Introduction
Rendering a wall is a vital element of the construction process that is sometimes disregarded. Here at Insulation Superstore, we want to make sure you understand why rendering a wall is vital and how to do it correctly, so keep reading to learn more.
What is rendering?
The term "rendering a wall" refers to the process of applying material to a wall in order to create a layer of protection. Rendering refers to the process of applying plaster to outside walls, while plastering refers to the process of applying plaster to inside walls. However, these phrases are occasionally used interchangeably.
Why is it important to render a wall?
1. Protect the building structure
There are several reasons to render a wall, but one of the most significant is for protection. Because the wall of your home or building is such an important aspect of the structure, it is critical to preserve it. Rendering a wall shields the bricks from the weather, decreasing the wear of the brickwork over time and maintaining the building's structural integrity.
2. Aesthetics
Instead of settling for open-faced brickwork, putting render to the exterior of a property will produce a uniform, clean, and finished appearance, onto which you can then add paint to get the finish you want. This is especially advantageous if the structure was constructed with a variety of various colored bricks.
3. Protection from damp
External render acts as a barrier to penetrating damp, which is a common problem with solid brick walls. Penetrating damp is the intrusion of water moisture into solid brick over a lengthy period of time, resulting in cracking and disintegrating brickwork.
4. Insulation
Render is an additional coating that is applied to an external wall to improve thermal characteristics and retain heat in. If an insulating render is employed, this can be considerably increased. Alternatively, render can be utilized as a waterproof overlay over external insulating materials.
How to render a wall
1. Preparation
When rendering a wall, the first step is to prepare the surface. Any existing render must be removed, as well as dust, debris, and grime, which must be removed with a stiff dry brush. Additionally, eradicate any mould with bleach or another cleaning solution before rinsing the wall with a hose to ensure the surface is entirely clear of debris.
Allow for drying time before applying the render - this could take a few days.
To prevent any render from falling onto the floor, place sheeting around the perimeter of the wall. The sheets can be made of anything from tarps to trash bags or cardboard, as long as they cover the entire area. Tape them to the ground to keep them from moving away from the wall's edge.
If there's a chance of rain while you're rendering the wall, cover it with a tarpaulin or some other sort of protection; water will prevent the render from adhering to the wall.
Fill a bucket halfway with render mix and stir according to the package's instructions. The standard proportions are 8 litres of water to 20 kilograms of render, with a paste-like consistency in mind. To mix the render, start with a shovel and then attach a paddle mixer to a power drill to ensure it is thoroughly combined.
If you don't wash the render off the tools as soon as you've finished mixing it, it will harden, dry, and become nearly impossible to remove.
3. Applying the first coat of render
To avoid waste, get the bucket of render as close to the wall as possible. Take a trowel and put render to it to apply the render. The trowel should then be pressed against the wall and moved upwards to the top of the wall. Create an even coat of render that is roughly 5mm thick with as few motions as possible.
Take a timber batten and move it upwards to smooth out the surface after you've applied the first coat of render — the movement should start at the bottom and go all the way to the top of the wall.
After the first coat of render has dried, the second coat can be applied to the wall. Apply a layer of render that is double the thickness (10mm) of the first application using the same way as before.
Allow 30 minutes for the second coat of render to dry before using the timber batten or straight edge to smooth out the coating - flatten any elevated spots and use the excess to fill in any depressions or thinner areas.
4. Applying the second coat of render
After the surface is even, use a scratching comb to make horizontal lines across it. If you don't have a scratching comb, nail many nails into a piece of wood and use it, or go over the surface with a screwdriver if you're working on a tiny wall. These lines don't have to run all the way down to the original wall surface, but they should be deep enough to allow the second layer of render to cling to it.
The render should then be left to dry and firm for up to two hours; inspect it after 30 minutes to see whether it has started to harden.
5. Finishing touches
Now, softly dampen a sponge and gently rub it against the wall. This ensures that the surface is smooth and that any holes in the render are filled. Any debris on the sponge can cause scratches in the render, so make sure it's rinsed and cleaned on a regular basis.
