Repairing chipped plastered corners 

Modern plastered external corners usually incorporate a metal corner strip and are so protected from damage. However, in older properties external corners were often made using render and plaster alone and can suffer damage from knocks and scrapes. Repairing such damage can be easily repaired using a suitable filler. 

• Start by brushing the damage clean of all loose dust and dirt. 
• Dampen (but don\’t soak) the area of damage using a moistened paint brush or water spray. 
• Use a wide filler knife to apply filler to the damage, work it into the damage to make sure that there are no air holes or voids in the filler. 
• Use the knife to get the filler level with the surrounding plaster. 

 When the filler has started to harden, use a wet finger to shape the corner to the profile above and below the damage. 

Te filler used may shrink as it hardens, and the surface may need to be built up using repeat coatings of filler. Between each coat, lightly sand the surrounding surface and moisten the previous filler. 

Repairing Outside Corners of Plaster Walls

Tack a length of wood that exceeds the vertical dimension of the corner flush with on of it corners, making sure the length of the wood extends past the hole on both the top and the bottom (A). This acts as a guide when you patch the outside corner to produce an edge that blends in with the undamaged portion of the corner. 

Remove loose plaster, going slightly beyond the hole to provide a good seat for the plaster patch. Smooth the patching plaster away from the wooden guide with a trowel, overlapping the existing wall slightly. 

After it has dried, switch the position of the wooden guide to the other side (B) of the damaged corner and repeat the process. Sand and smooth once the patch has dried completely. Fill in any holes used to tack the piece of wood with joint compound.

Plaster Wall Repair – Corners is a post from: DIY Guides

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• Small (1 or 2 m wide), random cracks general indicate no major structural problems. 
• Cracks which run in horizontal or vertical straight lines, or which run in a stepped pattern may indicate a professional assessment should be undertaken. 
• Cracks where the two sides form a step again may indicate the need for a professional assessment. 
• Any long cracks over about 3 mm wide, and also where something thin can be projected deep into the crack. 

Most small cracks can be easily covered by wallpaper. Where walls are going to be painted with ordinary paints, the cracks need to be filled and this page deals with filling small cracks in plaster walls. 

Repairing cracks in plastered walls 

The first thing to do is to widen small cracks in plaster to give a key for the filler. Use the corner of a scraper or filling knife to remove any loose plaster and to open up and deepen the crack. Try to undercut the crack to provide a key for the filler. 

Use a dry paint brush to clean the crack of loose dust and dirt. 

When the filler has been mixed and ready to use, dampen (but don\’t soak) the plaster in the crack by using a moistened brush.
Use a filling knife to press the filler into the crack along its length so that the filler is proud of the surrounding plaster.

Use a wet filling knife along the line of the cracks to level off the filler. 

The filler used in larger cracks may shrink as it hardens, and the surface may need to be built up using repeat coatings of filler. Between each coat, lightly sand the surrounding surface and moisten the previous filler before applying the next coat of filler.

Plasterwall Repair – Cracks is a post from: DIY Guides

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Small Area

•  Clean out all dust and loose plaster from the damaged area, if the laths are not exposed, cut back the plaster to form a deeper hole – try to undercut the plaster around the sides of the hole so that the new plaster will have something to stick to – try to avoid having tapered edges where the new plaster will have to taper down to almost no thickness on top of the original plaster. 

•  Mix up some new plaster filler and before applying, dampen the original plaster at the sides and back of the hole using a wet brush or water spray – take care not to over soak the plaster. 

•  Use a filling knife to fill the hole with plaster filler, take care to push the new plaster into the edges of the hole and any cracks, add enough filler so that it is above the level of the surrounding plaster. 

•  Use a wet wide bladed filling knife to level off the new filler to the surrounding plaster work – if the filler knife is not wide enough to bridge the repair, use the knife around the edges of it and then work into the middle. 

The plaster filler used in the repair may shrink as it hardens, and the surface may pull back from the original plaster level – the deeper the repair, the greater the risk that this will occur. To overcome this shrinkage, a number of layers of filler may need to be applied to build up the surface. Each layer must be allowed to harden before applying the next. Between each layer, the surface of the repair and the surrounding area should be lightly rubbed down using a fine sandpaper – this needs care as lime plaster is extremely soft and easily rubbed away. The surface of the repair filler should be dampened before covering with another layer. 

Large repairs 

When a large area of plaster needs to be repaired, a more satisfactory finish will be achieved if proper plaster and plastering techniques are used – i.e. apply three coatings, the render, the floating and the setting layers. 

•  Clear away dust and loose plaster around the hole that will prevent the patch from adhering to the wall.

