Cracks in stucco brown coat drying

These are typically so small they are not open and cant be seen from more than five feet away. Repair of portland cement plaster stucco a a a a aa aa a a a a a aa a a a a a finish coat brown coat scratch coat metal lath building paper fig. This type of cracking is basically a sign that the base coat did not cure properly. My cracks usually show up after the brown coat and keep increasing in size and numbers for weeks, even months after the job is done.

If you see cracking here, its a sign that fiberglass mesh tape wasnt used in installing the foam trim. Shrinkage cracks are the ones that look like a honey comb or spider web cracking on smooth coat stucco. Although not all cracks are objectionable, cracks in stucco acceptable to one person might be unacceptable to another person. The two coats, which are curing, drying and shrinking at the same time, will act as one coat, doubling the amount of stress they place on the stucco system. Fully hydrate the scratch coat daily from bottom to top so that. Jan 06, 20 the performance of any stucco application is controlled by the base coat. This is caused by either drying too quickly, too muck water in the mix, or mixed incorrectly or applied when it was too cold or too hot the day the stucco was applied.

Internal stresses are due to the natural curing and drying process of stucco. Cracks caused by plywood are distinguished by the directions they take. Oh, i thought it was a new house, an old spread footing should have settled in by now absent something strange going on underneath it. Waterresistant base used as a scratch and brown coat in nonstructural stucco wall construction. Premixed stucco patch is textured to match the existing stucco area easily. Sep 12, 2016 reentrant cracks are the hairline cracks that can appear at comers of square openings in the stucco such as windows. The two base coats of plaster are either handapplied or machine sprayed. Take extreme care to apply the brown coat smooth and evenly. Together with the lath it creates a rigid base for the application of the brown coat. Complies with astm c 926 requirements for cement based plaster.

While the stucco is drying, its important to keep it damp by misting the stucco with water. When is it time to repair stucco cracks in the walls. This is not recommended, a minimum 38 brown coat of portland cement plaster applied to the wall prior to the stucco color coat reduces the possibility of the grout lines telegraphing through the stucco color coat. After mixing the brown coat, allow it to sit for 20 minutes or so before applying it to the moist surface of the scratch coat. Portland cement stucco cracks develop for many reasons. Fogging or misting the finish coat to maintain a dark brown color during the curing window. The main cause for this stucco crack is from the base coat not curing properly. Mar 03, 2016 though cracks in stucco can occur due to different factors, including wrong mix proportions, insufficient mixing, poor workmanship, seismic movement and seasonal changes, two leading causes of cracks in stucco are the house settling process and shrinkageinduced stresses, which typically occur during the drying period. The initial scratch coat must fully encapsulate the metal lath to provide an adequate bond and protect the metal lath from deterioration. Hairline cracks in stucco construction contractor talk. Multiple hairline cracks in stucco hello everyone, i started this thread in february 20 although depressing i listened to your advice and took the step to hire a moisture inspector from exterior design institute the absolute best in eifs inspector training. I got smooth finish stucco added on my textured stucco house 2 yrs ago.

The finish coat can be troweled smooth, handtextured, floated to a sand finish or sprayed. About applying exterior stucco home guides sf gate. Strength development stucco requires fully developed tensile strength to resist cracking due to frequent stresses within the system. Rainy, high humidity weather will require less wetting that will dry, windy conditions. Some masons skip over this step, but it doesnt hurt to spend the time for this process. If cracks exceed 332 it is unacceptable and should be repaired. Changes in weather will impact installation scheduling and hydration requirements. The brown coat should also be 38 thick or per the manufacturers recommendations. The performance of any stucco application is controlled by the base coat. I am currently in the process of stucco ing my house.

