This is a cautionary tale.  The client was trying to sell his house and, quite openly, honestly and correctly had mentioned a long-ago problem of dry rot, which he believed he had cured.  As it had occurred four years ago and he hadn' seen any indications that it was still present, he wasn't too concerned.

However, the surveyor who carried out the Homebuyer report didn't want to take that for granted and he advised the prospective purchaser to have an 'independent' survey carried out.  The potential buyers asked a remedial treatments company to have a look.

This company, without any justification whatever, stated that the rot was still active and the cost of repairing it would run to several thousand pounds.  To cut a long story short, the sale fell through.  Rather than go through it all again with the next purchaser the client asked me to carry out a 'real' independent survey, which found nothing significantly wrong.

Ah well, one company's greed meant the loss of the sale for my client, who then had to put the house back onto a falling market.

Press the blue link above to read the survey report.

Property                                      Aberdeen, First Floor Apartment.

Instructions                             

To inspect the property and provide an opinion on the condition of timbers previously affected by rot.  In addition, a general examination of the apartment was conducted in order to provide an opinion on any areas of dampness and/or general timber rot/infestation.

Background                            

The client is selling the property, and as part of that process he is required to advise prospective purchasers of any defects he has knowledge of, either current or historic.

Therefore, on the appropriate disclosure form he indicated his belief that a rot, which he presumed was dry rot, had affected some of the flooring timbers beneath the front bedroom. He also advised that this condition became apparent in 2005 but that it was successfully treated shortly after its discovery.  In addition, the chartered surveyor who carried out the general survey is also aware of this problem has asked for further reports.

Other more general questions raised by the chartered surveyor will also be addressed in this report.    

Disclosures                             

 I am not aware of any affiliation, financial or otherwise, with the client or the property.

Limitations                              

Limited to the instructions

Restrictions                             

Some of the walls of the flat are dry-lined, i.e. they are clad with timber battens and [fibre] boards, which have then been plastered; other walls have a lath and plaster construction.  These walls were not disturbed other than to pierce them in appropriate places with a deep-probe moisture meter. 

The holes so created were filled once the readings were obtained.

Only those floorboards necessary to carry out an objective assessment were lifted.  These boards were in the bedroom and living room at the front of the apartment.

Date of Survey                         

Carried out over the 21st and 22nd May, 2009.

Weather

Mainly fine and sunny on both days, but with occasional heavy showers, mainly during the evening of   the 21st.  I am not aware of local weather conditions during the previous two-week period. 

Viewing Orientation 

Unless otherwise stated, all observations are made as if looking towards the house from the front.

Type of Property:

First floor flat, occupying the right-hand section of a three-storey building; it was constructed in 1887.  There is central heating and sealed unit double-glazing in PVCu frames.

External Observations:

The property is orientated such that its front elevation faces in a northerly direction, and it has rubble-filled, stone walls beneath a blue slate roof.

The pointing to the fair-faced stonework on the front elevation appears to be original, and as far as I could tell, it is in reasonable condition.  I did not form the impression it would allow wind-driven rain to penetrate into the property.

The stonework on both the gable and rear walls is not as precise as that on the front elevation and the pointing reflects this.  On the rear wall, it (pointing) has been repaired in places by means of ‘patch pointing’ with sand and cement mortar.  Sand and cement mortar is an inappropriate material to use on rubble-filled walls: lime mortar should have been used instead.

The modern, PVCu windows do not seem to have a flexible mastic sealant between the frames and the masonry; instead, sand and cement mortar has been used. This method of installation is inferior and the sand and cement is already beginning to crack and break off in places, particularly on the southerly facing rear elevation. Proprietary mastic sealant would have been a much better option.

The aluminium guttering on the front elevation is relatively new, and was replaced during 2005 or 2006.  I shall refer to this again, later in the report.  Unfortunately, vegetation has now taken root in this guttering and it should be cleared as a matter of urgency. This task may be possible from the windows of the second floor flat above.

The fall-pipe on the front elevation, to the right-hand side of the building, appears to be split and is badly stained with rust.  It should also be replaced as soon as possible. 

The rear guttering, which is made of metal, is in a parlous condition and also requires urgent replacement.

On the rear wall, adjacent to the central stairwell, the condition of the ground floor timber door, and also the first floor timber window, is rather poor, and the mastic pointing around both of these features is cracked and/or missing.  These faults are allowing water to penetrate into the rear wall of the communal stairwell.

Externally, there are no other observations that would influence this report.

Internal Observations:

Front Bed

This is the room where the outbreak of [dry] rot was first noticed.

