What is an internal drain, and what you need to know about it

An essential part of roofing systems are internal drains, which are made to effectively manage rainfall and guard against interior water damage. Internal drains are situated inside the roof structure itself, as opposed to external drains, which are found around the roof’s edge. Their main purpose is to gather rainwater that builds up on the roof’s surface and route it to a drainage system below via a network of pipes.

Maintaining the integrity of your roof requires that you have a thorough understanding of internal drains. These drains are made up of a sump, or drain basin, which is normally found at the roof’s lowest point. Water flows into this basin during rainy seasons and is collected there before being directed downward via vertical pipes called downspouts or leaders. The plumbing system of the building or an independent drainage network intended to remove water from the structure are connected to these pipes.

For internal drains to operate as intended, proper installation and upkeep are essential. Internal drains are strategically positioned; they are frequently found in regions where water naturally collects or where the slope of the roof directs water toward them. This positioning aids in preventing water from ponding or collecting on the roof, which may cause leaks, structural damage, or in severe circumstances, collapse.

To avoid clogs and blockages, internal drains must undergo routine cleaning and inspections. Over time, debris like leaves, twigs, and dirt can gather in the drain basin or pipes and impede the flow of water. Regular debris removal and cleaning ensures that water can pass through the system freely during rainfall, lowering the possibility of water damage and extending the roof’s lifespan.

"A vital part of roofing systems intended to effectively manage precipitation and avoid structural damage is an internal drain. Internal drains are concealed within the structure of the building, as opposed to external drains, which are visible on the surface of the roof. To guarantee appropriate drainage, stop leaks, and increase the roof’s lifespan, homeowners and building managers must be aware of their purpose and upkeep. This article discusses the fundamentals of internal drains, their significance for keeping a building dry and secure, and helpful hints for making sure they continue to work properly over time."

What is a system of internal drainage

The internal drain system is installed inside the structure and consists of risers, funnels, and ssnov. She gathers rainwater from the roof and directs it into the drainage system, stormwood, or sewer. Most contemporary homes and buildings with flat roofs, as well as those taller than ten meters, have internal drainage.

Why do you need an internal drainage

An additional source of internal leakage risk in the building is the internal drainage system. Furthermore, the issue at hand is not even the present roof; rather, it is a more significant one: leaks from the inner gutters have the potential to flood multiple storeys of the building simultaneously. Nonetheless, they take a significant and high risk. And all of this is due to the fact that installing an external drainage system on some buildings is theoretically impossible, and on others, doing so may have worse outcomes than having internal gutters flow.

These are the primary justifications for installing a drain inside the home:

  1. Safety of passers -by. The flow of water falling on a person from a height of 10 m is already at least painful. And if the height is 25 m? And if not a stream of water, but frozen snow or icicle? With a strong storm or during snow melting, water can easily shimmer through the groove of the external drainage and fall down, and the organization of the internal drainage excludes this.
  2. Foundation protection. Water pouring over the edge of the gutter is dangerous not only for passers -by, but also for the foundation of the house. Tons of water will be collected from the roof and fall on a narrow strip of earth along the walls, blurring the soil and weakening the foundation. The device of the internal drainage system directs all this water to the collectors of the sewage system or storm.
  3. Reducing the load on supporting structures. Very heavy rain is 30-40 liters of water per square meter, which fall in 1-1.5 hours. If the roof area is 500 m 2, then this is 15-20 tons of water, which must somehow be taken away. An external drain cannot cope with such a volume, which means that the water will stand in a huge puddle on the roof, creating a serious additional load on the supporting structures. The throughput of the internal gutters is multiple, and sometimes an order of magnitude larger.
  4. Defense against freezing of drainage. Ice traffic jams in the external drain is rather a rule than an exception in the northern and central regions of Russia. If the drain is inside the house, it is protected from freezing and effectively removes water at any temperature from the outside.
  5. EThe stitches of the building. Gutter and drain pipes change the silhouette of the house, often not for the better. In addition, if the drain is internal, the building does not need cornices. Consequently, the place of the roof transition to the walls can be arranged non -standard, for example, with rounding or, conversely, make it in the form of a stylish face.

Stated differently, there are sufficient benefits to internal gutters over external ones. They do, however, have a negative aspect.

