In the UK, there are five broad categories of single-ply roofing:
1) Poly-isobutylene (PIB)
This polymer was invented by chemists working for the BASF chemical company in 1931. Thus, PIB is the oldest single-ply roofing material in the world and is often regarded as a benchmark material for single-ply applications. One major advantage of PIB is that it has attained the standards ISO14040 as determined by the international standard organisation (ISO). It means that PIB has no major environmental impact and it is 100% recyclable. In addition, PIB is highly impermeable, durable and will withstand chemical corrosion and long periods of inclement weather. An added bonus is that PIB sheets are flexible and are relatively easy to install.
2) Thermoplastic Polyolefin (TPO)
These polymers were developed in the 1980’s and are in some respects more environmentally sound than PVC. The initials TPO cover any material that contains a synthetic polymer and filler such as fibreglass which strengthens the entire structure. TPO is used in a range of civil engineering applications including lining for artificial ponds and for waterproofing tunnels. The material is tough strong and durable with a wide range of applications but is only partially recyclable. TPO is only available in grey and can only be installed by heat welding. In addition the welding can only occur if the sheets are kept very clean. In turn they can only be kept in such a condition by regular washing with solvents, which of course undermines their environmental credentials.
3) Thermoplastic Poly-olefin Elastomer (TPE)
In effect TPE is the improved version of TPO and as such is the preferred of the two substances. It is completely recyclable and can be installed without welding meaning that the need for specialist (and more expensive) contractors is reduced. TPE is easier to clean and maintain and can be repaired by gentle heating of minor damage, whereas both TPO and PVC would require patching.
4) Poly Vinyl Chloride (PVC)
PVC is the third most used synthetic polymer in the world and is by far the most utilised single-ply roofing material in the UK. PVC is available in a very wide range of colours and styles and is easily installed and welded. Furthermore, PVC contains plasticisers and chlorine and if combusted will produce dioxins, which are highly toxic to both humans and animals. It also important to be aware, that PVC cannot be laid over substances such as bitumen without an isolating and / or waterproofing layer.
5) Ethylene Propylene Di-ene Monomer (EPDM)
EPDM is a semi-elastic synthetic rubber material which is very common in residential roofing applications. It is often made to measure and the joining, welding and attachment points are assessed off site. When brought on site the material is further sealed and treated to the requirements of the premises. Overall, EPDM is inexpensive but only available in black and must be treated to meet requisite standards of fire safety.
Clearly, it is essential to consult with professional contractors before deciding on the correct materials for any premises.
As human beings, we have been aware of static electricity for hundreds of years. This form electricity is a transfer of electrons (sub-atomic particles which carry electrical charge) as a result of friction. For example, if you rub a balloon on your clothing it will “stick” to a wall. Secondly if you rub a glass rod on your clothing and hold it next to a gentle stream of water from a tap the water stream will be pulled toward the rod. The early and neolithic humans were doubtless aware of electricity in the form of lightning.
The Battery and electric lighting
The technical term for a battery is an electrochemical cell and their invention is credited to the Italian scientist Alessandro Volta. He demonstrated that electricity could be harnessed by demonstrating that it could be made to flow through a conducting wire. The wire glowed further indicating that electrical energy could be transferred into light energy. By the middle of the 18th century the first circuits using electricity derived from electrodes standing in water had been developed.
The first practical application of using circuits to transmit electricity was electric lighting. Concurrently, this was made possible by the invention of the first functioning incandescent light bulbs by Thomas Edison. Many other inventors and scientists were aware of the concept but on October 22nd 1879 the first functioning bulb remained functioning for 14 hours.
Battery powered circuits
The early circuits were powered by batteries which produced a steady and constant flow of current from negative to positive terminals. This direct current (DC) always flows in the negative positive direction; the issue was that the electricity could not be transported over long distances. In fact for these early circuits any area exceeding about a square mile would present problems.
To the Engineers, scientists and proto-electricians of the time, the potential was obvious, but they could not overcome the distance issue. A Serbian engineer known as Nikola Tesla developed and applied the notion of an alternating current (AC). This current, as the name suggests, constantly changes and can be made to change direction and it changed everything.
How alternating current changed everything
If the electrical current is alternating the voltage level in a given circuit can be changed by a device known as transformer. The flow of electrical current always produces a magnetic field and so in a DC circuit the field does not change but in an AC circuit the field oscillates in tandem with the current.
