Premier Heritage have over the years undertaken investigation of some fairly horrendous attacks of fungal decay in all types of buildings which occurred as a consequence of unwanted moisture ingress and resulted in extensive damage to the interior fabric of the building, the loss of structural and joinery timbers and more importantly distress and expense to the property owners.

In a lot of cases these attacks could have been avoided with simple routine maintenance, cleaning of guttering drains etc which are one of the major contributors to fungal decay, particularly the dry rot fungus Serpula lacrymans.

When one undertakes a survey for fungal decay the initial objective is to establish the source of moisture responsible for the attack, however our recent investigation of a 1930’s detached bungalow, initially failed to identify the cause of a significant outbreak of decay that affected the two (back to back) bedrooms.

Our client’s first indication of anything being wrong was the discovery of a fruiting body on the external corner of a skirting, followed by deflection of the flooring this resulting in her vacating the room and her subsequent contact with ourselves.

Dry rot fruiting body on skirting board

On arriving at the property and commencing our survey the first observation made was that the attack was well away from any obvious internal sources of water (bathroom, kitchen etc) although could have been the result of a radiator pipe leak below floor level, although this may have become obvious to the occupants.

External inspection again confirmed no obvious down pipes or drainage systems adjacent to the decay and the property had a physical damp proof course and walls tested (using a moisture meter) detected no dampness to be present or to adjacent joinery, other than the skirting board above. One observation made however was that new sub floor air bricks had been fitted on to all elevations.

Why has the property got new airs we asked? We had cavity wall insulation installed about 3 years ago …………… alarm bells started to ring.

To cut a long story short having lifted the flooring within the front bedroom we discovered an extensive outbreak of fungal decay which extended through the internal wall into the rear bedroom covering around two thirds of the floor area in each room and evidently starting close to the location of the external wall and an air vent.

Dry rot in subfloor void

Dry rot mycelium growth

Dry Rot attack

The extent of the attack exposed following removal of the floor timbers.

Upon closer inspection however we discovered that the internal vent apertures had been blocked with cavity wall insulation and also found that the internal aperture didn’t align with the air vents located on the external wall.

Insulation materials evident in air vent aperture

Cavity brushes used to prevent insulation blocking air vents, although aperture clearly does not go through the wall.

During our initial survey we broke out several of the external air vents establishing that whilst the new vents installed had apparently been sleeved across the cavity (to prevent the materials blocking them) on removal they were not sleeved, but  fitted with cavity brushes, which served no practical purpose. Therefore the insulation had blocked the cavities, preventing air flow to the sub floor timbers, thus changing the environment within the sub floor void, creating damp conditions, sub floor condensation, thus resulting in the wetting of timbers and eventual development of the fungal attack.

Having established the cause and extent of the decay a specialist timber treatment contractor was appointed, undertaking the repairs and treatment of the floors, walls were re-plastered (where removed for cavity clearance) and new joinery fitted. Once the floors had been opened internally and aired and the cavities cleared etc the entire area dried down quite rapidly.

More importantly however was that every air brick fitted to the bungalow had to be individually broken out and subsequently replaced with sleeved vents directly through the walls to the sub floor area, thus reinstating the original sub floor ventilation, if not improving it!

From the point of discovering the decay to the re-occupation of the bedrooms took around 6 weeks and we are pleased (on this particular occasion) to report that the original contractors responsible for the installation of the cavity wall insulation have accepted full liability for the fungal decay as well as all costs.

How to avoid future problems? We at Premier have inspected and reported on numerous cases where Cavity Wall Insulation materials had caused bridging of moisture through the cavities, resulting in internal dampness and spoiling of decorations etc. Whilst our own evidence suggests that installers have tightened up on their pre-installation procedures in recent years, property owners still need to be aware of the potential issues that can cause future problems and expense (particularly if the installer is no longer trading).

Energy conservation is now government lead and more and more homes are being insulated, but it is important that prior to installing Cavity Wall Insulation  pre installation checks are undertaken by the installer which should include the most important factor, its suitability for cavity wall insulation i.e. the building’s construction (porosity of building materials) and its exposure to the prevailing weather.

Other checks should include visual inspection of the actual cavity at Damp Proof Course level, checking the cavity trays for debris and also for dirty wall ties, all of which are capable of transmitting moisture through a wall. More importantly check that the system (installation and materials) are covered by guarantees, preferably insurance backed.

We were called in to advise the owner on the type and causes of wood rot affecting the plywood timber decking forming the accommodation area of the motor home, this recently discovered during his routine ‘spring clean’ of the vehicle in preparation for use over the summer.

Motorhome with a wood rot problem

The obvious cause of the wet rot decay was due to the timbers contact with moisture, in part due to the poor detailing and water proofing of the structure beneath the vehicle and the sawn ends of the decking which are exposed within the side storage boxes.

