Cracks in stucco brown coat mix

Allow mixer to sit for 2 minutes, than remix for one minute. The paint needs to be rolled to force it into the cracks properly. On any stucco job, you have to expect both the scratch coat and the brown coats to have minor cracking from shrinking. Mar 03, 2016 but just like any other construction material that includes portland cement, stucco is prone to cracking. The set up so, you have installed a cement or hard coat stucco system. 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. Use the same plaster for the brown coat and apply it in much the same way. This acts as an ideal base for the finish coat, which is integrally colored in most cases and is what you see on stucco, so the base needs to be uniform. The next layer the brown coat may be applied the same day, providing the scratch coat has had adequate time to set up. 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. I am currently in the process of stucco ing my house. Then use a finishing trowel to paint on the damaged area and repair cracks. When is it time to repair stucco cracks in the walls.

A minimum finished thickness of 7 8 inch is typical for three coat work. This mix is the perfect base coat choice for a traditional three coat stucco application. This will form the bonding between the topcoat and the anchoring of the scratch coat. It is integrally colored with faderesistant pigments, and is economical with low maintenance. Stucco trouble shooting chart stucco manufacturers association. Sure enough, it always cracks, no matter how i cure it, and no matter what time of year. The stucco scratch coat mix is a simple recipe that really consists of sand, cement and water. What causes stucco to crack, crumble or come loose. This stucco system consists of a scratch coat, brown coat and finish coat. Consult the stucco finish manufacturer or contractor for recommended repair methods. Quikrete finish coat stucco is designed for use as a decorative finish over portland cement base coats or quikrete one coat fiberglass reinforced stucco. It is called the scratch coat because it is often scarified with a small raking tool to create a.

A too rich mix almost always results in cracking, especially when the coat is applied too thick. Mixing the mud and applying it creates a time lag and the stucco may prematurely dry while you are mixing your next batch creating a noticeable line between batches. On all the jobs i have seen, there have been two coats, the brown coat and the finish coat with color. Stucco cracking in portland cement plaster base coats. After the cement is on the wall, a scratcher is used to make horizontal lines in the stucco mix, in order for the next coat the brown coat to stick to it. Basic plastering skills, why, how to apply a scratch coat. But the specific issue i was asked to look at was the stucco.

One is essential, for mixing the stucco and another one can be used. Adding lime allows the stucco to flexible when applying and also is a sealer against water. These hairline cracks in no way compromise the integrity of the plaster coat nor shorten the useful life of the product. When the base coat doesnt cure properly, it means the plaster did not dry and settle into place correctly. Before applying the brown coat, webber verifies the hardness of the scratch coat by dragging a nail over the wall. Area of use crack isolation base may be applied over the following substrates. Repairing stucco cracks, why new stucco walls can crack. A very simple recipe for a stucco scratch coat consists of 3 parts. This first layer is called the scratch coat youll see why next. Prep the surface by generously dampening it with water before you begin. Aug 27, 2019 traditional, or 3 coat, stucco is applied over the lath in three thin coats. The stucco scratch coat mix is a simple recipe that really consists.

A small amount of water may be added at this time if mix is stiff. Excessive cracking, however, usually means something was done improperly for example, the mix may have been too rich too much cement, the stucco layers may have been too thick, or the walls may not have been allowed to. This product also can be used as the first coat in a two coat application for exterior stucco. Repairing stucco cracks, why new stucco walls can crack youtube. Normally, the scratch coat should just cover the wire. Be patient and properly slowcure moisture applied the stucco. Some masons skip over this step, but it doesnt hurt to spend the time for this process.

Quikrete 80lb premixed finish coat stucco mix at lowes. The scratch coat should be 38 thick, and it should cure for 48 hours before the brown coat is applied. If used, add manufactured coloring compounds to jobsite stucco finish mix per manufacturers recommendations. On large patches, the stucco should be applied in three coats, using a metal trowel. If you have stucco, you need to understand how the cracks come about, and when youll need to repair them. The brown coat properly prepares the surface making it more receptive to the color coat application. Make the coat as level as possible to provide a solid base for the finish coat. The mixing and application process, if done properly will help minimize cracking. The brown coat surface is much smoother than the scratch coat and is gritty to the touch but flatter and looks more appealing than the scratch. Allow the stucco to firm up, then scratch the surface.

