How to bash the problem of red ash in the home
One problem that residents don’t want to find in older homes is red ash, said Midlands green energy expert Ron Fox.
The first sign is when the floor bulges and becomes uneven, although sometimes there are no early telltale warnings.
He said this difficult situation started more than 75 years ago when red and black ash was used as a cheap and plentiful alternative hardcore during the house building boom in post war years. This byproduct of the pottery manufacturing process was used from the 1940s until the 1970s and has led to difficulties in selling homes in areas such as North Staffordshire.
What happens is that moisture reacts with the sulphates present in the red ash causing it to expand and often there is also a white residue visible between floor tiles.
“The good news is the ash will not be present in suspended timber floors or those above the ground floor,” said Ron, of Noreus Ltd on the University of Keele Science Innovation Park. “But it is important to have a floor survey done by an expert to solve the problem before there is any further structural damage and I would strongly advise employing a professional to carry out this work.”
Removing red ash is no easy task and it requires removing the flooring, breaking the concrete sub floor to take away the ground contaminated with the red ash, which could be from one foot to as much as four feet deep. This work can result in the property becoming temporarily uninhabitable.
Once the contaminated ground has been removed and the building control officer is satisfied – it is important for them to visit at every stage of the process – the hole must then be filled in.
“This is an important stage,” said Ron, “so check with the building control officer what the requirements are.”
Usually, the new flooring consists of a hardcore base, typically around six inches deep, then on top is a sand “blinding” layer. This is to prevent the hardcore puncturing the next layer which will be a damp proof membrane (DPM). This durable plastic sheet, similar to a tarpaulin, will act as a damp proof course to prevent moisture reaching the new floor.
Next there is the insulation, which is typically 100mm of rigid, foil backed insulation board, then another layer of DPM to keep the insulation protected from the concrete. Finally, around 6 inches of concrete will need to be poured in as the final floor level.
The new concrete floor will need to be left for 24 hours before anyone can walk on it. Then it advised to wait another 28 days before tiling or putting in any type flooring. It may be advisable to use a silicone based self levelling to smooth out the surface before installing the finished flooring.
“Finally,” said Ron, “it is vital the finished work is signed off by the building control officer who will provide a certificate. This will need to be shown to conveyancing solicitors and mortgage companies when the property is sold.”
For more advice removing red ash and on green energy, contact Ron Fox, on 0845 474 6641 or go to www.noreus.co.uk.
Caption: Floored! But the problem of red ash can be solved.
