Building&Living – Issue 03/2008

Building&Living – Issue 03/2008

The decision to build a new home is beset by an array of questions that need to be answered – such as the choice between a prefabricated house or on-site construction. TÜV SÜD's experts have prepared a checklist to serve as a useful guide in making this decision. Guttering and drainpipes can play a significant role in protecting the façade of your house. This autumn issue of Building&Living also describes the steps necessary to maintain the value of these protective features. As winter approaches, energy prices are remaining high; improving the air-tightness of a house is an effective method of saving on heating costs, but also involves paying careful attention to correct procedures for heating and airing the house. Part 2 of our energy-saving tips examines simple, yet highly effective ways of increasing the efficiency of your hot water system – TÜV SÜD's experts tell you how.

Topics

• Prefabricated – yes or no? Not one question, but many
• Vital procedure following heat insulation: airing your house correctly
• Really cool: saving money with hot water systems
• Guttering: running to plan
  
  

Prefabricated – yes or no? Not one question, but many!

The decision to build a home is beset by questions that need to be answered. A key issue is the choice between prefabricated or on-site construction. TÜV SÜD's experts in building technology explain the factors to be weighed up in the decision.

In simple terms, a prefabricated house is a turnkey house where the owner has no say in choosing the details of the fit-out. Prefabricated houses, which may be masonry, wood or concrete slab constructions, are completed within a matter of weeks for a guaranteed fixed price. Prefabricated and on-site constructed houses show only minor differences in terms of building life and resale value, say the TÜV SÜD experts.

• Do you plan to build a "house for life", in which individual floors can later become self-contained? Does the house need a small "granny flat"? Do you need to plan for moving walls if the use of the house changes at a later stage? If you answered any of these questions with "yes", a prefabricated house may not be the best choice for you; in classic prefabricated houses, walls cannot be moved. .
• Does the prefabricated house type you are considering fit the site available? For example, can the living-room be positioned to face south, in line with development plan provisions?
• Is the house on offer with or without a cellar? How high are development costs for the site? Don't forget to include fees in your calculation as well as the costs of construction! What proportion of the costs for site development and site installations will you be required to pay?
• What materials will be used for the individual sections of the house? Given the many different alternatives, TÜV SÜD's experts recommend addressing this question in some detail.
• What about heat and sound insulation? How will moisture exchange – buffering and storage of moisture and heat – function? This issue is critical for the indoor climate and living conditions of your new home.
• Prospective owners of a prefabricated house who have the option of completing some or all of the interior fit-out themselves should be sure to enlist a specialist to check their contracts. In this situation, the interfaces of the individual works are particularly critical points. For example, if a customer agrees to carry out interior tiling himself, is he also responsible for putting in sealant under the tiles, or is this the contractor's job?
• One thing is absolutely clear: each and every personalized detail in the fit-out of a prefabricated house represents additional costs. This is an important factor to clarify when making the basic decision for or against this type of house.
• Looking into the future: what about the possibility of adding to your prefabricated house in the future – solar panels, say?

Vital procedure following heat insulation: airing your house correctly

House-owners with an eye to the onset of winter and the permanent high level of energy prices can make considerable savings by deciding to wrap up their homes. However, TÜV SÜD's experts urge, home-owners should consult specialists to ensure that insulation is not followed by an outbreak of mould.

Improved insulation of exterior walls, loft and cellar can slash heating costs by over fifty per cent, depending on the original condition of the building. Optimizing the air-tightness of the building envelope alone can reduce heating bills by ten per cent. However, TÜV SÜD's experts strongly advise that experts should be consulted over specific measures to improve air-tightness and insulation and that implementation of these measures should be assigned to contractors with the necessary expertise.

Correct heating and airing are essential to prevent mould from forming in an airtight house. 20°C is an important rule of thumb for temperatures in living areas, and can be adjusted to cooler or cosier levels according to personal taste; however, temperatures in kitchens and corridors can be reduced to 18°C without impairing comfort, and bedrooms can even be kept at 16°C. Every degree by which heating temperatures are lowered represents roughly six per cent saved on heating costs.

Moving from temperatures to humidity levels, TÜV SÜD recommends a range of 30 to 60 per cent relative humidity for comfortable living; this level can be measured by using a hygrometer.

To maintain the comfort of your interior climate, regular airing of rooms is important; every two hours, open windows wide for five minutes to allow a through current of air. Bathrooms and rooms where washing is dried should be aired more frequently to prevent moisture from moving in and encouraging the growth of harmful mould.

Really cool: money-saving hot water systems

House owners can easily save up to 20 per cent of the costs of their hot water systems. The experts at TÜV SÜD explain how.

Most systems which use oil or gas to heat water centrally operate at a water temperature of 50 to 51 degrees Celsius – a temperature which is scarcely ever needed. TÜV SÜD's solution is to programme the heating at a water temperature of around 45 degrees Celsius. If hotter water is needed in the kitchen, a kettle or water heater is a more energy-saving method.

Heating the water to 55 ° C once a week is enough to prevent the spread of legionella bacteria in the pipes, say TÜV SÜD's experts. Another way of saving money is to add an insulation jacket to the hot-water boiler to reduce heat loss. Applying all these methods can save up to 20 per cent on heating costs.

A further low-cost investment with long-term benefits is to fit special energy-saving shower heads, enabling water and energy costs to be saved with no appreciable loss of comfort.

Guttering: Running to plan!

House roofs are exposed to considerable amounts of water, in the form of rain, sleet, hail or snow. This precipitation is caught in gutters and conducted away from the building and into the drains. But guttering systems not only serve to collect rainwater; they also play a key role in protecting the façade of your building. To ensure they can do their job smoothly, TÜV SÜD's building engineering experts have assembled a list of tips.

Avoid damage to plaster: Sloped roofs generally handle rainwater by a combination of rain gutters and downpipes that lead into a soakaway or public drain system. This system not only protects the house-dwellers from a soaking, but also shields the house façade from uncontrolled water runoff, thus avoiding damage to plaster and formation of algae or water penetration of the house walls. To ensure that the guttering allows free flow for water, gutters should run at a gradient of at least 0.5 per cent to downpipes, equal to a five-centimetre slope over a guttering length of ten metres. TÜV SÜD experts note that generally accepted engineering practice also allows a gradient of 0 per cent.

Avoid clogged pipes: A further requirement for smooth water flow is that pipes are kept clear. To ensure this, clean out the gutter once a year; fallen leaves, birds' nests or other objects may block the gutter and prevent water from draining away. TÜV SÜD's tip is to install a leaf guard or screen in the gutter to prevent blockages and allow water to flow freely. A filter at the top of the downpipe is also a useful addition.

Avoid cracks and holes: In addition to an annual cleaning, the experts also recommend that home-owners conduct a thorough inspection of gutters and downpipes every five years to check for cracks or holes. The lifespan of zinc-coated steel gutters can be extended by applying corrosion protection to their inner surfaces. Fastenings affixing the guttering to the roof skin and downpipe should also be checked at regular intervals. If gutters and pipes are bracketed to the composite thermal insulation system of the house, care should be taken to avoid water damage by selecting a waterproof fastening solution. And one final tip to conclude: contrary to what many a TV programme or film may suggest, drainpipes and gutters are not climbing-frames. To avoid damage, never lean ladders against drainpipes or hang heavy objects from gutters.

Media Contact: Dr. Thomas Oberst