You have been asked to undertake a building survey of a large semi-detached Victorian style domestic dwelling. The building is two storeys with a two storey bay window to the front living space and bedroom above. It is of brick construction with solid external walls. It has a suspended timber ground floor in the living room which incorporates the bay window. There have been complaints from the residents that the ground floor construction in this room exhibits signs of ‘springing’ at the junction of the floor with the front external wall particularly in the region of the bay window.
The starting point of any survey should be the assessing of information that already exists within plans and other documentation relating to the property and site e.g. age of property, size and characteristics. The topography of the site must be assessed. It must also be ensured that all equipment required is brought along; according to the RICS the are a number of standard pieces of equipment1 required to carry out a preliminary inspection:
- A4 Clipboard: – This is required as a firm base for the sketching and note paper used to record the survey information.
- Digital Camera: – To record appearance at time of the survey.
- Steel Tape (5m & 30m) – These are used to carry out a measured survey of the building or to record measured details of various elements within the building.
- Torch: – A robust torch allows the surveyor to see into dark confined areas such as roofspaces or underfloor areas.
- Hammer and Bolster: – To lift floorboards to inspect the underfloor areas etc.
- Extending Ladder – A folding ladder that extends to a minimum length of 3m
- A Penknife – Is used when inspecting wooden surfaces or to scrape at loose materials.
- Moisture Meter – This is used to assess the moisture content of timber and plaster.
- A PH reagent – This is used to access the PH vale of timber.
- Screwdrivers – These are vital if the surveyor is trying to access an area that has been screwed closed or also to probe suspect timber for rot.
- Spirit Level (1m): – For checking of slopes in roofs and floors.
This list is not exhaustive of the equipment required to take on a survey as protective gear and specialised electronic equipment etc. can all be required depending on the particular situation encountered. Although a surveyor has at their disposal many tools they have two important tools: SIGHT and SMELL. Before carrying out the survey a checklist should be made of the main elements that need to be assessed to enable a list of any defects found to be compiled.
After ensuring all of the above are in place, a visual inspection of the property should be carried out. A typical inspection should follow a logical order, starting at the top externally (the chimneystacks) and work down to the foundations and then assess the property internally from the roof void to ground level or below if access is available. However due to the fact we have been informed that the defect is confined to the front of the property, we can focus on that area. The first point that I would visually inspect would be the external elements of the building looking at:
- Roof Structure/coverings – I would be looking at the ridgeline to try and spot any sagging/deflection in the roof, trying to identify the condition of the pointing, flaunching, brickwork and flashings and soakers of the main roof and also the roof of the two storey bay window. Also I would insepect the type of roof covering and any form of deterioration including broken or missing ridge tiles
- Windows – I would inspect the windows to ascertain if they are structurally sound, the type of window and glazing i.e. Timber framed/UPVC, single/double glazed.
- Gutters and Rainwater Goods (RWG):- RWG of older premises such as Victorian style dwelling were made of cast iron or clay and both are susceptible to damage therefore may cause leaking. It maybe that this water is gaining entry to the property. Water stains on walls could be compared with internal information to ascertain if there is any damp ingress from leaking guttering. I would also inspect the guttering to ensure it is free from a build up of debris (moss, grass, weeds).
- Walls – Photographs are a good way of recording information about the elevations: inspection of the wall surface for fractures, spalling ect. Also to be noted are the conditions of weathering to the walls and if any re-pointing is required
- Damp Courses – A check should be made to see if a damp proof course is present and if present its type (slate/felt) and general condition.(difficult to ascertain)
- Under Floor Ventilation – Due to the fact the property has a suspended timber floor, which would need under floor ventilation, which maybe provided by wall vents at ground level, these will need to be checked to see if they are clear from debris to aid circulation of air
After carrying out an external survey of the property I would then move to the internal inspection to the defects that have been reported to elements of the building such as the ‘springing’ at the junction of the floor with the front external wall particularly in the region of the bay window. When entering the property I would start by carrying out a visual inspection looking at:
- Ceilings – I would inspect the ceiling in both the living room and the bedroom above to look for staining or water marks.
