Asphalt Blanket: The Complete Guide
An asphalt blanket is an option for waterproofing real estate full of advantages. Its cost-benefit ratio is also excellent, which makes it increasingly common in buildings. In this text, you will be able to discover all the information you need on the subject. Follow us!
Have you ever stopped to think that every building needs to be waterproofed? Without this care, the buildings are subject to infiltration, which can stain the interior wall of the property. Over time, the accumulation of water can also cause leakage, and damage the entire structure of the building. Thus, it is always essential to invest in solutions such as the asphalt blanket.
A common asphalt blanket, “in sheet”, is composed of five layers. The first of these is a polyethylene film, which characterizes its external face. Then there is a layer of modified asphalt, ideal for waterproofing spaces.
In the center of the blanket, there is a structuring material, usually a polyethylene or polyester film. Then there is a new layer of modified asphalt, and then its finish. The finishing of the material can be made of polyethylene, aluminum or other.
The technical standard that regulates the use of asphalt mat in Brazil is NBR 9952 – Asphalt Mat with Armor for Waterproofing – Requirements and Test Methods, from ABNT (Brazilian Association of Technical Standards). With it, those responsible for the works obtain safety guidelines and for the application of the waterproofing on slabs and roofs.
It is also the norm 9952 that classifies the types of blankets available on the market. This classification is made based on the thickness of the materials, water absorption and tensile indices. As well as low-temperature flexibility, product elongation and more. The minimum material thickness is 3 mm.
Asphalt blanket types
In addition to these classifications, the blankets can be divided according to their type of finish. In these cases, there are those with ardosiado, geotextile, polyethylene, aluminum and others. Among all, the most common are aluminum, polyester and polyethylene.
Aluminum asphalt blanket
An aluminum asphalt blanket serves both as protection against moisture and as thermal and acoustic insulation for the property. The material is suitable for slabs and roofs that are not passable or that are inclined. It can also be applied to roofs made of clay, zinc, fiber cement, with ecological tiles and others.
One of the advantages of the aluminum blanket is that it eliminates the need for mechanical protection. That is, the subfloor installation. If the blanket is installed on a roof, it is important that it follows the shape of the tiles, being sealed to each of them.
Polyester asphalt blanket
The asphalt polyester blanket is suitable for an endless number of spaces. It can be installed in planters and planters, retaining walls, passable slabs, swimming pools and fish farming tanks. As well as in water tanks and reservoirs, parking floors, vertical walls, terraces, balconies and in so-called cold areas (rooms such as the bathroom, kitchen and laundry). It is necessary to install the subfloor, on an intermediate base of Kraft paper.
Pre-molded polyethylene asphalt blanket
Finally, the pre-molded polyethylene asphalt blanket is suitable for areas larger than 100 square meters. They are ideal for terraces, water mirrors, elevated pools and passable slabs. It is interesting that this type of blanket is always installed with a minimum thickness of 4 mm.
Installing asphalt blankets in damp areas is to prevent a series of problems in the property. For this reason, it is always interesting to evaluate the type of waterproofing ideal in the building project. Thus, any and all structures can be assembled based on what will be required for the installation of the water protection system.
Remember to count on a specialized engineer or architect, as they will have an easy time planning and executing the necessary steps. Also, because the type of asphalt blanket will vary according to the characteristics of the work.
If necessary, the blanket can also be installed in buildings that have already been completed and/or have been used for years. It is usually a great solution against infiltration. In these cases, it is important to hire a specialized company to evaluate the space. In this way, it will be able to define the type of material most interesting to the building.
Advantages and disadvantages of the asphalt blanket
Undoubtedly, one of the main advantages of the asphalt blanket, of any type, is its incredible capacity for waterproofing the space. With it, the roof or the slab of the property does not suffer from the accumulation of liquids, even after heavy rains.
Another feature that draws attention to the material is that it is flexible, in addition to being very resistant to cracking. Thanks to these requirements, the product withstands thermal variations very well, without cracking or losing its capacity. If properly installed, the material has a durability of up to 20 years!
In any case, there are points that need to be considered before installing the asphalt blanket. Starting with your inability to withstand negative pressures.
Most of the time, it also requires the installation of a protective layer, a subfloor. In this case, there is an increase in construction costs, as well as the weight of the structure. That is why it is so important to plan the installation of the product as soon as possible in a building. In this way, the consumer can plan financially, and the architect can assess the necessary rigidity of the structure.
When installing the blanket, the responsible professional still needs to pay attention to the appropriate trim of the material. As well as the treatment of drains and expansion joints, which need to be considered for the proper accommodation of the waterproofing layer.
How to install the asphalt blanket?
There are two types of installation of the asphalt blanket. In both cases, the quality of the waterproofing result begins with care for the surface. This means that it is necessary to regularize the area, eliminating sudden unevenness or dirt.
