Premier Heritage has recently completed timber and damp surveys of the Victorian canopies over the platforms at 2 of the busiest railway stations on the main line linking London with the West Country.
Platform 3 at Salisbury Station that has recently been given listed status by English Heritage.
These structures which date back as far as the 1830’s provide weather protection for the main platforms and waiting passengers, and are supported on a series of cast iron stanchions and steel trusses. The structural timbers forming the canopies are of pine and underclad with tongue and grooved pine boarding.
One of the complicated Salisbury roof trusses on platforms 2 & 3.
Planned maintenance and proposed new roof coverings called for a full condition survey of the structural timbers to be undertaken. This would determine any timbers that required repair or replacement as a consequence of timber decay, resulting from water ingress / damp penetration, but more importantly would also determine any timbers that were considered at risk, so as to allow preventative works to be undertaken, along with any targeted timber treatments.
The underside of Platform 1 at Basingstoke Station.
The surveys included conventional techniques along with full moisture assessment of structural and other timbers and also included the use of the Micro Probe used for the non destructive investigation of concealed timbers. (For more information on the Micro Probe and to see it in action click here)
Moisture assessment of one of the main supporting timbers.
On completion of the surveys (which were carried out over a three month period) detailed reports were provided outlining the extent and areas of required repair and any other maintenance issues required to prolong the life of the canopies.
The underside of platforms 2 & 3 Salisbury Station.
Typical Condensation beads of water and steamed up window glazing.
Surface mould growth on walls and ceiling
Condensation (beads of water) forming under window.
The advice given below can go someway forward to helping with the control of condensation and mould problems.
The Control of Condensation
The control of condensation is based on two very simple primary measures, supported by a number of secondary measures.
Primary Measures
1. Improve Ventilation.
Condensation mould generally occurs in areas where the walls are obstructed by furniture and other stored effects.
By improving general ventilation this will sweep away the internal moisture-laden air and replace it with drier air from the outside (yes, the external air is drier than internal air most of the year!)
Use mechanical extractors and ventilation (where fitted) and keep bathroom and kitchen doors closed during use to prevent moisture movement to other parts of the house.
2. Improved Heating.
Coupled with ventilation, heating should be set or applied to give a low-level background heat. This will ensure no rapid changes to the environment, and will facilitate slight warming of wall surfaces over a period of time, thus reducing the risk of condensation.
Secondary Measures
- Remove excess sources of moisture – avoid drying clothes inside the house and the use of liquid gas and paraffin heaters.
- Insulate cold surfaces.
- Prevent other sources of water ingress and penetration.
- Install dehumidifiers, these can remove excess moisture from the air.
- In areas of continued risk to mould, wash down walls with mould / fungicidal washes and redecorate using specialist Anti-mould paints.
Further condensation advice on the control of condensation can be found in our condensation advice leaflet. Click here to download our condensation advice leaflet.
Please note that the advice given above is given in good faith and does not constitute a specification for the control of condensation, if further advice or a survey is required please contact our office.
Premier Heritage has recently completed a timber condition and defect survey of historic Worsley Court House in Salford, Manchester close to the Bridgwater Canal.
Worsley Court House was constructed on the site of the old village stocks and completed in early 1849, soon after on the 4th August the first court hearing was held where two local men were accused of fishing on the Bridgwater Canal and on the private fishing ponds of the Earl of Ellesmere. They were apparently found in the possession of a large eel and a 6lb carp, with one of the men found guilty and allegedly fined two pounds, a lot of money in those days!
Although operating as a Court until 1908, the building has been used in many ways over the years and has served as the Town Hall, as well as being used for public functions, dances and concerts, in some way fulfilling the function of the village hall. In 1973 it was purchased by the Salford District Council and is now a distinguished venue for weddings, public meetings and other private functions.
Despite its traditional external black and white timber framing and decorative gabled walls the Court House is a purely Victorian building with lavish internally panelled walls and a huge fireplace.
The building, which is now Grade II Listed, has been extensively extended over the years with numerous wings being added, however like many buildings of its age and construction it is vulnerable to the affects weathering and dampness and over the past decade or so; various structural timbers have had to be replaced due to fungal decay.
Premier have undertaken a detailed survey of the timber framing, which included the use of the Micro Drilling system and well as conventional survey techniques to advise on the on incidence to timber decay and future repair strategies.
Front entrance to the Worsley Court House
Non destructive detection of timber decay
More conventional decay detection of a corner post
The timber panelled wall of the Oak room
Closer inspection reveals wet rot decay to decorative timbers
Paul Carter of Premier Heritage was delighted to be informed that he had won the recent photographic competition held by the Property Care Association (PCA). The PCA, which incorporates the British Wood Preserving and Damp-proofing Association (BWPDA), had held a competition to find some of the most interesting photos from within the property care industry. The winning photograph taken by Paul, was one of two entered and shows what is commonly referred to as plaster fungus, it is however a specie of non wood rotting fungi called ‘Ink Cap Fungus’ (Coprinus spp), a fungi that develops on wet brickwork, plaster or timber.
‘Ink Cap’ fungus growing on the underside of a timber lintel
The winning photograph shows the fungi development on a large timber oak lintel. Our other entry, Peziza spp, was taken in a fire damaged farmhouse that had been saturated as a consequence of extinguishing the fire and its continued exposure to the weather.
Peziza; plaster fungus development on saturated ceiling plaster
These pictures along with other entries can be seen in the current publication of the industry magazine ‘Property Care’.
Micro Drilling for the Structural Assessment of Timber.
