings condensate. Therefore, as with all earth covered buildings, adequate ventilation systems can be designed to remove condensation. Wonder Buildings offer the ability to design these systems through the endwalls or roof. Discuss your options with your Wonder Building sales representative.

NAVY RECOMMENDATIONS FOR DAMP-PROOFING

For our customers’ reference, the following are the US Navy’s recommendations for damp proof-ing of Wonder Buildings.

After the metal arches have been erected and all bolts properly tightened and all other pene-trations made and completed, the exterior surfaces shall be damp-proofed. This work in-cludes sealing of the curb channels at the base of the metal arch walls; flashing of the joint between the metal arch and the concrete rear wall; protective coating of the exterior of the metal arch structure; and coating of the earth-fill side of the concrete headwall, side curb walls, and rear end wall.

Materials: Materials shall be delivered to the site in sealed containers bearing the manufac-turer’s original labels. Pitch shall be coal-tar pitch, Type II, conforming to ASTM Specification D450.

Cement shall be bituminous plastic cement for flashing, Type II, conforming to Specifica-tion SS-C-153.

Protective coatings for metal and concrete shall conform to Specification MIL-C-18480. Fabric shall be glass mesh fabric conforming to ASTM D1668, compatible with bituminous plastic cement, Type II.

Cement and sand for group shall conform to the applicable requirements of Section 03300 entitled CAST IN PLACE CONCRETE.

Preparation of Surfaces: Metal surfaces to receive protective coatings, coal tar pitch, or flashings shall be clean and dry. All oil, grease, dirt, loose rust, loose mill scale and other foreign substances shall be removed. The removal of oil or grease shall be accomplished in a manner that will not leave a greasy residue. Clean cloths and clean fluids shall be used as required.