How to add a mezzanine
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A mezzanine storey is a great design solution for a room with a double height ceiling or loft space above. It provides additional valuable floor area, together with the impressive sense of volume created by a high ceiling.
Adding a mezzanine is usually done as part of a conversion, renovation or extension – think two storey extensions, loft conversions, garage conversions with a room in the roof or as part of barn, school or church conversion.
Read this guide to find out then basics, then use our guides to extending a house or renovating a property to find out more about the rules, regs and planning involved in this type of project.
(Image credit: Rachael Smith)
Why would you install a mezzanine floor?
Typical situations that might suit a mezzanine are conversions, where the character of the building, be it a former barn or church, requires some double height space to remain on show. It may also be a good design solution in a listed building, where horizontal roof beams spanning the space are an obstacle to creating a full additional storey in the roof space and can’t be altered.
On a smaller scale, a mezzanine can be an enlarged landing area overlooking the stairwell, or a gallery within the loft space above a bedroom, overlooking the room below, perhaps because the roof space is too limited for a loft conversion. In most situations you can use a mezzanine space at first floor level for any function, including a living area, sleeping platform, or a kitchen.
Cantilevered stairs, by Glass UK, make a stylish feature and lead up to a mezzanine study overlooking the kitchen and living room in this converted power station
Do you need permission for installing a mezzanine?
Planning permission isn’t needed unless a house is listed, but all work must comply with building regulations. If the work affects party wall structures, you must notify your neighbours. Leaseholders need permission from the freeholder for structural changes.
(Image credit: Rachael Smith)
How to use the mezzanine space
Mezzanines are a great way to maximise the footprint of a single storey home with a high ceiling. For example, a sleeping loft over a living space can create guest accommodation where a room is not available. Where this is done, you must not cover more than 50 per cent of the room it sits over.
(Image credit: Stuart Cox)
Fire safety and mezzanines
(Image credit: Rachael Smith)
At second floor level a mezzanine space cannot form a habitable room, such as a bedroom (unless the floor level is 4.5m or less, or above outdoor ground level and there is a fire escape compliant window) as it doesn’t comply with building regulations for fire safety as it’s open to the room below. If you do want a habitable space over a first floor room, you will need to treat it like you would a loft conversion and apply the same fire safety measures.
Find out what this would entail in our loft conversion guide.
A second floor mezzanine must form a single space (no subdivision other than for storage, wardrobes etc) and the visible area of the room below should not be less than 50 per cent. Possible non-habitable uses for a second floor mezzanine can include adding an suite bathroom (although this would need to be open to the room below), dressing room or storage. Check out our dressing room ideas feature for inspiration.
(Image credit: Rachael Smith)
Staircases and balustrades for a mezzanine
Access to a mezzanine level is via a conventional staircase — but if space is tight, options include a spiral staircase or, for a space that’s only used occasionally, a space saver staircase with hit and miss treads, or a fixed loft ladder with hand rails. You need to keep a maximum distance of 3m between the mezzanine stairs and the room below’s door, with a maximum of 7.5m from the furthest point of the mezzanine to the stairs.
An engineer will need to calculate the strength of the floor and any alterations required to the roof structure. The roof/ceiling will have to be insulated, and some form of balustrade will be needed where it overlooks the space below.
The balustrade and stairs are an important design feature. A glass balustrade and a simple staircase, or a spiral flight, work well in a modern space. The balustrade and stairs in a barn conversion should be minimal or sturdy and practical. For a traditional look, spindles, a handrail and a cast-iron spiral flight are a classic solution.
Want more advice on conversions?
- Find out more about how to tackle a barn, school or church conversion
- The ultimate guide to converting a basement
- Ultimate guide to garage conversions
How Can I Carve Out a New Room Without Adding On
Whether you have a growing household, need more space for guests or are hoping to bump up the price when you sell your property, adding an extra room can be a real bonus for any home. And the place to look is often upward. Using the height of your home to increase space doesn’t have to involve a full attic conversion (or even an attic), or even any structural work to your building. Here, three space-expanding experts share their tricks for ways to maximize the space in your home. Be sure to consult local building codes for requirements on stairs and guardrails.