Stucco cracking in portland cement plaster base coats. Was it a new 3coat stucco job over the entire house, or was it it patched and a. Outside stress relief cracks tend to be longer, often from one natural break to another. There are two fundamental types of stresses that cause stucco cracksinternal and external. Applying the brown coat the brown coat is the second coat of stucco. It can be used right out of the container to repair cracks and patch worn or damaged areas. A minimum finished thickness of 7 8 inch is typical for three coat work. The remaining stucco coats, the brown coat and inish coat, must be adhered to each other and to the scratch coat to prevent delamination of the stucco. The next brown coat, must be allowed another slowcure of 48 hours. When patching plaster, each succeeding coat is cut back further than the preceding coat, the base coat being the smallest area and the finish coat being the largest area to be patched. Hairline stucco cracks at windows jlconline forums.

The scratch can be applied with a hawk and trowel, or sprayed on. After the moistcure is completed, let the entire system drycure for 10 days even though most manufacturers require only five days. Small, tight cracks indicate what you would expect to show up normally. Hairline cracks in stucco could be, west facing gets that afternoon sun and can be pretty intense. Identifying various cracks in stucco the stucco guy. It may be a good idea to add a little water to the first coat in order to help it absorb into the pores better. Allow mixer to sit for 2 minutes, than remix for one minute. I would really appreciate if you can share your expertise and let. Stucco is by nature hard and strong, but it is relatively thin and brittle and will crack when subjected to stresses that exceed its tensile strength. Fiberglass mesh for stucco cracks, embed or on top of brown coat.

Shrinkageinduced stresses naturally occur during the stucco drying process too. Hairline cracks in this color coat are inevitable, but if the base coats are well cured, these surface cracks will not communicate water through the stucco. The two types of stucco cracks are structural and shrinkage. A scratcher tool is used to get the horizontal lines in the cement and a green float is used. This consists of either a twolayer application of a scratch and brown coat or a singlelayer base coat that performs both functions called a onecoat system, even though an additional finish coat is subsequently applied. Scratch and brown coat in a three coat stucco application. Improving stucco durability using moistcuring construction. By code, builders should provide at least 48 hours of curing time after the first coat is applied and wait seven days after the second coat before applying the finish. Reentrant cracks are the hairline cracks that can appear at comers of square openings in the stucco such as windows.

The brown coat adds strength and acts as a base for the finish coat, which can be handtroweled to create a custom surface texture. The cementrich scratch coat, a first coat, adheres to and embeds into the lath to form a stable base. For larger cracks wider than 116, use an elastomeric caulk. They can occur from normal movement caused by the houses wood frame settlingshifting. The rate and length of this moist curing period may vary with the weather. Repairs cracks, holes or other minor defects up to 14 in. I would, will, and have painted my stucco on my houses. I have used dozens of different stucco subs over the years and always get the same answers and similar results.

The finish coat is only 18 thick and will not hide bumps or irregularities in the brown coat surface. The excessive stress is released as deep cracks, which may run through both coats and even shear the metal lath. The structural are the ones we see most because they are large and very common. I would think that the soakingthen drying process would cause cracks. This shrinkage, when restrained, may create hairline cracks. The thinner finish weighs from 5 to 6 pounds per square foot, compared to 9 pounds for threecoat, and it is costcompetitive with traditional stucco. Drying timber, shifting foundations, and construction work will all sometimes lead to hairline cracks. Stucco cracks are basically inevitable and not necessarily an indication of defects. If you are going to put designs on the stucco you can either do this at this stage or you can simply put on a smooth coat and then apply swirls or other features at a fourth stage.

How to repair cracks in stucco walls home of smiths. When a base coat is soft there is a cause for concern. Cracks that appear within the first 30 days after installation and are larger than 116 the thick. Take time to spray it 3 to 4 times a day for 3 or 4 days. For example, if the brown coat is applied to a scratch coat that hasnt sufficiently cured yet, it will cause the scratch coat to absorb water from the brown coat and continue to cure. A minimum finished thickness of 7 8 inch is typical for threecoat work. How to keep stucco from cracking professional builder.

The scratch coat is applied to a thickness of half an inch and should completely surround the lath. How to repair cracks in stucco walls home cracks appear in stucco walls of buildings because the ground actually moves, and the building actually moves, and with time and the wetdrywetdry annual seasonal patterns, the ground swellsandshrinks and the. While the ubc allows the application of the finish coat seven days after the brown has been applied, the ideal curing time is a minimum of fourteen days to allow the normal hydration cracks to develop and break through the finish coat. Repair a hole in stucco plastered wall plumbing repairs, fix holes in walls by plumbing with stucco duration.

