Thursday, 28 August 2014

Repainting Factory Prefinished Metal Panels

Prefinished sheet steel is used on many building products from wall cladding, to architectural roofing to interior panels. Prefinished sheet steel has been used in Canada for over 30 years and there may be sites were the paint surface is in need of repainting.

Due to the diversity of factory applied prefinished systems, and the diversity of potential field applied repaint systems, it is impossible to offer one comprehensive repaint procedure for all possible situations. However, it is possible to offer a set of guidelines to be considered in every potential situation.


Before You Begin
CONSULT a local, respected professional painter, experienced and equipped to do the job correctly. They can often recommend a coating system for your application that has been proven by experience. Since local environmental conditions can be unique, local experience is valuable.

CONSULT with the original panel fabricator/supplier who can enlist the expertise of the prefinished sheet suppliers to give proven compatible repaint recommendations.

Repaint Procedures
The purpose of every repaint procedure is to prepare the surface to be painted to achieve maximum "recoatability" and intercoat adhesion; that is, to make certain that the new paint sticks to the old surface. Some type of surface cleaning, such as described in CSSBI Sheet Steel Facts #3, should be employed to remove loose surface dirt, chalk, mildew, etc., to facilitate maximum repaint adhesion.

Special attention and treatment must be given to areas that may have already begun to corrode. In those areas, all traces of white, black or red rust must be removed, usually with wire brushing, and primed with a properly formulated corrosion resistant "zinc rich", or similar primer, before repainting with the desired colour coat.

Recoatability Test
To be certain an old surface is ready to accept repainting, it is recommended that a "recoatability test" is run. The following procedure has served the industry well for a number of years:
  1. Clean and otherwise prepare several small test areas representative of the entire surface to be repainted.
  2. Apply a coat of the desired repaint according to the manufacturer's instructions. Allow each test area to dry according to the manufacturer's instructions.
  3. After drying, using about 200 mm of gray "duct" tape for each area to be tested, firmly smooth about 75 to 125 mm of the tape onto the repainted areas. Rapidly pull off the tape, attempting to remove the recently applied air-dried coating.
  4. Unsatisfactory adhesion/compatibility is indicated if the new coating is removed with the tape.
  5. If an unsatisfactory test occurs, it may be necessary to conduct a different or additional cleaning procedure, apply an intercoat adhesion primer, or select a different type or different manufacturer's repaint coating.
  6. Repeat the "recoatability test" until satisfactory results are obtained.

Quality Paint Means a Quality Job
Remember, typical field-applied air-dry paint finishes usually demonstrate permanence and performance that correspond to their purchase price. Retail house paint applied to a commercial/industrial building will perform like retail house paint and may not give expected performance. The cost of house paint may be lower initially, but because it is not specifically formulated to adhere to metal siding, it will not last nearly as long or perform nearly as well as systems specifically design for repainting sheet steel.

Thursday, 21 August 2014

Low Slope Steel Roofing - the Winners in Life Cycle Cost Analysis

An independent assessment of the life cycle cost for various low slope roof systems revealed that steel roofing had the longest life span, no leaks due to material failures, and the lowest overall maintenance cost.

These are the results of a study conducted by Ducker Research Company1 for the National Roofing Contractors Association (NRCA). The purpose of the study was to compare three commonly used types of low slope roofing systems (2:12 roof slope or less) from the standpoints of service life, maintenance cost, and overall life cycle cost.

The study looked at the following three different roofing types:
  1. Metal (mostly unpainted coated steel roofs)
  2. Built Up Roofs (BUR) - modified bitumen, asphalt
  3. Single ply membrane (EPDM/PVC/TPO)

Four different building categories were surveyed:
  1. Office/Bank
  2. Retail (store, mercantile)
  3. Manufacturing (industrial, warehouse)
  4. Institutional (education, healthcare, hotel/motel)

Based on 41 plus interviews with building owners and managers, 36 case studies of roofing systems were selected from the western, northern and southern regions of the United States. In all, twelve case studies were evaluated on each of the three roofing types. Steel comprised the vast majority of the metal roofing systems.2 Most of the roofs were installed between 1981 and 1994; roof areas varied from 4,000 to 750,000 square feet with the average being approximately 92,000 square feet. The expected service life of steel roofing was determined to be 40 years – 17 years longer that Built Up Roofs and 20 years longer than Single Ply systems (see Figure 1).

