A balcony can add more elegance to the overall exterior aesthetics of your homes. Balconies are great venues for family and friends gathering, weekend barbeques, relaxing, enjoying the views, and watching the world go by.
If you are considering adding a balcony structure at home, do you already have a design ready? Or do you know what balcony decking design is suitable for your home?
Below are the different types of balconies that will help you come up with the balcony structure that will work best for your home.
As recent news stories reveal, wood rotting and structural failures of balconies and decks can have costly consequences. The structural design and construction of decks and balconies, including their guardrails (or handrails), are critical for the safe performance of these structures and to avoid structural failure.
Check out Hitch Property Constructions for a wide range of balcony repairs.
Decks vs. Balconies
A major cause of balcony failure is connected to the “live loads” – or how much weight is being held by the balcony at one time. Loading criteria for balconies and decks changed between the 2006 International Building Code (IBC) and the 2009 IBC. The 2006 IBC prescribed different live loads for balconies than for decks.
Balconies are defined by the 2006 IBC as an exterior floor projecting from and supported by a structure without additional independent supports. In other words, a floor projection that cantilevers out from an exterior wall. A deck is defined as an exterior floor supported on at least two opposing sides by an adjacent structure or posts, piers or other independent supports. The 2009 IBC does not differentiate live loads between decks and balconies and does not provide definitions for either.
Most single-family homes and multi-family residential structures have decks, not balconies, as defined by the 2006 IBC.
A Self Supporting Balcony System is the Safest Balcony System
Self-supporting balcony systems, or bolt-on balconies, are the safest balcony systems over wooden cantilever balconies. The reason self-supporting balcony systems are safer is exemplified by the Berkeley, CA cantilever balcony tragedy. The tragedy demonstrates how hidden wood cantilever joists hide dangerous structural rotting conditions, whereas self-supporting balcony systems have visible building connections to maintain life safety.
The recent tragedy of the wood balcony system in Berkeley, CA, raises awareness for the potentially catastrophic failure of wooden cantilever balconies. The engineers who inspected the site said there were clear signs the wood beams supporting the deck had rotted due to water exposure.
Visual Inspections are Important for Balcony Safety
Anyone can do a basic visual inspection for ensured and continual safety of a bolt-on balcony. The most difficult challenge of a cantilevered balcony is maintaining a tight weather joint where the joists pass through the wall. Joists will move with changes in moisture and temperature, as the result of expansion and contraction. The result is unseen rot and water damage, with a great safety risk. Caulk is often the weather sealant from water damage, and caulk wears quickly in outdoor elements. The repair of an unsafe wooden balcony often requires: rebuild, repair to the inside joists, drywall removal, and interior fixes. These fixes can be lengthy and costly.
A Safer Balcony Option
Bolt-on balconies are self-supporting to the building, which make them a safer balcony choice. No joists exist behind the interior structure. Installation is two to three times faster than a wooden cantilever balcony (if prefabricated and shipped complete by Midwest Stairs & Iron.) Longevity is enhanced with secure connections, aluminium metal construction, and powder coating. Typically, a bolt-on balcony is made out of aluminium or steel, with options of glass railing, acrylic railing, cable railing, etc. The steel or aluminium can be powder coated with a wide spectrum of colours. Aluminium balconies are growing fast in popularity for their durability and enhanced resistance to the weather elements. One of the best things about bolt-on balconies is the ability to easily remove and reinstall whether you want a new colour, new style, or for some reason someone took a sledgehammer and did some damage. Tenants like visual safety and aesthetics. Architects like the vast design possibilities. Property developers like the cost value and life safety enhancement.
How to test your current wooden balcony for safety?
Call an expert. An expert will inspect methods that may include using a ladder to examine the exterior and interior wood cantilevered joists. The typical safety test uses a screwdriver or awl to probe the joists, look for gaps, and to punch a small hole for a rot check. The inside of the building may show signs of water damage, such as a bump in the floor. A weak frame is a life safety hazard and is a constant problem in traditional wooden cantilever construction at low-rise apartments and condominium complexes.
The Different Types Of Balcony Structures
This type of balcony structure is made of stainless steel cables that are fixed on the edges of the balcony. The large plate is connected to the building at a 45-degree angle.
It is as simple as fixing the steel cables on the walls, attach to the plate, and hang the balcony. The method works by using the bolt strength at the wall 50% shear, and 50% pull out forces. The design is minimalist and is not commonly used.
Balconies on pillars are the most common and popular balcony decking design due to its simplicity. Apart from that, these stacked balconies only have a minimal load on the building or structure. Stacked balconies are not connected to the building; it is, in fact, a separate structure to the building.
