Making roof insulation of a house

Modern roofing materials for roof insulation are of high quality and do an excellent job of protecting the house from precipitation. However, moisture can occur under the roof not only due to roof leaks. Much more often, the appearance of water is associated with the condensation of moist air vapour on cold roof surfaces.

The occurrence of moisture in the roofing pie is unacceptable, as this significantly reduces the service life of the wooden elements of the rafter system and roof insulation. That’s why a dry roof and its insulation from moisture and steam are so important. Let’s consider the main points when performing hydro- and vapour barriers at a house’s top.


First of all, let’s remember the filling of the roofing pie and determine the place in it for insulation installers Wollongong materials:

  • Roof;
  • Lathing;
  • Waterproofing film;
  • Rafters;
  • Insulation;
  • Vapor barrier;
  • Finishing the interior of the attic (often plasterboard).

There are different types of waterproofing materials:

  • regular film
  • anti-condensation film,
  • diffusion membrane,

Their difference lies in the ability to retain and evaporate condensate. Conventional films solely represent a moisture barrier, while anti-condensation films and diffusion membranes can maintain a significant amount of condensate and evaporate it with well-arranged ventilation.

The basic rules for laying any waterproofing material are simple:

  • waterproofing joints are laid with an overlap of 10-15 cm;
  • waterproofing is laid on the entire surface of the roof, including places under the overhangs of the eaves and gables;
  • waterproofing at the eaves overhang is discharged into the gutter or behind the front board;
  • all roof connections – pipes, ventilation shafts – must be insulated especially carefully

Cold roof waterproofing

The need to waterproof a roof over an unheated attic could be more precise. However, no one is immune from rainwater and snow getting under the top, as well as the appearance of condensation under the top, which often happens when various communications, such as a chimney, pass under the roof.

The advantage of waterproofing a cold roof is that the conversion process will be pretty simple if you still want to create a warm room under the top.

It is recommended to use anti-condensation films; their purchase is more economical than membranes, but unlike conventional films, they contain a particular fleecy layer that retains excess moisture until it evaporates.

The waterproofing material is laid on the rafters with a mandatory overlap of the joints of up to 10-15 cm. It is essential to maintain a distance of 5 cm from the film to the roofing material, which requires the installation of additional elements (counter battens and sheathing). This will equalize the temperature of the outer and inner sides of the film.

Warm roof waterproofing

Insulating the roof with insulation is a mandatory procedure. Using some types of insulation implies the formation of condensation due to the significant temperature difference between the roofing material and the insulation. The waterproofing layer protects the insulation and the rafter system from excess moisture.

Installation of roof waterproofing is closely related to the creation of ventilation circuits necessary to evaporate accumulated moisture. It is possible to form different types of ventilation in the under-roof space:

  • ventilation with one circuit between the waterproofing and the roof;
  • ventilation with two circuits: between waterproofing materials and roofing and between waterproofing and insulation.

In any case, creating a distance between the waterproofing film and the roof insulation is essential. This can be done by incompletely embedding the insulation between the rafters or by stuffing additional slats onto the rafters before laying the waterproofing.

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Vapor barrier

Roof insulation, which contains insulation, is required. The air masses of a warm living room have a large amount of water vapour, which will penetrate the insulation without vapour protection and significantly reduce the life and quality of its service. The vapour barrier is laid on top of the insulation inside the house. A lath is placed on top of it, and material such as drywall is attached to finish the room.

The modern roofing materials market offers a wide selection of vapour barriers. Vapour permeability is determined by density in grams per m2: the higher this value, the more influential the material. The main types of vapour barriers are:

  • polyethylene film;
  • membrane materials.

The latter do not allow moisture to enter the insulation but also independently evaporate the accumulated condensate.

Also Read : The must-haves for your new home

Flat roof insulation

We will separately consider possible insulation options for a flat roof. Typically, a vapour barrier is not required here or is part of the ceiling sheathing process. Waterproofing is mandatory for roof insulatin .

There are several options for insulating a flat roof:

  • built-up roofing materials based on bitumen. This will require the use of a gas burner, which requires some skill in handling;
  • using sprayed roofing, which is called liquid rubber. It can be used on any roof, including pitched tops. Flat roof insulation

Spray roofing can be applied to any substrate, including roof coverings. This makes it one of the favourites in the insulation materials market in recent years. Using this material, you can insulate the roof being built and repair the old one if its waterproofing layer has become leaky over time and does not cope with its task.

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