Do It Yourself

By:Peter Huber
posted by: bhis.com
Source: http://bhis.com.au/2013/02/overcoming-damp-problems/

From time to time the CSIRO is asked to suggest remedies for dampness caused by rain penetrating solid masonry walls, below are some of their invaluable findings and suggestions which are worth passing on.
Single-leaf construction cannot be expected to be water-tight, especially if it is subjected to wind-driven rain. If the wall thickness is increased it should be more resistant to rain penetration, but poor workmanship in the form of unfilled joints and un-tooled face joints can result in walls that are prone to dampness despite their thickness and apparent solidity.

Often people seek a quick and easy “brush-on” treatment, preferably to be applied from the inside, but we consider the latter to be unrealistic and a false economy. External treatment aimed at preventing the masonry from becoming damp in the first place is a more sound approach. Some possibilities are described:

SILICONE TREATMENT

Silicone formulations brushed or sprayed onto porous surfaces make them water repellent, so that water then runs down treated walls instead of being absorbed. There is a risk in this, however, because fissures wider than hairline crack are not bridged by these materials. The increased amount of water running down the wall during a shower can result in more water penetrating the wall, via such fissures, than before the treatment. With this in mind walls should be examined carefully, and repaired if necessary, before silicone is applied. Silicones deteriorate in sunlight and periodic reapplication is required if the wall is to remain water repellent.

CEMENT-BASED PAINT

This is a useful treatment. Two coats should be applied on the wall after the necessary preparation. A minimum preparation would be to repair gaps and defects in the mortar joints, but in practice “bagging” of the whole wall is advisable. A mixture of 1:4 cement: plasterer’s sand is suggested for this, the wall being “wetted down” before starting.

ORGANIC PAINTS

If organic paints are to be used “bagging” is an essential preparation. As long as the paint film is intact the system will be effective, but once cracking starts water will be trapped behind the paint. This water will take a long time to evaporate and, under adverse conditions, the wall can become progressively damper. In any case the life of the paint system there-after is likely to be short.

RENDERING

This treatment is virtually permanent and should be effective in all but the most severe conditions. For resistance to rain penetration a rough-textured and porous rendering is normally more effective than a dense and impermeable plain finish. Suitable cement: l lime: sand mixes are given in the British Standard Code of Practice CP 221, “External rendered finishes”, available from the Standards Association of Australia.

The discussions and hint given above will suit most homes that have damp problems, in fact silicone treatment seems to be the most popular, especially in the case where the external walls are face bricks.

If you have any further questions please call our office.

We want you the reader to write to us on, any Building matters, and questions or if you seek advice, we will gladly answer any topic that you wish us to discuss, so please send your letters to “B. & H. I. S.” C/O. 17 Battye Road, Kardinya, W.A. 6163 or fax/ph (09) 331-3031

By: Peter Huber
Posted By:BHIS
Source:http://bit.ly/1VoHkbJ

The other day I spoke to a gentleman who asked me, to confirm to him that he needs to replace his concrete tiles on his house with clay tiles, I questioned his rationale and a mountain of misleading statements flowed from his mouth, perhaps the most memorable was that “as concrete tiles become older they start to leak and there is nothing short of replacing them with clay tiles”

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I must say I have heard many such rumour floating around, all of which I am hopefully about to dispelled. I decided to see if the concrete tile manufacturers have become aware of these rumours and what if any, their official response was?

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After talking to several people connected to the concrete tile industry, a brochure was mailed to us prophetically titled “THE FACTS ON CONCRETE TILES”

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I will summarise and add some of our own comments to the questions and topics covered in this brochure.

“ARE CONCRETE TILES DURABLE?”

The modern manufacturing process makes the tiles exceptionally durable, they are manufactured to Australian standards and the physical properties of concrete will remain unchanged well in the excess of fifty or more years, irrespective of climatic conditions.

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Concrete actually becomes stronger with time and remember concrete is the preferred material for major structures such as bridges and high rise towers because of its inherent qualities of strength and longevity, additionally it out last other roof cover materials as it does not rust or corrode.

“DO CONCRETE TILES ABSORB WATER AND THEREFORE DOUBLE IN WEIGHT?” No this is incorrect and a myth. The Australian standards AS1757-1989 actually specifies a maximum water absorption of only 10% per total immersion in water for 24 hrs. In practice the absorption of water by capillary action during periods of heavy rain would increase the weight of the tile by around 5%. Contrary to claims of some roofing companies, this weight increase is unlikely to cause structural roof or stump failure.

