Features of roof insulation
How to insulate the roof of a house? The technology depends on several factors, primarily the type of structure. It can be flat or sloped.
Pitched roof
It can be single-slope, gable, or four-slope. As a rule, the structure is based on wooden beams (rafters) located at an angle resting on the mauerlat. The system is covered on top with roofing material that does not allow precipitation into the house. The space under a pitched roof can be very small or large. It may not be used; that is, it may be a cold attic or used to make a full-fledged warm room – a loft.
If you leave a cold attic under the roof, the roof itself does not need insulation; it is enough to insulate the attic floor. This is done from the attic side.
If you decide to equip a warm attic, you need to protect the roof. It is best to carry out the work during the construction of the house, in which case you can place the insulating product between the rafters or above them if you want to leave the wooden beams exposed as decorative elements.
Flat roof
A reinforced concrete slab most often represents a flat roof. The design can be “atticless” when the slab simultaneously serves as the house’s roof and the upper floor’s ceiling. Less commonly, a flat roof is an attic when there is a small space between it and the top.
The “loftless” type is best insulated from the outside, choosing a thermal insulation “pie” with or without a screed. Collecting a “pie” on the ceiling protects the attic type from the cold inside.
Thermal insulation products
Products for insulation are varied. Some homeowners use sawdust, while others use more modern effects like spray polyurethane foam. We will look at four popular insulation materials.
Mineral wool
Mineral wool or mineral wool is an Insulation material that appeared at the turn of the 19th and 20th centuries. The product comes in three types:
- glass wool – produced from waste from the glass industry;
- slag wool – made from melted blast furnace slag;
- rock wool – created from the melt of igneous rocks.
The latter type has the best properties; slag wool is not used for insulating houses.
As for the properties of cotton wool, it has low thermal conductivity, which means it does not release heat from the room. At the same time, due to its high vapor permeability, the insulation breathes. Cotton wool is fireproof because it is environmentally friendly and does not burn even at +400°. It has high noise insulation characteristics. The service life of the insulation is up to half a century.
The disadvantages include hygroscopicity – the fibrous product absorbs moisture, and as a result, it becomes deformed and loses its high thermal insulation qualities. Waterproofing the mineral wool while assembling the “pie carefully” is necessary. Also, when working with mineral wool, it is essential to protect the skin carefully and mucous membranes from the smallest insulation particles – they can irritate.
Mineral wool is suitable for insulating pitched roofs and thermal insulation of attic flat roofs.
Expanded polystyrene
Expanded polystyrene is about half a century younger than mineral wool. This material is foamed and extruded (EPS). Both types are produced in slab format, consisting of compressed hollow granules. The manufacturing method makes EPS granules smaller, so the insulation boards are thinner.
Like mineral wool, it has low thermal conductivity, so it maintains a comfortable temperature in the premises. Expanded polystyrene boards are lightweight and easy to install with your hands; you can cut the material into suitable fragments with an ordinary construction knife. Expanded polystyrene is not afraid of water – it almost does not absorb moisture. It doesn’t grow mold. A high-quality product does not harm the house’s residents or the environment. The insulation lasts up to one hundred years.
However, expanded polystyrene has low vapor permeability and requires a high-quality ventilation system. The material loses its properties when exposed to direct sunlight (for example, when stored outside before installation), so it should be kept closed for a short time. Also, some types of insulation of the roof can be explosive. Therefore, before purchasing, ensure the product has the appropriate certificates. If you decide to insulate the roof of a private house using polystyrene foam, This is an environmentally friendly product, suitable for facilities with increased fire safety requirements. You can view the certificates on the manufacturer’s website in the “Documents” section.
Using polystyrene foam, it is best to insulate a flat roof without an attic from the outside and insulate the attic from the inside.
roof insulation with polystyrene foam
Sprayed polyurethane foam (PPU)
Polyurethane foam is the same age as expanded polystyrene and belongs to foamed plastics. Polyurethane foam can be slab or sprayed. Sprayed polyurethane foam allows you to create a seamless thermal insulation layer, minimizing the possibility of the appearance of cold bridges. Thanks to the application method using polyurethane foam, it is possible to insulate complex, uneven surfaces.
The thermal conductivity coefficient of this product is low. The material is not afraid of fire and water, as well as fungi and mould, and it does not emit harmful substances after hardening. Sprayed polyurethane foam has been coping with its tasks for half a century. Sprayed polyurethane foam (PPU)The disadvantages of the product are the high price and the need for special equipment for application. If you use polyurethane foam to insulate the roof from the inside with your hands, you will have to rent equipment and prepare a special protective suit. But it is better to contact specialists.
PPU is suitable for insulating attics and attic floors.
Penoizol
It is liquid plastic. The method of applying penoizol, like that of polyurethane foam, is spraying. The material’s thermal conductivity is not inferior to that of mineral wool and expanded polystyrene. At the same time, penoizol creates a seamless layer without cold bridges. Ten centimeters of pension can replace 15 centimeters of expanded polystyrene and 20 centimeters of mineral wool. The product blocks not only heat but also noise. In addition, penoizol is cheaper than expensive polyurethane foam.
The material is elastic but less durable than polyurethane foam.
The product is suitable for insulating roofs home insulation sydney from the inside, insulating attics, and attic floors.
Stages of insulation
How to insulation in a private house? The technology will depend on the type of construction, the readiness of the house (whether it is under construction or already completed), and whether thermal Insulation of the roof is carried out from the inside or outside. For example, consider the stages of assembling a “pie” from the inside of a pitched roof and the locations of external insulation of a flat roof.
How to insulate a roof from the inside
- At the preparatory stage, it is necessary to saturate the rafters with fire retardants and antiseptics and wait until these products dry entirely.
- Then, you need to install the waterproofing film. Place it on top of the beams on the street side. Lay the sheets of film across the wooden elements, overlapping – so that one layer of waterproofing overlaps the other by 10-15 centimeters. Please note: the film should sag a little so it does not tear in frosty weather.
- Further work proceeds from the inside, from the attic side. It is necessary to install insulation – mineral wool or expanded polystyrene slabs. The polystyrene foam board’s width should equal the distance between the beams. The width of mineral wool slabs should be slightly larger since wool is elastic. Please note: if the thickness of the thermal insulation material is greater than the width of the rafters, it is necessary to additionally stuff the slats so that the insulation does not extend beyond the edges of the beams.
- The thermal insulation layer must be covered with a vapor barrier membrane to protect the Insulation of the roof from moisture coming from the room. The membrane, like waterproofing, is overlapped and secured to the rafters with a construction stapler.
- You can stuff counter slats on top and mount boards, sheets of plywood, drywall, or any other material covering the “pie” on them.
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How to properly insulate a roof from the outside
- Preparation of the base involves cleaning it sealing small cracks and potholes (if any) with cement-sand mortar.
- Then, you need to create a vapor barrier layer. We overlap the film and seal the joints with tape.
- We lay expanded polystyrene slabs onto the vapor barrier, tightly fitting each other. Make sure there are no gaps between them.
- Then there are two options: cover the previous layers with geotextiles or make a screed three centimeters thick. The design with a screed will be more reliable but heavier. Take this into account when choosing a technology.
The final layer of the “pie” is a roofing polymer material. Please note: you must wait until the screed is completely dry before installing the roof.
This is what the insulation process generally looks like. The use of high-quality materials and preliminary calculations will significantly simplify the thermal insulation process.