Wet Rot affected timbers

Wet Rot in a side storage box

We are pleased to confirm that with a bit of help from Premier Heritage the owner has now reached a satisfactory agreement with the suppliers / manufacturers of the vehicle and repairs / modifications are currently in hand.

What to do if you suspect Wet Rot in a motorhome / caravan

It is important to get any signs of wood rot checked out by a professional qualified surveyor  who will be able to diagnose the type of wood rot (Wet Rot, Dry Rot etc) and help advise the best cause of action to take.

It has become extremely popular over the past decade or so, to rip up those carpets, drive down to your local timber yard and purchase and lay that beautiful oak floor that you’ve always craved for!

Costs a lot of money, but hey………. it looks great, feels great and more importantly will last for years.

But hang on, what’s this…………. You start to notice little holes appearing in the floorboards, what can it be? Its woodworm, the little blighters have got into my new floor.

However the culprit in this particular case is unlikely to be your ordinary woodworm the Common Furniture Beetle (Anobium punctatum) as generally found in domestic housing, as well as period and commercial buildings, but is more likely to be Lyctus Brunneus, otherwise known as the Powder Post Beetle.

Powder Post Beetle following emergence from oak floor boarding

Powder Post Beetles are insects that attack the sapwood of wide pored hardwoods such as Oak & Elm and over the last 10 years or so we at Premier Heritage have investigated numerous cases of this particular insect. It seems to be becoming more frequent with reported cases most commonly in flooring, but also identified in new furniture, as well as structural and decorative oak timbers introduced during new build construction.

Powder Post Beetles attack the sapwood that has a sufficient starch content (greater than 3%) and it is evident therefore that it is a very specialised insect indeed and has very specific requirements, especially in relation to starch. Indeed, it is the starch content of potentially susceptible hardwoods which make them prone to attack by the Powder Post Beetle.

It should however be noted that as wood ages the starch content declines (due to bacterial action) and therefore after around 10 years or so, the levels will have dropped so that infestation/activity is no longer possible.

Furthermore, given the special requirements of the insect it is not going to infest the existing old hardwood timbers (if any) or those softwoods found in housing.

Given the very special requirements of the insect and the wood it attacks (newly converted wide pored hardwoods with sufficient starch content), then your normal domestic house will not contain such timbers, except where they have been introduced to form a new hardwood floor.

Powder Post Beetle damage to a newly laid oak floor

It is also extremely unlikely that this insect will fly into your property where such susceptible timbers have just been laid, but almost inevitable the insect would have been introduced with wood already infected; this occurs where such wood may have been stored, i.e. timber yards, furniture manufacturers etc.
 

What to do if you find Powder Post Beetle in an oak floor

If you find woodworm in your new Oak floor what should you do?

• Well firstly the infestation needs to be correctly identified; incorrect identification could result in unnecessary chemical treatments being applied and as such the floor should therefore be inspected by a qualified Timber Infestation Surveyor (CTIS or CSRT).

• Having identified that the infestation is the Powder Post Beetle then it should be considered that the flooring materials would almost certainly have been infested prior to purchase and being laid in your property. You should therefore consider taking the following initial action.

Contact and advise the contractor who laid the floor (this is with whom your contract would normally be formed) or the suppliers of the timber, that the flooring is infected by woodworm and as such should be considered ‘defective’ and not of merchantable quality.

Powder Post Beetle frass and beetle emergence holes

If the wood is of aesthetic value then it may be argued that the damage (holes) make it not fit for its purpose. If one examines the wood and finds elongated surface scoring then this indicates that the damage was present when the wood was sawn and planed, i.e., long before you bought and laid it in your property.
 
You should then consider the following actions:

1] Ask for the wood to be replaced as it was supplied defective.
2] If the damage is very minor (on a few sapwood edges), then you could consider using an ‘injector’ to apply a wood preservative into the holes and this could be an acceptable solution. Nevertheless, inform the supplier of the problem and it may be prudent to put them ‘on notice’ that if the infestation should worsen then you will expect them to take appropriate action over it.

Note: Do not chemically spray the entire floor! Most floors retain some form of stain or varnish that would limit chemical uptake. Also treatment in most cases, to be fully effective, rely on chemical being applied to both sides, which after the floor is laid won’t be possible, and clearly to lift the floor would be very expensive, and almost certainly cause irreversible damage.
 
Finally, don’t let the supplier of the timber fob you off with the ……”It’s nothing to do with us mate – you’ve got woodworm”. Yes you have, but inevitably this insect was brought in to your home with the new hardwood, and it is therefore certainly the supplier’s problem.

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.

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

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

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

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

1920’s brick constructed house, south facing elevation with polystyrene bead insulation and poor quality mortar. Caused extensive damp to internal decorations and accelerated corrosion of wall ties (rusting ends just visable), cost in excess of £3,500 to remove insulation and install new wall ties.