Professional advice from:
Pravin Muthiah, Coupdeville
Jamie Falla, Jamie Falla Architecture
Colm Doyle, DMVF Architects
Max out your living space. Building a mezzanine (an in-between floor) or loft level for your bed is a fantastic way to increase the floor space of a compact flat. In this apartment, owned and designed by architect Pravin Muthiah, of Coupdeville in London, moving the bedroom to a higher level has allowed the flat’s living area to be made into a larger, open-plan space — the sort of spatial luxury that really makes a difference in a one-bedroom home.
“With most small, modern spaces, normally both the living room and bedroom would be on the same floor,” says Muthiah, “but this is a good example of how a small space can feel much more generous by having a mezzanine. It effectively adds another room, as well as increasing resale value.”
Dyer Grimes Architecture
Be budget friendly. Aside from the fact that building a loft is typically cheaper than converting an attic, it’s also potentially an option in buildings that aren’t suitable for additions due to planning restrictions, since the structure is internal. There may be issues with adding some types of windows, though probably not simple skylights — check your zoning regulations.
Any construction will, however, need to meet building regulations and, depending on what you’re having done, it could be wise to consult a structural engineer.
Construct a stand-alone structure … Having an attic space is not a prerequisite for building a new, high-up area in your home; there are many ways to construct a loft.
The creative approach to building a new room seen here is the work of Colm Doyle of Irish architecture firm DMVF, and it has effectively turned an uninhabitable former fisherman’s cottage into a fully equipped one-bedroom house. Previously, the 270-square-foot property had no bathroom and just two rooms. But thanks to the addition of this birch plywood box, it now has a bedroom (up the stairs), a dinky but fully equipped kitchen, a utility room and a shower room, all below the sleeping platform. The rest of the space is now all living area.
… especially in protected or listed buildings. Doyle explains why he didn’t do an attic conversion in the cottage instead. “It’s a protected structure,” he says. “It was built in the 16th century, so we couldn’t put any windows on the front, nor dormers, nor break the roofline.” Skylights were permissible and illuminate the bed area.
Brighten up your home with a new skylight
8181819915772px;”/>The beamless structure, though meticulously designed, was far simpler to do than an attic conversion or even many kinds of lofts. “There’s no steelwork in there. We designed it with our cabinetmaker as a huge piece of furniture,” Doyle says.
Consider adding living space rather than sleep space on high. This building is an old barn, and the vast space inside such structures can feel imposing when they become homes. “You don’t want all double-height space,” says Jamie Falla of Jamie Falla Architecture in the Channel Islands. “It’s almost too grand, and you’re trying to create coziness within a large space.”
Falla adds, “The use of glass is not the cheapest, but it’s about creating a visual connection.” It also allows you to borrow more light from the lower space.
MSD Interior Designer
Build over what’s already there. This bijou French library and micro lounge is another example of how a new floor area can be constructed to sit over existing rooms. Here, the
designers reduced the height of the bathroom ceiling to create space above it for a mini loft.
Part of the motivation, as well as to add living space, was to create architectural interest in a previously plain interior. The construction alone does that — especially with the monochromatic paintwork to accentuate the lines — but additional details, such as the wall niches for display, and a new window, add yet more dimension. And no space has been wasted, as the barrier doubles as a bookcase.
The stairs are particularly clever: Half of each tread has been designed to float, so as not to block the sight line.
Measure your ceiling height. Headspace, naturally, is a significant consideration. In Muthiah’s flat, which is in a 1960s building, the ceilings are a little over 15 feet high. “I think the minimum overall height you could start with would be 4.4 meters [14 feet],” he says. “Otherwise you won’t have standing space above.”
Alex Maguire Photography
Consider your light source. It’s important to work out how you’re going to illuminate both your elevated room and the newly enclosed space below. In Muthiah’s flat in the previous image, floor-to-ceiling windows offer plenty of light for both levels. In this space, however, skylights have been added on both sides of the roof to flood the mezzanine with light, while a small window brightens the area underneath.
Michelle Chaplin Interiors
Add an office. If your house or apartment has the height, and you work from home, building into the roof could be the way to get your laptop off the kitchen table and into its own peaceful area. This could also be worth considering if you don’t think there’s space for a bed or living area up there.