If you want a textured or brushed look, instead of using a sponge, use a bristles brush.
Allow 24 hours for the wall to dry. After 24 hours, spray the wall once a day for 5 days with water that is around room temperature. This will keep the render from drying out too soon, which might result in cracks and splits.
The render should then be left to dry and firm for up to two hours; inspect it after 30 minutes to see whether it has started to harden.
How to Install External Wall Insulation
External wall insulation is a great option for improving a building's insulation, reducing heat loss, and improving the building envelope. Buildings built before the 1930s typically have solid walls, which means there are no cavities that can be filled with insulation. Therefore, in order to improve the insulating properties of the building, insulation must be fitted on the exterior of the walls – installing insulation on the interior would decrease the usable space and room sizes.
Where to find insulation for external walls
External wall insulation boards are available from Insulation Superstore. Choose between Kingspan Kooltherm external wall insulation, Diffutherm insulation boards, Diffuboard insulation boards, and Pavatherm insulation boards.
Due to the complexity of the procedures involved, external wall insulation is typically installed by a professional rather than a homeowner or DIYer. Furthermore, external wall insulation will change the appearance of your home, so planning permission may be required in some cases.
As previously stated, the process of installing external wall insulation is relatively complex, which is why it is most commonly performed by professionals. However, we've outlined some of the fundamental steps involved in installing external wall insulation below.
How to install external wall insulation
Render Test
The first step before beginning the installation of external wall insulation is to perform a render test. This will determine whether the current render is strong enough to support the insulation. If the render is strong enough, it can simply be smoothed and the insulation applied directly on top of it. If the render is not strong enough, all existing render must be removed before installing insulation.
Remove and Adjust Pipework
After the render has been tested and smoothed down or removed as needed, all pipework from the building must be removed before the installation process can begin. Temporary downpipes must also be installed to prevent water from running down the side of the building, and any waste or soil pipes should be removed or extended away from the walls, allowing the building to function normally during the installation process.
Protect Windows
Professionals will frequently apply a protective layer or film to your windows and doors to prevent them from being damaged during the installation process.
Fitting a Starter Track
Before the installation begins, it is important to decide at what height you’d like the insulation to begin. External wall insulation typically does not reach the ground, but rather begins a few inches or feet above. This is where the aluminium start track, or carrier tray, will be installed once the height has been determined. This provides a level starting point and can also be used to accommodate beading.
Installing Insulation Boards
After the starter track has been installed, the insulation boards can be applied to the wall. Each board is coated with adhesive before being nailed to the wall in a staggered pattern. When the insulation boards reach windows and other obstructions, they are cut to fit around them. After the insulation boards have been installed, a rasp is used to file off the boards' edges where necessary to ensure the surface is completely flat.
Adding Mechanical Fixings
Mechanical fixings, in addition to adhesive, are used to secure the insulation boards. To ensure that the insulation boards do not get blown off or fall off during bad weather, approximately 10 fixings are hammered in per square metre.
Adding Beading
Corner beads and stop beads are great for securing and tightening insulation around windows, doors, and other impediments, producing neat and tight edges and avoiding the insulation from touching other materials.
Adding Reinforcing Mesh and Render
After the boards and beading are installed, two layers of render with reinforcing characteristics are applied, with a fibreglass mesh sitting between the two layers of render.
Apply Primer
A primer is applied after the strengthening render and reinforcing mesh have been installed. This primer frequently contains granules that aid in the adhesion of the final render coat, and it is usually color matched to the final render to ensure no colors show through.
Apply the Final Render
Now is the time to apply the final coat of render. This render is the last coating in the installation procedure, – this means that it is essential to choose the specific colour and texture you like, as it is now in view on the outside of the building.
Reinstall Pipework
All pipework and other fixtures that were removed from the walls can now be reinstalled, and any openings where pipework extends through the render should be sealed.
After the exterior wall insulation has been installed, your window sills may have to be made deeper to enable for the thicker wall. This can be accomplished with a window sill extension or by adding new wider sills on top.
Additionally, new or extended verge trims where the roof meets the wall may be required to extend over the newly widened wall.
