Whenever you need a building inspection in Perth or around WA, BHIS is the company you can depend on. We offer our expert inspections services for specific buildings as well as for private properties. With over 30 years’ experience, precision comes with experience and we have thus become renowned to provide our clients with thorough and dependable structural reports. When you come to BHIS you can expect unbiased and independent pre-purchase building inspections reports.
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.
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.
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.
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.
It goes like this, before you buy something, and a friend had
described it to you in detail ”warts and all”, it would have helped in
shaping your ideas in the purchase of that something.
Well the same goes for when buying a car or a house. These are major
purchases for most people and for some it is the single most important
investment in their live. This being the case then, would it then not
make sense that before buying, some one thoroughly checks out your
proposed purchase before a final commitment is made on paper in the form
of an offer to purchase. Preferably a mate in the building industry or a professional inspection institution can be called upon to give an
unbiased opinion based on the structural nature of the building.
The things that a buyer should be aware of is that firstly the
foundation, walls and roof construction are sound, as theses components
constitute the shell and anything else is purely cosmetic.
Firstly the foundations:- If they are Limestone, then one would have
to appreciate that they are large chunks of rock, shaped and placed into
a hand dug trench and mortared into position, there was never any
compaction carried out to the soil below the first laid limestone, hence
the ground could move and settle as the weight of the walls was placed
upon the Limestone. Large homes were built upon the limestone
foundations and later the settling took place and was and still is
evidenced in settling cracks noted on wall.
These days we build the foundations a different way, mostly it is a
concrete perimeter beam and a floating slab is resting on top of these
footings. This latter method is built on soil that has been compacted to
a uniform compaction. If this compaction is not uniform then uneven
settling can be the major source of settling cracks, as the foundation
settles under the weight of the walls and roof. The importance of
uniform compaction is so vital that theoretically, if the compaction was
uniform then no settling would occur.
The importance of keeping the perimeter foundation at a constant
moisture level is equally as important since a constant change in
concentrated moisture levels content will cause the soils supporting the
perimeter footing beam to move. This movement is transferred to the
walls and settling cracks appear over windows and doors as these are the
most vulnerable areas. So it is important that the down pipes are
connected to soakwells which are at least 1.8 meters away from any
footing.
“FREEZTEQ” as discussed in last weeks column is a unique and highly effective damp coursing system which has been patented in the UK and overseas and it offers several major advantages over other chemical techniques.
The system is based on siliconate solutions which are inserted into holes drilled into the mortar line of the wall to be treated being in the form of a circular section pre-frozen pellets which are inserted into the pre-drilled holes.
The slow melting system ensures a continuous water repellent barrier throughout the treated area, because the system depends on natural seepage (diffusion), which research has shown to be the most effective method for fluid distribution in masonry, accurate dosages can be readily achieved and application costs are thus remarkably low.
The “FREEZTEQ” or known as the Passive system, is suitable for damp coursing all types of walls including stone and rubble and has shown itself particularly effective in treatment of older properties.
According to a spokesperson for “Consolidated Protective Coatings” who specialise in using the “FREEZTEQ” (444-2929) system say that, it is important to do a diagnostic analysis on the walls and then recommend which type of application to use in curing the rising damp. It apparently is not straight forward, since if the mechanical method is used, that is, injecting silicon liquid under pressure, then if the mortar is friable and the bricks are old and crumbly(Spalding) there is a good chance that they may fall apart or out, due to the Pressure that is used (between 50 to 120 psi) during the injection method. Hence the more Passive method comes into it’s own.
He also said that to perform a quality job the plaster needs to be removed and skirting which may be in the way all these will eventually have to be replaced and are reasonably costly items, but the choices are very limited.
Requirements for Damp-proof coursing and flashing materials are covered in detail in the AUSTRALIAN Standards 2904-1986 In fact if building a new home and the Builder is registered with the Builders Registration Board, a directive from the Board has been issued to the builders to make sure that all shower cubicles are water tight and that the home built in general does not leak as it will be the Builders responsibility for 6 years.
In summary the main causes for rising damp in older homes are, the break down of the original damp proofing needing chemical intervention) In newly built homes, poor quality and control of workmanship is usually the cause. There is no excuse with today’s technology, know how and information to have a damp or leaking abode.