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“DOES WEATHERING OF THE ORIGINAL TILE COATING MAKE TILES POROUS?” Not true. The colour coating is purely decorative and is not designed as a water proofing film. As in most water proof purpose made concrete, water proofing is achieved by using carefully selected, formulated, batched and graded materials which are then compacted during manufacture. This then produces a concrete product of high density and strength which naturally keeps out water.

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“ARE CONCRETE TILES FIRE RESISTANT” yes they are totally incombustible and fully fire resistant according to ASTM (USA)E108-88 tests, there is no comparable test available in Australia.

“WHAT ABOUT THERMAL AND SOUND INSULATION” Tiles take longer to heat up and tiled roofs usually have a larger volume roof spaces which “breathe” so houses with tiles roofs stay cooler longer, but once the heat build up accumulates for long periods, it also works in reverse that it takes longer to cool down.

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Due to the greater mass of concrete tiles they do provide a better sound insulating quality than metal roofing, they help to reduce to noise intrusion in particular caused by rain and hail.

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We will continue to discuss the myths and facts of roof tiles

Source:http://bit.ly/1VoHkbJ

By: Peter Huber
Posted By:BHIS
Source:http://bit.ly/1rtHhzd

Ok lets continue where we left of in the last article, on the fact and fiction about roof tiles.

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If you are worried about the usage of concrete tiles when collecting rain water, well there is nothing to worry about as we are assured that the surface of the concrete tile is a suitable surface from which to gather water for drinking, and best results are achieved when an appropriate collection system is fitted.

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If you are building near the coast you also need not worry, as the prolonged exposure of concrete tiles have a proven record of resistance to corrosive atmospheres.

Similarly in tropical conditions the added weight of a concrete roof helps to counteract wind uplift during storms making it less susceptible to damage than some other roofing materials.

Normally concrete tiles require very little if any maintenance due to their exceptional durability, if some is required then only the affected tile will need to be replaced.

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Cleaning of the tiles is also not a necessity but Lichen and moss can be removed by high pressure jet water sprays or by the application of a specific chemical formula sold for this purpose of removing the lichen and moss. In fact the formula for the magic potion is this:- 200 grams of copper sulphate, to 4.5 litres of water The average roof will need ten times this amount, the solution is broomed onto the offending areas and eradication will take place over the following couple of months and it should be left to work on its own as the moss and lichen will gradually disappear. On porous tiles the solution has a residual affect as it remains and inhibits any future or early re-growths.

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When using copper sulphate solutions be careful that metalwork such as guttering is protected to prevent corrosive action. Gutters should be filled with water by blocking the downpipes as any solution running into the gutter will be extremely diluted and not affect the metal gutter.

By comparison concrete tiles are very affordable and generally cost less than metal or clay covering, on most profiles the fit is neat and even, but the coating that is applied to the tiles is still subject to weathering and will eventually wear off and needs re-painting.

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So myths like, Lichen and Moss will eat into your tiles and weathering of the original surface coating makes old tiles porous, is all a lot of old wife’s tales and scare tactics, invented by itinerant traders.

Every so often we would like to publish questions with answers that our readers may have on renovating or building, so please share your comments.

By: Peter Huber
Posted By: BHIS
Source:http://bit.ly/1Ww1RM1

What is probably as important as consistent compaction is the design of the footings and the actual digging and pouring is equally as important. Firstly footings should be designed according to the nature of the soil. For example you would not design the same size footing when building in clay soils as you would if you were to build on sandy well drained soil.

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It has always been our advise to firstly sample and categorise the soil, if you are to build on clay or loamy soil, especially where drainage is poor. This will then determine the type of footing design for the home and will minimize any settling or cracking that would normally occur.

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Well we now have got, consistent compaction and a footing, designed specifically for the soil and a slab to match. The next step is to examine the perimeter masonry walls to see if and what type of settling cracks have occurred if any.

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The settling cracks that are visible on the brick work or internal walls are a signature or blue print as to what has occurred under the slab.

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The walls are a reflection or and indication as to the stability of the foundation. Below are some diagrams showing the different type of cracks that can occur and why.