With the exception of one small area, referred to below, there were no visible signs of any form of rot, either in the guise of mycelium, fruiting bodies or distressed timber.

The exception to the above was noted at the base of the front wall, just to the edge of the skirting board, where cuboidal cracking of the framing timbers has occurred. These timbers are located immediately behind the plasterboards, just above floor level, and constitute part of the dry-lining system; the presence of this type of cracking indicates rot once affected them. 

Although there was no other supportive evidence for a precise diagnosis of the rot’s species, the nature of the cuboidal cracking suggests that the organism responsible was Serpula Lacrymans, commonly referred to as dry rot.

Several floorboards were lifted and the timber joists beneath were examined.  It is clear that many of these joists are relatively new, and have been installed to reinforce the original timbers where these were weakened by rot; the old and new timbers are bolted together using metal bolts and plates.

The new joists appear to have been pre-treated against rot and insect activity prior to installation, probably by a process of pressurised treatment using Chromated Copper Arsenate (CCA). I understand those original timbers that were left in situ were also sprayed with fungicide.

This is a common method of refurbishing damaged floors and the work carried out, although not of the highest standards in terms of levels and precision etc, is nevertheless performing its function adequately. The floor is firm and does not display any undue deflection when walked upon.

There were no indications of any form of active rot in any of the timbers in this floor and their moisture content was +/- 12% w/w (N.B. rot cannot survive in timber with a moisture content lower than 20% w/w). 

I also drilled a series of holes through the surface plaster on the front wall, in an area ranging from just above floor level, to a height of two meters. Using a deep probe MMS moisture meter I then obtained readings from the both the timber framework and also the masonry itself.  In the case of those readings obtained from the timber, the highest recorded level was 16%; and those taken from the masonry did not indicate the need for further investigations (meter readings taken from masonry are not quantitive and as such are used for guidance purposes only).

I did not notice any instances of active insect infestation in any of the timbers in this room.

Living Room                             

Sections of the hardboard overlay were removed and the timber floor beneath was exposed.  Floorboards were removed in the area adjacent to the front wall and the flooring joists beneath were examined.

There were no indications that rot has ever affected any of these timbers and their moisture content was <15% in all cases.

I also took deep probe moisture meter readings in a similar manner to those mentioned previously.  None of these readings indicated that rot could occur to the framing timbers beneath the plaster surfaces.

There are indications that wood-boring insects once colonised some of these timbers in this floor but it is equally obvious that any infestation died out many years ago, and the problem is historic. Certainly, there is insufficient evidence to justify treatment with insecticides at this time and I do not expect this situation to alter in the foreseeable future.

The area in the rear, right-hand corner of this room was also examined, in line with the observations made by the chartered surveyor.

Other than for stains on the surface, there were no indications of any form of distress, and the moisture content of the timbers was below the level at which rot could either initiate or flourish.

This should not be taken as meaning that the original fault that caused this staining has been cured or that timbers beneath the bath have not been affected. It may be that there has been a leak on the plumbing beneath the bath, but as I had neither the time, nor the equipment available to remove/replace the bath panel, I cannot be sure.  Removing this panel would not be a particularly onerous task but it will require the services of a joiner.

Kitchen                                     

There has obviously been a problem that has affected the ceiling in the rear, left-hand corner of this room, and this area has been re-plastered.  I have no knowledge of this problem and can only comment that if it was a result of a leak, this is no longer occurring, and the entire area is now dry. Any timbers that may have been affected, perhaps by a leak from the apartment above, will not be suffering from any form of active rot.

Rear Bedroom                          

There were no indications of any problems in either this room or the small annexe leading from it.

Bathroom                              

I did not find any problems in this room.  However, as noted previously, the bath panel should be removed and the plumbing beneath the bath should be inspected for leaks.

Communal Hall/Landing Several areas of the rear wall recorded high moisture meter readings, although there was little in the way of physical distress to the wall surface itself.

I think these readings have occurred because of the poor condition of the pointing on the rear wall and the damaged mastic pointing around the door and first-floor window: together these faults are combining to allow wind-driven rain to enter into this wall.  At the moment it is not a major problem but it will not be resolved until the wall is re-pointed and the mastic replaced.  The window and door should also be re-decorated at that time. 

If the situation is not addressed, the internal surfaces of the wall may eventually become damaged and the timber staircases themselves could be placed in jeopardy. 

Discussion                              

The description of the symptoms, and the chronology of events described by my client indicate that during 2005 and 2006 this property was affected by dry rot; and that this was probably caused by the poor condition of the front guttering, which had allowed rainwater to enter into the rubble infill of the front wall. From there it soaked into the framing timbers and floor joists in the front bedroom.  Both of these timber components are in direct contact with the masonry comprising the front wall.

