The technique of performing plastering work is not as easy as it might seem, this is why we have put this material together to make it more clear to understand. Whether you are a student and want to become a master in plastering or a client who wants to know the process, in this article, we’ll take you through them step by step.
1.Tools and Material You Will Need
● Hawk – a tool used to hold a plaster, mortar, or a similar material, so that the user can repeatedly, quickly and easily get some of that material on the tool which then applies it to a surface by Trowel.
● Trowel – Make sure it is a good quality.
● Bucket Trowel-You need this to scoop you plaster up with.
● Tape measure- to measure the corners and reveals when installing the beads
● Plastering snips- for cutting the beads
● Hammer – to install the beads
● Brush – Small for corners, wide to splash the wall, and cleaning brush to clean the tools.
● Paint roller- to apply primer
● Jointing knife is essential for defining a straight line and edging into tight spaces such as corners and those areas that are tight, such as between a window near the wall and the wall that is perpendicular to it. They come in a variety of shapes and sizes as needed. Angled jointing knives help reach hard to reach angles.
● Power mixer- used to mix or blend a wide range of materials
● Mixing and water bucket- You can get the big and small Gorilla tubs which are a brilliant option. There flexible and strong.
● Halogen light- It shows all the details on the surface, which helps to avoid errors
● Ladder or step
● PPE- as a plasterer it is essential to use personal protective equipment for your health and safety. You can find the details later on in the next article or visit this site
http://www.citbni.org.uk/CITB/files/a5/a56c0b6f-d11a-49aa-bcf4-bf090f87189d.pdf /PAGE 27
● Clean tap water
● Dust sheet or waterproof protection, masking tape- to protect the floor, furniture,fittings ,doors,windows etc.
● Plaster- undercoat plaster or finishing plaster
● Right Primer- we will explain later how to choose the right primer
● Angle beads, stop beads
● Joint tape- to apply on plasterboards joints or existing plaster cracks
● Nails and staples – to install the beads
● Fibreglass mesh- High strength reinforcing mesh, will be needed only if the client will request it. However, it is always good to recommend as this material helps to straighten the walls and give more chances.
Plastering can be a messy job. Make sure that you use waterproof protection for floors and furniture to avoid damage. When the protection is not needed it is still good to use at least dust sheet just to keep reasonably clean during the plastering which will make it easy for you at the end.
Please don’t forget to unscrew your light switches and plug sockets and cover them with a plastic sheet and masking tape to save you more work.
You also need to consider removing skirting boards, dado rails, picture rails, in fact, anything that is nailed or stuck to the wall, and that may include radiator, so you need to shut the heating system off and drain it before you do that. It’s better because it saves getting plaster all over the fittings. This just makes your life a lot easier when plastering.
3. Strip all the wallpaper
You need to strip all the wallpaper and make sure the wall is clear. You cannot even leave a small piece of wallpaper, because the plaster will not stick to it and will come off within a time. You don’t want any hidden problems because of a bit of wallpaper. Take your time on this.
4. Wash the walls down
It is recommended but you will find out some walls doesn’t need doing this. Just don’t make a mistake while estimating the condition. As if the walls are grease you might have a problem as the plaster won’t stick to the surface!
5.Check the condition of your walls
Once the wallpaper is gone, you can see the condition of the walls.
Check for any loose plaster and make sure to get all off. Check areas for cracks or blown plaster make sure you scrape it off and tape the cracks. Remove any peeling paint. You do not want to risk applying plaster on not prepared walls because then it would risk falling off and you will have more work to do and an unhappy client.
You also need to check to see if the previous coat of plaster is solid. We can’t plaster onto a wall that is drummy or unstable. If you tap the walls you can hear when plaster is solid to the brick. It doesn’t move, doesn’t sound hollow and definitely doesn’t fall away with pressure.
● Cracks are signs of weakness in the walls so tap around any areas that seem unstable. If any sections sound hollow or move you need to hack the old plaster off. Optionally when the condition of the surface is weak and cracked but you don’t want to touch the wall too much you can treat the walls with the Special Deep Penetrating Primer and install FibreGlass Mesh before plastering (see below) it will help strengthens the surface and prevent cracking.
6. Using the right Primer is a key to a job done well
Properly preparing the surface that you want to plaster is essential if you want to achieve a great finish. The suction of the wall has an enormous impact on the finish of the work. Before you choose the right primer, you’ll need to determine if your wall has a high or low level of suction.
A high suction wall will soak up moisture very quickly. This will cause your plaster to dry too rapidly, and you won’t be able to smooth it out. However, if your wall is low suction, you’ll find that your plaster struggles to bond to the surface. The plaster will be fragile and it may start to crumble.
