We have recently suffered severe flood damage here in Iowa. My building is exposed concrete masonry. What should I do to the masonry? Do I need to tear the wall down? When can I repaint?
The walls need not be torn down. Masonry holds up well under these conditions. The wall does need to dry thoroughly before repainting. Removing the existing paint on the interior will help the walls dry out faster and allow you to determine when the walls are dry. Because the walls have been saturated, the paint should come off fairly easily. You can let the wall dry out naturally. It may be a month or more before the wall is dry enough to paint. You may want to drain water from the cores. Some water likely is trapped in the cells of the units, and you can try to remove it to speed up the drying time. Determine which cells are holding water by looking for wet units and joints. If a cell is holding water, the cell and the mortar joint below it will remain wet even after the rest of the wall has dried in sunlight. Holes can be drilled in the joint at the base of the wet area. After the core is drained, the hole can be patched with mortar. Don't paint until the wall surface has been dry to the touch for at least a week. Paint the interior surface of the walls with a vapor-permeable paint such as an acrylic latex so as not to trap water in the walls. I recommend painting a test area first. If after a week you have not seen any blisters or other problems, the surface is probably dry enough.