Rammed Earth is a beautiful product that can last hundreds of years when properly installed and is resilient to most environmental conditions.
The basic method of construction is to use locally obtained earth if suitable, combined with a mix of sand, aggregate, with some cement to stabilize the mix and some waterproofing admixture.
The mixture is heavily compacted between formwork, which when removed produces natural looking earthy walls. 
Careful batch mixing and maintenance is however important, to ensure that the finished product is stable, otherwise some areas may weather or degrade as in these photos as additional waterproofing is required every 10 or so years.
As a walling product, it has fantastic thermal value for internal walls and has great sound absorption qualities. External walls can absorb heat and cold, so often insulation (foam panels) can be added during the build.
As a product it is also fire proof, it is termite proof and relatively stable to environmental conditions, although incorporated into a structure, often includes other materials that are not.
Wall thickness varies but 300mm is standard and provides a load bearing wall to support roof framing, although this still requires engineering for council approval.
Fixings such as masonry plugs or anchors can be used, but at twice the normal length of embedment, services such as plumbing and electrical are installed during the build process, so as to not affect the finished wall surfaces.

The builder can often leave your new home, completed but still requiring pathways, storm water or earthworks to be completed.
Your engineering report will state that these must be done, unfortunately this can be overlooked for many years, resulting in areas of concern.
This week I looked at a house that was built 10 years ago and still had incomplete external pathway areas.
The builders timber debris was still lying around in the mud, resulting in termite activity.
The mud had breached the concrete slab damp proof course and encapsulated the brick expansion joints and the lower course of the brickwork. This had resulted in moisture transfer on to the house brickwork, as well as breaching the termite control systems done when the house was built.
Moisture salting can be noticed on the brick and mortar face.
Termite attacked timber was located right next to this area.
Inspections are a must in all houses that you want to purchase.

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​In my opinion the current housing market has gone crazy with purchasers bidding without wanting inspections due to the fear of missing out, combined with the trend of the Vendor wanting to accept no conditions on the sale of their property, so they are excluding both the building inspections and subject to finance clauses from the sale contract conditions. This gives the purchaser auction-like conditions once they have made an offer that gets presented, if they want the house. The vendor then knows all the forwarded offers, but unlike an auction, the purchasers do not know where the price is at when making their offer. The risk is all on the buyer and my opinion is this should only be considered as acceptable risk if the property is that new that it is still covered by the builders warranty and you know what it costs to buy land and build. Due diligence is required when buying in today's market, as prices may fall just as it has in other states in Australia in the last few months. 
Below are some photos of the damage that my client got to see of this 33 year old house, but I am sure the purchaser probably did not know about it at the time of the fast paced auction. During the Building and Pest inspection that I did for my client, mud tracks were followed through the roof and a termite nest was located in the wall. Notable flooring damage, hidden by a coffee table and rug on the floor. My client attended the auction with the knowledge that work was required when buying the house and knew when to stop bidding.

​When you are at an open inspection, you are rushing around and would be lucky to spend 20 mins looking at the whole house. Often multiple open inspections are done, with other potential buyers, all possibly making an early offer.
Here is a heads up on the warning signs, that you should take note of.
In older homes with timber floors, often a carpet is positioned over a floor area. This can be hiding termite damage, or simply a staging prop. If possible, walk over the carpeted area and listen for creaking noises and feel for joist movement. If no one is around peel back the carpet and have a look, however this will be frowned on by the agent. Look for termite floor traps, suggesting prior inspections and for drill holes in the perimeter pathways, that show prior treatment.
Exterior timber windows that were freshly painted for the sale of the property, can also be hiding existing wood rot, look for the texture difference and feel the difference between the putty and the timber. The putty will over time just fall out, leaving the damaged windows.
Wood rot in timber fascia’s is often difficult to see without a ladder. Look for recently replaced guttering and metal capping covering the mitred fascia corners.
Rising damp can be seen by small paint blisters, these can appear after the first few rainy days and often located near damaged downpipes.
Rising damp or waterproofing issues in bathrooms can be seen with a torch, looking down the wall surface for small paint blisters.
A building inspector will have a Tramex moisture meter to check for all the above issues and many other inspection tools, so it's best to use an inspector after you have made an offer or prior to the auction day.
Happy house hunting.

Firstly, I am not an engineer, however the concepts involved are not that difficult to grasp. Underpinning is simply one way to stabilise the movement of house wall but is not the answer in all cases. Digging out and introducing a new stabilised footing under you house slab can and will rectify a lot of the issues, but is this expensive repair technique really the only answer?  The other alternative is using an expensive resin injection system to push up the sinking slab to rectify the cracking walls.
All concrete slabs and footings are engineered to be serviceable for the life of the house, however the engineers do request that the entire perimeter of the house be surrounded by pathways that direct water away from the slab edge. When looking at houses for sale, quite often this has been neglected.
Understanding that cracks in ceilings or walls are due to slab heave, that occurs when the soil moisture content under the house has been changed and is no longer uniform under the slab. Reactive clay soils will swell when damp and shrink when dry. When the soil around the outside of the house becomes wet the clay soils absorb moisture and expand pushing up on the external edges of the slab or strip footing. The soil in the middle of the slab remains constant, so the expansion of the slab and cracking of the walls begin. These expansive forces are powerful enough to lift a house and easily crack the concrete strip footings of older homes.
If for example you do spend many thousands of dollars with either resin injection or underpinning, but do not rectify what caused the issues, you may soon find out that any warranty provided by the companies involved is probably void.
In lots of cases simply doing what was requested by the original engineer, making sure that water is directed away from the house and that the house has a decent pathway surrounding the slab to prevent heave is all that may be required.
I would suggest simply doing this and observing the cracking is a great start, then if the ground is not more stable after a year or so, then consider spending your money with an established underpinning or resin injecting business. You may only require patience, some quality crack filler and a slap of paint to keep it looking good.

