Rising Damp – v – Penetrating Damp (A case of Misdiagnosis)

Looking in detail at a case of misdiagnosis of damp in a property

This semi-detached, 1930’s, ex local authority house is brick built with walls of conventional cavity construction (rendered externally) and retains a physical damp proof course. The property has been subjected to past refurbishment and had been cavity insulated (polystyrene beads) and fitted with Upvc double glazed replacement windows.

 Instructions were received to investigate dampness affecting the front and side walls (weather prevailing elevations) where there were continuing problems with damp causing decorative spoiling and plaster damage at high level, despite previous chemical damp proofing and replastering works having been undertaken by the previous owners in 1995.

Front weather prevailing elevation

Front weather prevailing elevation

Background

We were given sight of the original damp report prepared by the contractors in 1995 (who had since ceased trading) and their report, whilst brief, identified rising damp due to a failed damp proof course to the front and side elevation walls. Their recommendations were to strip and replaster to a height of 1.0mtr and inject a chemical damp proof course along with fitting new skirting boards. The quote provided was £1,500.00 + vat, which excluded costs for redecoration, removal of fixtures and fittings, reinstatement etc.

Line of damp along join of old and new plasterwork

Line of damp along join of old and new plasterwork

Despite these earlier works, dampness has started to reoccur since the new owner’s occupation in 2006 and is also now causing fungal decay to skirtings and other joinery.

Due to the client’s concerns over the reoccurrence of dampness to the walls, she tried to make contact with the original contractor, only to find that they had ceased trading and that their guarantee was completely worthless. She then instructed 2 specialist damp proofing contractors who undertook ‘free surveys’ with a view to providing a solution to the damp problems.

Decay of staircase joinery

Decay of staircase joinery

Company one advised that the works undertaken in 1995 had failed and that further works would be necessary, providing a quotation in excess of £1800 + vat. The second company concluded that the damp proof course was not working and that the original height to which plaster was removed was insufficient. They also proposed further injection damp proofing and replastering to full ceiling height at a cost of around £2,500.00 + vat. They also recommended the installation of a Ventilation System at a cost of £800 + vat. Again none of these costs took into account redecoration, removal / reinstatement of fixtures and fittings etc. and more importantly the general inconvenience to the occupants.

Due to her concerns over the conflicting advice given, she was advised to obtain a survey from an Independent Damp Surveyor (with no commercial interest) and contacted Premier Heritage.

Spoiling of decorations and plasterwork

Spoiling of decorations and plasterwork

The Survey

Following our own survey, we identified the 2 main areas of dampness, these being the front wall (sitting and dining room) and the side wall (dining room and kitchen) all other walls within the property were found to be free from any dampness. Where decorative spoiling and plaster damage did exist this was however mainly found at high level and on and above the line of the original 1.0mtr of replastering, although the underlying brickwork was found to be extremely damp from floor to almost ceiling height, where tested with various moisture measuring instruments.

Some skirtings also retained high levels of moisture and showed signs of incipient wet rot decay, as did the lower section of the stair stringer.

From the visual pattern, height and extent of dampness detected, along with the high level decorative spoiling and plaster damage it was evident that this problem was not caused by true ‘rising damp’ and further investigation was advised.

Wall stripped of plaster to expose extent of dampness

Wall stripped of plaster to expose extent of dampness

Following discussion with our client, we undertook an Optical Boroscope inspection of the cavities (followed by opening up), only to find that the insulation materials introduced in the 1970’s were absolutely saturated, due to lateral damp penetration of the external render and brickwork, on the weather prevailing elevations, which was further aggravated by cracking in the render. This had resulted in a long term build up of moisture within the brickwork, cavity debris and between / in the insulation materials which eventually, after several years, bridged the cavity and penetrated the internal walls, resulting in the misdiagnosis of rising damp and remedial works being undertaken in 1995.

Unfortunately the works carried out in 1995 did not identify or deal with the source of moisture, but only the symptoms and as a consequence of these works all the remedial replastering succeeded in providing was a hard cement impermeable render, thus slowing down the moisture movement from the underlying wall to the new plasterwork. As a direct result of the replastering, moisture rose / moved higher up the wall, only to evaporate through the original ash / lime mortar, resulting in the decorative spoiling and plaster damage that was now evident. The decay of the skirtings and staircase joinery was also occurring as a consequence of dampness at the floor / wall junction and where joinery was in direct contact with the brickwork.

Having completed our survey it was obvious that the two ‘free surveys’ undertaken had again misdiagnosed the dampness problem and in our opinion, the pattern and extent of dampness should have put the contractors ‘on notice’ to at least undertake further investigation, particularly in light of the property’s age and more importantly that it retained a perfectly good physical damp proof course.

Are these beads designed to stick to your hand

Are these beads designed to stick to your hand

Remedial Works

The works undertaken in 1995 were clearly a waste of time and money and unfortunately only succeeded in prolonging the problem, which the new owners would eventually have to deal with and regrettably at far greater expense.

Recommendations were made for the removal of damp plaster (from floor to ceiling height) and opening up of the cavities, so as to allow the removal of the insulation materials which were responsible for the dampness. Having removed the insulation, the walls dried down quite rapidly and eventually external render was repaired, internal plaster work was reinstated (using a permeable render /plaster) and joinery repaired and replaced.

The walls are now free from dampness and the property is dry and comfortable.

Conclusions

Cavity walls were designed and constructed for a reason, so as to provide an effective barrier against lateral rain driven moisture, the outer skin of the wall acting as a raincoat. The filling of the cavity can in some situations allow dampness to bridge and penetrate the inner walls resulting in damp staining, decorative and plaster spoiling as well as putting timbers at risk from decay.

This form of dampness is quite common in the South West and is likely to increase with the Government’s drive to encourage home owners to improve the insulation and energy performance of their homes in line with the new legislation introduced in October 2008, which requires all domestic buildings being built, rented or sold to have an Energy Performance Certificate (EPC).

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