Archive for September, 2009

Sep 28

A recent inspection of a 1930’s mid terraced house in Wiltshire exposed a farcical series of events due to the incompetence of the Chartered Surveyor undertaking the Home Buyers Survey and also the damp proofing specialist who (on the recommendation of the Surveyor) followed him.

This traditional cavity brick built, mid-terraced house was subjected to a Home Buyers Survey, which identified dampness within the front living room and rear dining room walls, as a consequence of which recommendations where made to instruct a Specialist Damp Proofing Co to undertake a full survey (standard recommendation) and carry out any remedial works.

After an investigation by a local damp proofing company, rising damp was identified and recommendations put forward for a chemical injection damp proof course and re-plastering to the value of £1800 + Vat.

No visual evidence of dampness to the front bay window

No visual evidence of dampness to the front bay window

 
Apparently happy with this quote, the prospective purchaser’s builder expressed his concerns with the diagnosis, as the property had (what appeared to be) a perfectly good slate damp proof course (as was installed at the time of construction) visible to both the front bay and rear dining room external facing walls.

A second opinion was sought and Premier Heritage were invited to undertake a survey of the property for Structural Dampness which found the following;-

  •  No obvious external defects or sources of moisture
  • No apparent internal decorative spoiling (other than badly applied wall paper)
  • No obvious plaster deterioration
  • No surface mould growth
  • No significant levels of moisture within the skirtings or adjacent timbers
  • However, high and consistent damp readings to ceiling height on both walls.

Question………What type of dampness would cause this?

Answer……….  The Metal foil backed paper type of dampness. 

Lifting the wall paper expose’s the metal foil paper responsible for the damp readings!

Lifting the wall paper expose’s the metal foil paper responsible for the damp readings!

Wrong Diagnosis

The damp problem had been incorrectly diagnosed, as it was metal foil paper (under the wallpaper) that was interfering with the damp meter, causing it to give the readings. The user should however (if he had known what he was doing) been ‘put on notice’ to the fact that the readings were consistent throughout the walls height (unusual) and that there was no obvious spoiling of decorations / plasterwork etc.

This should have at the very least, made him suspicious and he should have looked beyond the damp meter readings. More importantly is the fact that the property had a fully effective physical damp proof course.

The Outcome

The survey and investigation of dampness in an occupied house can sometimes be restricted as destructive investigation cannot always be carried out or approved. The misdiagnosis of dampness in buildings generally results from the misuse of the ‘moisture meter’ as in this case, but one should not rely on the moisture meter alone and should depend on the surveyors experience, eyes and common sense, all of which will tell him far more than the moisture meter alone. But such instruments are there to support and aid in the diagnosis of dampness (if used correctly) and as such their importance should not be overlooked.

We were somewhat surprised that the Chartered Surveyor had failed to identify the problem and far too quickly ‘passed the buck’ to the damp proofing company. We were however not too surprised with the damp-proofing surveyors findings as he was not only inexperienced, but also held no formal qualifications in damp surveying.

The foil backed paper had been applied to the walls due to the colonisation of mould during the winter months, the mould clearly a symptom of a seasonal condensation.

The foil paper, marketed as an aid to ‘damp control’, was naively applied by the Vendor in an innocent attempt to eradicate the mould, which clearly was never going to happen.

Premier Heritage identified that no structural dampness existed within this property and therefore no works were needed. Following the removal of the foil backed paper and redecoration they all lived happily ever after, apart from the surveyor and the damp-company who were asked to  contribute towards Premier Heritages costs, which could have been avoided had they looked beyond the end of their noses!

Sep 17
In early August Premier received instructions to undertake a timber condition survey of the signal box located at Ryde St John Station on the Isle of Wight.

The station, which opened in August 1864, was the Isle of Wight railway’s northern terminus, (one of three stations in Ryde), before being expanded in 1866 to accommodate the opening of the new Ventnor to Shanklin line.

Ryde St John Signal Box

Ryde St John Signal Box

The islands railway now boasts an annual passenger usage of around 170,000, being the only commercial public transport railway line on the island and relied on by many local residents for access to other parts of the island.

The timber framed, two storey signal box originally located at London Waterloo East, was dismantled in 1926, timbers numbered and moved piece by piece to be re-erected at its present location. This is the only operational signal box on the Isle of Wight line today and hence it has become known as the ‘Island Line Signalling Centre’!

