Why is my new plaster cracking

This is not a new technique; we are not recommending a revolution in thinking. It used to be that builders of old would use horsehair to achieve the same effect. Now, however, we use these synthetic fibres to bind the material together, while absorbing some of the tension created when it dries, and throughout the life of the build, as the construction naturally moves with heat and moisture.

You can get our Siteworx plaster and render fibres in g bags , and it can be stirred into your mixture of plaster or render before application. Find out more about the Growtivation Product That Works range by downloading our Product Guide and your free copy of our Landscaping That Works guide to weed control and geotextile fabrics. To discover where you can buy Growtivation products visit our online Where to Buy facility or contact the friendly team at Growtivation for advice on or email sales growtivation.

How to prevent plaster and render from cracking Home » News » How to prevent plaster and render from cracking. Contact Us. View previous article. View all articles. View next article. Substrate preparation All bases should be sufficiently rigid, clean of any surface contamination that may prevent good suction. Dampen the substrate before few hours from the plaster application Fill the empty gaps in the joints of the block wall with block mortar weberbloc fix or weberbloc fix LW Plaster application Depending on the type of substrate, plaster should be recommended: For normal and hollow blocks: use weberpremix hand or weberpremix SP or weberpremix SP-1 For light weight block: use weberpremix SP or weberpremix SP3-FL Spray the plaster on the dampened and prepared surface or apply it manually with a plastering trowel at a thickness between 10 and 20mm in one layer.

For higher thicknesses kindly consult the technical department. Follow the application method statement instructions Finish the surface with a wooden or steel float as required Let the product set properly on the surface before any curing Cure for 3 days. Non-structural cracks repair: Concrete substrate Plaster de-bonding on concrete with or without cracks: De-bonded plaster on concrete substrate is repaired after removal of the entire de-bonded surface and creating a grip key with well-adhered plaster.

While removing the plaster, examine the rush coat for better repair: if the rush coat is rough and strong, apply plaster to the rush coated surface If the rush coat is rough and weak, remove it and apply a new rush coat If the rush coat is smooth and strong, apply another layer of rush coat If the rush coat is smooth and soft, remove and apply a new one according to the technical data sheet 1. Rush coat application : According to the type of concrete, the suitable rush coat is recommended For normal concrete: weberpremix key coat or weberpremix SRC-2 For very dense concrete: weberpremix SRC-S is recommended.

Weak and failed rush coat should be removed properly. A new application with the convenient rush coat shall be executed on the prepared surface. Substrate must be sound and clean. Substrate must be wet before application. Free water on the substrate should be allowed to dry before any application. For dense concrete, the substrate should left without curing for a minimum 24 hours before rush coat application Recommended rush coat the proper rush coat must be chosen according to substrate is re-applied on smooth surfaces and cured for 3 days, and 3 times a day.

Make sure that the applied rush coat has a rough finish to secure the bonding of the plaster Allow to harden depending on site conditions.

For more details, consult the technical department 2. Plaster application: The convenient plaster should be used according to the type of substrate and the compatibility with the applied rush coat In case of dense concrete, it is recommended that the rush coat to be left without curing before 24 hours from the plaster application.

Mix the plaster with a clean and cool water Apply and press firmly the plaster over the rush coat. If the surrounding area is too warm, for example, if you have your central heating on in the days after the wall has been freshly plastered, you may be in for a surprise - and not a good one. Cracks can also appear if the hot sun is beating down through your windows onto the fresh plaster. Sunshine on a scorching hot day can result in some damage, which we want to avoid.

Ensure that the atmosphere surrounding your new plaster is at the most optimal level for drying. Keep your home cool, open the windows to allow a steady flow of air through the rooms. This will dry the plaster naturally. Hairline cracks are not the be-all and end-all; they can be fixed.

These types of cracks can be filled with caulking. Caulking or caulk is used as a sealant to fill cracks or gaps around the home. It can be used to fill gaps around windows doors, plumbing and pipes to keep the draft out, and those nasty bugs from invading your home.