Colin Cadle Photography
Simply add storage. If height really is an issue, or a mezzanine would involve more building work than you currently want to do, opening into the eaves of a property with a pitched roof is another idea. You can create a lot of new storage with very little disruption or cost, and you don’t even need to have a staircase built, as a (safe) ladder is often enough.
The shoes in this example double as an interesting display, but you could equally pack lots more stuff out of sight into a newly exposed cavity like this.
Provide separation in an open-plan family living space. “Originally, this was my house,” says Falla of this raised living area. “You want a big, open-plan, family-friendly space downstairs in these sorts of homes, but it’s also good to have somewhere for parents to retreat to in the evenings, to escape from children and other frenetic chaos and noise downstairs.”
He adds, “In these open-plan spaces, the aim is still always to engage with people, so while this TV room is separate, you’re not enclosing the space and cutting it off — it’s still part of the family room, but it creates a little privacy.”
The house was originally an old barn, and Falla was keen to work in harmony with the building. His team lowered the ground floor by 2 feet rather than interfering with the roof externally to make space for the mezzanine level. They also replaced the roof’s original tie — the horizontal piece of timber that stretches between the sides of the roof to help hold it together — to allow this structure to be raised a little higher to provide more space. For strength, the new tie is steel rather than wood. “This was the biggest structural work we did,” says Falla, “and it was a flourish, rather than a necessity.”
Enhance privacy. A mezzanine floor doesn’t need to be open to the room below like a balcony if privacy is required. Here, an internal window lets in light from the space below. As already outlined, skylights are unlikely to prompt planning issues and can be used to add light if little can be borrowed from the room below. Ventilation is also a consideration.
RUSSIAN FOR FISH
Custom design a bed. This is the simple version of Doyle’s “huge piece of furniture” idea. Essentially, this combination of storage and sleeping space is a custom bunk bed, but it shows how beautifully this sort of structure can be made, and how it can blend in with existing features to look architectural rather than like a piece of furniture. This superstylish design is for a child, but what’s to stop you from commissioning a double- or king-size version for yourself? The space beneath can be used as a wardrobe or desk space or as a little reading corner.
Consider custom-made furniture for one-of-a-kind decor and style
If you’re in a long-term rental, a version of this could also be the answer if you’re short of bedroom space. In theory, you can always take it with you when you leave.
Gregory Phillips Architects
Get creative with stairs. “You’ll probably need to get building control or a structural engineer involved in most mezzanine cases,” says Falla, “but you can get away without doing a formal staircase. A parrot staircase [see image] where you step up with opposite feet, or a ladder, will benefit floor space.”
Build storage into your new stairs … If you don’t go for the ladder option, one advantage of having the excuse to build a staircase from scratch to reach your new level is that you can build storage into it.
… and add a dresser. This storage staircase has drawers accessible from the space in the lower part of the room, as well as a built-in dresser. Each storage element cleverly fits within the run of the staircase.
Consider a storage-packed sleeping platform if the height is tight. “In a lot of these spaces, people will make the new space for sleeping, and a lot of
estate agents would also focus on an extra bedroom,” says Falla. This can mean it’s worth looking at small rooms in a new light — could you effectively double the size of yours?
“Anything over 3.5 meters [about 11 feet] is a dimension where you can have a half level and then a mezzanine,” says Falla. He suggests, as he’s done in a recent project, building storage and putting a sleep space on top. Here, the bed’s platform has drawers. It’s an idea that can also work in many open-plan living areas.
“Psychologically, it will feel bigger, so you get the benefit of more space but at lower cost,” Falla says. The space may not be big enough to fit in new levels that allow standing space above and below, but you can still create valuable space. “It’s also a lot less upheaval than a loft conversion,” he says.
Tell us: Have you added a living, sleeping or storage space to your home? We’d love to hear all about it and see your photos in the Comments.
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Alteration of the mansard roof into a full-fledged floor. Building advice from Semenych
Houses with attics are common today, they are built both for summer cottages and for permanent residence. Technically, the attic is the most common attic; this room is formed by roof planes and gables. It is insulated, finished, windows are installed in it, after which it can be used for seasonal or year-round living – it depends on the degree of improvement. In order to decide whether this is necessary in a particular case, all the advantages and disadvantages of attic floors are first evaluated, and only then a verdict is made.