•  Dampen the edge of the hole and fill with patching plaster using a spackling tool. Make sure the patching plaster does not fill the hole level with the existing wall. It should fill the hole to a level just below the surface of the existing plaster – you want to leave enough space for the joint compound to cover the plaster patch and still be even with the wall\’s surface. Score the surface of the plaster patch with your spackling tool with vertical and horizontal lines, then allow to dry for 24 hours.

•  After the render layer has hardened, dampen the surface and apply the floating layer and bring the level up to about 3mm (1/8 inch) below the surrounding plaster. 

•  After the floating layer has hardened, dampen the surface and apply the setting layer of plaster and bring the level up to the surrounding plaster. 

Plaster Wall Repair is a post from: DIY Guides

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Here are a few good tips:

1. Always start cutting the longer sheets first. When you have cut the long sheet measure the off cut and find a place for it to be used and cut it to size straight away. This prevents a build up of off cuts. Use any remaining off cuts in the pile that fits the wall size you want to reduce waste.
2. When cutting a strip or have a large window off cut, don\’t just put the off cut aside. Narrow strips are very handy up the sides of doors or in cupboards etc. It is easier to cut a small strip off a larger sheet than from a small strip. So find a place to use the off cut and cut then measure both pieces and cut the smaller one first. 
3. For an obtuse internal corner, always try the cut and fold method first. The cut and fold method eliminates the need to stop up the obtuse internal, saving a lot of time. When you cut the back of the sheet and fold it around, provided that the cut is perfectly straight, it will give you a nice straight crease that will make up the obtuse corner. It is vital that you measure very accurately and the walls are plumb. 

Always remember to install plasterboards that are meant for the ceiling first. This is because the wall sheets help hold up the ceiling sheets. If you hang the wall sheets first, it also reduces the amount of options you have in the length of the sheet, therefore increasing the chance of jamming the sheet as you lift it up.

Cut all the sheets and put them in position in the rooms before you start fixing. Place them on the wall where your first sheet will go up face out. If your room is not square put the shortest sheets in the room first then the longest, so the longest sheet is the first to put up. This makes it easier to check out the piece where the room gets smaller. Also by setting the room up this way you will not need to turn any sheets around. Hire a sheet lifter if possible to help you when installing the ceiling sheets. 2 x 4 stud (called dead man studs) will help hold up one end first, as you work your way down the ceiling sheet to the other end.

Recommended viewing : http://video.bobvila.com/m/21319557/blue-board-plaster-walls.htm

Plasterboard Installation is a post from: DIY Guides

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Plaster of Paris

Mix some plaster of paris (with manufacturer\’s recommendation) and start at the ceiling line and work your way down. Apply an even coat over the wall in long fluid smooth motions.

Most plasters have a grace period of 50 minutes before it hardens, if it does start to harden, throw water on it to smooth it out.

Roll-on Plaster

Roll-on plasters are designed for DIY enthusiasts, who wish to plaster their own interior walls or ceilings. The plaster is designed for interior use only. It provides a coating to interior plasterboard walls and when smoothed out with a spreader leaves a level finish ready for painting. 

The method of applying the plaster is simple. The user rolls on the plaster with a standard high density roller from the bucket and provides a smooth finish with the spreader. It is fast drying and virtually non drip. 

It is extremely important that the proper preparation is completed on the area to be plastered. All surfaces must be dust free. The surface should be smooth and all holes filled to a level finish with the wall. All fragments, nails and pins or any other items that will impact the application such as adhesives left from tiles etc. Place appropriate cover over the floor and furniture. Ensure taping and jointing is properly filled in and smoothed.

Depending on manufacturer’s specification, most roll-on plasters have coverage listed below:

2.5 litre bucket is for covering a small area of approximately 10 square metres.

7 litre bucket is for covering a medium area up to approximately 30 square metres.

10 litre bucket is for covering an average sized room covering approx 40 square metres.

Note: This coverage is subject to how liberal or the thickness of the plaster applied. Coverage may vary.

Dip roller into plaster fully and apply the plaster on the wall. Use a spreader to smooth the plaster after it has been applied with the roller, angle the spreader about 20 degrees from the surface in an even downward motion. When the plaster has dried for approximately 1-2 hours, dip the wet and dry sponge sanding block in some water and gently sand away any irregularities that may occur during application. It is recommended that you clean the excess plaster off the spreader by scraping it back into the bucket and cleaning the spreader using the bucket of water. Use the spreader or paintbrush to cover the areas the roller cannot reach and level out with the spreader. 

Repeat this process until the wall or ceiling is completed. 

