I have several 1920 and 1950 era duplex homes in Cleveland Ohio area where Basements are known for there dampness and disfunctioning footer drains. Digging up around house is just about impossible due to close proximity of houses to each other. Personally I Have removed as much previous applied paint as possible, clean walls with a disinfectant, applied muratic acid to etch, rinse then used fiberglass wall straps drilled into slab and sill board and epoxy to prevent wall movement 4in straps 4’oc. 12” wide straps if walls are not cinder block but old clay tile block. Sealed bad spots with water plug. Then applied a layer of Ames block and wall. Just like blue max but I think it is more adhesive and well white in color. Then ensuring down spots and gutters take water away from foundation and slope soil or flower beds away from home and use a visqueen (impervious plastic membrane under flower beds and souls against house typ. 4’ from house if possible) under slopped soil. This has always dried up basements for me. Have renovated over 20 pre wwII homes own 7 rental units. But since I am a state registered professional structural engineer I would also say eliminating any hydrostatic pressure from walls is indeed best but sometimes not possible and in that senerio the above has worked well for me.

The use of doulbe-wythe exterior brick wall construction has not been common since the 40's due to cost and the introduction of thermal insulation. The modern equivalent is a single wythe of "brick veneer" (4" nominal brick) in front of a drainage cavity with a CMU "back-up" wall tied together with metal brick ties at 2 ft o.c. each way. That back-up wall can also be wood framing and sheathing. The back-up wall supports the structure of the building leaving the exterior brick veneer to move independently reducing stress damage. Whatever the back-up wall, this system is known as a "brick veneer cavity wall" in spite of what some manufacturers like to call their thin-brick adhered systems. A "Cinder Block" is a special kind of Concrete Masonry Unit (CMU) made from the ash of burned coal and it is less resistant to moisture penetration than CMU made of stone aggregate so it should not be be used in exposed single-wythe exterior wall construction. Single-Wythe CMU Wall Construction Issues: (from a HUD study) Water Repellency. If concrete masonry is chosen as the exterior finish material, a water repellent should be used to effectively control water penetration. There are two general types of water repellents: surface treatments and integral water repellents. 1) Surface treatments. Surface treatment repellents are applied to the weather-exposed side of the wall after the wall is constructed. Surface treatments can be categorized as appearance- altering treatments such as cementitious coatings (stucco) and colored paints, and clear surface treatments such as silicone or acrylic films. 2) Integral treatments. Integral treatments, or admixtures, are specified for the concrete masonry blocks and the mortar before the wall is constructed. The water repellent is incorporated into the concrete mix at the block manufacturing plant, and for mortar the admixture is added to the mix on the jobsite. The same admixture should be used in the mortar as was used in the block to ensure compatibility, bond, and performance. Insulation Strategies: Concrete masonry walls can be insulated on either the exterior or interior face of the block, or in the cores of the block. In addition, the thermal performance of masonry walls can take advantage of the thermal mass of the masonry, depending on many factors including the location of the insulating material in the wall assembly (thermal mass is discussed in the Energy Codes section of this document). The three options are discussed below. 1) Exterior insulation. Rigid board such as polystyrene or polyisocyanurate is typically used for exterior insulation and can be adhered or mechanically attached to the masonry. Because the insulation must be protected from weather and impact, this approach lends itself to either a cementitious coating or siding, and would not be used with architectural block. 2) Integral insulation. Under this approach, the cores of the hollow masonry units are filled with insulating material such as vermiculite, polystyrene inserts, or an expanding foam such as polyurethane. (The polystyrene inserts are either placed in the cores of conventional masonry units or are part of an integrated system used in proprietary blocks. The inserts may be installed in the masonry units at the jobsite or in the case of the proprietary blocks, installed at the manufacturing plant.) Depending on the shape of the insert, and the level of grouting and reinforcing in the masonry wall, the integral insulation strategy may reduce the cold bridges (breaks in the insulation) through the thermal envelope. This approach can be used with any of the exterior finish materials described above. 3) Interior insulation. Similar to exterior insulation, interior insulation is typically a rigid board product such as polystyrene or polyisocyanurate, and is adhered or mechanically fastened. To accommodate an interior finish (typically gypsum wallboard), studs, furring, specially-designed clips and metal channels can also be used. One example of the clip/channel approach involves a “kerfed-edge” insulation board which reduces the thermal bridging.

Bill, We are in the process of redoing our bathroom floor to put down tile. Before we bough tout house we knew there was water damage to the bathroom floor from a long lasting leak from the washer. We have repaired all that damage by replacing the studs in the walls, replacing the sheet rock with the moisture resistant sheet rock, and building up the floor from the joists up and topped with 3/4" Advantech Plywood. We are ready to start replacing the tile but are unsure if we need to put down cement board or redguard, or both. What do you recommend? The subfloors are all replaced with the Advantech, but we aren't sure if we can just redguard and go. Any advice would be helpful. (additional info- we are not replacing the tub/surround, we will be putting our washer/dryer in there again) Thanks!

If you are really concerned about water penetration, apply a crystalline waterproofing product. Also, repair any mortar joints that have deteriorated.