Advantages and disadvantages of a semi-attic
The construction of an attic or semi-attic floor will significantly save money costs, in contrast to the construction of a full-fledged floor.
The advantages of a semi-attic floor include several factors. It is possible to use vertical, that is, end-to-end full-fledged glazing, without the use of skylights, which are rather expensive . It also turns out to use the space of this floor more rationally than in the attic floor.
A typical house with a semi-attic instead of a second floor
The main disadvantage of attic and semi-mansard floors is large heat loss through the roofing . But this flaw is easy to eliminate by carrying out careful work on the installation of thermal insulation, following all the steps and using high-quality and proven materials.
A semi-mansard floor will also cost more than an attic floor, but less than a full floor.
Alteration of the mansard roof into a full-fledged floor
Good afternoon! As far as possible, make walls out of a mansard sloping roof to make a regular 2nd floor. At the same time, leave the gables as they are (of course, having increased them to the side walls). Thank you for your reply.
Hello, Love from Moscow!
There are no impossible tasks, there are incapable people.
What I mean is that the reconstruction of an attic with a sloping roof into a full-fledged second floor is a completely feasible operation. And this is often very often done.
True, there are certain difficulties in building up the existing gables to the side walls, since sometimes it is easier to immediately demolish these gables along with the dismantled roof. And proceed to the installation of the second floor.
But, as the builders say, any whim for your money. If building up the gables to the corner sections of the walls is technically feasible and does not weaken the structure of the house, then this can be done.
So go ahead! Decide with the builders and rebuild your house.
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Semenych (author of materials)
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Semi-mansard roof rafter system
When designing a frame structure, it is necessary to take into account the future slope of the roof. The architectural features of this building allow for a high roof to be in harmony with the overall look of the entire assignment. Also, when designing the roof, it is important to take into account all the loads. It must withstand snow, rain, wind. When designing a roof, the future rafter system is very carefully developed.
This system will be non-thrust, it is important that the rafter leg does bending work without transferring the load to the walls. One of the supports will be fixed but rotatable, and the second support will be movable and free to rotate. It is important to remember about the Mauerlat device and the mounting of the ridge run, which rests on the racks.
General view of the semi-attic truss system with a roof bend
There are different ways to mount a non-stretching structure. The lower part of the rafter is hemmed with a support bar , a special groove is made in this bar to rest against the Mauerlat. And in the horizontal part of the rafter leg, they make a cut with a bevel to rest on the timber.
This bevel will avoid expansion, which will allow the rafter to bend. Fastening occurs with the help of nails, corners or staples. The upper ends of the rafter legs are laid on the ridge run, and is attached according to the principle of sliding support . This principle allows the structure to move within certain, given boundaries during deformations and changes.
You can also use the more common version. The rafters are stacked in each other or in a run, linking them together with toothed metal plates. The upper parts of the rafters are fixed with a bolt. A nail is driven into the side part at a certain angle.
More detailed diagram of the semi-mansard truss system
Also, reinforcement is made using metal plates or steel corners, which fix the rafter leg on both sides. You should not rigidly fasten the entire structure, otherwise you will deprive it of the necessary movement, and because of this, the spacer load will no longer be transferred to the Mauerlat.
Attic: history, tips and details of building
The second floor of the house under the roof owes its name to the Frenchman Francois Mansart . He was the first to come up with such an architectural solution. An example of his work, which he did in Paris in the 17th century, can still be seen in that city.
In modern times such construction was resorted to to improve the appearance of palaces and castles . And nowadays, this architectural solution finds more and more fans. The attic is not just additional space, it is also a bright addition to the look of modern buildings. A huge variety of attic rooms enlivened the appearance of cities, adding color to the external appearance.
It is worth noting that not every attic will be able to build such a room. Ceiling height can limit the architectural aspirations of homeowners. If it is less than two and a half meters in the highest part, then you will have to say goodbye to ideas about the attic. It is also believed that if the horizontal ties are at a low level, then any construction will be undesirable. Raising the level of screeds is almost impossible, besides, attempts to do this can easily lead to a violation of the integrity of the roof.