Using caulking is a quick and easy fix to get your wall back into tip-top shape. Although cracks are generally harmless, they could also indicate structural damage to the building and the need for some professional help. Cracks that are jagged in appearance or resemble stairs could be caused by structural movement, which could result in damage to your home. How do you know if a crack could be harmful? The rule of thumb is that the larger the crack, the more serious it is.

The positioning of the crack is also a tell-tale sign of how serious it could be. The majority of small cracks emanating from your windows and doors are considered harmless. Do not attempt to repair large cracks without speaking with a professional, as this could result in some seriously costly problems in the future. Plastering is a complex and time-consuming job. It more often than not needs two coats, plus a base layer of PVA in order to do the job correctly.

Generally speaking, you will only have to apply one coat of this type of plaster due to its thickness, compared to the many layers you need to build up regular plastering.

One coat plaster acts as a base and top coat in one, instead of separate layers. This type of plaster is best used when repairing previous plastering jobs, and for use in small areas. One coat plaster has two main advantages over your usual plaster: cost and time. As you are only mixing up one patch and coating the wall with one layer, both the cost of resources and the time taken to complete the job is reduced a considerable amount. We recommend you only use this for small DIY fixes, and not for large plastering jobs as the end result will not be as even and smooth as normal plaster.

Blown plaster refers to plaster losing its adhesion to the surface it was applied to. You can tell when your new plaster has blown because sections of the plaster will be coming away from the surface behind it. Often chunks of plaster can completely fall off, leaving visible holes on the wall. Repairing blown plaster is a little bit trickier than just filling in a crack.

Here are the steps to follow:. When plaster is applied, it needs to bond and stick to the surface behind it; otherwise, it will not stay in place. Usually, plasterers apply a layer of PVA to the surface first, before adding the initial layer of plaster. If this step is not taken, it can cause the plaster to come away.

Before applying the adhesive layer, the surface must be clean and free of dust. If the area is contaminated with dirt, the sealer will not adhere to the wall correctly, causing the sealer and plaster to blow in the future.

Blown plaster can also happen when the surface the plaster has been applied to is extremely porous. This is due to the surface sucking the water out of the new plaster before it has time to adhere; therefore, the plaster dries but does not stick. Patch test the wall first, before carrying out the job.

Trialling some plaster on a small area of the wall first will tell you a lot about the porosity of the surface. If the plaster feels dry after a short amount of time, you have a high suction wall. If the plaster is still considerably wet to the touch, you have a low suction wall. If you have a low suction wall, one coat of PVA before plastering will be sufficient.

If you have a high suction wall, you will need to apply multiple coats of PVA to ensure that the bonds are correctly made. If you do not add enough layers of PVA to a high suction wall, the surface will begin to absorb the water out of the plaster when it is applied, which will result in it drying out too quickly. When plaster dries out too quickly, it has a tendency to crack, and blow.

When hiring a plasterer, costs vary depending on both how long the job will take, and how many walls need plastering. Usually, when speaking to a plasterer, they will analyse the site, work out the costs and quote you for the job. Most plasterers use square metres as an indication of how much a job will cost. The more square metres that need plastering, the more time and materials the job will take.

The plasterer has to take into account the costs of materials as well as the physical work. When hiring a plasterer, there are two types of jobs: Re-Plastering and New Plastering. Plastering can be done to both walls and ceilings. Here are some average prices based on the type of plasterwork, size of the room, and how long the job will take to complete keep in mind that these prices are the average, so you may be quoted higher or lower :. A: The number of coats of paint on new plaster should be at minimum 2.

However, the number of coats your wall will need depends on the quality of the plasterwork, and how professional you would like the finish to look. Before applying a topcoat of paint, new plasterwork needs at least one layer of mist coat. This is an emulsion created with a ratio of paint to water. You must apply a thin layer of this emulsion to your new plaster once it is fully dry, and then analyse the wall for imperfections.