No fancy computerised systems here! All hand operated by an experienced Signalman

No fancy computerised systems here! All hand operated by an experienced Signalman

Premier’s brief was to undertake a detailed investigation of the main structural supporting timbers and to prepare a specification of repair and preservation to allow for the continued use of the Signal Box well into the 21st century.

The main soft wood timber frame which sits on a concrete ringed foundation suffers from wet rot fungal decay and general deterioration, in part due to general weathering and the lack of routine maintenance, but also as a consequence of past flooding that affected the track and station buildings in the early and late 1990’s. Investigation of the timbers included the use of conventional survey techniques and moisture measurement, but also Micro Drilling using the Sibtec Digital Probe to determine the integral condition of the main wall plates, cill beams and large corner posts.

Significant wet rot fungal decay affecting the large corner posts  and cill beams

Significant wet rot fungal decay affecting the large corner posts and cill beams

Wet rot decay affects the internal wall plates

Wet rot decay affects the internal wall plates

Wet rot fungal decay affects the joists to the canter levered jetty on the southern elevation

Wet rot fungal decay affects the joists to the canter levered jetty on the southern elevation

Sep 04

When the owners of a farm house suffering with damp problems needed a damp proofing solution Premier Heritage were on hand to assist with a traditional solution to damp.

This detached, stone built former Devon Farmhouse was refurbished by its previous owners in the 1970’s and unfortunately like many properties of this age was stripped of much of its original fabric, including its lime plasterwork, renders and pointing mortar.

Farmhouse prior to damp proofing taking place

Farmhouse prior to traditional form of damp proofing taking place

In early 2008 Premier Heritage received instructions from its new owners to undertake a full survey of the property for dampness and associated defects and to put forward a specification for remedial works to deal with the dampness present and any associated defects.

Drying out the dampness in the property

Drying out the dampness in the property

The main areas of concern identified by our investigation confirmed the presence of rising and penetrating dampness affecting various walls, although the latter mainly affecting the weather prevailing elevations and most noticeably the front sitting room, rear drawing room and stair area. No structural dampness was identified at first floor level.

As a consequence of the longstanding dampness to the lower sections of the south and western walls, several timber lintels were also showing signs of decay (some having already been replaced) and also death watch beetle activity.

Lintels showing signs of death watch beetle activity and fungal decay

Lintels showing signs of death watch beetle activity and fungal decay

The structural timbers supporting the half landing were also affected by wet rot where bearing into the wall as were numerous skirting and window boards.

To the western wall there was also the added complication of raised external ground levels sloping towards the house and also an obvious, insufficient overhang of the thatched roofing, increasing moisture at ground level and within the walls.

Replaced timbers

Replaced timbers

It was established that the conditions affecting this property had resulted as a consequence of the building’s past refurbishment and the removal of the original permeable mortars and renders used in the buildings original construction (i.e. the lime plaster, bedding and pointing mortar etc). Subsequent replacement with modern cement, being less permeable has resulted in dampness becoming trapped within the fabric of the wall ‘due to its inability to breathe’. This problem has built up over many years being further compounded by the numerous layers of masonry paint applied to the walls over the past 30 years or so!

Premier Heritage’s specification for remedial works concentrated on the removal of the cement materials (both inside and out) to allow the walls to dry down, along with subsequent repairs to structural and joinery timbers. The main contractor was appointed and the works were project managed by Premier Heritage.

The first task was to remove the external paintwork and cement pointing which was impermeable and trapping moisture / dampness within the wall’s, increasing the levels of dampness and internal damage to the building’s fabric. Having removed all external coatings and cement mortar (including that to the interior of the sitting room) the walls started to dry down.

New oak lintels were introduced, where existing were structurally unsound and timber repairs were completed to the interior staircase and landing etc.

Ground levels to the western wall were also reduced, with improved drainage and a vertical slate barrier fitted to the lower sections of the wall to minimise damp penetration.

Following the drying period re-pointing commenced to the exposed stone walls and this was undertaken using a lime based (permeable / breathable) mortar, after which the building was re-thatched and finally redecorated throughout.

The building has now been restored to its former condition and is dry and comfortable as well as looking great!

The finished farmhouse free of damp

The finished farmhouse free of damp

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