When considering glancing ligtglancing, there are a number of things the Tasmania home builders at Tas Homes take into consideration. Starting with our design team, right through to our Tasmania house builders and any subcontractors we might use, we are always usingez building best practices and levels of finish according to Australian Standards.

While some of the considerations touched on below might seem a little technical, if you have any questions simply give our house builders in Victoria a call to discuss them further.

Plasterboard Installation and Finishing

The installation of plasterboard walls and ceilings is a key part of reducing the impact of glancing light as there are a number of design and installation choices which can significantly impact the appearance of the surface.

Orientation

Running the plasterboard so that the long joints are parallel to the direction of the light will help reduce the effects of glancing light. The use of longer sheets to reduce the number of butt joints is also beneficial.

Choosing the Best Level of Finish

The Australian Standard AS/NZS 2589:2007  (Gypsum linings- Application and finishing) defines three levels of finish for plasterboard walls and ceilings and provides minimum specifications for the installation process, from framing preparation to finishing.

The levels used are:

Level 3: This is for use in areas that do not require a finish, such as above ceilings and inside service shafts and other inaccessible spaces. All joints are to be taped with two applications of compound and all fastener heads are to be covered. The compound is to be finished smooth, such as by scraping ridges with a trowel.

Level 4: This is the generally accepted level of finish for domestic construction. Joints are to follow a three coat system; a tape coat and two subsequent coats that are applied over the tape coat and fastener heads. All joint compounds should be sanded to a smooth finish free of tool marks and ridges. A low sheen, light coloured paint finish is recommended.

Level 5: This finish requires a lower level of frame alignment deviation to ensure a smoother surface and a three coat jointing system is required as for Level 4.

All joint compounds should be sanded to a smooth finish free of tool marks and ridges. This should be followed by the application of a skim coat over the entire area to remove differential surface textures and porosity.  SKIM coastingis a term used to describe a thin finish coat, rolled, trowelled or airless sprayed and then lightly sanded, to achieve a smooth and even finish. It is normally less than 1mm in thickness and is applied over the entire plasterboard surface to conceal imperfections in the joint work, smooth the paper texture and provide a uniform surface for decorating.

This Level 5 finish should be used wherever:

• critical light conditions occur such as from windows, skylights, or silhouette and spot lighting
• gloss or semi-gloss paints are to be used
• mid or dark coloured paint is to be used

Standards and Tolerances

The Tasmania Building Commission’s Guide to Standards and Tolerances outlines the following standard for inspection of vertical and horizontal surfaces.

‘Generally, variations in the surface colour, texture and finish of walls, ceilings, floors and roofs, and variations in glass and similar transparent materials are to be viewed where possible from a normal viewing position. A normal viewing position is looking at a distance of 1.5 m or greater (600 mm for appliances and fixtures) with the surface or material being illuminated by “non-critical light”. “Non-critical light” means the light that strikes the surface is diffused and is not glancing or parallel to that surface. Slight variations in the colour and finish of materials do not always constitute a defect’.

Painting

The paint surface on walls and ceilings plays a very important role in determining the effects of glancing light in a period home or most any home. A Level 4 finish presents the painter with a surface comprised of two different materials, namely the plasterboard paper surface and the jointing compound, which have different textures and porosity.

In order to achieve a consistent finish across these materials it is vital that a plasterboard primer sealer is applied. Australian standards requires that a sealer plus two coats of water based paint must be applied as a minimum to provide a surface with minimal difference in texture and porosity.

A roller application for all coats is strongly recommended as it imparts a light texture to the surface and minimises visible differences. If spray application is used, each paint coat should be back rolled while still wet, to create a lightly textured finish, and allowed to dry completely before applying the next coat. A similar paint system is recommended for a Level 5 finish to ensure the best possible result.

Paint Finishes

The choice of gloss level can also have a significant impact on the perceived quality of the surface in glancing light conditions. A matte paint finish provides the highest level of light diffusion and helps to disguise any surface irregularities. It is recommended that a matte finish be used in areas where a higher gloss is not required for functional reasons, such as ceilings. Higher gloss levels, such as satin, semi gloss and gloss, can accentuate any minor variations in the surface and are recommended only for use over a Level 5 finish.

Colour

Light colours diffuse light more effectively than dark shades and reduce the effects of glancing light. In rooms where a dark colour is to be used a Level 5 finish is recommended.

Again, we’ve covered some reasonably technical topics in this blog post, so if you have any questions simply give our friendly, expert Melbourne house builders a call and we’ll organise a meeting to Minimize the issue of glancing light.