Guide to Plastering an Old House

Plastering an older house is a difficult task but essential to maintaining its charm and integrity. Most houses built before 1950 still have their original plaster walls. These require extra care and attention when it comes time to repair and maintain them.

This guide provides all the information you need to do the job right, whether you’re looking to fix a small crack in a wall or replaster an entire room.

Absolutely, when considering plastering an older house, understanding the type of plaster used is crucial. Over time, plastering materials have evolved, leading to various types like lime plaster found in older houses. Repairing such plaster demands specific materials and techniques. Seeking an experienced plasterer in West Auckland who specializes in handling diverse plaster types can ensure a proper and effective restoration process.

It is important to understand the type of plaster used in your home to ensure repairs are made correctly and that further damage to walls is not caused.

The plastering guide will also address common problems that can occur during the process of plastering, such as bulges and cracks, with solutions for fixing them.

What type of plaster is in my home?

  • Lime plaster was used as a finishing material in homes built before 1919. However, its use could have continued until the 1950s, when plasterboard and Gypsum were more popular. For more details, consider exploring our lime plaster guide.
  • A plaster bound with gypsum will have a pinkish color.
  • Lime plaster is usually characterized by a slight tint of off-white.
  • A shade of earthy color indicates the presence earth binder.
  • If your home is old and has been replastered with modern materials, or you have damp walls, lime plaster could be a good option.

Watch Out For Historic Markings

It’s important that you look for historic markings on the plaster when renovating an historic home. These markings provide insight into the house’s history and can serve as inspiration during renovation.

The original plaster should be preserved as much as possible. It may be necessary to patch up any damaged areas with new plaster after carefully removing the damaged ones. To maintain the historical integrity of your home, it’s important to use plasters that match the original as closely and accurately as possible.

How traditional Plaster is Made

The traditional plaster mixture is made of lime, sand and water. Sometimes, it also contains horsehair or another fiber. This mixture of lime, sand, and water is then applied to a surface (usually a timber lath) to produce a durable, smooth finish. The plaster mixture can be applied in three layers: the scratch coat (or first coat), the brown coat (or second coat), and the final coat.
The first, thickest plaster coat that is applied to lath is called the scratch coat. The scratch coat creates a base on which the subsequent coats can adhere. The scratch coat has deep grooves, scratches and is rough. This helps the next coat adhere to it.

The second layer of plaster is called the brown coat and is applied on top of the scratch coat. The brown coat has a smoother surface than the scratch coat, but is still rough. The brown coat serves to smooth the surface, and provides a base coat for the final coating.

The final plaster coat is applied on top of the brown coat. The finish coat is the thinnest and smoothest plaster coat. The finish coat is used to achieve a smooth and even surface.

Traditional plastering is an age-old method of creating a beautiful and durable finish for walls and ceilings. Timber laths, lime plaster and a breathable wall finish are important to the longevity of plaster.

The modern alternative to lime plaster is Gypsum Plaster. Gypsum is a powder that is combined with water to make a plaster. The application of gypsum plaster is quicker and easier than lime plaster. However, it is less durable or breathable.

When is it time to replaster walls and ceilings?

Planning is essential when plastering an older house. Plaster walls and ceilings in older houses may require repairs or a complete replastering. It can be difficult for homeowners to know when to replaster, but it is important to take care of any problems before they get worse and more expensive to fix.

Plasterwork was designed to last forever, but deterioration can take many forms.

  • Cracks forming
  • Plaster that is not stable or separates layers
  • Stains are present
  • Water damage
  • Cracking or flaking
  • Damage to the mechanical system and missing areas
  • Repair is often a better option than replacement.

If a replacement is required, it should be made from the same material and have the same number of coats. It is important to ensure that there are enough hairs or other reinforcements when working with flexible substrates.

Avoid using plasterboard whenever possible. Plasterboard, unlike traditional plaster finishes is flat. It can look out of place in an older property, especially with older ceilings.

Ceilings can be replastered relatively easily. Laths are easily replaced when necessary. Screws should be used to secure them and reduce vibrations. Then, lime plaster is applied to the surface of the laths.

What is the cost of plastering?

Plastering a house that is older can be an expensive and complex process. However, it’s well worth the cost to restore its beauty and character. Plastering costs vary depending on a number of factors including the size and type of the room as well as whether it is a professional job or a DIY.

It is usually more expensive to hire a plasterer with expertise in traditional finishes for period homes than to do a typical plastering job.

The cost of a standard job using gypsum finishes is usually between PS450 and PS750 for walls, and PS200 to PS350 for ceilings in a room with an average size. The price could double if you need to apply lime or a unique clay finish.

Plastering an Old House with Lime

Hire a plasterer who has a proven track record. Some plasterers claim to be able to do this, but not all are. You can ask for references from recent projects.

You can also hire a trainer on site to teach a group eager plasterers. Your local lime supplier will be able suggest a trainer.

When purchasing lime, ask for technical advice from the suppliers.

You’ll need two or three coats depending on how smooth you want the end result to be. Three coats of paint are required for the best quality, but two coats will do. Consider using reed laths instead of riven ones for your ceiling, especially if you are on a budget.

This alternative will save you a lot of money. Use screws and laths to secure it at the bottom of the joists. For the first coat or’scratchcoat’, mix one part of lime putty with three parts of sharp, well graded sand and generously add animal hair. This mixture is called ‘haired fine stuff’.

Apply a setting layer consisting of two parts fine sand and one part lime for a smooth finish. This is called ‘fine stuff. You can also buy this mixture ready-mixed. If your plasterer does not advise you otherwise, buy your plaster by the tonne. It will be delivered to your location.

The alkalinity of the lime will cause the hair to begin decomposing if you leave the bags unopened for longer than four weeks.

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