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Buying a Home with Pyrite Damage

Found your ideal home.

Now that you have found the ideal home,  you can get ready to get all your contracts signed, organise your mortgage and look forward to moving into your new home. You have agreed a price with the estate agent and decide that its better to be safe than sorry and organise to get a pre purchase building survey carried out on the property.  Your surveyor inspects the property and finds numerous cracks in floors and walls. The surveyor is well aware of the devastation caused by pyrite damage and due to the age and location of the property and the type of cracks noticed, he advises you to take no chances and you should have the house tested for pyrite.

The normal reactions you get from both buyers and sellers are,

  • Both the buyer and seller are surprised, the surprised seller turns to a shocked seller when he realizes the consequences of pyrite damage
  • The buyer will walk away from the sale unless he is assured that there is no pyrite under the concrete floors
  • The seller will wonder what can they do to solve this issue, especially when it can take up to ten years before cracks can become evident

The frequently asked questions about pyrite testing and pyrite damage that always arises for both buyers and sellers are,

What is pyrite?

Pyrite is a natural mineral.  Traces of pyrite are found in the rock sourced in quarries which are used to make the crushed stone backfill used under the concrete floors.

Why is this a problem?

The pyrite in the backfill oxidizes when it comes into contact with air and moisture.  Through a chemical reaction the backfill will expand and structural damage the foundations, floors and walls in the house.  Not only will the backfill swell and raise the floors, but the concrete floors and concrete foundations can begin to crumble due to the chemical reaction.   The interior partition walls resting on the floors will also lift leading to further damage to the first floors including walls and ceilings.

The swelling is worst where there is a greater percentage of pyrite in the backfill and also where a thicker and greater amount of contaminated backfill is compacted under the concrete floors.

How much damage can be caused?

The amount of damage caused by pyrite will vary greatly from house to house.  In some serious cases the swelling or heaving of the concrete slab can be 150 mm’s high including the pushing and spreading out of the foundation and rising walls.

In other cases, a homeowner in the initial period may have no idea that there is anything dramatic going on. The home owner may put the damage down to minor settlement of drying cracks.  Only in recent years that the full effects of pyrite are becoming known and the true extent of the damage and further expansion possible is becoming apparent.

How long does it take for pyrite damage to show?

Looking at the Canadian experience it can take an average of about 10 years to see any damage from pyrite. The pyrite can take up to about forty years before it stabilises or ceases.

How do I know if I have pyrite?

An experienced surveyor should be able to include in his report the likelihood of pyrite during a building survey. A pyrite test will need to be undertaken to be 100% certain, the sample of backfill taken from under the concrete floor slab will be tested in an approved laboratory.

The results of the testing will need to be assessed by a building surveyor experienced with pyrite and to determine the severity of future damage to the structure and the costs of repair.

What counties are known to be affected?

Dublin, Meath, Louth, Kildare, Wicklow, Westmeath and Offaly. If pyrite type cracking is noted, expert advice should be sought if the property is not located in the mentioned counties.

Are all homes affected by pyrite?

Pyrite is not normally seen in very new construction nor in older properties built before the 1990.  Any property with an extension added between 1990 and 2008 may have pyrite under the extension floors.