“Red Ash” and Sulphate attacks

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Red Ash sulphate attack in a garage floor

What is “Red Ash”?

Between the 1940s and 1972 industrial waste materials were used as infill material below solid concrete floors and sometimes suspended timber floors. This practice was particularly common in mining areas such as Stoke-On-Trent. Red Ash is just one of four categories of this kind of material the others are; Slag, Black Ash and Grey Fly Ash.

What is Sulphate Attack?

Sulphate attack happens when the concrete in the floor reacts with sulphates in the contaminated infill. The products from this reaction expand, which in turn pushes the floors up, creating the characteristic dome.

Damage from contaminated infill materials can take years and decades to show up. This delay is because the initial expansion fills any gaps in the material first. Only after the gaps have been filled does the effect start to show.

What are the symptoms?

It is quite possible that you have “Red Ash” in your floor without any symptoms, for the reasons shown above. However if you live in a house, or are looking to buy a house, built between the 1940s and 1972 within Stoke-On-Trent, Newcastle or other areas in Staffordshire it is entirely possible your house has “Red Ash”.

The most common symptoms are uneven floors that dome up in the centre. The doming in the floors can cause internal walls and doorways to be distored as well.

What to do next?

If you are not sure if the house you are buying is affected by “Red Ash” but it is in an affected area you should speak to the estate agent. There is a chance that a “Red Ash” test has already been done, and they have access to it. If a “Red Ash” test has not been carried out contact a specialist who will talk through the process and arrange access with the vendor to do a test.

If the results come back that you have “Red Ash” there are a few options for you. Firstly there are varying levels of contamination that may be reported. Within your specialist report it will comment on the likelihood that the property will be affected. If it is not affected then that’s brilliant.

If your property is at risk of being affected then you may need to undertake some works. Sadly the only way to remove the contaminated infill is to dig it out from the floor. This is obviously a tricky job and can be very costly, upwards of £5,000.

Here at Crookshank & Co we will try and let you know if we know the property you are buying is in a high risk area. That way you can get a specialist out to check before you get your survey from us.

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What is “Red Ash”? find out in this blog post