Insulation for a flat roof: how to make thermal insulation under a screed - Setafi

Insulation for a flat roof must be durable, resistant to adverse weather, sunlight and other influences. Many artificial materials fit these criteria, but each of them has its pros and cons. About which insulation is better to choose, and how to properly install it is described in detail below.

What material is suitable

Flat roof insulation can be done using different materials. It can be both artificial and natural materials, the most common are:

1. Expanded polystyrene provides good protection from the cold due to numerous air bubbles. They do not let heat through and also dampen sounds well. The material is quite light, easy to install, does not suffer from temperature changes or high humidity, which is especially important when thermal insulation of a flat roof is planned from the outside.
2. Backfill heaters - expanded clay and perlite sand are often used as them. Affordable and easy to use, but quickly absorb water. In addition, due to the slope of the roof, it becomes more difficult to ensure uniform thermal insulation. Therefore, it is necessary to know the device of a flat roof with insulation, as shown in the diagram.
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3. Mineral wool, consisting of basalt fibers. Such insulation for a flat roof under a screed protects well from the cold, is durable and resistant to fire, and also does not contain harmful substances. But cotton wool perfectly absorbs moisture and begins to deteriorate. Therefore, the installation of a waterproofing layer is required.
4. Foam glass is a material that is made from glass mass that has passed the foaming stage. Differs in good resistance to temperature, moisture, action of sunshine. This is one of the best options, although the cost is significantly higher.
5. Polyurethane foam - insulation in liquid form, which is applied directly to the surface. It is also highly resistant to various types of influences, however, it is expensive at a price.

Insulation thickness

Before you understand how to insulate a flat roof, you need to figure out what types of structures are, because the technology for performing work largely depends on this. There are 2 main types:

1. Attic - the ceiling is separated from the attic. In this case, the roof is not heated from the inside, so more layers of insulation will be needed. But there are also pluses, for example, you can think about how to make an exploitable flat roof, and thus create an attic.
2. Atticlesswhen the structure is combined with the ceiling coming from the inside. The roof warms up well from the inside, so it is insulated in the traditional way - several layers of material are laid and covered with waterproofing.

The very thickness of the insulation for a flat roof depends on the material itself, as well as on the climatic features of the area:

• in the temperate zone (middle lane) sufficient thickness (for example, mineral wool) 100 mm;
• in the northern regions it is necessary to increase to 150-200 mm;
• if the insulation of a flat roof is made of polystyrene foam, then 60 mm is enough for the temperate zone;
• for the northern regions, the thickness of the expanded polystyrene should be 80-100 mm.

How to insulate the roof

Insulation of a flat roof with expanded polystyrene can be planned with laying on a profiled sheet. The basic rules are:

1. The slabs are laid from the corner, which is located below the milestones. If there is no such place, they start working from the place of installation of the funnel or water gutter.
2. During laying, the sheets are laid in such a way that their large side is perpendicular to the corrugation.
3. As a rule, flat roof insulation with mineral wool or polystyrene foam is done in several layers. Then they are placed according to the brickwork scheme.

The flat roof insulation pie provides for a layer of waterproofing that follows on top of the base material. You can take a bituminous membrane as a basis, lay it in 2 layers and weld it.

At the final stage, the insulation must be fixed. There are 3 ways to do this:

1. mechanical technology - fixation with telescopic fasteners, which consists of several self-tapping screws. To do this, you need to hammer the anchors into the concrete slab, and attach the screws to the screed.
2. Adhesive - using mastic bitumen-polymer composition. It must be glued evenly so that the insulation is in contact with the base at least 30% of the area.
3. Ballast - the insulation is covered with waterproofing, and gravel mixed with pebbles is poured on top.

Thus, a flat roof is insulated with foam, mineral wool and other materials. Installation can be done independently, if you correctly calculate the thickness and make high-quality waterproofing. Particular attention should be paid to attic structures. They need enhanced insulation, since the roof is not heated from below.