Today, Savo Kusić is focused on timber windows, timber-aluminium windows, custom-made windows, doors and quotation requests. This text remains a home-improvement archive and is not an offer to design, carry out or supervise attic conversions.
Planning the attic room
The basic prerequisite for comfort is sufficient space. In family buildings, it is possible to increase the space by using the attic space, which is less and less needed today, to build a mansard room.
Staircase, fire protection and chimneys
It starts with remodeling and strengthening the staircase. While the ideal depth of the steps is 30, and the height is 15 cm, for attic stairs we also meet heights of 22-25 cm with a depth of only 12 cm, of which about 6 cm is located under the next step (fig. 1, part a). If the attic staircase is very steep, the possibility of building a new staircase should be considered, possibly outside the building covered with corrugated sheets of artificial material. In any case, the basic requirement is that the staircase has a good railing and non-slippery steps. The railing must extend all the way to the attic to prevent someone from falling down the stairs into the stairwell.
At the lower approach of the attic staircase, on the ground floor, a fireproof door (clad in sheet steel) should be installed to meet fire safety regulations. It is recommended to cover the fireproof door with a non-combustible but decorative material, which is also a thermal and acoustic insulator (glass wool, etc.).
It is very important to control and trim all chimneys, and to cover those that will be in the living space with ceramic tiles to make them more decorative and, just as importantly, safer in terms of fire. An important general rule is to place heat-insulating and refractory asbestos waste, etc., between the chimney and the new wall cladding materials. Furniture, carpets or other flammable objects must not be placed near the chimney. That part should be shaped so that it becomes a kind of free fireplace space.
Safety note: this is a historical text. Asbestos materials must not be used or processed. Converting an attic can affect load-bearing capacity, fire safety, escape routes, chimneys and services, so the existing condition and proposed solution must be checked by appropriately authorised professionals in accordance with current regulations.
Windows and roof construction
We must provide a window for natural light and ventilation. If one wall of the room is the gable wall of the attic, a window can be installed in that wall. The procedure is as follows: where the lintel is to be installed, one course of bricks should be removed by first taking off the dry plaster from the attic side, inserting an extension board for the lintel, then continuing from the outside and driving the board fully into place. Working from top to bottom, bricks should be removed from the future window opening, while a support post must be installed beneath the section above the opening and temporarily secured with two wedges. Finally, the entire opening is formed (fig. 1, part b.). If the gable wall consists of a single course of bricks (wall 12), it is advisable to demolish the whole wall and rebuild it at 25 cm, or preferably at 38 cm. A window frame can then be installed in this wall. Great care is required because masonry falling towards the street can cause serious accidents, while bricks falling into the attic can even break through the ceiling below.
It is a much more complicated case if none of the attic walls coincide with the gable wall, because in that case the lighting should be solved with an attic window. The difference between these two types of mansards is very nicely shown in picture 1, part c.
FIGURE 1
A detailed view of the dormer window is given in figure no. 2. Removing the roof covering and constructing the dormer framing should be entrusted to a professional. The work is easier where the spacing between the roof purlins is greater, because the window can then be positioned between two purlins without moving them (fig. 2, part b). If a wider window is required, the roof structure must be adapted as shown in the drawing (fig. 2, part a).
FIGURE 2
As a compromise, a wider window can be installed without moving the purlins, leaving them in front of the window. In this case the window sashes can open only outwards, and the sloping purlin between the left and right sashes is certainly not the most attractive solution (it may be incorporated into a triangular partition clad with manufactured board). It is very important to provide small gutters on the outside of the dormer structure and a drainage channel at its junction with the roof.
Frame, services and heating
The walls of the mansard room can be installed only after making the skeleton from beams 7,5 / 12 that are previously protected against fire. In fact, this consists in increasing the number of supports of the roof structure and cladding the existing ones on the inside. The inner side of the roof supports should be lined with boards of the same width, but only 1/2“ - 1“ (12-24 mm) thick, so that their inner surfaces are in the same plane as the new “thickened” beams, roof supports.
Of course, the skeleton should eventually be formed in such a way that it corresponds to the existing roof structure of the building. It is important that the nails and screws for fixing the skeleton are not over-dimensioned, so as not to significantly weaken the bearing capacity of the beams, rafters of the ridge roof structure. Cladding boards should be attached instead of nails, gluing or, if this is not enough, then (by pre-drilling holes) with wood screws. With careful planning, the attic walls (maybe not all) can be placed above the supporting walls of the ground floor. The walls of the mansard should be made of bricks with a minimum dimension of 38 cm.
If the skeleton is made, utilities can be laid.
Electrical cables should follow the shortest possible route, be well insulated and run in Bergman conduit. The attic should not be overcrowded with electrical installations. One protected circuit with a switch, a multiple socket and one ceiling (or wall) light is sufficient. A suitably robust cable with careful insulation should be used. The main switch should be located on the ground floor by the access point, with an indicator light so that the power can be turned off when no one is in the attic. The water supply for a small washbasin and the waste pipe should likewise follow the shortest route. It is therefore best to position the mansard beside or above a wet-services area. The pipes can run side by side so that they share thermal insulation (water can freeze in winter and become so warm in summer that it cannot be used as drinking water). Apart from the washbasin, it is not advisable to have other water outlets in the attic.
The historical text describes steam or hot-water heating as the most suitable way to heat the attic. If heating cannot be provided in this way, other possibilities mentioned are gas convectors, an oil stove or electric heaters positioned beside the gable wall and, only as a last resort, a solid-fuel stove.
Floor, interior lining and insulation
After the solution of the utilities, the skeleton and the staircase, the floor is installed.
If the ceiling of the building has already been built in such a way that the construction of the mansard is also taken into account, then it is only necessary to place the material for decoration and thermal insulation (PVC floor or wall-to-wall carpet) on the floor, which is already aligned and can bear the load.
Ordinary attics, however, are not built this way. Load-bearing boards must first be placed on the tie beams, followed by tongue-and-groove floorboards covered with carpet or PVC. At the same time, the entire space between the boards and the finished floor should be filled with an inexpensive, non-combustible insulating material. Foam material and glass wool in bags or quilted form can be used for this purpose because they are easier to position.
After this, an internal lining of 1/2“ boards protected against fire should be installed. On top comes a lining of fibreboard, plywood, chipboard, panels, etc. (fig. 3). At this point the historical text also referred readers to ordering and cutting services for chipboard, MDF and other boards; that service is not part of the new public offer.
FIGURE 3
In the end, it remains to lay an insulating layer on the outside, similar to the floor. It is easiest to work with insulation material that can be obtained in boards, although it is somewhat more expensive.
Note: the technical values, materials and procedures above are presented as historical content, not as a modern design or installation instruction. Load-bearing capacity, moisture and condensation, ventilation, roof openings, waterproofing, fire protection and all services should be resolved for the actual building in accordance with current rules and the system manufacturers’ instructions.