The disadvantages of the internal drainage device

As we have already indicated, leaks can always occur in a building’s internal drains. As a result, during installation, careful consideration is given to the system’s sealing as well as its dependability, toughness, and load resistance. This causes a multitude of issues. When comparing the building’s internal and external drains, the internal drain is as follows:

  1. Significantly more expensive. Supporting risers, taps, funnels and accompanying elements of the system are expensive, even if they are made of light plastic, and not from steel or, moreover, cast iron.
  2. It is more difficult to maintain. In a closed system, blockages arise much more often than in open, and to find blockage and eliminate it, you need special equipment.
  3. It is more difficult to design and installation. It is very simple to calculate and make an external drain: usually its calculation is performed by the dealer manager for free, but even if there is no such service, the manufacturer"s instructions are simple and understandable. Calculating the internal drain, its elements and a device are many times more difficult – this is only work for an experienced designer. The same fundamental difference in the approach to the installation of the system: in one case it is hung on the building, in the other – part of the building.

Due to these factors, internal drains are rarely completed when external drains can. That is, on houses with pitched roofs that are one or two stories tall.

Two types of internal drainage

There are two types of internal drains based on how they work: gravity and siphon-vacuum.

In summary, the only benefit is that internal drainage is less expensive. He uses a standard funnel to remove water from the roof, which suctions up to 70–80% of the air along with the water. When there is a lot of rain, the air slows down the water flow in the system, especially when pipes are being removed, and this can cause air traffic congestion.

As a result, the drainage system’s capacity decreases and does so in an unpredictable manner. For example, a system that functions flawlessly during a strong downpour may overflow and create puddles on the roof during a subsequent, less intense downpour. This makes the drainage system’s computation extremely difficult.

The greater the area of the roof, the more challenging it is and the greater the chance that the gravity system will malfunction. Thus, small buildings with a straightforward flat roof devoid of height drops are typically the ones with this type of drainage.

Although siphon and vacuum drainage is more costly, it works far better. The inner gutters’ funnel device is the primary feature that sets these systems apart. Funnels with stream stabilizers are used with siphon and vacuum systems to lessen air fall.

There are three modes of operation for each input component of the vacuum drainage system and siphon:

  1. Through the bottom of the funnels, the water around them is sucked into the drainage system.
  2. In the upper part of the pipe, a water column is rapidly formed, the height of which depends on the intensity of precipitation.
  3. Under the influence of gravity, the pillar falls down the drain, creating a discharge (a zone of reduced pressure) near the funnel, which is why water begins to be sucked into it with increased force.

Since this cycle repeats itself repeatedly, areas filled with water and air alternate during periods of light to medium rain. However, since the water’s speed in such a drain is much faster than gravity’s, air traffic jams do not happen.

When there is a lot of precipitation, water fills the internal drain all the way from the funnel to the plum. As a result of the large mass that forms in the water column, it flows very quickly, clearing the pipes of debris, foreign objects, and other possible obstructions while also enabling you to remove more water from the roof in a shorter amount of time. In other words, the gutrum system will function more effectively the more precipitation there is.

This feature means that fewer entry points are required for the Siphon and Wakuum system to function normally than a gravity. It is sometimes possible to cut the number of funnels in half. As a result, the affordability of gravity internal drainage is subject to certain limitations based on the particular building. In certain homes, the arrangement of an internal drain using a vacuum and siphon type may prove to be even more advantageous than the gravity system device.

Plastic, steel, or maybe copper?

The building’s drain was previously composed of asbestos, cast iron, steel, or copper pipes. Cast iron pipes are too heavy to be used, and asbestos pipes are too complicated to seal. However, various kinds of plastic emerged as new materials for drains.

Five types of plastic drains

Five different types of plastic are used to make internal drain pipes:

  • polyethylene;
  • polypropylene;
  • polybutilene;
  • PVC;
  • fiberglass.

Low-pressure polyethylene (also known as high-density polyethylene, or PND) is used in the production of premium pipes for internal drains rather than regular polyethylene. These pipes are simple to use and long-lasting, with a roughly 50-year service life. Gutter installation is made easier by the PND’s elasticity and multitude of connection options. They are also incredibly dependable because the low-pressure polyethylene pipe weld is stronger than the pipe itself. Additional PND gutters are impervious to strong chemicals such as acids, alkalis, salts, and solutions containing oil products.

The high cost, vulnerability to UV rays, and poor mechanical strength of PND pipes are some of their drawbacks. In addition, they become brittle when it gets very cold. This means that in order to prevent hypothermia and funnel destruction in the northern regions, a PND drain must be fitted with an anti-icing system.

Polypropylene pipes are marginally less expensive than plastic for internal drains. They are also stronger, more rigid, and less prone to wear, but because of their high thermal expansion coefficient, their gutrum system is less resilient to temperature changes. The service life and other characteristics of polypropylene and polyethylene gutters are comparable.

