Roof Pitch

T-Seam® can be effectively used on very low building slope due to its inherent design. The adjacent seams are overlapped and closed with an electrically operated seaming machine. Also the sheets are roll-formed on site in a single length, avoiding overlap joints. Both these features allow the roof slope to be reduced as low as 1.50 degrees or 2.60 percent.

This limitation of the roof slope can be further relaxed if the sheets run in single length from eaves to eaves and all the roof penetrations are properly welded. In this case the roof slope to be minimum such that no water pooling takes place and the water can freely flow to the drainage channels.

In roof construction where the sheets are overlapped and sealed with silicon sealant, then a minimum roof slope of 2.6 degrees or 5 percent should be used.

Minimum roof pitch

Without horizontal joints 1.5º (2.6%)

• Running from the eaves in one length

• All joints are welded

• Factory welded soakers welded into roof skin

With horizontal joints 2.9º (5.0%)

• With sealed horizontal joints

• Soakers welded into the roof skin

• Factory welded soakers sealed into roof skin

Corrosion Protection:

Protection by oxidation:

Aluminum forms a protective coat of a natural oxide layer when exposed to the atmosphere. This oxide layer will act as a corrosion protective coat against normal weathering. However if the roof is exposed to a highly aggressive atmosphere, then it is recommended to apply a protective resin coating of a minimum thickness of 25 microns.

Dissimilar Material Contact Corrosion:

Precaution must be taken to avoid direct contact of aluminum with dissimilar materials such as bare steel, copper. Concrete , timber etc. Direct contact with dissimilar material in the presence of moisture can cause electrolytic corrosion.

It is recommended to separate the dissimilar material with the use of plastic tapes, bituminous layers, etc. In case of coated material, separation tapes may not be required.

Breathing Roof:

T-Seam® is a breathing roof, in the sense it allows the trapped moisture to escape through the seam. The T-Seam® joint do not use any sealants. The weather tightness is guaranteed with the capillary groove provided in the small seam.

Non hygroscopic insulation materials such as Rock wool will not absorb any moisture in the roof construction but will retain the same on the surface of its fibres. During the daytime, the temperature rises and the trapped moisture is transformed to vapours, which results in an overpressure and is released through the seams. This overpressure happens only within the roof construction and thisensures that the flow of the humidity is always from the inside to outside.

Condensation Risk:

Condensation happens when the moisture is cooled below its dew point temperature. The pre-requisites for the condensation risk is the presence of moisture and the temperature differential. The risk of moist air entering the T-Seam® roof construction from the external atmosphere is remote due to the overpressure in the roof construction. So the moist air enters the roof construction from the building interior. The moist air will have to travel through the insulation and touch the cold inner surfaces of the T-Seam® roofing so that it can condense. A vapor check barrier such as polyethylene sheet, aluminum foil or cold adhesive vapor check membranes are to be used over the inner liner sheets (warm side of the roof).

Vapor Check Details:

Care has to be taken while installing the vapor barrier that all the joints/penetrations are sealed properly.