Transformers work by a physical science principle known as magnetic induction, which can only occur in an AC circuit. In essence Nikola Tesla invented a method by which the voltage magnitude of a circuit can be increased enabling long distance transmission of electricity. Quite literally, the rest as the colloquium goes, is history.
The above introduction shows, that there are many devices which can cause an electrical discharge, but electricity as a form of energy is useless to us, without circuits.
Part of the process of deciding which system is suitable for your premises involves gaining an understanding the different types of available materials. Put simply, it is impossible to arrive at an informed decision if the relative merits of cost, sustainability, reliability and useful lifespan are not assessed. In addition the range of available styles and brands ensures that choosing the correct materials is no small undertaking.
Overall, a single-ply roof is composed of a synthetic (derived from crude oil) polymer which is applied to the roof in a single layer. The material is usually supplied in large rolls and applied in sheets which may (or may not) contain a reinforced layer. The layers are connected together by heat sealing or by fixing and ballasting. In addition, whilst there is no such thing as completely environment-friendly roofing system massive strides have been made in the materials technology. The roofing sheets contain no heavy metals and aside from PVC contain no halogens (Chlorine is halogen) or plasticisers
All single-ply roofing materials have been developed to cope with the most extreme conditions they can expect to encounter within their design remit. In effect this means extremes of temperature and impact, in certain applications “durability” will also cover corrosion by industrial chemicals.
The roofing materials themselves have a very high tensile strength, the strongest materials can withstand 1200N (Newton’s)/mm2, making them as durable as the best titanium alloys. In roofing systems which require welding of the seams between the polymer sheets both durability and water proofing properties are enhanced.
A cost effective Investment
Once the correct choice of materials has been made there are specific techniques which enable the sheets to be installed rapidly and efficiently, thus reducing labour costs.
Additionally, disruption of the day-to-day running of the premises will be minimised which offers clear advantages when it comes to necessary refurbishment and maintenance work. Finally, the roofs are designed to last for decades and so are generally installed to last at least as long as the useful life of the premises itself.
Fire and Safety
When the roofing systems which require heat sealing a hot stream of air is used instead of an acetylene flame, thus making the installation process itself intrinsically safer. Furthermore, legal statutes exist to ensure that the roof work itself is resistant to combustion and melting in the event of a fire. With this in mind, the roofing materials manufactured in the UK have the appropriate fire safety ratings.
The sheets are generally designed to be attached to the roof of the building. This in combination with effective sealing or fastening of the sheets to each other effectively removes the possibility that the roof will be lifted off should storms or other extreme weather events occur.
The advantages of single-ply roofing lie in the swift and safe installation of the materials and with the added benefits outlined above the popularity of such systems will continue to increase.
Irrespective of the circumstances the complexities of choosing the correct roofing material can be broken down ad expressed as the optimum balance of design, requirements, longevity, sustainability as well as cost.
Environmental impact and sustainability
Of the five main materials PVC is widely acknowledge to be the most long lived and durable. At time of writing over 80% of all the single ply roofing material in the UK is PVC based, which says much about its utility. However, it is considered the least environmentally sound because of the presence of chlorine and other substances. Conversely, if it were substituted properly many of its components can be recycled and converted to other applications in alternative single ply roofing systems.
A substance known as EPDM which is the mainstay of domestic roofing systems cannot be recycled and can only be reused if it is originally set down in mechanically fixed loose layers. Having a roof constructed in this way would clearly defeat the whole point of the exercise. A polymer known as TPO is as durable as PVC but does not contain chlorine or plasticising substances and can be itself recycled and made from recycled materials.
However, it can only be installed after cleaning with solvents. This last factor brought forward the necessity for the alternative TPE. From an environmental point of view PIB with its ISO 14040 standard is the most environmentally sound single-ply roofing material.
Cost of materials
Clearly, there is a strong element of completion and an onus on the end user to play the market and secure for themselves the best possible deal. It must be remembered that although cost is “a” factor it is rarely “the” factor, the performance of the materials of which the roofing sheet is made will often over ride pure cost considerations. In General Terms EPDM is likely to be the cheapest material and PIB the most expensive, with PVC, TPO and TPE situated somewhere in the middle.
Longevity of materials
The quality of materials is always evolving, such that new products are always coming on stream and innovations to existing materials continually present themselves. Overall, PIB will last for between 30 and 50 years, which partly explain its cost. The useful life of PVC sheet depends on its chemical composition but a quality product will last for between 25 and 45 years.