Arrangement of an attic in an empty attic brings with it a number of advantages:
However, unfortunately, there are a number of negative factors that significantly affect the level of comfortable living in the house:
Design features and strength
The truss structure requires sliding and a certain freedom, otherwise all its work will be wrong. Usually, the rafter legs are fixed at one end with the principle of a sliding support, and at the other with a swivel joint. This fastener is the most correct and effective , as it fully supports the entire structure in the correct condition, allows it to work correctly.
The ridge purlin must be firmly supported against the gables to prevent the structure from moving due to uneven distribution of forces, vertical posts alone will not be enough for this.
To give stability to the entire system, the bottom of the racks that support the run are rigidly clamped by cutting into the bed, and also attached to the floors. Mount also the horizontal bout , fixing it with nails to the uprights. This fight is a pre-emergency element for the entire structural system and can save the situation if the load on the roof is too large and deformation occurs.
Calculation of the main parameters of the roof
The correctness of the calculations directly affects the degree of reliability, strength and durability of the mansard roof. If the design is carried out by a person without architectural education, it is better to calculate the mansard roof with an online calculator: it will allow you to quickly and accurately calculate the main parameters of the roof. This will make it possible to decide on the purchase of the necessary equipment and building material. In addition, it is important to make sure that the foundation of the building is of the required strength.
The calculation of the attic roof consists of the following indicators:
What is a semi-mansard roof
Unlike an ordinary attic, a semi-mansard floor is formed not only by the roof slopes, but also by the walls of the building. Those. walls are erected above the ceiling between the attic and the lower floor, but below the ceiling of the attic floor. This allows you to abandon the broken rafters.
In other words, the structure is a conventional gable roof. However, there is one caveat here – the walls that are erected above the ceiling are not pulled together by beams or slabs. Therefore, they do not tolerate the expansion load that occurs when laying hanging rafters.
Sloped truss systems do not allow the use of a half-attic as a living floor
At the same time, the use of slatted rafters, which avoid such loads, is not allowed, since in this case the space of the half-attic floor will suffer.
The deflection of the rafters allows to eliminate the thrust on the walls, however, in this case, the rafter legs must be displaced relative to the mauerlat or ridge run.
There are several ways to construct a truss system that meets all these requirements. Next, I want to introduce you to the most modern system that allows you to reduce spacer loads to a minimum.
Attic – general concepts
Many people dream of having an attic when planning the construction of a private house, although the end result may not be the desired one. Therefore, you should decide on the concept of the attic floor. A clear explanation is given by SNiP (building norms and rules). We note right away that all legal actions related to registration (re-registration at the BTI, and so on) are necessarily based on this set of laws.
According to SNiP 2.08.01-89, an attic or attic floor is an upper tier located in the attic space of a house made of timber. Its facade is formed partially or completely by the plane of the roof of the building. The height of the walls formed should not exceed 1.5 meters from the floor level to the line of intersection with the roof surface, otherwise it is a full-fledged second floor.
Someone will object that he has an attic in a house made of timber has the same shape. It is quite possible, but the fundamental difference is that the attic room is a specially equipped and intended for living area under the roof of the house. This is the second main functional indicator. For this reason, the attic floor needs high-quality insulation, especially for timber houses. Thermal insulation of additional living space requires additional costs, but as a result, the rooms will be completely suitable for long-term living. Ventilation is required. Without it, ascending air currents from the lower floors will not allow residents to feel comfortable. In addition, the problem of condensation on walls and ceilings is immediately solved.
We divide the process of rafter system installation into three stages:
The main stages of installation of the truss system
Next, we will consider the device step by step from beginning to end.
Preparation of Materials
To provide a large bending moment for the truss system, the following materials will be needed for its installation:
Slider fasteners to slide the rafters
After preparing the materials, you can start working.
Preparing the structure for the installation of rafters
Preparing the structure with your own hands for installing the rafters is carried out as follows:
This measure will prevent the penetration of moisture from the walls into the wooden structure.
The section of the ridge run is selected individually, depending on the length of the span. You can get this information from reference literature or an online calculator.
The structure is now ready for the rafter legs.