In any case, it is also necessary that the surface is maintained with a minimum drop of 1% towards the water drainage points. This will prevent the accumulation of liquids on the slab, and preserve the impermeability of the area.
To smooth the surface, it is recommended to use mortar with a finished finish. The dough should be at least two centimeters thick.
After the mortar, the person responsible for the work needs to apply the primer over the area. The primer is a product similar to paints, which aims to seal the porosity of a surface. It also generally improves the adhesion of the surface to other coatings.
In the next waterproofing layer, the asphalt blanket is installed. Then there is a separating layer, made of Kraft paper or a polyethylene film. Finally, the surface receives a subfloor to protect the other coatings.
Installation methods of the asphalt blanket
Method 1: with melted asphalt
For this type of waterproofing application, the oxidized asphalt is melted in a boiler. Then, it is spread over the surface to be covered, and leveled immediately afterwards. The method requires high specialization of the workers, as it must be carried out with great care.
Method 2: with the “leaf”
When installing “sheet blankets”, it is necessary to apply two coats of the asphalt primer in the space. Then, the blankets are spread over the area, and “glued” to the surface with the aid of a blowtorch.
This method requires extra care against bubbles. Applicators also need to make sure that all parts of the mat adhere to the surface. This is what will guarantee complete waterproofing. Considered more practical and safer, the technique is the most used in the market.
Care for waterproofing application
Regardless of the method used for the application of the asphalt blanket, the executors of the work must take some precautions. To begin with, it is essential that all workers use their Personal Protective Equipment (PPE). This includes boots, rubber gloves, helmet, protective mask, safety glasses, pants and a long-sleeved shirt.
All this care is important for two reasons. First, because, as a rule, the application of the asphalt blanket is done on slabs and roofs. That is, in high spaces. Using safety equipment is to ensures the care of workers in these environments, including in the event of a fall.
Second, PPE is necessary because, normally, the mat is applied while it is still hot on the surface. If you have direct contact with the product or its odor, the applicator can suffer serious injuries.
It is also important that applicators maintain a certain distance from the material during application. In addition, it is not possible to walk on the liquid waterproofing mat. Traffic is also not suitable for “sheet” blankets. Traffic on the surface should only be carried out after the product has been cured and tested for leaks. Tightness is nothing more than checking that there are no holes, cracks or porosities on the blanket.
Asphalt blanket: price
It is possible to purchase asphalt blankets at the most varied building materials stores on the market. This is the case of the “sheet” blanket since the net option must be handled only by specialized companies.
The cost of materials varies, especially according to the type of blanket. Those with slate finish, for example, generally have a price very different from the aluminum ones, more common. The thickness of the product also greatly influences its costs.
In any case, we can establish an average price. On the market, a blanket roll, 10 square meters and 3 mm thick, costs R $ 180. Experts estimate that it is necessary to use an average of 1.15 m² of blanket for each square meter of the surface. Especially because, for the complete waterproofing of the space, overlays and finishes are necessary.
Other types of waterproofing for slab
In addition to the asphalt blanket, the Civil Construction market offers interesting options for the care of slabs and roofs. The products can be divided into two main categories: those of flexible waterproofing, and those of rigid waterproofing.
Products for the rigid waterproofing of space are indicated for places where there is no traffic of people on the surface. Just like when there is not much thermal variation on it. This is because, the materials are not resistant to these factors, and maybe lacking in terms of protection against water.
In this way, rigid materials are generally applied to foundations, buckets, elevator shafts and retaining walls. As in lower water reservoirs and buried pools.
Rigid products include waterproof mortars, epoxy and polymeric mortars.
In the case of flexible waterproofing, the consumer can count on the asphalt blanket, the asphalt emulsion, modified asphalt, neoprene and the elastomeric blanket (butyl / EPDM). There is also the polymeric blanket (of PVC), the asphalt solution and the acrylic emulsion.
One of the main advantages of flexible materials is that they are resistant. Resistant to user movement and thermal variations. They are indicated for slabs, terraces, gardens, balconies, balconies and for the floor of “wet” rooms, such as the bathroom and the service area of the home.
The choice of the best type of material for waterproofing your slab or roof must be made by a professional. So, if your property is still under construction, consult your architect or engineer. Based on the entire building project, it will be easy to define everything necessary for the care of surfaces.
In case the construction is completed, look for a company specialized in waterproofing the spaces. It must follow the ABNT rules, and then it can suggest the most advantageous option for your environment.
The better the company’s reputation in the market, the better the result of your work will probably be. So, search for the company on the internet, and choose the one that has the most praise from previous consumers. This aspect, together with the budget, will be decisive for the best hiring.
Now you know everything you need about the asphalt blanket. Did you have any questions? Send it to us in the comments!