Stacked balconies are supported using vertical posts or pillars. Concrete pads are erected on the ground, where the weight of the stacked balconies is transferred from these vertical posts or pillars.
Some balconies on pillars or stacked balconies are made of aluminium materials that give a smooth and uniform appearance on buildings or apartments.
Stacked balconies are commonly used in apartment and residential buildings due to its unified appearance, simplicity of structure, and ease of implementation.
Cantilever or projecting balconies
Cantilever balconies are platforms added to a building in a manner that the balcony is projected from the face of the building without any visible support. The weight of the balcony decking is support by cantilevering the structure off the wall.
Cantilever balconies are pre-designed and cannot be added on existing building or structure as projecting balconies demand larger point loads on the building where these are going to be attached to.
Traditional cantilever balconies are made of steel or concrete. But modern designs innovative materials and ways to have these projecting balconies add more aesthetic results.
Projecting balconies are usually made to 1500-1800mm depth. Although this type of balcony structure has the most artistic result, users sometimes complain about the movement that they experience when they step out on this platform.
Cantilevered balconies tend to bounce due to its depth. The smaller the depth, the less bounce you can expect.
Balcony decking needs several considerations to achieve the best and appropriate design. These considerations include the material, colour, government, and local code requirements, who is going to use it, and how it would complement the building in the end.
As these considerations affect the final design of your balcony installation project, it is best to consult a professional balcony contractor.
Looking for balcony repairs Melbourne? Look no further. Hitch Property Constructions has you covered.
Site manufactured reinforced concrete balconies and hanging corridors.
At the end of the XIXth. And at the beginning of the XXth. Centuries, the appearance of (in the beginning almost exclusively site manufactured) reinforced concrete structures, brought about a revolutionary and lasting change in our architecture.
At first, the utilization of the new material was the imitation of traditional forms and structural dispositions. In the case of balconies, this meant horizontal slabs set on consoles. The consoles (which were previously affixed only thru weigh-down now) could now be connected with steel bars laid into the reinforced concrete to the structure of the pillar or the beam using the possibilities allowed by the monolithic technology. Only in later times did the cantilevered, reinforced concrete slab solution become widely popular and abundant.
Early reinforced concrete structures were generally well constructed. Faults and damages are mostly caused by dampness entering the hairline cracks of the concrete and corroding the steel. Corrosion, in turn, will cause volume expansion which breaks off the concrete’s surface. Fortunately, in the case of consoles, the real load-bearing tension-steel elements are located at the top, under the slab and are therefore less exposed to the described damages.
In the case of prefabricated reinforced concrete beam slab types abundant after the end of the second world war (typical examples are: soft steel ÉTI beams with brick and concrete tray inlays, later: tensioned beams with concrete or ceramic block inlays) the consoled balconies (and the consequently less abundantly built hanging corridors) were made of monolithic concrete slabs. The steel of reinforced concrete balconies with a small outcrop was more than often connected only to the ring beam (which causes a torsion load), or were led into the overlaying concrete of the slab (if there was such). The steel was in better cases anchored down behind a slab beam, or as a less frequent solution, in a reinforcement bar, running across the beams.
These solutions (especially when the slab is only connected to the ring beam) in many occasions (in family homes, or small apartment buildings) were made without or regardless of the construction plans, inconsiderate to the rules and regulations of the time and as a result with inadequate load-bearing capacity. This poses danger which is especially difficult to judge during renewal or reconstruction work (in these cases, we may only be certain of the applied solution thru exploration of instrumental investigation). The professional solution – the internal, slab high, reinforced concrete cantilever slab section in the prefabricated slab – was rarely used, since this solution (would have) required thoughtful design and (prefabricated slab based) relative intricate fabrication work. A relatively frequent solution was the outcropping consoled site-fabricated beam that was weighed down by the load-bearing wall above, because this did not interfere with the prefabricated slab sections of the building. In these cases, the balcony slab was resting either directly on the consoled beams or an edge beam in between the consoled beams and the ring beam of the building itself. From a statical point of view, the latter described two balcony solutions are usually adequately, or even more than adequately safe.
The thermal bridge effects of site manufactured reinforced concrete balconies were not, or only sporadically considered until the 1990s. The new tendencies were slow to enter the design practice but were even slower to enter the construction field. Thermal bridge gap utilization became usual only at the turn of the millennium. However, even their use was sometimes inconsequential. A total absence of thermal bridges became a practical requirement only in the latest years.
