Combating challenges with coatings for acoustic ceilings

by mdoyle | April 22, 2013 2:23 pm

[1]

By Ken Woolf, PE
When acoustical coatings first came to the marketplace in the early 1980s, an untapped market was finally addressed. This market was represented in commercial spaces by ceiling tiles that no longer appeared new and were traditional candidates for replacement, despite still being structurally sound. They no longer appeared white, failed to disburse light as they should, and were spotted with random water stains.

When a space such as a retail store, school, or office building is occupied, it means construction work must be done outside of normal business hours so regular operations can proceed unencumbered. The short period of time, between public evening closing and morning opening, limits the amount of work that can be done in one shift. This makes ceiling removal and replacement a long, involved project. It can also be costly, depending on the style of tile to be switched out.

For a coating to be successful in restoring an old ceiling, it must not:

• reduce the noise reduction co-efficient (NRC);
• leave tiles stuck to the supporting T-bar system;
• damage the fire rating;
• perform less effectively than a new tile coating; and
• exceed combustion toxicity testing as compared to conventional ceiling paints.

More popular coatings are receptive to waterborne tinting (i.e. allow a full range of colours, including white with light reflectance superior to new tiles), and elastic enough to allow for expansion, contraction, and bending (as in the case of vinyl-covered tiles).

An industry is born
In 1983, a restoration coating was developed meeting this criteria, and introduced to the U.S. market. Since then, architects in Canada, the United States, and other countries have specified these products and services.

Acoustical ceiling restoration can be accomplished in about a third of the time compared to ceiling removal and replacement, with an experienced installer. It is also less expensive, usually costing the property owner about half the price of conventional replacement. Further, it is environmentally responsible in that it diverts solid waste from landfills and contributes to energy efficiency.

Acoustical ceiling restoration is a system typically specified when the renovation of a commercial property is being designed. Some coating manufacturers can provide a guide spec in three-part format for ceiling restoration.

Restoring ceilings in fully occupied commercial spaces is a procedure that has been perfected over the years. For a grocery store with merchandise on display, the ideal situation for an owner would be having the ceilings sprayed with a pigmented coating, without a speck of spray dust left behind. To do this, without a prohibitive amount of labour cost associated with the masking and area preparation, is an achievement made possible by this technology.

When a ceiling is sprayed with a pigmented coating, dust in the air cannot be avoided. The dust travels and settles on unprotected areas. In the case of a grocery store, this means shelves and floors would be covered with white, chalky dust. Lighting lenses over-sprayed with the product would also be subject to settling dust. However, ceiling restoration professionals should know how to avoid these problems without eliminating profits.

In order for the coating product to be deemed acceptable for such an application, the resulting surface finish should be equal to, or better than, the one typically applied by tile manufacturers in both appearance and functionally.

This means, after being restored, the acoustical properties are not diminished, fire retardant quality is intact, tiles are not stuck to the grid, and light disbursement remains equal to or better than a new tile under the same conditions Further, if a fire were to occur, the ceiling surface material would not emit a dangerous gas. The only way for a manufacturer to make impressive claims regarding their product’s performance in these areas is if it can provide substantiating data produced by an independent testing laboratory.

Product testing
Since the ceiling’s ability to perform as stated is crucial, the kingpin in the restoration process is ensuring the selected acoustical coating will perform as expected. Independent laboratories should document six major performance characteristics of an acoustical coating to be considered by the architect. Without hard test data to support claims made in product literature, promises about performance can be suspicious.

Not only should the product be tested in the following areas, but procedures must also be conducted in accordance with specific ASTM or industry standard tests. From an architect’s perspective, if a restoration product manufacturer cannot provide independent testing data in each of these six areas, there is an unnecessary risk in accepting verbal claims.

Acoustics
The application of a restoration coating should not negatively affect the tile’s ability to absorb sound. In accordance with ASTM C423, Standard Test Method for Sound Absorption and Sound Absorption Co-efficients by the Reverberation Room Method, and ASTM E795, Standard Practices for Mounting Test Specimens During Sound Absorption Tests, one coating manufacturer reports an improvement of a 0.55 NRC tile to 0.60 has been reported.

While the exactness of these tests can be questioned because every test has levels of accuracy, there is a slight improvement generally attributed to the softer composition of an acoustical coating, rather than a harder conventional paint. Regardless of whether there is a slight improvement to the NRC, however, most restoration products see no decrease or negative effect, which is preferable to the alternative.

Fire retardancy
The rate at which a flame is delayed from spreading across a ceiling surface is measured by the Steiner Tunnel Test—ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials. In this test, ‘0’ represents the rate at which flame spreads using cinder block as a substrate and ‘100’ when using white oak. (The closer the number is to zero, the better the results.) Class A is defined as a flame spread between ‘0’ and ‘25,’ Class B between ‘26’ and ‘50,’ and so on. The Steiner Tunnel Test also measures the amount of smoke developed by the coating material’s burning. (Again, the lower the number, the better.)

Light reflectance
The coating’s ability to disperse light is important from an energy standpoint. The better the light dispersion, the less dependency on artificial electrical sources (and, as such, less energy use). When the coatings were developed, this was measured by ASTM C523-68, Test Method for Light Reflectance of Acoustical Materials by the Integrating Sphere Reflectometre.

Combustion toxicity
Since fires are always a possibility, it is important to know whether the burning of the coating material itself gives off a gas dangerous to occupants. In place of an ASTM test, the industry standard is The Protocol of the University of Pittsburgh for the Evaluation of Acute Toxicity of Thermal Combustion Products.

Aging
A common question when considering options other than replacement with new materials, is about the restoration’s longevity. The assimilated time exposure test of ASTM E313, Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Colour Co-ordinates, demonstrates how long the restoration coating will last by comparing samples exposed to the same conditions.