When you're at an open inspection looking at a house, you get to see all the nicely decorated rooms and freshly painted walls. But what is through that personal access hatch that you need to know about?

​This space located between the ceilings that you can see and under the roofing surface that you can see from the road, is full of expensive repairs that let's face it, do not get repaired before a sale as they are not seen. This area is often only rectified, if the house has been on the market so long that it has had multiple prior inspections and it becomes apparent to the seller that it will not sell unless, at an auction where no inspection was arranged by the purchaser. The Vendor may at this point decide that they desperately want to sell and will spend some money to patch it up for sale, or spend so much rectifying the issue, they end up keeping the property after doing the renovations.
The issues can be simple insulation installation issues that may cause ceiling fires or even ceiling collapse. Older houses often have halogen downlights, that require 200mm clearance from the recessed luminaire, 200mm clearance from a timber structural member and 50mm clearance from the transformer. This is often not done and a fire can occur. 
Other insulation issues are missing insulation batts, that will result in insufficient thermal areas, but this is a minor issue compared to a collapsed ceiling. Where no insulation is present in a ceiling, the unpainted side of the exposed gyprock absorbs moisture, gains weight and sags. The sagging gyprock then pulls through the nails and glue that holds the ceilings up. From inside the room all you may notice is a small ring crack around the nail or screw head. Each room that requires the ceilings to be replaced however can cost up to $3,000 to remove, replace and repaint. The costs are so high that an electrician will need to be involved, the insulation will probably require replacement and the clean up required afterwards. 
Damaged timberwork can be the result of prior tradesmen simply removing structural timbers or altering truss sections to make their job easier. Other notable areas of damage is truss plate delamination, mould damaged timbers, chemical delignification damage, wood rot or termite damaged timbers. All of these items are an expensive repair and can require engineering recommendations and certification. The structural members of a roof are designed by an engineer and can not just be modified or repaired on site by anyone. Roof sheeting can rust and lead flashings can crack allowing for moisture ingress to the ceiling space, also roof tiling can crack or terracotta roof tiles can fret.

​Have you wondered why your concrete paving looks damaged?
Concrete paving consists of cement, sand, fine rock aggregate and water that has been press formed in a mold. The concrete cures when the water in it has evaporated. Being a medium strength concrete product and depending on your paver choice, it can be as low as a 10mpa strength product, meaning that the paving has the ability to transfer water. Even in the construction of bridges, using 50mpa strength concrete will still require additives to be waterproof, so the weaker paving blocks are never going to be a water-resistant product, basically no concrete is without additives. The constant presence of water will weaken the bond of the surface materials. Once that surface has weakened and begins to wear off, it then allows the concrete to have further rapid failure.
Moisture can transfer from the ground upwards if there was a plumbing or drainage problem. Especially if the rubble base and the coarse river sand bed was not adequately prepared prior to paving being laid, as water can be held by the clay subsoil and then wick up through the paver.
Alternatively simply due to a lack of adequate drainage or fall in the paving surface, can cause water to pool and then be absorbed into the paver. 
In the photos attached you can see the concrete paved areas have lost all its durability. The paving surface is crumbling and the paving requires full replacement. Inspection of the base is recommended as the paving may have been installed directly to the soil. No drainage was noted in the area and guttering overflowing issues have also attributed to this issue.
The house slab edge was not adequately protected from the moisture issues and the moisture has transferred into the slab edge causing concrete spalling. The render under the sliding doors has also been damaged due to this moisture transfer.
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Sometimes locating termite activity can be easy, however it is often very difficult to adequately assess, without the correct inspection tools.
Termite mud tracking can be easy to notice if the house has adequately exposed concrete around the perimeter, such as the suggested 75mm by the Building Code of Australia.
Garden beds against the house slab can often hide the mud tracks, as can the garden vegetation itself.
The issue to understand is termites are attracted to damp moist timber and inadequate drainage away from the house can increase the chances of termites. Garden and lawn beds are watered for the plants health, however this too is simply attracting termites to the house.
Another interesting point is that soil types also change the amount of fall required for pathways around the house, with clay type soils requiring far greater fall away from the house, than sandy type soils. Unfortunately most DIY pathways are inadequately sloped away from the house. This is a great concern when concrete pathways are installed, often with no or little consideration for drainage allowances and can be a great expense to replace.
Termites however are happy to live in most soil types.
In most building and pest reports, this area of concern will be highlighted as a significant issue that needs rectification.
When researching a property prior to purchase, consider an additional expense such as removing paving and relaying if often not thought of. But then again neither is additional costs of replacing structural walls or flooring members. 
I inspected a 9 year old home this week and found enough issues for the purchaser to pull out of the sale. This buyer had bothered with a building and pest inspection, you should seriously think about having one done too.
Below are some images of the mud tracking into the house and the Termatrac radar unit locating movement within the wall above the mud tracks. The Tramex moisture meter is at maximum damp readings here and all along the inside wall of the house when inspected. ​