The relatively recent TPO and TPE will last for a minimum of 40 years but as with PVC the potential costs in sound reusing and recycling methods must be factored in to the decision to use them. Furthermore, the actual projected lifespan of the building its self and whether or not the roofing project is a new build or refurbishment must be considered. Finally, the end user is advised to check the credentials of both the product and the contractor installing it.
As can be seen a clear and definite trade-off between several of intertwined factors exists. There are no clear cut boundaries and so the buyer must evaluate all variables in their own individual context.
When roughly equal amounts of sodium bicarbonate or bicarbonate of soda (BOS) and warm vinegar are mixed a characteristic fizzing is seen. As any year 7 (first year of secondary school) science text book explains, the fizz is one of the characteristics which tells us that a chemical reaction is occurring. The reaction represents a highly effective and affordable method for both effective preventative drain maintenance and for removing minor blockages. The reacting mixture should be poured straight into the drain.
Alternatively, pour the bicarbonate of soda into the pipe work and then follow up with the vinegar. Ideally, the reaction should be left to run for several hours and should be repeated as necessary and flushed through with boiling water. Additionally, for DIY drain cleaning using BOS and vinegar together reduces the need for chemical cleaners and for professional assistance.
Why does the reaction happen?
It all comes down to one of the principal thread which runs through the study of chemistry. Put simply BOS (NaHCO3) is an alkali and vinegar or acetic acid (HCH3COO), is a weak organic (carbon based) acid dissolved in water. In chemistry acids and alkalis always react in what are known as neutralisation reactions. Put simply hydrogen in its charged (ionic state) is transferred to the alkali creating new compounds in the process.
This particular reaction is a two-step process. The products of the reaction are carbon dioxide gas – CO2 – (which produces the fizzing and bubbling), water and dilute solution sodium acetate (C2H3NaO2). In chemical terms the BOS removes hydrogen atoms from the vinegar and when this occurs the BOS is converted to water and carbon dioxide. The bubbles of CO2 are denser than the surrounding air and so collect on internal surface of the drain aiding the removal of unwanted material.
The reaction between the BOS and vinegar is a complex process and occurs because there is an exchange of atoms. The exchange happens due to the behaviour of the electrons which are farthest from the nucleus of each atom in the reacting substances.
Each molecule of BOS contains an atom of sodium, hydrogen and oxygen and a molecule of CO2 while acetic acid contains hydrogen and an acetate ion. An ion is any positively or negatively charged atom or molecule and the charge on the acetate ion is negative. When BOS and vinegar react together (and while the hydrogen is removed from the vinegar by the BOS), the hydrogen atom in the acetic acid combines with the hydrogen and oxygen in the BOS to form a molecule of water.
Simultaneously, the acetate ion in the vinegar chemically bonds with the sodium atom in the BOS forming the sodium acetate in solution. The CO2 itself does not react with any of the reagents, that is the vinegar and BOS. However, the chemical bonds which attached it to the BOS molecule are broken and so it is able to bubble off into the surrounding atmosphere.
The above reaction is one of many neutralisation reactions that have clear benefits and represent a clear alternative to chemical cleaners for low key applications.
A standard method of understanding the flow of electrical current is to compare it to a mammalian circulatory system. In a mammal the heart is the pump that drives the circulation of the blood throughout the whole organism, such that the blood reaches every single cell in the animal. Similarly, the wires in an electrical circuit carry the electrical current throughout the whole circuit making sure the device the current powers can function. In a circuit the power source is either a battery (or electrochemical cell) or generator which supplies mains electricity.
For electricity to be transported the circuit must be complete and a voltage or potential difference must exist. Just as when we cut ourselves, blood flows outside of the circulatory system, if the current cannot complete a circuit then electricity will not be transported and the device or mains appliance will not function. At its simplest an electrical current is a flow of electrons, which are negatively charged sub-atomic particles.
Voltage (potential difference) is the force required measured in volts to push the electrons through the circuit. Any GCSE physics text book will impart that the flow can only occur if there is a build of electrons (and therefore negative charge) at the negative (anode) terminal of the circuit. This means that there is a deficit of electrical charge at the positive anode (cathode). The flow of electrical current always occurs as a result of a flow of electrons from the anode to the cathode.
The more energy the electrons have (not necessarily the actual number of particles) determines the voltage needed to move them around the circuit. Hence the electrons in a torch have less energy than the electrons in car battery. The flow of electrons from the anode to cathode is measured in amperes. Put simply voltage and amperes can be mathematically connected to produce a unit we understand as electrical power. The greater either value is the more power produced as measured in Watts.