What is Micro Drilling?
Micro drilling is a non-destructive timber investigation technique allowing the structural assessment of timbers and areas that can be hidden or obstructed by decorative finishes or plasterwork and can allow for cost effective care and repair of buildings without the loss of building fabric, which is extremely important when dealing with period or buildings of historic interest.
The Micro Drill cuts a fine 1mm probe into the timber to be investigated and through measuring the speed of penetration, records variations and defects in the timber caused by insect attack, fungal decay or other defects to a computer or field printer, allowing accurate assessment of the timber without the need for full destructive opening up.
The video below shows Paul Carter putting the Micro Drill through its paces….
This system of non-destructive timber investigation is of benefit when trying to assess the condition of built in timbers such as truss ends, bearer beams and lintels etc. and can also be used for large dimension joinery timbers. The system can be of great value to Architects, Engineers and Surveyors when proposing conversion, refurbishment and repair schemes of period and historic buildings as it allows minimal interference and the ability to provide conservation approaches to the repair strategy.
To arrange a timber survey through Premier Heritage click here or call 0800 0 199 211
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
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!
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!
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
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
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
Wet rot decay affects the internal wall plates
Wet rot fungal decay affects the joists to the canter levered jetty on the southern elevation
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 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
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
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
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
This 1976 brick built Dorset bungalow retained blown fibre insulation introduced in the late 1990’s.
Wall showing rain penetration
Saturated perp end joint
Saturated motar between the brick work
Moisture squeezed from the insulation material
Cavity Wall Insulation
(What are the benefits? …..…..DAMP)
From October 2008 all domestic buildings (being built, rented or sold) were required ‘by Law’ to have an Energy Performance Certificate (EPC) to help improve the energy efficiency of the building. The EPC provides an ‘A’ to ‘G’ rating for the building, ‘A’ being the most efficient and ‘G’ the least and to-date a ‘D’ rating is currently being banded as the average.
It is claimed that around a third of heat loss in a house is through its roof and walls and currently there is a government drive (supported by television advertising and the offer of Home Improvement Insulation Grants) to encourage home owners to increase loft insulation and also to fit cavity wall insulation, as it is claimed this can save on average around £180 per annum on heating costs!
However were you aware that by installing cavity wall insulation, whilst you may well be saving some money on fuel costs, you could also be creating a major expense for the future……..damp!
Example of cavity wall insulation
The cavity wall (as we know it) dates back to the early 1900’s and is commonly found in the coastal areas around Britain, used to reduce the risk of rain penetration. In the 1920’s, local building by-laws encouraged the construction of the cavity wall and by the 1940’s it had become the Industry Standard. The familiar cavity wall (as we know it) is two leaves of brickwork, forming a 60mm cavity and tied together with metal wall ties.
Even back in the good old 1970’s concerns were being expressed over Energy Conservation and home owners were then being encouraged to introduce loft insulation and it wasn’t long after that cavity wall insulation was also being recommended.
Fill your cavities with foam, polystyrene, mineral wool or any other material you can introduce through a small hole in the wall and you will save energy and loads of money. Sounds good, but what if by introducing this insulation you increased the risk of damp to your property, which in turn would cause internal decorative spoiling, plaster damage, fungal decay to structural and joinery timbers and also accelerate the risk of corrosion to the metal wall ties.
Could that really happen? Well the answer is yes and it is.
Paul Carter, the principal of Premier Heritage, has investigated hundreds of buildings over the past 20 years of so, where damp has affected internal decorations etc and found that the damp present was due to bridging of the cavity by the earlier installed insulation materials. Whilst some of these cases were wrongly diagnosed by others as rising damp, most of these buildings (if not all) retained a physical damp proof course, the newest being a 1980’s brick built bungalow in Hampshire.
Ok, lets put this into perspective, there have been thousands of cavity built houses within the UK that have been insulated and a good majority of these don’t currently have nor will ever have a problem with damp. But there are a great number that have and no doubt more will be affected in the years to come!
Increased rainfall in past years has resulted in a noticeable increase in damp problems affecting conventional cavity-constructed housing, due to moisture penetrating / bridging the cavities and in particular on the weather prevailing elevations and this isn’t a problem relating to current rainfall, but a gradual build of damp over many years.
Rainwater driving into the masonry of a building can penetrate the outer leaf brickwork leading to the wetting of the insulation materials, increased damp penetration and a reduced thermal performance of the material. Poor construction methods, mortar and perp joints, debris within the cavities, dirty wall ties and poor installation procedures by installers all contribute to the overall problem, which generally will result in the need to remove the insulation, which is not only expensive, but will almost certainly cosmetically scar the building when finished. Unfortunately it doesn’t come out through the same hole through which it went in!
So how do you avoid this problem? Well there’s no easy answer to this other than to look carefully at the building’s construction (porosity of building materials) and its exposure to the prevailing weather conditions. If having then decided to proceed, ensure that the chosen contractor / installer, during the survey, checks the cavities and cavity trays for debris and dirty wall ties, but more importantly offers a system and material that guarantees (preferably insurance backed) that the materials being installed will not transmit / bridge moisture through and into the internal wall!
Alternatively, if you’re still unsure then don’t install.
Examples of Cavity Wall Insulation causing damp:
Cavity Foam Insulation
1970’s block constructed bugalow with poorly installed cavity foam insulation and debris bridging moisture via wall ties, cost around £800 to remove and rectify internal damage caused.
Polystyrene bead cavity insulation
Polystyrene bead cavity insulation 2