Life Cycle Cost: All relevant aspects of low-slope roofing were considered: roof design, number of layers, sheet gauge, standing seam or through-fastened, insulation type and thickness, installation systems (i.e. seamed, ballasted, etc.), labour, balance of systems (i.e. venting, parapets, etc.), geographical effects, life span and additional items relating to the full life cycle, as well as the original installation cost.

Steel roofing has two characteristics that the other two roofing materials do not:
  1. Steel is a non-porous material and under some conditions requires no underlayment to keep the building dry
  2. Steel is easily engineered to withstand increased gravity and wind loads

Service life, durability and life cycle cost are considered the most important criteria in the selection of roofing type, according to building owners. While the majority of buildings had experienced roof leaks, none of the steel roofs had leaked as a result of material failure. By comparison, 30% of the Built Up Roofs and 56% of the Single Ply roofs experienced leaks resulting from material failure.

Furthermore, owners of buildings having steel roofs reported having little or no regular maintenance performed on their roofs. The leaks reported on steel roofing were a result of contractor installation problems. Regardless of roofing type, failure to achieve a quality installation is the primary reason for roof failure. (see Figures 2 and 3)

The service life of a roof will vary by system type and it is critical to apply the average annual cost across the full life of the roof system as illustrated in Figure 4. The Ducker Research study also identified that roofing material quality heavily impacts the overall life cycle cost (e.g. greater level of maintenance activities). In this regard, steel roofing and Built Up Roofing were more consistent across all four building categories.

The Ducker Research Company study showed that the life cycle cost of a metal roof is significantly less than BUR and Single Ply roofing. Steel roofing had the lowest maintenance costs and had, on average, a 17+ year greater lifespan than the other two roofing systems. The study also concluded that
building owners believe that service life and life cycle costs are the most important factors in roofing material selection and overall, metal roofing is by far the best option based on its lowest life cycle cost. Add to this the fact that steel roofing is 100% recyclable, has industry leading recycled content and easily qualifies for LEED Canada certification.

Wednesday, 6 August 2014

Greener by design – SBS have eco-friendly advantages built right in

Steel Building Systems (SBS) are breaking new ground and helping architects and builders construct more eco-friendly buildings for today’s environmentally conscious world.

SBS are pre-engineered systems completely customized to meet the needs of specific projects, regardless of size. The systems involve numerous interrelated steel components that are cut, engineered, and primarily assembled at the manufacturer. All components are designed to work together and they do it best when an SBS manufacturer is brought in at the design stage of a project.

The SBS manufacturers work with the project’s architects and builders to maximize design and economical benefits, plus take advantage of SBS multiple green features. The LEED Canada New Construction Rating System recognizes buildings incorporating leading design, construction, and efficient operational practices with reduced impacts on environment and the public. Projects are evaluated and earn points across six categories towards LEED certification. SBS can help builders and architects pick up much needed points in five of these categories.

Recycling means green at the factory floor! 

SBS components are manufactured from cold-formed sheet steel. As the world’s most recycled material, every newly manufactured steel product has some component of recycled material in it – anywhere from 30% to 95% – depending upon manufacturer and product. At the end of a steel product’s life, 100% of it can be recycled again and again. SBS building components are among the greenest construction materials around because all may be reclaimed and recycled for future use.

Faster construction for less site disturbance

When building with SBS, less people are required at the job site than traditional construction methods. This means that the actual impact on the environment and site disturbance is reduced. Components arrive at the job site as needed and with most of the work already completed.

Superior strength weighs less and conserves natural environments

Unlike other building materials, steel is dimensionally stable and not susceptible to rot or chemical breakdowns. Steel’s overall durability and longevity can be greatly enhanced by a wide variety of coatings and paints to further extend its lifecycle. SBS buildings are designed to last, but when the building’s overall use has been redefined, SBS allows for easy expansion by removing end or sidewalls, and even adding floors.

Energy efficiency and thermal performance 

In Canada, when you choose an SBS manufacturer, you are often choosing a single- source supplier for all of your project’s steel needs. Many SBS manufacturers also provide high-performance steel roofing systems complete with vapour barriers and high R-value insulation to minimize thermal transfer and maximize energy efficiency. Combine these benefits with insulated steel interior walls,
windows, and doors and the whole system can provide an extremely tight building envelope, which means less air loss, better HVAC performance, and energy conservation.

Green choices close to home 

SBS manufacturers are located right across Canada in strategic locations to easily manufacture, assemble, and ship SBS components to project sites.Whether it’s by rail or road, choosing a nearby SBS Canadian manufacturer greatly reduces the transportation costs and pollution associated with gathering the building components.