Resisting the flow of electricity
In the circulatory system the flow of blood is impeded by the friction generated as it contacts the vessel walls and the reduction in pressure as it is pumped back to the heart. Similarly, when electrons flow through the conducting wire there speed is reduced as they come into contact with the atoms which compose the conducting material.
The wire is said to resist the flow of electrons and the greater the degree of resistance the more voltage is needed to push the electrons through the circuit. The degree of resistance depends on the material used to create the wire, its diameter and its length. As with power resistance can be calculated through the mathematical relationship between voltage and current.
Electricity is a natural phenomenon which has become inextricably linked with the continued evolution of the human species. In short, it is a simple flow of electrons from negative to positive terminals which we simply cannot do without.
In Scotland, the organisation responsible for maintaining the supply and sanitation of fresh water is Scottish Water (SW). The body in charge of ensuring adherence to environmental regulations is the Scottish Environmental Protection Agency (SEPA).
In turn potable (drinking) water standards as well as discharges of effluent are set by the EU. Within the standards set by European-wide water management policies, SW operates the following infrastructure:
Water treatment is concerned with the entire set of processes that produce water that is fit for a particular purpose, this may not mean for human consumption. Waste water treatment is distinct from this definition because it is concerned with the collective set of physical and biochemical techniques employed to ensure that water is specifically safe for human consumption.
In addition, waste water treatment is normally associated with processing water that has been utilised in some way, for instance in an industrial process or is actually sewage.
Why treat the water?
Most of water that comes from the taps of Glasgow and Scotland is sourced from reservoirs, lochs and river systems. Although not likely to be as polluted as effluent water, this fresh water is unlikely to be pure and so it must be treated, it is likely to contain substances such as:
The EU regulations mentioned above require Scottish water to carry regular sampling of the sources of water which they use to supply the drainage system of the country, a remit which also covers ground water and aquifers. For example the microbes that cause water-borne diseases such as cholera (vibrio cholerae) and amoebic dysentery (Entamoeba histolytica), must be removed.
Colloidal clay occurs when the particle is dissolved within another molecule or substance and so cannot be removed by those techniques designed to remove suspensions. Colloids in their entirety are removed by adding coagulants such as aluminium sulphate (Alum Al2(SO4)2). Nitrates are particularly toxic to infants and young animals and so there level is kept below 50mg/l.
Water Treatment Techniques:
A stringent sampling regime therefore ensures that the treatment techniques are effective; the water is treated in the following stages:
The material formed as a result of these complex chemical reactions form a surface layer of sludge. The sludge is removed, and the remaining water is then allowed to settle in a process called clarification that occurs in sedimentation tanks.
Clarification and other processes
Clarification refers to a set of chemical techniques which are applied to the water during and after it has undergone coagulation and flocculation. For example, dissolved air flotation occurs when a high-pressure stream of very fine bubbles is blown into the flocculated water. This forces any remaining suspended material to the surface where it is continually skimmed off.
Simultaneously, at very high speed the water is passed through another set of sand or carbon filters. This rapid gravity filtration ensures that any other suspended particles are extricated from the system. The water is often sampled at this stage and if necessary recycled back into the system for secondary treatment. Once it is of sufficient purity any microbes, pathogens and dissolved ions are removed. In the latter case, PO43+ ions are removed by the controlled addition of powdered iron fillings.
If necessary, NO3– ions are removed by specialist nitrifying bacteria that convert the ions to nitrogen gas. In some cases, specialist ion exchange techniques are used to eliminate these and other types of inorganic ions. Further filtration removes any additional sludge material.
Disinfecting the water
Disinfection is only effective if the maximum possible quantities of suspended and colloidal materials have been removed. This includes natural organic compounds dissolved in the water that have a tendency to react with chloride (Cl–) ions forming a class of compounds called tri-halo-methanes (THM). These form when three of the hydrogen atoms in a molecule of methane (CH4) are substituted for chlorine atoms.
The THM’s cause discolouration of the water and if consumed can cause damage (amongst other undesirable effects) to the renal organs. Micro-organisms (beneficial or pathogenic) are removed by bubbling ozone (O3) through the water or more commonly chlorine, or compounds that contain chlorine are added. The chlorine dissolves in the water forming a substance called hypochlorous acid, which can pass through the membranes of both bacteria and water borne disease microbes. Once inside cell or microbe the hypochlorous acid reacts with its constituent proteins thus overwhelming its metabolic processes. To be effective, the water must be kept alkaline between pH 7.2 and 7.8. This treatment is analogous to the addition of chlorine to swimming pools and other water recreational facilities.
