Metal Roof Condensation Problems And Resolving Them to Prevent Rusting
It is easy and economical to install metal roofs over houses, sheds, barns, warehouses and even commercial buildings. With proper care, galvanized or powder coated metal roofs should last a lifetime. However, as we know, moisture combined with oxygen is the worst enemy of iron.
What happens in winter or when it rains is that the exterior temperature is lower than interior temperature. This, combined with higher humidity levels in the air inside can lead to condensation on the inner surfaces of metal tin roofs. Apart from the minor inconvenience of drips caused by metal roof condensation, the major, long term impact is that metal corrodes. If neglected, that part of the roof may need to be replaced because no amount of patching will prevent rainwater leaks in the future. If metal is laid over plywood, felt or glass wool, the condensed water can cause further damage.
One solution to preventing such condensation-related problems is to replace the entire roof with plywood or fiberglass sheets. Many have also tried attaching plastic sheeting to the tin roof as a vapour barrier, but it is a cumbersome and ineffective process. One common method of insulating the roof is to use glass wool in a bag attached to the underside of the metal roof. Humid air penetrating through gaps and cracks can still reach metal and condense causing water to collect and wet the insulation. This water does not dry out quickly and combining with oxygen in the air corrodes iron sheets quickly. In such cases where roofs have under-decks, the problem is not apparent until a large portion has corroded and water starts to drip in when it rains.
This can be resolved by coating the underside of metal tin roofs. Painting can prevent corrosion but it cannot prevent condensation. Water will still drip. A better way to protect tin sheets, and at the same time prevent condensation is to cover the underside of the roof with foam. This acts as a vapour barrier and also as an insulating material, preventing warm air inside from touching the cold metal surface and thus preventing condensation.
You can get sheets of flexible foam with an open cell or closed cell structure and glue them to the underside of the tin roof. However, in a majority of cases, such roofs usually have some form of under-decking that makes this a difficult process. The answer, therefore, is spray foam insulation. Spraying with the help of high pressure jetting equipment forces the foam in between the gaps and covers the metal with a porous, yet insulating, vapour-resistant insulating bond. The insulating layer prevents warm humid air inside from touching the cold metal surface. Moisture no longer condenses. You are no longer bothered by the problem of water drips or ponding. Your roof and the underdeck remain dry, safe and retain their physical integrity for years.
Another benefit of this type of in-situ spray foam insulation is that it eliminates the need for frequent painting of the metal surface. At the same time, since the liquid foam adheres to the metal and expands into foam to form a strong bond with metal, it also serves as an effective barrier for vapour, sound, and heat. The foam will not only prevent heat losses from inside during winter, but it will also serve as insulation against exterior heat during summer. Just spray it once and then enjoy a lifetime of peace. Condensation will not take place, and metal is fully covered with an impregnable layer of polyurethane and the roof lasts for decades.
Spray foam insulation is a precise technique that only experts with the right experience, the equipment, and the know-how can carry out to ensure perfect bonding. Their expertise also helps them calculate the precise amount of resin that will be use for a given thickness of foam insulation. Experts can also give “R” figures if asked to show the insulation value. Generally speaking, polyurethane foam has better insulation characteristics compared to glass wool or mineral wool, which means a 5 mm layer has the same insulation factor as a 10 mm rockwool layer. You only need to make sure the work is assigned to experts.