Do-it-yourself ceiling insulation in the house

Recommendation points

• When insulation is required
• Overlap: thickness and material of insulation
• How does the design and type of ceiling affect
• Fastening different types of insulation
• Thermal insulation protection

With a cold attic and weak thermal insulation, up to a third of the heat is lost, and without insulation, the service life of critical structures is significantly reduced. We will tell you how to do the insulation of the ceiling in the house with your own hands, as well as provide detailed installation instructions for doing work without outside help..

When insulation is required

It is very important to understand one detail. Without a sufficient layer of insulation in the floor, it makes no sense to carry out insulation from the inside of the room.

The main task of additional internal insulation is to minimize the heterogeneity of the partial pressure of air saturated with moisture by shifting the dew point as close as possible to the outer surface of the enclosing structure, or to eliminate it completely.

The thickness of the insulation in the floor corresponds to the dimensions of the beams. If their height is not enough, you have to resort to such tricks as packing counter rails and overhead installation of thermal insulation. Of course, these are auxiliary measures, in the general case, the ratio of additional insulation to the main one is at least 1: 3.

Overlap: thickness and material of insulation

There are not so many worthy solutions for warming the attic floor. Polyfoam is of little use for such purposes due to its high toxicity and the main disadvantage that most types of mineral wool also suffer from – rodents actively start in these materials.

It is considered the most suitable insulation based on overdried cellulose. It can be ecowool and some exotic materials such as coconut fiber or cereal husk. Time-tested budgetary methods are also suitable, for example, the following: the beams from the bottom are lined with a ceiling crate, a plastic wrap is laid in the pockets; The overlap cavities are filled with a mixture of undried wood chips, cement and slaked lime in a volume ratio of 10: 2: 3. After the floor of the attic is covered with an unedged board or covered with slag. Even for frosty regions, such insulation with a total thickness of 350-400 mm will be enough, living creatures in such a composition will not start, excess moisture is harmlessly absorbed and evaporated.

Modern technologies also offer decent solutions. It is a method of filling the floor with non-combustible foaming materials. These include, first of all, polyurethane foam and foam glass, which are also used in panel materials for insulation..

How does the design and type of ceiling affect

The main question when insulating the ceiling is how to properly assemble the floor cake. The first difficulties are encountered already at the stage of filing the sheathing: what board to beat, is it possible with a gap, or, on the contrary, should the sheathing be compacted as much as possible? Let it not be a surprise for you that in some cases the crate may be absent altogether. For example, if gypsum board is sewn right along the beams for finishing.

The execution of the crate is determined solely by its function – to support the weight of the insulation and prevent it from waking up. You already understand that the approach will be completely different with the use of bulk materials and polyurethane boards. It is possible to completely abandon the bottom filing only if the floor structure provides for any other mechanical connections between the beams without taking into account the flooring of the attic floor. These can be crossbeams placed in a checkerboard pattern – a honeycomb overlap. For him, you need to choose a heater that is hard and light, you need to fix it with adhesive sealing compounds.

Another stumbling block is the vapor barrier. It is enough to remember that it fits only on one side – warm. In no case should the insulation be closed between the two vapor barrier membranes, but the opposite is possible. The vapor barrier can be placed directly under the joists, on top of the ceiling lathing or even directly under the plasterboard trim.

1 – ceiling filing; 2 – lathing; 3 – vapor barrier; 4 – floor beams; 5 – thermal insulation

The structural features of the floor determine all the specifics of your further work: preparation of a rough ceiling, installation of a profile or rack frame, and cladding. They also determine the insulating ability: the more heterogeneous the overlap cake will be, the more layers it contains, the lower the overall thermal conductivity. But you can’t overdo it either: the more complex the ceiling design, the more mass will be suspended above the residents’ head.

Fastening different types of insulation

It’s time to practice. All methods of fixing thermal insulation are divided into the top tab and the hem. In the first case, everything is extremely simple: first, the entire frame structure is assembled, which is subsequently hemmed from below with a rough ceiling or finishing material. The interior space is filled from the attic side, possibly in layers. One thing is invariable – the vapor barrier is always mounted directly under the ceiling lining.

If you use panel materials for insulation, such as polyurethane foam or PSB-S, it is better to glue them to the sheathing boards. Thus, you can add up to 120 mm of insulation under the ceiling. For gluing, choose compositions on any basis, except for oil, polyurethane or rubber glue is optimal. When gluing plate heaters, it is imperative to fill with an adhesive compound all joints, abutments to walls and places of passage of fasteners.

Finishing is carried out on a layer of preparatory cladding – OSB or GKL. To fix them, you need to hem the insulated ceiling with slats, screwing long screws through the thermal insulation. Suspended systems can be mounted on “Armstrong” type sweat spokes, which were installed in advance along the entire ceiling and passed through the insulation as it was installed. This method is most suitable for apartments and houses with reinforced concrete floors.

In this case, the vapor barrier is cut into strips, the width of which is equal to the step between the strips or the profile. The membrane is applied to the frame slats with an overlap of 15–20 mm on each side and glued along the entire length with aluminum tape. So, when installing the cladding, the self-tapping screws will not pull and wind the threads of the barrier, while the edges of the film will press firmly and tightly.

Another option is to lay a soft insulation after installing the frame system. In these cases, the insulation is laid between the lathing and the frame of the suspended ceiling; additional fastening is practically not required. The vapor barrier is glued to the sub-ceiling so that the internal thermal insulation is at room humidity. If the ceiling has a sufficiently thick layer of thermal insulation, the typical wetting of the ceiling will not occur. To protect the insulation from spilling and weathering, it can be protected from below with a windproof membrane, but it must be completely vapor permeable.

Thermal insulation protection

In conclusion, let’s take a closer look at the protection of thermal insulation. We are talking about fiberglass, ecowool and mineral wool, that is, materials that are sensitive to moisture saturation. The insulation in the ceiling must be ventilated with outside air, so there can be no films and protective barriers on top. If you are laying an attic floor with edged boards, space the elements with thin chips, leaving minimal gaps through which moisture can escape..

Most rodent control chemicals do not help. To prevent the colonization of pests, it is recommended to use ultrasonic repellers, or to lay the floor of the attic with a solid board and seal all the junctions.