On the diagram – the device of a non-expanding truss system
Calculation of the main parameters
The reliability, strength and durability of the attic roof structure depend on the correct calculation, based on this, in the absence of experience in design work of such complexity, it is better to use an online calculator. A special program will help you quickly and accurately calculate the main parameters of the roof in order to buy the right amount of building materials and make sure that the foundation is strong enough. The calculation of the attic roof includes the following indicators:
Converting an attic into a warm residential attic
Just add meters
Converting a non-residential attic into an attic is the easiest and most inexpensive way to expand the living space of your own house or cottage. Most individual houses have a pitched roof, the design of which allows you to quickly and at low cost get at your disposal a bright and spacious room.
From an economic point of view, there is no choice. If we talk about the cost of building materials and labor costs, the construction of an attic will cost less than the construction of an additional floor, regardless of the material of the walls and the number of storeys of the house.
Judge for yourself. The load-bearing wall, as a rule, consists of the main material (brick, concrete, timber, etc.), insulation and exterior finishing material. During the construction of the attic, the matter is limited to the truss structure, insulation and roofing material (interior decoration in both cases is a separate issue). And no matter how much the rafters and roofing cost, their price can not be taken into account when comparing, because even in a house with a non-residential cold attic, these items of expenditure cannot be dispensed with.
Attics can be located both in the alignment of the outer walls of the house, and go beyond their boundaries. With a slight extension of the attic floor, it is supported on the cantilevered extension of the floor lying below, and with a large extension, additional supports are created – columns, walls. From the point of view of architecture, the attic can have a triangular or broken silhouette, be symmetrical and asymmetrical, be located along the entire width of the building or only on one side of its longitudinal axis.
Attic rooms can have vertical walls or sloping – according to the configuration of the roof slopes. The second option is more unusual and brings a touch of romance to the living space. In this case, interior solutions will require a more careful approach: furniture will have to be made to order. But this disadvantage of a room with sloping walls is more than compensated by the beautiful view from the window to the rooftops, clouds and the sun.
Of course, the attic has its disadvantages
First of all, do not forget that the design of the attic itself implies the loss of usable space. Sloped ceilings reduce the height of the walls, therefore, there may be problems with the placement of furniture. In addition, with all the advantages of special roof windows, their cost is on average one and a half to two times higher than the prices of ordinary windows. In the summer, when the roofing under the direct rays of the sun can warm up to 100 ° C, it is not necessary to talk about the comfort of attic rooms without an air conditioning system.
Features of alteration of the attic
Of course, it is most advantageous to provide for the construction of the attic at the stage of choosing a house project. In addition to saving labor costs and building materials, in this case it will be much easier to carry out house communications inside – heating, plumbing, sewerage. But in practice, developers often do not follow this recommendation and leave the development of the attic for the future. If at the time of building a house, finances are running out, then this is a completely reasonable decision. In many cases, alteration of the attic does not require the dismantling of roof structures, and all work is carried out from the inside.
To build an attic, first check and, if necessary, reinforce the ceiling with wooden or metal beams so that they can support the weight of people and furniture in the attic. Of course, you will have to install a full staircase to facilitate access to the new living space. You also need to carefully insulate the roof slopes, perform interior decoration and lay the necessary communications. And, of course, provide ventilation and sufficient natural light by installing windows.
Heat under the roof slopes
Insulation of the future attic is a mandatory procedure that is definitely not worth saving. The attic loses heat more intensively than the lower floors, due to the large area of contact with the external environment. In winter, the roof practically does not retain heat, and in summer it does not protect at all from the heat. For insulation, it is better to choose non-combustible and vapor-permeable heat-insulating materials based on stone wool or glass wool. In order to avoid “cold bridges”, such plates are installed in a thrust between the rafters without cracks and gaps. Moreover, the thickness of such a heater for our climatic conditions should be at least 250 mm.
To prevent moisture from accumulating in the heat-insulating layer, a 2-5 cm thick ventilation gap must be provided between the insulation layer and the crate.
In this way, all layers of the roofing cake and wooden structures (rafters and lathing) will remain dry regardless of the weather. In addition, in order to protect the slab of heat-insulating material from getting wet in case of leaks of the roofing material, it must be closed from the side of the ventilated layer with a special waterproofing vapor-permeable membrane.