Mixing stucco in a wheelbarrow then installing it youtube. Jul 23, 2008 this stucco system consists of a scratch coat, brown coat and finish coat. Complies with astm c 926 requirements for cement based plaster. Jul 28, 2014 repairing stucco cracks, why new stucco walls can crack. If available use a branded stucco mix that is already premeasured in a bag. The january 2007 article on stucco cracks dealt with myths, planning, caveats and suggested contract language when working with such systems. 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. Basic plastering skills, why, how to apply a scratch coat in stucco. Once the crack has been filled, fogcoat may be used to even out the color around the repaired area.

Besides, stuccoing and mixing are hard work and your performance on the wall could wane over time. Drying time is a factor in the development of cracks. Stucco, cracking, plaster basecoat, portland plaster. How to parge and sculpt with rapid set mortar mix part a duration. Ideally, both surfaces should be misted after theyve been allowed. Mar 20, 2007 the january 2007 article on stucco cracks dealt with myths, planning, caveats and suggested contract language when working with such systems. Parex usa select finishes or dpr acrylic finishes can. The scratch coat is applied first to provide a strong base for the system. Before the finish coat is applied, bmi 690 needs to be cured for a minimum of 7 days per ubc code 2508.

Now in the winter i am seeing more and more hairline cracks and some spider cracks but still hairline. Traditionally, stucco was composed of lime, sand and water but now portland cement is added. The underlying cause of the hairline wall crack may be due to problems with the walls framing, contraction or expansion of wood sheathing, settling, thermal expansion or contraction, rapid changes in temperature, weak areas in the wall or abnormal. This improves water resistance, reduces cracking and provides a good key for the finish coat.

Also, the mortar might have been retempered mixing water in the mortar after it starts to set. It looks like they applied some sort of finish paintwhatever coat directly to the brown coat instead of a color coat. When the brown coat is dry then the final finish coat is applied. This article will give you some helpful advice on how to properly mix stucco. Wet the wall several times per day for a period of several days after the completion of the stucco. A basic overview of the three coat stucco system duration. Cracks are a common and accepted occurrence in stucco assemblies but by utilizing stucco level coat with embedded mesh over the stucco base provides enhanced crack resistance to the wall. 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. How to handle cracks in 3coat stucco professional builder. To ensure bond, mix merlex acrylex acrylic admixture into the finish coat plaster at a ratio of gallon per 90 lb.

The scratch can be applied with a hawk and trowel, or sprayed on. Cracking in stucco or dryvit walls happens when there is more stress placed on the wall than the material can withstand. The solution to stucco hairline cracks is to use elastomeric paint. Our recommended tools, greeting our ambitious and faithful subscribers, as well as fellow plasterers. Wet the scratch coat prior to application of the brown coat or the finish coat if using the doubleback method of application over concrete masonry. They ranged any where from 45 feet long to the length of my garage wall 16 plus feet between the front windows. 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. The brown coat is followed by the finish or color 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. These come in all different shapes and sizes and can be found at most home. Aug 08, 1986 you can mix portland cement instead of mortar cement with sand to make stucco, but you have to add about onetenth by volume of hydrated lime for a workable, pliable mix. Twocoat stucco is used on concrete, brick, and block.

The scratch coat is applied first and is embedded into the metal lath to provide a strong base for other two coats. 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. The sheet rockers hung the sheetrock after we applied the second or last coat of stucco, which caused the stucco to hairline crack, however even if the sheet rockers did not hammer on the inside. The brown coat was applied three weeks ago, when we wet the surface, we. The various layers that make up a stucco exterior wall finish contain basically the same ingredients, but are mixed at different ratios. It is similar in appearance to portland cement plaster and may be applied using similar methods. It may be used as a leveling or patching material over approved substrates. To achieve this, run a squeegee trowel over the entire patch once its in place. Cracks normally occur in the base coats and simply transfer through the finish.