In this case, the coated surface of a new tile and a restored one can be tested simultaneously and the whiteness index of each sample monitored over time. Acoustical restoration coatings typically perform better in these tests than the coatings applied to new tiles or high-quality latex paints, primarily due to its superior composition.

Low VOCs
The better acoustical coatings have minimal volatile organic compound (VOC) content and as a result are acceptable by environmentalists. Manufacturers should provide a material safety data sheet (MSDS) report that contains VOC levels.

[2]

Other restoration applications
These acoustical coatings also work well on other ceiling systems such as acoustical plaster, popcorn, and other seamless products that have become aged and discoloured. The benefits are the same as described for acoustical ceiling tiles.

Generally, the least expensive paint products are commonly produced for ceiling applications. Conversely, the acoustical coating is of a higher quality than common ceiling paint, and therefore, performs better.

There is a limitation when it comes to applying such a coating to an acoustical wall surface. These non-bridging products are water-based and cannot be scrubbed when soiled. The binders required to create a hard paint surface (cleanable with vigor) are what must be avoided when formulating an acoustical coating. Therefore, acoustical wall panels are frequently treated with an acoustical coating, but only to about 1.8 m (6 ft) above the floor. Below that level, the surface is likely to be soiled to the extent someone will eventually want to clean, and it is likely they will scrub right through the coating. Architects can be creative in designing a break at that level, introducing another surface material from that point down.

An additional market: New construction
Through the years, manufacturers have produced a diverse range of acoustical products. Clouds that hang above open spaces, sound baffles, acoustical plasters and other seamless ceiling systems have become part of the architects’ tool and trade. However, architects also combine colour with design and manufacturers cannot always produce products in the desired array of hues. Even when products are available in the desired colour, it is may not be within reasonable delivery times or at a cost fitting within the project budget.

Further, the composition of some products limits the number of colours that can be provided, restricting esthetic options.

It is becoming common to have a product installed in its least-expensive shade (i.e. white) and then have it sprayed in place with an acoustical coating tinted to the desired colour. The cost of adding the coating is normally far less than the charge for a product in the desired colour, within a reasonable delivery period.

Time is a major consideration as project delays can be costly. When delivery time of a particular product is extended, the impact on the construction schedule can be financially painful. Trained acoustical ceiling restoration professionals can complete hundreds of square metres per shift, which is higher production than other systems.

Who will do it?
The fact remains any product is only as good as its installation. The architect can specify the product, but it is not enough to ensure success. Architects familiar with the system should also specify a certified applicator be used—one familiar with the nuances of a specialty coating of this type.

The better manufacturers of acoustical coatings have a certification program that includes on-the-job training for contractors. When asked to recommend a contractor in a particular geographic area, manufacturers turn to the list of certified applicators.

Whether or not the project is to be competitively bid, it is wise to contact the manufacturer and obtain the names of recommended, certified applicators.

Lifecycle analysis
When making a decision on which response to use in addressing an element of the construction, it is recommended to review the options analytically. When it comes to the financial implications, a long-term assessment should be used.

In cases where the existing ceiling is aged and discoloured, but still structurally sound, the options other than ceiling coating restoration are:

• replacement with new materials;
• painting the entire ceiling system with conventional products; and
• chemical cleaning (used primarily for acoustical tile systems).

Each of these options has an average life expectancy and cost per area. It is relatively simple to assume the expectancy and cost for a ceiling area of 929 m² (10,000 sf). Then, one should list for each, how many times over a 12-year period (based on the average life expectancy) the process must be repeated. This is then carried out in combination with average costs per area and it is easy to determine what each process costs over the 12-year period.

An example of a lifecycle analysis is shown in Figure 1[3]. The numbers are based on non-union costs in the United States, but conversions can easily be made to Canadian currency and the benefits would be proportionate. Further, the assumed life of the ceiling restoration option is conservatively shown as equal to new ceiling tiles when in reality the better acoustical coatings hold their colour much longer.

For that table, all pricing is based on the average job size/masking complexity, and non-union wages. While the actual costs in a particular market may vary from the assumed averaged shown in this analysis, it is more important to note the relative costs of each process to that of replacement with new materials. It is also understood when replacing the ceiling tiles with new material, treatment to the grid system and air diffusers (cleaning and/or painting) is also included. This allows and apples-to-apples comparison with restoration that also treats the entire ceiling system. In other words, if ceiling restoration in this analysis saves 52.8 per cent of the cost of replacement, then it is reasonable to assume a similar percentage savings at the locations with various labour bases.)

In addition to cost considerations, the option providing the best light-disbursing ability should be reviewed. The less dependency there is on artificial light, the less energy is consumed. Lighting is important to commercial facilities, such as retail stores. Also, the better the lighting, the more ‘natural’ merchandise appears in terms of colour and overall appearance.

Conclusion
Ceiling restoration in commercial property renovation is by no means a panacea. It is not the preferred approach each and every time, but, when it can be used it is beneficial. The ability to install new ceiling systems in designer colours is becoming a reality. The common denominator, the quality acoustical coating, is a valuable option for the architect and building owner/manager.

[4]Ken Woolf, PE, founded ProCoat Products, a Massachusetts-based manufacturer of acoustical restoration products and supplies that does work throughout North America. A registered engineer and management consultant, he is recognized as a pioneer in the field of acoustical tile restoration and is frequently called on as a consultant, author, and speaker in the field. Woolf can be contacted via e-mail at ken.woolf@procoat.com[5].

 

To read about light reflectance in offices and retail environments, click here[6].

Source URL: https://www.constructioncanada.net/combating-challenges-with-coatings-for-acoustic-ceilings/

---