Although theoretically dry rot can affect timber with a moisture content of 20% w/w, in practice it will not usually occur until a level in excess of 27% w/w is reached. Leaks from plumbing fixtures and rainwater goods are easily capable of producing this level of moisture in timber and as such are the commonest moisture source for activation of dry rot. It is almost certain that in this case, the defective guttering was responsible.

Once this rot has established, it can be quite virulent, and Building Research Establishment (BRE) experimentation has indicated that under favourable conditions it often spreads by at least 800mm per annum; and will continue to grow at this rate as long as it has a supply of food (timber), water and air.  The removal of any of these essential requirements will result in its demise.

The last statement is particularly relevant, and in practice one of the best ways to eradicate dry rot is to remove its source of moisture, and then to promote rapid drying of affected timbers.  This is known as the ‘primary cure’. 

Once this is done, the next stage of treatment is to remove any affected timbers and replace, or augment them, with new ones. Ideally, all affected timber will be removed but often this is not possible, especially where this would result in excessive damage to other features, such as walls or panelling etc. In these instances it is acceptable to leave timbers in situ, but with the express proviso that their moisture content is kept below the ‘trigger’ level of 20% w/w at all times.

Such a ‘primary cure’ was applied in this instance: the source of moisture was removed by repairing the leaking guttering; the floors were opened up to allow rapid drying; and the damaged sections of the structurally significant timbers, i.e. the floor joists, were removed or augmented by use of new, pre-treated timbers.

The framing timbers behind the wall surfaces were not removed because of the considerable damage this would have inflicted on the property’s internal wall surfaces; but as noted above, at the time of my inspection none of these timbers had a moisture content above 20% w/w, and as long as this situation continues, they will not be in jeopardy.

It is therefore worthwhile to reiterate at this point that the guttering, particularly on the front wall, must not be allowed to leak; and the grass that is presently growing in it must be removed as soon as possible.  If this is not done, the leak could reoccur and the rot could begin again.  It is often that a lack of attention to maintenance precedes this rot, and this is an ideal example of that situation.

I am content the rot did not extend beyond the bedroom, and did not affect the timbers in any other rooms, particularly the living room, which is also on the front elevation.  The timbers in the floor in this room have not been replaced, and there are no indications that any type of rot has ever affected them. There are clear signs that in the past, woodworm has been active in the floorboards in this room, but this activity has long ceased, and treatment with pesticides is not necessary at this time.

I cannot comment on the timbers beneath the bath, as I could not access them.  However, and as mentioned previously, the moisture content of the floor to the rear of the living room is below the danger level and I would be surprised if any timbers in this area are presently suffering from rot.

I am not sure who has responsibility for the internal staircase but the rear wall is showing signs of water ingression, and this may eventually create problems for the communal staircase.  This problem has probably been occurring for some considerable time and is almost certainly due to the poor condition of the pointing on the external face of this wall. 

Repairs, in the form of patch pointing, have been carried out in the past but these have been done with a sand and cement mortar.  This type of mortar is wholly inappropriate for use on solid walls, as it easily cracks and allows wind-driven rain to enter into the masonry. There is an article on this problem on my website, which can be seen at the following address: www.pdoyle.net/content/view/48/53/.

Conclusions:                            

The [dry] rot that once affected this property is no longer active, and unless conditions within the property change, this situation will remain constant.

The significant danger is that posed by the guttering on the front and rear elevations.  To combat this, the grass now growing in the front guttering should be removed as soon as possible, and the metal guttering on the rear elevation should be replaced.

At the same time, any fall pipes associated with these fixtures should be inspected and replaced as necessary.  In particular, the fallpipe to the front, right-hand side of the building should be replaced.

Ongoing maintenance to these items is essential, and an effective regime should be introduced to deal with this.

The pointing on the rear wall should be raked out and replaced with a lime-based mortar.  This also includes the latterly applied sand and cement pointing.

The mastic seals around the door and window on the rear elevation should also be raked out and re-made.  These items should then be decorated. It would also be advisable to ensure that flexible mastic seals are applied to the PVCu windows on both elevations.

There are indications that water has leaked into the space beneath the bath, although presently this does not seem to be causing significant problems.  A joiner should remove the bath panel and the plumbing etc should then be examined.  The sealant around the bath should also be checked.

I did not detect any problems with the [historic] repairs to the kitchen ceiling.

I trust the above is satisfactory for your purposes but if you require further clarification please do not hesitate to contact me.

Surveyor                                  Patrick F Doyle CSRT M. Inst. R.T.S.

Date of Report                           May 2009