SIG Design & Technology have compared five of the popular types of liquid roofing products to help you choose the right product for your project.
1. Early Rain Resistance
If there is a sudden rainstorm shortly after installation, will this affect the performance of the product? With most liquid applied systems this is an issue to some extent but GRP is particularly weather and rain sensitive. Alpha Hybrid systems are impervious to rain almost immediately.
2. Apply in a Single Pass
Most popular liquid waterproofing products need to be applied in several layers. In the case of the Alpha Hybrid systems, the operative can apply the base coat, bed in the polyester reinforcement and immediately saturate job done. There is no drying time between coats and many jobs can therefore be completed in a day. When labour is the most expensive part of the job, applying in a single pass can massively reduce the installed cost of your liquid roofing, which is how you should measure the true cost to the end user.
3. Re-use Opened Container
If you can reuse an open container there are several benefits. There is a reduction in waste as unused product can be used elsewhere. Some liquid systems can be used straight out of the bucket, but if you have to add a catalyst the finished product will go off and the contents must be used straight away or disposed of, for example, with PMMAs the catalyst requires that the product be used within 30 to 40 minutes. Many PU systems also rely on a catalyst for curing.
4. Cold Weather Application
GRP roofs cannot be installed when the air temperature is near 0°C as they require temperature to assist curing. This is important when considering programming of roofing works. One of the reasons that Alpha Hybrid technology has become so popular in recent years is that it is relatively unaffected by cold weather. It can be applied in temperatures down to 0°C.
5. Low Odour
Products with a high odour can be unpleasant to install, and whilst the odour may not be hazardous to health, it can still make the process of installation difficult. The effect on the public is particularly important to consider if the buildings have tenants, office workers or school children, or are in built up areas.
6. Non Flammable
Products that do not constitute a fire risk are becoming increasingly popular with clients, particularly local authorities and other institutions that follow strict health and safety procedures. Note that Hot Melt is not a fire risk in its cold state but does have to be heated before application to around 200 degrees.
7. Negligible VOCs
Volatile Organic Compounds (VOCs) are hazardous to health and have been associated with respiratory, allergic or immune effects. If your operatives are working in an enclosed environment or exceeding the exposure time on the material safety data sheets (MSDSs), they will need to wear breathing equipment. On a still, hot day this will be much less pleasant and also produces a higher risk to the installer.
8. Solvent and Oil Resistant
When would solvents or oils be deposited on a roof? There are two main causes plant and aircraft. Roof mounted plant needs maintenance, and the presence of substances likely to affect the performance of your waterproofing should steer you clear of non-resistant products in this case. Equally if your building is in an area of aircraft activity or in the vicinity of an airport, the flushing out of fuel tanks may be hazardous to the roof performance.
9. Resistant to Ponding
Most popular waterproofing products are resistant to the effects of ponding water; the exception here is GRP. If you are installing a GRP roof it is particularly important that the roof is designed with sufficient falls and outlets to ensure that water does not collect on the roof. Ponding water can produce osmosis in GRP roofs where the water passes through the fabric and causes problems inside the building.
10. No Isocyanurates
Isocyanurates are a particular VOC that has been identified as carcinogenic in high doses. Products with isocyanurates in them will carry warning labels and require special equipment to apply safely. Certain clients are increasingly insisting that roofing products do not contain isocyanurates because they represent a known risk to health. The products marked YES on this characteristic either have no isocyanurates or those that exist have been neutralised in the process of production so the product does not contain them.
11. Cold applied
Being able to apply your liquid waterproofing cold (i.e. without having to heat it) has some benefits, and these should be weighed up against the other factors. For example if you have to heat a product before applying it, you wont want to carry around hot liquids to several small roofs or balconies. Conversely if you have large areas of concrete deck, heating the product before applying it may not be an issue and can be outweighed by some of the other benefits of the product you choose.
12. Single Component
Will the contractor be using the product straight out of the bucket or will they have to add some kind of hardener or catalyst with it before it is applied? If a single component not only are there possible benefits for re-use of the remaining unused product, but the process is simpler and less at risk from the wrong quantities or inadequate mixing. Single component liquids are more convenient.
13. Multiple Substrate type application
Some of the products in our list lend themselves particularly well to application on a range of substrates. This is particularly useful if you have an existing roof you wish to refurbish which has been patched with different products or is made up of a number of types of decking. If you can specify a product suitable for multiple substrate application, your contractor wont have to source more than one product, have several types of skilled workers, or develop complex details between materials.