Sunday, September 13, 2015

Best Wall Coverings practices | Pre Purchase Building Inspections Perth

By:Peter Huber

Vinyl wall coverings (vinyl laminated to paper or fabric) have become very popular over the last few years, largely because they are more easily cleaned than the uncoated open-textured types. Yet it is just this impervious, otherwise-desirable surface that sometimes creates a mould problem.

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In one home examined by the Division of CSIRO, red and purple stains were found to be showing through from behind a light coloured vinyl wall covering within two weeks of application. The stains, which originated in the paste layer, were identified as a type of mould. The key factor in this rapid mould growth was the fact that paste had been sandwiched between a painted wall and a sub-substantial vinyl membrane.

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On one hand, the impervious vinyl layer prevented evaporation of moisture from the paste layer while on the other hand, the painted background drastically reduced absorption of water into the wall. Thus, the paste was kept moist long enough for mould growth to start. Had an adhesive offering less nourishment to moulds been used, mould growth would have been unlikely. Similarly, had the wall covering been a plain paper or one of the “spongeable” wallpapers (papers with a very thin plastic film on the surface), or one of the “breathable” vinyls, mould growth would again have been unlikely since such coverings “breathe”, enabling the paste to dry by evaporation.

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When hanging wall coverings of solid vinyl sheet laminated to paper, it is a wise precaution to apply a fungicidal wash such as two percent sodium hypochlorite solution to the wall before sizing it with a dilute solution of a cellulose adhesive with fungicide added. For best results manufacturers suggest applying lining paper to the wall before finally hanging the wall covering, using the heavy-duty cellulose adhesive for both operations. In the case of mould staining described above the vinyl wall overing had been hung, without a preliminary fungicidal ash, using a starch paste (instead of a cellulose adhesive) with fungicide added. Obviously this was not enough protection.

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When the weather is very cold and damp the cellulose adhesive may take a long time to set, so an acrylic-reinforced latex adhesive might be advisable under such conditions, to avoid lifting of the seams. Alternatively, he cellulose adhesive could be used and, if the seams do lift, they could be bonded to the wall with the latex. When hanging wall coverings of vinyl sheet laminated to fabric, only the specially formulated adhesives recommended by the manufacturers should be used.

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Normally, coverings are not hung on absorbent surfaces. Manufacturers recommend that bare surfaces be painted with a flat oil paint, and it has been assumed in the above that this has been done.

For now till next week when we will discuss

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Any questions that our readers may have would be gladly welcomed and endeavoured to be answered as seen fit.


Friday, September 4, 2015

How to stop condensation? | Professional Building Inspections WA

Posted By:Peter Huber
Continued from the post > CondensationIssues
Condensation is basically simple. It involves preventing moist air from coming into contact with cold surfaces (ie. surfaces at temperatures below the dew point of air). In practice this can be achieved by:
§  Removing moisture laden air (by ventilation) and/or
§  Raising the temperature of any cold interior surface to a level above the room air dew point (by heating).
The best way to remove moist air is to use exhaust fans as its source. An electric fan should be installed in the ceilings of the bathrooms and switched on when using showers or baths. To enable the fan to work more effectively, leave a door or window slightly open while the fan is running.
A ceiling vent is recommended over every sink, basin or trough in the house.
More water vapour is normally generated in laundries tan in any other room. Clothes driers should be ducted to the outside air.
A hood fitted with an exhaust fan is recommended over hot plates and stoves as follows:
§  The exhaust fan should be at least 200 mm in diameter.
§  The distance between the hotplate and hood should be 600 mm, this distance may be increased to 750 mm if absolutely necessary.
§  The width and depth of the hood should be preferably the same as the hot plate or stove.

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If it is not practical to install a hood, an exhaust fan may be located in the ceiling over the stove and used while cooking.
In rooms where exhaust fans are impracticable (eg. bedrooms) adequate ventilation can be obtained by opening windows.
Remember it is better to ventilate continuously by having all windows slightly open than by opening one window wide for a short time.
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In addition to good ventilation, heating can also help to reduce condensation on walls and ceilings. Condensation on window panes and metal window frames, however, is not significantly reduced by heating. This is because glass and metal are good conductors of heat. Any heat which reaches these surfaces does not warm them appreciably as the heat quickly is lost to the outside air.
In very cold climates (and in Australia this can be takes to mean in areas above the snow line), it may be necessary to provide double glazing to raise the temperature of the inner pane.
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It is better to provide some continuous background heating rather than short burst of heating. Continuous heating allows wall and ceiling surfaces to warm up and stay warm, which greatly reduces the risk of condensation. On cold days try to keep inside air temperatures at least 5oC higher than outside air temperatures.
The risk of condensation is considerably reduce in any room if walls and ceiling are insulated, because it allows these surfaces to reach a higher temperature. For an existing house it may not be practical to insulate walls, but ceilings can usually be easily insulated. Apart from reducing the risk of condensation and mould growth, insulation will substantially reduce heating costs.
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Technical information by Courtesy of CSIRO.
Your “Handy Jock”.
Any questions that our readers may have would be gladly welcomed and endeavoured to be answered as seen fit.