PVC drains inside Their affordability, resilience to heat, cold, and fire, and strong resistance to ultraviolet light are what initially drew people to them. However, while this material can withstand loads, it is not as strong as polypropylene or polyethylene and is more brittle.

Polybulene conduits They share many characteristics with PND pipes, including being strong, flexible, and heat-resistant. However, in contrast to polyethylene, polybutine is more UV resistant, can withstand temperature fluctuations, exhibits significantly less "creep," and retains heat even better. Polybulane pipes are widely used in drainage systems throughout Europe, particularly the UK, but their use is still relatively low in Russia due to their high cost and relative "youth."

Rare are fiberglass internal drains. They are only employed in situations where the pipes’ exceptional strength and ability to withstand axial loads are crucial.

Fiberglass’s properties are generally not worse than those of PND or polybulene pipes, but its highly variable nature stems from its strict adherence to production technology. As a result, a manufacturer’s pipe can function peacefully for decades, but a similar drain made of fiberglass from a different brand may crack and start to malfunction after five to seven years.

Steel internal gutters

Steel is a common drainage material. Steel pipes are inexpensive, strong, resistant to heat, and do not burn easily.

However, steel internal gutters are becoming less and less effective. Steel is not as smooth as any kind of plastic and is prone to corrosion, so steel gutters get clogged more frequently. Their walls also gradually grow over time, which causes the pipe’s lumen to narrow. All of this shortens the steel drainage systems’ service life; typically, repairs are required 15 to 20 years after installation.

The compounds’ tightness is yet another major issue. Steel gutters leak more frequently than plastic ones. Specialized equipment is used to weld plastic pipes, thereby virtually eliminating error. Furthermore, the installer’s skill level and attention to detail have a significant impact on the quality of the steel pipe welding.

Moreover, steel gutters have a number of minor but still annoying issues, such as low resistance to hydraulic producers and noise.

As a result, the steel internal drain device is an affordable choice that is primarily appropriate for quickly vested structures with a short service life. Steel drainage is not the ideal option if the building is capital. The cost of upkeep and the requirement for sporadic repairs offset the cost savings.

Copper drains

Copper is the ideal material for pipes, whether they are for drainage, water supply, or heating.

Because a layer of blue-green copper oxide called a patina forms on them during the first 10-15 years of their existence, copper drains have a service life of 100–150 years. The metal is shielded from further deterioration by this patina. Because copper is a malleable metal, it is a strong, dependable, chemically persistent, and relatively easy to seal.

Copper pipes are also exquisitely beautiful. Copper drains can blend in naturally with the interior if the risers of drainage systems made of other materials must be concealed to preserve the interior’s aesthetics. Additionally, as they were just installed, they were already covered in a green patina and still had their distinctive golden color.

Let’s talk about the shortcomings now. Fasteners cannot be used to mount copper because it is prone to electrochemical corrosion, which separates copper from other metals. Copper pipes get clogged more frequently than plastic ones, much like steel gutters. However, these are all minor details set against the backdrop of the primary concern, which is the cost. Due to their extreme cost, copper drains are mostly found in luxury and commercial residential buildings. They can occasionally be discovered in posh office buildings.

The device of the internal drain

Internal gutters and their mechanism are essentially the same regardless of the material and type.

There are always four components to the internal drainage system installed in a building:

  1. Water collection funnels. Their task is to remove water from the served area of ​​the roof as effectively as possible, while not missing garbage. Funnels can be flat and caps, one- and two-stage, with a diameter of 75 mm to 160 mm, with various additional options: from stabilization of the stream for siphon and vacuum systems to built-in heating. The choice of a particular model depends on the calculated parameters of the drainage system and the type of roof.
  2. Diting pipes. These are areas of the drainage system, according to which water from the roof enters the drainage riser, and then into the sewer or storm. Division is a vulnerable part of the drainage system, since it often includes not only even segments, but also the knees that turn the flow under 45 ° or 90 °. It is in these areas that clogs most often appear.
  3. Riser. The drain pipe, which is laid over the entire height of the building and is located strictly vertically. It is very simple in installation, and in gravity systems is protected from leaks, even if there are small flash flaws.
  4. Lukes-revisions. These are pipes with a small round door, which are made approximately every 15 m riser. They are needed to examine and maintain drainage systems.

The internal drain is also made up of fasteners, such as hooks, clamps, brackets, and metizes.