Leave for 24 hours and then the plaster board wall or ceiling should be ready for painting. 

The plaster should then be covered with a neutral sealer or primer paint.

Plasterboard Applying Plaster is a post from: DIY Guides

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REMEMBER : Fibre glass plastering tape should only be used on plasterboard wall joins. There are different types of paper tape for plasterboard ceiling joins, plasterboard butt joints and internal corners. Never use fibreglass tape on plasterboard butt joins or internal corners.

Scrape back excess plasterboard jointing cement between coats and do not try to fully fill plasterboard joins on the 1st coat (ALWAYS use a 3 coat system). 

Several critical areas to check for a flat finish : 

•  
  •  The junction of a plasterboard join and an external corner.

•  
  •  The junction of a plasterboard join and an internal corner.

•  
  •  The Junction of a recessed plasterboard join and a butt join

•  
  •  The 3 way intersections of internal corners

To check these area use a plasterers 12 inch joint knife on its edge.

Keep sanding plasterboard joins to a minimum, do not to scuff board when sanding. Store bags of plasterboard stopping plaster off concrete and make sure top coat is not out of date (some products can get mouldy if out of date).

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Plaster walls once framed home interiors, molded onto a lath with trowel and manipulated with a float until a smooth finish is achieved. They were heavy to handle and requires skill, making it all but obsolete in new construction. Solid plaster often provides a superior sound barrier and is harder and stronger than what has all-but-replaced it, which is drywall. Drywall became a common usage in modern house interiors because it is manufactured in sheets that can be cut to size, is easy to install and requires less talent. The drywall is then covered with plaster to create the interior cosmetic finish. Oftentimes the interior plaster is sprayed on and textured. Spray-on plaster can even be pre-mixed with paint to save considerable time and labor. 

All is not lost however for plaster walls. The advantages of plaster are many, especially if you’re thinking long-term benefits. Plaster walls look better with a flatter even surface. They also take paint uniformly especially when a semi-gloss paint that accentuates imperfections is used. With drywall, paint often appears different over the joint compound than over the drywall. Plaster wall also nicks less easily than drywall to maintain its beauty even with children around. It can be washed without the possibility of water damage with drywall. Once cured, plaster is resistant to short-term water exposure. It is also easier to strip old wallpaper off plaster without damaging the wall surface. You can use stronger enzyme solutions and scrape more vigorously to remove the old adhesive. 

Decide on whether a plaster or drywall is desired before any wall finishing has begun. The gypsum lath panels are nailed to the studs on the walls for the plaster base before a thin 1/16 inch layer of plaster is applied over this to create a smooth hard finished surface. If you have already put up the drywall, it is too late to select plaster if you decide to do so late. These special panels/plasterboards are often called “blue boards” because they have a special water resistant paper coating with a bluish color. This special water resistant coating prevents the moisture in the plaster from damaging the inner gypsum core. This application moisture is why standard drywall cannot be used with plaster.

Tools and materials needed: 

• Drywall saw
• Trowel
• Bucket
• Screwdriver/hammer
• Plaster/Roll-on plaster
• Plaster/blue board
• nails or screws

Things to remember when installing plasterboards

•  Plasterboard sheets should always be placed at right angles to framing members.

•  Plasterboard should always have a 10mm gap between the floor and the 1st wall sheet.

•  Never place a nail next to or through a daub of plasterboard adhesive.

•  Only apply plasterboard adhesive when you are ready to fix the plasterboard sheet. If the plasterboard adhesive is applied too soon, it will form a skin and not bond to the plasterboard sheet.

•  Evenly space plasterboard adhesive daubs across the width of the sheet.

•  Do not nail centre of plasterboard wall sheets. If the plasterboard sheets need pinning back, nail through a temporary plasterboard block and remove the block and nail after the plasterboard adhesive has set. This will prevent popped nail heads.

•  Keep plasterboard nails around doors and window close enough to the edge so the architrave will cover them.

•  Make sure all plasterboard nail heads are below the surface. (If you break the paper around a nail head put another nail beside it to avoid popping).

•  Double nail or screw the center of plasterboard ceiling sheets about 40 mm apart, this helps prevent plasterboard nails or screws popping.

•  Wherever possible keep plasterboard recessed edges together and butt edges together. Avoid plasterboard recessed edges and butt edges adjoining each other.

•  Never place plasterboard butt joints directly over the door stud or window stud.

•  Always back block plasterboard ceiling joins.

•  Use plasterboard back blocking cement or cornice cement for back blocking.

•  Citric acid will slow down the setting time of plasterboard back blocking/cornice cement, use about a teaspoon full in a back blocking mix.