Overall, water treatment is a complex series of mechanical, biological and chemical steps that must be carried out in a precise order and with great care and attention. In addition, many of the techniques have been in operation for over a century and are being continually improved, irrespective of the already strict legislation.
The term pipework refers to any pipes that compose any machine or building. The term drains refers to the system of pipes that are joined together and drain liquids away from the premises. In very general terms looking after the drainage and pipe work in Glasgow and indeed anywhere else in Scotland falls to two agencies.
The owner of the property is responsible for the drainage system inside the building and the water provider for that which leads up to the premises. In general terms, the water supply pipe runs from the edge of the buildings to the stop valve inside. Both commercial and residential insurance policies will stipulate the extent of the water supply pipe and who is responsible for it.
Burst pipes and the water supply
From bitter and costly experience, I can assure readers that flooding is no laughing matter. The potential for harm is not merely the inconvenience of restricted or even curtailed access to running water, but can seriously damage the property and its contents. At DPG Plus a full and comprehensive CCTV pipework survey is offered as standard.
The survey will identify potential problems, and our fully trained and registered plumbers will advise on the best course of preventative action. The study will also indicate where damage has occurred. At DPG plus we advise that property owners check their insurer as to how often a survey must be undertaken and for which components they are responsible for. On this note, it is highly likely that the insurer will require a clear delimitation of responsibility as a condition of the buildings insurance.
The water communication pipe runs from the water main to the stop-valve and water meter. In some cases the water provider owns either the stop-valve or the communication pipe. In other situations, it could be that the provider owns both. Furthermore, it may transpire that even though they do not own it, the registered property owner may be responsible for maintenance of either or both components. This can be confusing but the onus is not on the water provider to establish the limits of responsibility.
Overall, the water provider is responsible for the repair and maintenance of the water supply into an area such as Glasgow. This responsibility ends once the communication pipe reaches a given property.
In the UK, almost £20 million per annum is spent on unblocking accumulated blockages of thick grease and material trapped within drainage and pipework. The figure does not include the cost of clean up after undetected blockages have resulted in flood damage to residential or business across Glasgow every year.
Dozens of tonnes of this waste is poured into the pipework every single day in a large city such as Glasgow. The waste fats solidify inside the drainage pipework and start to collect on the internal surface of the pipe and so its bore diameter is progressively reduced. As the fat accumulates the internal wall narrows, the flow rate is gradually reduced which allows for the build-up of more greasy fat. If nothing is done you have a clog in the pipework and there you have it, the entire drainage system backs up.
When waste water leaves a sink it first passes through the water trap beneath the sink and the trap which leads to the external water pipe. The usually warm waste water comes into contact with the cold water in the drainage piping. The fat effectively precipitates out of the hot water and collects in between the two traps.
To make matters worse if there are any clothing fibres or dirt particles then further combination occurs, resulting in a matrix that has the consistency of semi-solid cement. If the blockage has got to this stage then even regularly punching holes through it will only temporarily solve the problem. Eventually, you will need to call out a contractor or use the appropriate chemical cleaner. Clearly, preventing such an accumulation is preferred.
Preventing and clearing the blockage
Regularly flushing the drain with a solution of vinegar or citric acid, salt, bicarbonate of soda or borax will reduce the incidence of blocked drains. For example a 50:50 mix of vinegar and bicarbonate soda causing a foaming brew that will sit in between the water traps and begin to dislodge any accumulating material. Leave for at least 30 minutes and repeat if necessary.
After this time use a plunger to dislodge the clog and if that doesn’t work further action is required. If you are successful in your endeavours, finish by running hot water or several kettles of boiling water through the system, plunging as you go. Chemical cleaners work on a similar principle but if the above preventive measures are employed there necessity is reduced.
Calling a contractor
If the blockage just is not shifting it will be time to call in the professionals. It may be inevitable to do so because the blockage may be located more than 20cm below the sink. After this distance most available chemical cleaners become so diluted that they are useless once they come into contact with the clog. The contractor will have an array of specialist chemicals, spraying equipment, plumbing rods and other tools.
In conclusion, prevention is better than cure so regularly flush your drainage system. If after all your best efforts success is still elusive, then there is no shame in admitting defeat and getting on the phone.