There are a few factors that you need to keep in mind when you are selecting concrete roof waterproofing membranes. The first among them is UV (ultraviolet) stability. Since the membrane would be exposed to sunlight it should be able to resist UV rays or at least be stable when faced with such exposure. Otherwise, it would lose its quality with time.

How much can they be elongated?

This implies the ability of the membrane to be stretched. It is normally measured in terms of percentage. This means that if such a product comes with an elongation of 150% it implies that it can be stretched 1.5 times more than its normal length when you pull it.        

Your concrete roof waterproofing membranes need to possess this quality. This is especially true in the context of buildings that would move such as high rises as well as buildings that are flexible like ones made from steel. Having this property would allow the membrane to stretch over the cracks that may come into being in the days to come. You can get membranes that come with elongation properties of at least 200%.

How breathable are they?   

One of the major issues with proper waterproofing is that at times water seeps into it through certain points and spreads throughout the surface. However, it gets trapped over there and is unable to get out. The concrete roof waterproofing membranes that you choose should be breathable as well so that water never gets trapped in the same. There are some products in this regard that are designed in such a way that water can never pass through them. However, they allow water vapour to pass through them. This is how with time these membranes let water vapour to get evaporated into the atmosphere. 

How well can they resist tear?

When it comes to concrete roof waterproofing membranes this happens to be an important characteristic. This is because, in the case of some such products, which have excellent stretchability, it has been seen that they tend to get torn rather easily. The best way to find this out would be to take a sample of the product and try to tear it apart. This will give you a fair idea of how tear-resistant it is. Remember that you are looking for a membrane that would not tear even when a reasonable amount of force gets exerted on the same.

How well can they resist abrasion?

The concrete roof waterproofing membranes that you choose should be able to resist both wear and tear. These membranes are used mostly to cover concrete tiles and screeds. Their abrasion resistance is thus tested when the property is being built. This is when the workers would be walking across the surface, scrapping hard objects such as rebar against the membrane, and dropping screws and nails on the same. If the membrane is soft and has low resistance to abrasion it would get damaged rather easily in such a situation thus leading to a leak.