Plasterboard – Tools and Material is a post from: DIY Guides

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There are different tapes with different function for different areas of the wall. Below lists the different types of tape as well as their function. 

1. Self adhesive fibre glass tape for recessed plasterboard wall joins

2. Paper tape for plasterboard ceiling/wall joins, butt joins, internal angles

Recessed Joins

Apart from being the strongest plasterers tape, it is also the most difficult to use for the casual DIY. The main difficulties experienced are bubbles showing up after painting or tape showing through the plasterboard join requiring the join to be over filled to hide the tape.

Bubbles forming under the tape is caused by either no base coat under the tape or the base coat has not been applied consistently and has dried out in parts before the tape has been embedded.

To avoid this, your mix needs to be a bit “wet” (not runny). Make sure you fill the plasterboard recessed join with base coat ensure no plasterboard or dry spots appear before applying tape. Bed the tape into the plasterboard recessed join using a 5″ or 6″ joint knife.

To avoid the tape showing through, first make sure there are no bumps in the plasterboard. If so, cut them out with a trimming knife. If cutting out the bump creates a large gap, pre-fill the gap and scrap back level before taping. Bed the tape tightly and evenly into the recess, use quite a lot of pressure to squeeze out base coat from under the tape. Use the mix squeezed out to apply over the tape. It is important that the back of the tape is “wet” with plaster. Try short sections at a time until you get used to it. Paper tape stretches, so once the tape is embedded, to finish coating over, start from the center and work to each end. Finally run through the entire plasterboard join from end to end to smooth out any excess. Remember to scrape back the join after the base coat has set, before applying second coat.

Butt Joins

Plasterboard butt joints have the added difficulty of not being recessed, so whatever tape and base coat applied is going to sit proud of the surrounding surface. To make a butt joint hidden requires a slightly different technique.

Start the same way as with a plasterboard recessed join but make sure you squeeze out all excess plaster from under the tape. The back of the tape should be “wet” with plaster but don\’t try to cover the tape. Using an 8″ joint knife, fill out each side of the tape, (without applying any more base coat over the tape itself), the edge of the tape sets the level. Use the full width of the joint knife. By using this method you are reducing the build up over the tape and spreading out the join level either side.

Internal Corners

Internal corners are best taped in after the plasterboard wall joins. Pre-fill and scape back any gaps over 5mm. As with all paper tape applications it is important to have a continuous “wet” layer of base coat before applying tape.

The easiest way to tape in an internal is to use an internal taping tool. The trap using this tool is, not setting the angle of the tool correctly; or not applying enough pressure to squeeze out all the base coat from under the tape. Make sure the back of the tape is “wet” with plaster and feather out the edges.

Using a 3″ or 4″ joint knife is another method of taping in an internal. The same principles as above apply, however getting a square corner can be difficult. In most internal corners the board on one side will be in behind the gap created by the corner. To get a square finish, on your final sweep with the joint knife, angle the joint knife into the sheet that is in behind the gap. This prevents digging out the plaster that is filling the gap. Use long smooth strokes for the best result.

3. Wet and Stick Paper tape for internal angles 

This tape has an adhesive backing similar to that of a postage stamp. The tape is cut to length and run through water to wet the tape. The tape is placed in position and wiped in with a 3″ joint knife. Once dry apply a thin coat of base coat over the tape.

Similar problems can occur using wet and stick as normal paper tape. Unless proper preparation is done these problems can be worse. To prepare the internal for using wet and stick, pre-fill all gaps over 2mm and pre fill all nail holes. Wet and stick tape is also very useful to repair cracked plasterboard joins. It allows you to repair the join with the minimum amount of build up4.

4. Flexi Paper tape for unusual obtuse internal angles

Flexi Paper tape is a stiffened paper tape that can be bent to shape, Used for obtuse internals that a 135 degree metal angle won\’t fit.

Flexi tape will take out minor imperfections in the line of the angle but to get perfect straight angle may still take more work. Flexi tape is used in the same manner as normal paper tape.

To straighten an obtuse angle, hold a chalk line from one end to the other, adjust the position of the line until you “even” up the line, and flick the line to give you a straight line to work to. If you only need to fill a short length, say 300mm to straighten the join, working along the length of the join may be ok, just follow the chalk line. For long runs that may need to be filled out up to 20mm, you will need to work away from the join. The best tool for this is a 12″ joint knife or trowel. This is commonly known as “cross troweling”. Move along the line filling away from the join, working from one side of the join only. This creates a new straight line to work to. Apply a second and top coat working along the join being guided by the chalk line.

Plasterboard Types of Tape is a post from: DIY Guides

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