Prefabricated reinforced concrete balconies and hanging corridors
Prefabricated reinforced concrete elements in the structural group under investigation were never typical. However, there were some trials. In the early period (the beginning decades of the XXth. century) we may mention prefabricated reinforced concrete console elements that were intended to replace the stone consoles in a manner that was identical in use (e.g. inner slab beams as consoles) István Medgyaszay was the designer. In more recent times, we may mention some console ready slab beam or slab plank solutions (e.g. Fk-beams, Ytong, DE planks etc.) or the pre-fabrication used in the panel structures (loggia elements).
Pillar supported structures (loggias, circular corridors)
For the sake of complete coverage, we need to say a few words about pillar supported structures (upper floor terraces, multi-story loggias, circular corridors) which are commonly –and mistakenly – also called balconies or hanging corridors. These may also be made of wood, stone, cast iron, steel, reinforced concrete, or a mixture of materials. On the basis of the various materials and structural components, we may state about the same as before in the case of the previously detailed consoled structures, aside from evident differences inherent to the different statics play. The most important difference is that the more advantageous (dual or multiple support) statics models have greater stability reserve, which results with damages causing less frequently life-threatening situations.
Iconic examples of the group are (brick or stone) pillar resting beam-, or laid vault supported multi-story loggias, slender cast-iron pillar supported circular courtyard corridors which may be observed in several representative XIXth. And early XXth. Century buildings.
An evaluation concerning the adequacy for requirements:
As discussed above, historical (approx. between 1850 and 1990 built) structures that satisfy the rules and regulations of the time at which they were built are – if not according to today’s standards, but on the basis of experience based on use – generally considered safe for use (until the appearance of structural damage). Chances for sudden deterioration is mostly to be expected as the breaking of the stone supports (or sometimes of the stone slabs) or as the braking of slag-concrete slabs.
Although at the time of their building, thermo-dynamical considerations were not important in any of the cases above, the level of thermal bridge effects is by far not the same for all situations: stone consoles laid into the wall pose a relatively small spot-like thermal bridge effect (at least until the wall is insulated). In contrast, the monolithic reinforced concrete slab console is a drastic heat loss effect thermal bridge source.
From an acoustic standpoint, we may also state that the spot-like wall connection of the consoled solutions is better, as, in these situations, only the consoles themselves transmit structure-borne noise.
Waterproofing insulation against precipitation was not fabricated in the vast majority of cases until the most recent times. An adequately inclined layer of frost-proof stone slabs or a surface finish that may be considered as homogeneous (e.g. artificial stone) are much better from this aspect than tiles laid in mortar as in the latter case water infiltration, and consequential damages are usually only a question of time. It is also important, how the outer edge of the balcony or hanging corridor is made, whether there is a drip edge and whether the water is appropriately led off from the edge. In the absence of a drip edge, the water that reaches the bottom line will not drop freely, but rather will flow back towards the interior, deteriorating the plastering. The most dangerous – from this later aspect – are the U profiled steel edge beam constructions of hanging corridors. Here, in most cases, water will easily reach and infiltrate to under the upper segment of the U beam at the edge of the tiling, causing extensive damage.
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What are the critical components for long term performance of decks and balconies?
Support columns need to be designed for the maximum load expected and the unsupported height of the column. Notching of columns as is sometimes done at beam or girder connections, need to be properly designed, detailed and constructed to provide safe support for decks.
Ledgers, the members attached to the exterior walls which the deck’s joists are connected to, are critical components to a deck’s performance. Ledgers are typically lag bolted to the exterior walls. The allowable loads for lag bolts are quite low and, for typical deck sizes, require multiple lag bolts for each joist. Deck joists are typically supported from the ledger boards with metal joist hangers which have high allowable loads and are rarely a problem as long as they are installed per manufacturer’s instructions. Ledgers also create other problems for the support of decks. Ledgers create openings within the exterior walls where water can penetrate to the interior of the walls causing deterioration of the wall components. Proper flashing and water management details are critical for the long term performance of decks.
Guardrails are required to safely support a 200 hundred pound load, acting in any direction, at any point along the top of the guardrail or a 50 pound per foot load, acting in any direction, along the top of the guardrail. These loads must be safely transferred through the supports of the structure. The connection of the handrail posts is a critical component of guardrails. Guardrails are required by code to be 42 inches above the deck surface. This height, combined with the required 200-pound load creates a large bending force at the base of handrail posts. Handrail posts bolted to the joists typically do not have the design strength to resist these loads without additional blocking or straps to secure the posts.
Decks and balconies are an attractive and well-used feature in residential structures. However, they can be deadly if their design, construction, and maintenance are not carefully considered. By their very nature, they are exposed to the damaging effects of weather and typically interrupt the structure’s weather-resistant cladding at their connections to the structure. Homeowners and condominiums boards should be aware of these potential dangers and institute inspection and maintenance programs for decks and balconies.