Base coat stucco is a portlandbased stucco used for scratch coat stucco applications, brown coat stucco applications and to repair stucco walls. For best results the stucco mix should be applied within a. Mix a small batch of brown stucco for the base coat, following the manufacturers instructions. Other common repair methods may be better suited to active cracks.

Other additives like glass fibers and acrylic strands strengthen mix and prevent it from cracking and it can be applied with a trowel or sprayed on. A finish coat of stucco over painted stucco depends on, condition bond of the paint, type of paint, and the finish coat being applied. Anyone with stucco walls will tell you that cracks seem to be a way of life for them. Painting stucco is an acceptable method to change color. Stucco mix can be scratched, browned or applied in one coat to 34 in. Mix the mortar cement and sand with enough water to make a workable mix that does not sag or run but is pliable. There are other formulas that you can use but in its simplest form it is merely a 3 to 1 ratio of sand to cement. But the whole point of the lath and brown coat were to give a viable and strong substrate to which the finish coat could be applied, while also allowing for some minor separation of the base coat from direct contact with the. If mixture becomes stiff and difficult to trowel, discard it. If mortar is mixed in a mixer, clean water should be used, the mixer not allowed to run too long, as the longer you mix, the faster the mortar sets.

As an alternative optional, merlex superhold eva bonder may be applied directly to basex prior to application of finish plaster. Active versus static cracks both volume change and external stresses must be considered before one can take steps to design against portland cement plaster cracking. This minimizes the number of cracks that may come through and enhances the overall aesthetic appeal of the exterior. Meets astm c926 standard specification for application of portland cementbased plaster. The finish is where the texture andor color is added. For best results, apply the stucco mix within a temperature range of 4080 degrees fahrenheit. The brown coat is applied next to create an even surface for the finish coat. Preblended with sand, requiring only the addition of water. This article will focus on the investigation of cracks and some suggested repairs. Must the scratch coat cure for 48 hours before applying the brown coat, or can the. Avoid cement rich mixes stay within astmnwcb ratios. There is a lot of confusion when it comes to mixing any kind of stucco, but we will be discussing the base coat mix in this article. Crack isolation base is a base coat for embedding mesh in the omega crack isolation system. I would really appreciate if you can share your expertise and let.

The brown coat must be compacted and hard floated to densify. Most of these were over expanded metal, and a couple were over cempo icfs made with recycled polystyrene and a cement slurry. Often, when wallpaper was being applied to a rooms plaster, the brown coat was the final coat, as there was no reason for the finish coat. Exterior stucco color coat is designed for application over cement plaster brown coat, it will not properly bond to drywall or other common interior surfaces without extensive surface preparation. The crumbling is because the brown coat dried out before it set up, as a result of being too thin. How to apply scratch with brown stucco cement on the same day. If the nail does not dig in but leaves a white line, the stucco is hard enough for the brown coat. Jan 24, 2019 when the brown coat is dry then the final finish coat is applied. Hard float the brown coat to densify plaster membrane. The main cause for this stucco crack is from the base coat not curing properly. This process can take some time and patience, but is not too difficult to do, in fact it is the easiest process out of all of the basefinish coats. 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 scratch coat is followed by whats called a brown coat.

Tape the cracks with fiberglass mesh and joint compound as for any minor plaster crack. Mix only quantities that can be applied within one hour. The mix proportions are carefully controlled to create a stucco mix that, when adequately hydrated, allows each coat to relieve stresses through a dispersed pattern of micro cracks prior to the application of the next coat. Feb 10, 2016 fiberglass mesh for stucco cracks, embed or on top of brown coat. Its embedded in metal lath, which strengthens and secures the coat. Quikrete one coat render cement plaster, mixing quikrete in buckets. Patching of hairline cracks is not recommended as it will detract from the natural beauty of the stucco and will serve no useful purpose. Identifying various cracks in stucco the stucco guy.