-For low suction or smooth background use Grit Bonding Agent or ThistleBond-it
-For very weak condition background use Ceresit CT17
The best way to check the suction of your wall is to do a patch test. Take a small section of your wall, around 50mm x 50mm, and apply freshly mixed plaster to it. Leave the area for a few minutes. Use your finger to lightly trace a line through the plaster. During the patch test, if the plaster feels considerably drier than before, you have a high suction wall. However, if the patch has not dried you have a low suction wall.
7. Repairs before skimming – solid walls
Repairing small damage areas in plaster
If you removed any loose or blown plaster and prepared surface with right primer now you can apply the Base Coat Plaster (see below). If the patch has a depth of around 12mm (1/2″), you should be able to plaster it in one go; if it is more in-depth, you may have to make two applications. Otherwise, the weight of the wet plaster will drag itself away from the wall.
Repairing larger damage areas in plaster
a) Wet Plaster ( Float and set)
Wet Plastering, known as float and set refers to the process of applying a wet plaster base to the substrate surface before the finish or skim coat. As a minimum, this is a two-stage process which in general can take longer than the dry lining or dot, and dab methods as the base coat must dry to a certain level before the finish coat can be applied.
There are different base coats which can be used depending on the base material and function (see below).
Type of Base Coat Plaster for internal walls:
Thistle Bonding -is an undercoat plaster ideal for smooth and low suction backgrounds, including:
-Dense blocks (on smooth Low-Suction blocks)
– Thistle Hardwall -is an undercoat plaster with high impact resistance and quicker drying surface. Suitable for most masonry backgrounds including:
– Ordinary bricks, blocks (Not on smooth Low-Suction Blocks)
Type of undercoat plaster for “internal surface of external wall”:
– Rendering- use sand and cement as Base Coat before skim. Suitable for externals walls, weak condition walls, area at risk of damp.
-Brick or Blockworks
– Thistle Hardwall -is an undercoat plaster with high impact resistance and quicker drying surface. Suitable for most masonry backgrounds including
-Common bricks, blocks (Not on smooth Low-Suction Blocks)
b) Dot and Dab (Dry lining)
Dry Lining refers to the process used when attaching plaster-based sheet boards to either a wooden stud framework, metal stud work or direct to brick or block works using an adhesive compound in a process called dot & dab.
It is popular, on both new build applications and refurbishment projects.
There are many different types of board used in dry lining, each one suited to a particular purpose or need, from standard wall boards to speciality boards:
-Moisture Boards: Used for bathrooms and rooms with high levels of condensation.
-Fireline boards: Especially suited where additional support is required for extended fire retardation.
-Soundboards: Used to reduce sound travel through walls and partitions or coupled with resilient bar can offer sound protection between floors.
-Insulated Boards: Coupled with a layer of insulation these boards can be used to reduce heat loss and lower carbon emissions. Whatever the application there is a board to a suite, and using the correct board for the job makes all the difference
8. Repairs before skimming – stud walls
-To repair a small area of damage you need to apply drywall compound around the hole with a putty knife. Use scissors to cut a piece of fibre glass mesh to fit over the hole, sizing the patch to extend 1 inch beyond the hole. Place the patch over the hole and press the edges firmly into the wet compound. Lets the patch dry and apply a second coat of compound if needed.
-To repair a large area of damage to plasterboard, the damaged area needs to be cut out back to the joists and a new piece of plasterboard fitted.
If there are any minor damp issues, they can be taken care of with some sealant used to cover the wall surface. If you have encountered some more severe moisture and damp problems, note that they will have to be solved before you carry on with your work.
9.Install of plaster Fibreglass mesh
In drywall, cracks tend to follow the joints between drywall sheets, but in plaster, they can run in any direction, and they tend to appear more frequently. They occur because plaster is brittle and can’t withstand movements in the framing caused by moisture and settling. You can repair these cracks using either plaster or drywall joint compound, but they will keep coming back if you don’t tape them first with self-adhesive joint tape or by installing Fiberglass mesh to the whole plastered surface, this the best solution for the job.
10. Straighten the surface
Next, make sure the surface is as level as possible – the easiest way to do this is to use a Feather Edge or Level 2m in length. Place it on the wall in various directions and check that it touches the wall at each end and that there are no significant gaps between it and the wall along its length.
Any gaps 5mm or less will not unduly affect the, but anything much substantial than this could cause problems because you would see the waved surfaces especially in the corners between two walls or between wall and ceiling. If the wall is not in a level using one of Base Coat plaster (see above) to form a more level surface.
11. Make sure all preparation before skimming is done properly
There are many steps involved in plastering process, each with particular requirements concerning skill, tools and materials but no matter how professionally each stage is performed the end result could be a disaster if you do not prepare the area fully before starting.
………The next step will be Applying the skim coat to walls and ceilings…….