Private developer’s ABC: Right calculations and quality assembling are essential for rainwater downpipe system

Private developer’s ABC: Right calculations and quality assembling are essential for rainwater downpipe system
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How to choose and what should be taken into account when assembling a rainwater downpipe system around your house?

A rainwater downpipe system is one of the most important components of a good house. It is a compulsory part of a roof structure. What systems are available on the market, what are their specific characteristics and what should be taken into account while choosing a rainwater downpipe system?

To start with let’s talk a little bit about the weather. Wherever you build a house it will protect you against wind and snow in the north, hot sunny rays in the south, and rain in the central part of Russia.

Rainwater might spoil the exterior finishing of a house, flood the cellar or damage the foundations. You may fail to notice contamination but, as they say, water finds its way, and you might notice dampness, fungi and other unfavorable phenomena. A rainwater downpipe system is designed to protect your house against such negative processes. 

A modern rainwater downpipe system guarantees the dry and neat look of a house and the land plot round it.

Two types of rainwater downpipe systems are currently available on the market — metallic and plastic ones.

Let’s consider the advantages and drawbacks of each of them.

Private developer’s ABC: Right calculations and quality assembling are essential for rainwater downpipe system


Metallic rainwater downpipe system

A metallic rainwater downpipe system ideally fits houses with metal roofing (metal tile sheet, profiled sheeting, etc.). Many householders choose it because metal is more reliable, strong and durable.

Every producer of metallic rainwater downpipe systems tries to improve the initial performances of the material. A polymeric protective layer, different admixtures, and unique methods of metal processing constitute the ways to prolong the durability of such systems up for to 50 years, protecting the material against corrosion, bleaching and variations in temperature.

Different sized rainwater downpipes are produced according to the pipes and channels’ cross section.  A small system (as a rule, 125*90 mm) is recommended for a low-rise construction and in regions without much annual precipitation. For a multi-storey building, a cottage for a large family or an industrial premises, a large rainwater downpipe system should be used (150*100 mm).

The advantages of a metallic rainwater downpipe are as follows:

 – protection against corrosion;

 – anti-bleaching and high temperature resistance;

 – anti-split and leakage protection;

 – contamination resistibility;

 – long service life.

Metallic systems have only two drawbacks, but they are rather significant.

The first one is their weight. Metal is heavy by nature, so assembling such a system might require reinforced brackets and special technology.

The other drawback is that a metallic rainwater downpipe system cannot be assembled well on technologically complicated roofs, where elaborate bypass structures are required.  The reason is that the assortment of metallic rainwater downpipe elements is rather restricted and only minimal accessories are available. 

If you choose a metallic system do not forget to buy a waterproof silicone joint sealant to properly fix all the coupling elements.

A premium-class metallic rainwater downpipe system is presented by a copper one. This is an exclusive material on the market. Copper elements of a downpipe system gain a luxurious appearance as time passes. Under precipitated water and sunrays its golden colour changes to dark-brown with a noble emerald green patina. It is the final stage of oxidisation, and later the downpipe will not change its colour. 

The peculiarities of a copper downpipe system are the same as of a common metallic one, but due to oxidisation  the durability is 10—15 years longer.


Plastic rainwater downpipe system

This is becoming more popular due to budget saving. Is the economy reasonable and are there any specialties in the use of PVC systems? 

One of the primary criteria while choosing plastic downpipes is the exclusion of any corrosion or oxidisation. Plastic does not react to water or dampness. This is an advantage when compared with metal.

Plastic rainwater downpipe systems are produced from a high quality polyvinyl chloride (PVC). The material is rather strong and at the same time flexible. That is why a PVC downpipe system is very convenient for non-standard roofing solutions and complex structures. A great number of accessories and non-standard precast components make plastic downpipes universal and fit for any roofing. They are also produced in several sizes. 

A plastic downpipe system will operate properly in any climatic zone of Russia, both in the south and in the north, because the basic compound for “casting” its downpipe elements contains different plasticisers and special admixtures, making the material resistible against any temperatures and UV-rays.

Private developer’s ABC: Right calculations and quality assembling are essential for rainwater downpipe system

The advantages of plastic rainwater downpipe systems are as follows:

– light weight;

– simple assembling and maintenance;

– resistibility against an aggressive environment and temperature drop;

– absence of corrosion;

– noise attenuation during rain or hail showers;

– resistibility to heavy snow and wind;

– opportunity to install a heating system against snow and ice hillock.


However, there are drawbacks as well. Thus, some elements of the system might crack due to heavy frosts. Additionally, the plastic might bleach over the course of time. The likelihood of material expansion due to day and night temperature drops must be taken into account during assembling. Lastly, there is another negative in that the structural elements of plastic downpipes cannot be repaired, and instead can only be replaced with new ones.

If you choose a plastic rainwater downpipe system for your house pay attention to the producers who make the system with rubber gaskets. It will give you an opportunity to change a damaged element easily.  Glued coupling makes a system one-piece and non-dismountable.

Anyway, when choosing a downpipe system consider their performances, price, annual precipitation in the region you live in and the capacity of the downpipe system.

Proper assembly and an accurate calculation of the material needed are also required because the reliability of the rainwater downpipe system depends on all these factors.