The scratch coat should be at least 3 8 inch thick, the brown coat at least 3 8 inch thick, and the finish coat at least 1 8 inch thick. Multiple hairline cracks in stucco home inspection. Feb 10, 2016 repair a hole in stucco plastered wall plumbing repairs, fix holes in walls by plumbing with stucco duration. Elastomeric is selfpriming on new stucco, meaning you dont need to use a separate primer. This could be due to the plaster drying too quickly, too much water being present in the mix, or the plaster was applied when it was too hot or too cold outside. What is the wait time for a scratch coat before applying the. Hairline cracks are typically around a 116 of an inch wide or smaller, if the crack is bigger than that, than chances are that some other element is the culprit.

Below are some examples of some hairline cracks that have occurred. I would think that the soakingthendrying process would cause cracks. Plywood installation is probably the leading cause of cracks in stucco. A small amount of water may be added at this time if mix is stiff. I have even painted parts of the walls with elastomeric to reduce the moisture load on the walls from seeping through the stucco and the walls and it was successful and not only did not cause any problems, it solved the existing problem of the stuccoblock not drying out. All these systems apply a single base coat and a top coat with a total thickness of 28 to 12inch, compared to 78 to 1 inch for traditional threecoat stucco. Jan 06, 20 fogging or misting the finish coat to maintain a dark brown color during the curing window. What causes stucco to crack, crumble or come loose. When the base coat doesnt cure properly, it means the plaster did not dry and settle into place correctly. This could be due to the plaster drying too quickly, too much water being present in the mix, or the plaster was applied when it was too hot or too cold. After the moistcure is completed, let the entire system drycure for 10 days even. How to repair cracks in stucco walls home cracks appear in stucco walls of buildings because the ground actually moves, and the building actually moves, and with time and the wetdrywetdry annual seasonal patterns, the ground swellsandshrinks and the building settles somewhat unpredictably over the decades. Mix only quantities that can be applied within one hour. The foam trim used on stucco will sometimes form cracks too.

The brown coat in the stucco process is applied over the scratch coat mostly but can also be applied over cement based substrates as well, like the scratch coat. Meets astm c 926 for portland cement based plaster. It has started to turn white in areas and crumble off the block wall first and now parts of the house. This prevents the stucco from drying too quickly, which could cause cracks. After my contractor applied the brown coat its been over a week now i see a lot of hair line cracks and lines on one of the walls. Twocoat stucco is used on concrete, brick, and block walls. If mixture becomes stiff and difficult to trowel, discard it. The traditional application of stucco and lath occurs in three coats the scratch coat, the brown coat and the finish coat. Jul 23, 2008 for example, if the brown coat is applied to a scratch coat that hasnt sufficiently cured yet, it will cause the scratch coat to absorb water from the brown coat and continue to cure. Aug 15, 2017 the main cause for this stucco crack is from the base coat not curing properly.

Stucco is designed to carry and bind the aggregate, bond in place, and get hard. I see a lot of cracks on the foam trim that is used on stucco houses quite often and. Cracks in brown coat i am using 12 sack mason cement,12 sack portland cement,and 22 shovels of sand. If vapor permeable finish coat is used, the cement base coat will cure regardless of how soon the finish is applied. The brown coat properly prepares the surface making it more receptive to the color coat application. Premixed stucco patch is used to repair imperfections in stucco surfaces. Before drying, it is scored or grooved to create a strong mechanical bond with the subsequent coat. Improving stucco durability using moistcuring page 2 of 3. Also might be that the color coat was put on before the brown coat had cracked out. Keep fresh stucco moist by fogging with water andor covering with a plastic sheet to avoid premature drying of the stucco and ensure complete hydration. This will form the bonding between the topcoat and the anchoring of the scratch coat. Drying time is a factor in the development of cracks.