Furthermore, the building’s roof may be regarded as a component of the internal drainage system. Water runs off the flat plane of a pitched roof and into the gutters. The same result is obtained on a flat roof with an external drainage system because of a slight tilt in the roof. However, this approach is ineffective when there is a drain inside the home. In this instance, how is the internal drain structured? Create a channel system and discount to accomplish this.

Each funnel is designed for the drainage system with the knowledge that it will collect water from 15 to 20 m 2 of surface area. Since a flat roof would not allow for this, the funnel is surrounded by a small circular slope where the water drains to it. Because of this, the roof appears to be made up of large, gentle dents, with a water collection in the middle of each one.

It functions properly when there is a consistent water load on the slop’s roof. However, if the load is uneven for any reason, it also causes issues.

For instance, a powerful wind may carry the majority of the water to one of the roof’s sides. In this instance, puddles will remain in the zones from the leeward side of the roof for an extended period of time, while a portion of the zones with funnels from the windward side will dry out quickly. In other words, the drainage system will function, if not optimally. Usually, a discourse is conducted using the channel system to address this issue.

All zones are connected into a single network by channels, which are pipes or a gutter. Through the channels, water from more loaded zones flows into less loaded zones, distributing the water evenly throughout the roof, thereby balancing the load on the water system. This helps the drainage system function more efficiently and enables you to make up for any malfunctions. Therefore, water from the problematic area just leaks into the adjacent area if there is a blockage in one of the diverting pipes or if the funnel itself becomes clogged.

Features of the installation of internal drains

Like any other intricate engineering system, the internal drainage device’s operation cannot be summed up in two words. This is covered in a different article. However, there are a few crucial elements and guidelines that are unstateable:

  1. The calculation of the internal drain must be done at the stage of designing the building. You can create such a drainage system in a finished house, but it is like mounting a sewer in a building in which it has never been: it is very difficult and expensive.
  2. The internal drain in a private house with a pitched roof is usually laid in the wall or between the wall and the skin. This means that for such a drainage system, only pre -insulated plastic pipes can be used, otherwise the drain can freeze.
  3. Although in the rules the minimum distance between the water column and walls is 1 m, they need to be mounted as close to the center of the roof. The fact is that flat roofs are often fenced with parapets, and this is a pocket for snow. Therefore, the closer to the edge of the roof, the higher the likelihood that the water combat funnel will be regularly filled with snow.
  4. The internal drain must be equipped with an anti -icing system. At least about funnels. This will not allow many problems that previously solved with the help of expensive design solutions and permanent maintenance of the drainage system in winter.
  5. Each level of a multi -level roof, especially with a height drop of more than 4 m, should be supplied with its drainage system.
  6. When installing an internal drain, you should always give preference to aintrous, better welded joints. The price of the leakage is much larger than the possible benefit from the convenience of maintaining the system with detachable connections.
  7. The risers and diving pipes of the internal drain should be either in the heated parts of the building or are equipped with heating cables.
  8. Near funnels, even in the rain of medium intensity, a puddle will form. Therefore, multi-level sealing of a funnel with a layering of 2-3 layers of waterproofing material and the use of sealant is justified.

These regulations are always applicable, and breaking them results in significant extra expenses. even in the event that you create an interior garage drain.

Internal Drain An internal drain is a drainage system installed within a building structure, typically used to channel water away from the roof towards a designated drainage point inside the building.
Key Points to Know 1. **Purpose**: Prevents water accumulation on the roof. 2. **Components**: Includes pipes, grates, and a drainage outlet. 3. **Maintenance**: Regular cleaning to avoid clogging is essential. 4. **Installation**: Best done during initial construction or major renovations.

One essential part of a roofing system intended to efficiently manage rainwater is an internal drain. Internal drains are hidden inside the building and typically connect to a system of pipes that direct water away from the structure, in contrast to external drains, which are visible on the surface of the roof. This configuration not only makes the roof look better, but it also makes sure that water drains off the roof effectively.

Homeowners and building managers need to know how internal drains function. Rainwater pooling on the roof can be avoided with proper maintenance and recurring inspections. Blockages brought on by debris or structural problems can also be avoided. Frequent inspections can help detect possible issues early on, enabling prompt repairs and reducing the chance that the roof and interior spaces will sustain water damage.

Seeking advice from qualified experts is essential when building or remodeling a roof that has an internal drainage system. Based on variables like roof size, slope, and local climate, they can suggest the best drain design. Longevity and efficiency also depend on the materials used for the pipes and drains.

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Alexander Sorokin

The owner of the roofing company, an expert in the roofing markets. I'll tell you about the novelties of the roofing industry and help you choose the best option for your home.

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