Elastomeric wall coatings are designed for exterior masonry surfaces like concrete, stucco and concrete block. They are generally acrylic latex masonry paints designed to be applied in very thick films (about 10 times as thick as regular paints); they are tough and flexible, and stretch as cracks underneath open and close, thus bridging the cracks and keeping wind driven rain out while maintaining a nice appearance. These coatings are called EWCs for short. They can be tinted to a light color. The EWC should be applied after cracks more than 1/16" are caulked with a quality acrylic ( e.g. Multiflex AC) or siliconized (not SILICONE) caulk. (If the stucco is particularly porous, a masonry primer or paintable sealer should be applied first. Use Ultraprime, (a special primer for EWCs) Applications of the EWC RainShield is usually at about 13-15 square feet/kg, and two coats should be applied.

Normally paints will not give same effect as you get with a properly applied elastomeric wall coating. Elastomeric wall coatings are exterior acrylic latex masonry paints designed to be applied in very thick films (about 10 times as thick as regular paints); they are tough and flexible, and stretch as cracks underneath open and close, thus bridging the cracks and keeping water out while maintaining a nice appearance. These coatings are called EWCs for short. They can be tinted to a light color.

The EWC should be applied after cracks more than 1/16" are caulked. Applications are usually at about 13 - 15 square feet/kg, and two coats should be applied. The crack bridging capability is related to film thickness. The thickness is of course much greater than with a conventional paint and this leads to significantly higher initial cost vs. with regular paint. It is also important that water is not allowed behind the EWC, so all caulking must be in good shape, chimneys must have rain caps, wall tops must be water proof, etc. EWCs are not be applied to surfaces where water normally gets behind them, like retaining walls.

Apart from protection from water, EWCs also keep heat out of building, which makes inside room cool.

EWCs are manufactured to get high elongation and good dirt resistance, elastomeric wall coatings may "chalk," particularly in sunny exposures, to the point where dark colors may lighten more than surrounding trim painted with conventional paints. Hence dark colours are not offered in elastomerics. A more colourant will lead to cost increase. A better approach is to apply two coats of normal paints such as Reflection ( Refer www.walruspaints.com for more details) in desired colours over elastomeric coatings.

You may use an elastomeric coating, but the main question is, will water access the stucco from behind… if so, it will lift the coating and cause potentially serious blistering. This can happen if the wall is a retaining wall with earth behind it, or there is any way water can otherwise get into it, say through a wall cap, which is often the problem with free-standing walls used as partitions.

On the other hand, if the wall is part of an enclosed structure, e.g., the outside wall of the house, then an elastomeric coating can be fine. Keep in mind that you'll be covering the cracks, so moisture will not now be able to escape there, which could have kept the oil-based paint from peeling. If in doubt, use one coat of a flat latex paint, which is the most forgiving type for letting moisture pass through. In any case, first go over the stucco thoroughly with a stiff metal wire brush ( with proper safety precaution) to remove all loose paint and unbound sand. Repair visible cracks with Multiflex AC, then proceed with painting.

, EIFS is an excellent candidate for painting, in order to change color, refresh the appearance, and to enhance protection. Surface preparation is similar to that with stucco and other masonry surfaces: remove dirt, mildew, any loose sand. Use particular care if power washing, to not force water into joints and any cracks. Power washing should be done with plain water without cleaner or bleach added. Use a quality acrylic (E.g. Multiflex AC) or siliconized caulk to seal any cracks and openings. Leave the caulk to dry over night, and make a second application if necessary. Leave the surface preferably for 48 hours to allow all water from caulk to go out. Apply a masonry primer for best results (sheen uniformity, mildew resistance) e.g. Ultraprime. Then use RainShield EWC a 100% acrylic latex elastomeric wall coating, applied in two heavy coats.

It is always preferable to apply another coat of elastomeric coating, which does not cost much, as the thickness may be much less than what it was applied in the beginning. In fact durability can be further extended to another 5 years with single coat of elastomeric coating, if overall thickness is maintained at 300 microns.

But in case you still prefer to go for paint, then use a quality exterior 100% acrylic latex paint in a flat, satin or semigloss finish. In fact, some paint manufacturers are now recommending their products for this. Here are some guidelines for painting buildings done previously with an elastomeric:

• 1. Remove all dirt, mildew and chalk; treat mildew with a 3:1 water:bleach solution, leaving on for 20 minutes, then rinse thoroughly; careful power washing with plain water (no cleaning agent or bleach added), being sure to not drive water into any openings there may be in the existing coating.
• 2. Seal all cracks and openings, using a quality acrylic (e.g. Multiflex AC) or siliconized acrylic caulk. Do not use silicone caulk.
• 3. Check entire elastomeric surface for blistering or other adhesion loss: A) carefully remove any blistering or failing coating; seal the edge of the surrounding remaining coating with a quality acrylic latex caulk; apply a water-based (E.g. UltraPrime) or solvent-based clear masonry sealer (e.g. ClearSeal S) to the masonry surface thus exposed; then apply an elastomeric coating to the repaired area, overlapping it and feathering, onto the remaining elastomeric. B) identify any source of intruding water or moisture that may have caused the blistering or other adhesion loss, and eliminate it.
• 4. Apply a top quality exterior 100% acrylic latex house paint in a flat, satin or semigloss finish (e.g. Reflection, refer www.walruspaints.com for more details), that is recommended by the manufacturer for application over existing elastomeric coatings. It is important that steps be taken to minimize chance of cracking of the new paint as applied over the elastomeric: A) the paint must be of high quality, meaning, for example, that with flat paints, excessive extenders should not be used, that appropriate mildewcide is included, that an appropriate binder is employed, etc.; therefore, the manufacturer's top line product should be specified. B) The paint must be applied under moderate weather conditions: applying below the recommended minimum application temperature can result in serious cracking; it is preferable that the air temperature be at or above the minimum recommended application temperature for at least the following 24 hours. C) the paint must be applied at sufficient thickness. In general, a dry paint film of 30 microns per coat is appropriate; two coats will provide ample crack resistance. Pre-thinning of the paint will reduce the solids content by volume, and additional wet paint film thickness has to be applied to compensate, so pre-thinning should be discouraged. D) There is always the chance that some cracking of the new paint will occur at some point, so it can be helpful to utilize a color similar to that of the existing elastomeric coating to minimize show-through.