Structural elements of a residential attic
The attic floor is more susceptible to heat loss than the lower floors for the simple reason that there is no “thermal cushion” above it.
Thermal properties of the roof
It has a large total contact surface with the outside. Therefore, for reasons of comfort and economy, effective and thorough thermal insulation is necessary.
Heat-saving capacity of the attic
The moisture content of warm indoor air is higher than cold outdoor air, so the diffusion of water vapor both through the attic roof and through the outer walls of the building is directed from the room to the outside. The outer part of the roofing is a waterproofing layer that does not pass water vapor well and contributes to the formation of condensation moisture from the inside. The consequences will not be long in coming. Wet spots and mold will appear, the thermal insulation qualities of the insulation will deteriorate, and water droplets will begin to fall from the ceiling.
Given the negative effect of moisture on thermal insulation characteristics, the insulation must be protected with a layer of vapor barrier material, positioned from the side of the room. To remove moisture that for some reason got into the heat-insulating material, a ventilated air gap should be provided between the insulation and the waterproofing layer.
Very often, non-residential attic spaces are converted into residential attics, while maintaining the existing truss system. At the same time, in an effort to minimize the additional load on the supporting structures of the building, light, low-density insulation is usually used. Under the influence of wind, the insulation is blown through, accompanied by heat removal, therefore, in order to maintain the heat-shielding characteristics of the structure, a layer of windproof but vapor-permeable material is laid on the surface of the thermal insulation bordering on the ventilated layer.
Insulation of roof coverings
Structurally, the roof covering consists of a system of rafters installed at intervals of 600…1000 mm. The space between the rafters is filled with insulation. As an insulating material, it is recommended to use mineral wool slabs based on basalt fiber or fiberglass, which are laid in several layers. If the height of the section of the rafters is less than the required thickness of the insulating layer, horizontally arranged wooden antiseptic bars can be attached to the rafter legs. In this case, one layer of insulation is located between the rafters, and the other – between the horizontal bars.
When insulating the attic, remember that heat loss occurs not only through the coating, but also through the end wall. Therefore, the gable of the house also needs to be well insulated.
Ventilated air gap
The width of the air gap between the insulation and the roof depends on the profile of the coating material. When using tiles, metal tiles and other corrugated sheets, the thickness of the ventilated air gap must be at least 25 mm. When installing a roof made of flat sheets (galvanized steel, soft bituminous tiles, rolled materials), an air gap of at least 50 mm thick is required. Ventilation of the air layer is carried out through the holes in the eaves and ridge.
Insulation wind protection
On the side of the ventilated air gap, the thermal insulation material must be protected with a vapor-permeable membrane. The use of vapor-tight materials such as roofing material or polyethylene film in this capacity is unacceptable! It should be noted that membranes, which perfectly pass water vapor, do not, however, let water in the liquid phase, and therefore prevent the insulation from getting wet from moisture condensing on the inner surface of the roof.
When constructing a new house, the wind protection material is laid over the rafters and secured with wooden beams. When installing an attic in an existing attic, the windproof vapor-permeable material is fastened with slats to the existing rafters
Attic vapor barrier device
polyethylene film, roofing felt or foil vapor barrier material.
Lay the fabric overlapping and seal the seams with adhesive tape. The use of adhesive tape not only ensures the tightness of the seams, but also allows you to reduce the amount of overlap to 100 mm (both vertically and horizontally), regardless of the roof slope. The film is attached to rafters or bars with thin wooden slats. Foil materials are laid with foil towards the room, and it is desirable to leave a small gap between the vapor barrier and the inner lining. In this case, the shiny surface of the aluminum foil will reflect the heat radiation coming from the room to the outside, and reduce the amount of heat loss through the attic.
Attic finishing touches
The simplest and most common way to finish walls is to cover the space between the rafters with wooden clapboard, plasterboard sheets or wall panels. The rafters themselves are most often varnished, it is better to use antiseptic compounds. The floor of the attic is also best made of wood.
Drywall because it is durable and highly resistant to moisture. In addition, it allows you to arbitrarily model the surface of walls and ceilings. Its surface can be painted with water-based or oil paint or wallpapered, after applying a layer of putty.