What is Stucco?
Stucco is a fine Portland cement plaster used for covering walls. It is readily available, durable and has a versatile appearance that is used for all types of buildings. It can last for 100 years or more but is not impervious. Cracks and holes can develop in stucco surfaces that will then allow water to get in and lead to further damage that will then have to be remedied by stucco repairs.
Areas of stucco can also break away from any wood or metal lath that it has been fixed to and these loose areas will continue to grow. Small holes can turn into bigger ones, inviting in more moisture that ultimately leads to it being damaged with the continual exposure. Most external wall stucco is 3/4 of an inch thick and any repairs must ensure that the thickness remains constant.
Repair vs Replacement
Repairs to stucco is a procedure that is quite straightforward and can help to bring the damaged surface back to its original good condition. Older surfaces that have been plastered can get worn due to constant exposure to sunshine, rain, and possibly snow. Before you begin any stucco repairs you must examine the walls thoroughly and ensure that they are structurally sound and that there are no problems that have been causing added strains on the plaster that is leading to its getting damaged. If this is the case any repairs you undertake will be cosmetic and the problem will recur within a short time. So, if there is a basic underlying problem for the wall or its foundation, make sure you first address this, before you undertake any repairs to the plaster on the wall.
Stucco can even get damaged if walls have not been properly cured during installation, and this can cause the wall to absorb the moisture from the stucco and cause it to shrink and crack. Minor cracks may not need immediate repair, but in most cases, they will detract from its unblemished look. As long as the cracks are not very wide, they will not allow water to pass through them, but in such cases, it is always better to make your repairs with cement-based paint as a fog coat that will cover up the minor cracks.
What about if it’s damaged?
When the damage to the stucco is more it is best to remove all the damaged or loose stucco with a hammer and chisel. Tap on the stucco surface and remove the portions that sound hollow, as this will mean that the stucco plaster has separated from the original surface that it is meant to adhere to. Continue removing the loose pieces until you reach areas that sound solid and have no visible cracks that need repairs. If your stucco has been applied on sheathing or wood lath, be careful not to damage these when you are using the hammer and chisel to remove the loose or damaged stucco. If there is metal lath behind the damaged stucco it can make sense to also replace this lath as in most cases it will also show signs of rust or other damage. Cut it out along the perimeter of the area where you have removed the stucco.
Now you have a large patch where the stucco and its supporting lath has been removed. You can cover this over with building paper. Building paper has bitumen that has been reinforced with fiber that is sandwiched between sheets of kraft paper. Cut this paper to fit into the area of stucco that needs to be patched. Staple this paper to the wall surface behind, and add a second layer of paper similarly. Now you need to again add a new piece of metal mesh to make up for the one removed. This lath must match the area of the stucco repairs so that there is no gap with the original lath that is behind undamaged stucco. This lath must be firmly held in position with galvanized roofing nails.
The stucco for the repair can be mixed using traditional recipes and the right proportions of cement, sand, and water. You can also get premixed stucco repair mixes that must match the original stucco. You can also get mixes that are quick setting as this can make the repair job much faster. Most of these will have a working time of 45 minutes, and you have to make sure you complete the repair job within this period.
Stucco repair is best conducted in three coats, and your first coat, the scratch coat, must cover the entire damaged surface and the mesh. Smooth this coat and scratch it after it has achieved its initial set. Spray this coat periodically with water to cure it. Mix a new batch of plaster for the second coat and finish it to within 1/8 inch of the original surrounding stucco.
Your final coat must contain any color or pigment that will match the surrounding stucco. Apply this final coat and trowel it to finish flush with the surrounding area. Your repair job is now complete. Cure it as needed. If you are not sure if you should repair or replace the stucco on your home or office building contact us below.