Foam Spray The Perfect Solution For Metal Roof Condensation

By Author: Ecotite
Total Articles: 24

During winter and during rainy seasons it is a common occurrence for condensation to occur. This is noticeable on metal roofs. It can be annoying if there is only slight condensation and there is an occasional water drop. However, it can aggravate the problem if water condenses in higher amounts, stays trapped in insulating pockets and then leads to corrosion of the metal roof. This can lead to long term damage necessitating expensive repairs.

Drawback of traditional insulation

Metal roofing is an attractive and affordable alternative to other forms such as asbestos, tiles and wood. It is usual to install metal roofs over a framework and the underside is usually clad in mineral or glass wool insulation for energy efficiency. This type of insulation material is available in roll form and it is either glued to the underside of the metal roof or affixed in place mechanically. The drawback to using this type of insulation is that it leaves pockets of air. During cold weather it is common for moisture to condense on the underside of the metal roof. Water can drip into the mineral or glass wool.

Being porous the material absorbs a lot of moisture but there is no easy way for it to evaporate. Water can drip once the insulating material is saturated. Worse, because it stays wet and is in contact with the metal roof, the moisture can lead to corrosion of metal. Ordinary paint offers little protection against this type of corrosion. It may not be noticeable from the top side. It is only when the sheet weakens and gaps start to show through that one realizes the extent of damage. By then it is too late and the only solution is to replace the entire sheet.

Spray foam, the ideal insulation for metal roof

The best solution so far to prevent metal roof condensation is to use spray foam technique. In this method of roof protection, special spray equipment are used in conjunction with a specially formulated polyurethane resin. Once the components are mixed and sprayed onto the underside of the metal the resin generates gas bubbles that cause it to foam. Since the resin adheres to all the contours of the surface there are no air gaps left. The foam is fully conformal coating, even covering cracks and bends completely. What is more important is that the PU foam has a closed cell structure, which means an impervious skin is formed on the surface. The foam forms a protective barrier and does not permit ingress of air or moisture. The issue of condensation does not arise since warm air does not come in contact with the metal surface. Foam is a good insulator and, unlike metal, it will not allow condensation of moisture when air touches its surface. Polyurethane is the preferred material since it has the highest insulating factor (R value) for a given thickness and it is also quite durable. Another advantage of polyurethane resin is that it is quite sticky and adheres well to metal, asbestos and even cement concrete. It does not separate with the passage of time.

Making it cost effective

In situ spray painting is an art and science requiring quite a bit of skill, knowledge and experience. The right equipments must be used. However, it is not sufficient just to have the equipments. The technician must be knowledgeable about the characteristics of the resin, it’s setting time and the spraying technique to achieve a layer of uniform thickness. Besides, the process must be carried out quickly, within the time it takes for the resin to bubble and form foam and set. It takes experience to achieve a consistently uniform layer that results in cost efficiency as well as perfection in reaching crevices and corners. One single application carried out by professionals should prevent any future condensation and it should last for more than 5 years or even 10. A spin off is that polyurethane also serves as thermal insulation and reduces energy bills. It does cost more but the payback is faster by way of reduced bills and an extended lifespan of the metal structure.