- Internal Walls -Defects that would be looked for would be bulging walls and the size of any cracks and their directions also any signs of penetrative damp staining.
- Windows – I would inspect the internal condition of the windows to ascertain if they are structurally sound and to see if there is a sign of wood boring insects’ activity.
- Internal Woodwork – I would be looking at the condition of all woodwork: wood is especially susceptible to damp and therefore is vulnerable to wet and dry rot and wood boring insects. Wood will shrink (not in length but in depth) and warp if central heating dries it out too much.
- Location for services – I would be looking at any service in the area of concern such as heaters and electrical. It may be that the radiator is leaking and has gone unnoticed. It also needs to be ensured that any electrical sockets or equipment are not unsafe to use.
- Surface finishing – I would also be looking for evidence of the problem on the floor finishing, such damp patches on the carpet or water marks on a wooden floor.
A visual inspection of the property will provide a wealth of information; however there are a number of other ways to identify a problem such as by smell and touch. While walking around the property I would be searching for odours of damp and rot and also touching any areas of water marks to feel if they were still wet. I would also be checking the temperature of the rooms.
Having inspected the property and ensured that there were no leaks present; I would investigate the problem area of the floor. In order to inspect the floor joists both visually and using instruments some of the joists will have to be lifted. I would be looking for visual signs of rot by looking at the colour of the wood which can be an indication of decay. Wood-rotting fungi can be divided into two groups, according to their effect on the wood: rot brown or white (BRE Digest 345 P2). I would be looking for certain characteristics on the wood to indicate if any rot is present. Brown rot causes the wood to become darker in colour and to crack both along and across the grain; this may cause the wood to crumble to dust when it is dry and if it is very decayed. White rot will cause the wood to have a lint-like texture; however cracking will only appear along the grain; the wood will also become lighter in colour. With a wet rot the wood is soft and pulpy but with dry rot the wood will have a dry and brittle look. According to BRE, (345. P1) the most serious type of decay is dry rot which is caused by the fungus Serpula lacrymans.
Identifying Dry Rot (Serpula lacrymans)
Dry rot is only found internally in a building. The main characteristics of dry rot are the distinct musty mushroom like smell, fluffy white masses and it often has yellow patches. It may have matted grey skin or be lilac in colour and has branching grey strands approximately 2.8mm thick. A fruit body is formed at a certain age of maturity called the sporophores, which are flat pancakes in appearance with white edges and a brick red centre. This will result in the wood being dry, brittle, crumbly and light in weight. Yet another way to identify dry rot is to look at the brickwork as the grey strands of dry rot can be visible on them. Another way to identify if the problem is dry rot is to use a PH reagent: this would entail drilling a number of holes in the timber and placing the sensors in them. The sensor will change colour if the PH level of the substrate is reduced. Dry rot (Serpula lacrymans) is due to timbers becoming damp and lack of ventilation.
Identifying Wet Rot (Coniophora Pueana/Cerebella)
The main factors distinguishing a wet rot attack from the true dry rot is that wet rot requires damp timber in order to become active and spread. It will confine itself to the affected and immediate and adjacent timbers. It thrives with a moisture content of between 50-60% but also dies if the moisture is allowed to drop to around 43%. The main characteristics of wet rot are fruit bodies which are olive green to olive brown with a cream margin which is paler when young. Its surface is covered with small irregular lumps and the fungi produce strands which are cream when young but when they mature, have a characteristic brown to blackish colour. As previously noted it can be visually identified by cracking along the grain with some cross grain cracking, and another way to identify the problem is to use a moisture meter which is used to measure the moisture content of timber.
Initially dry rot can be difficult to find, as it is often found behind panelling or under floors and more inaccessible places, although it is difficult to identify the difference between wet and dry rot at first instances. It is important therefore, in the first instance, that an outbreak is identified correctly. After locating and identifying the source of the initial fault (s) and eliminating the cause of the dampness (primary control measure), attempts should be made to dry the timber by heating and ventilation at high levels which ensure rapid drying of the property. Air flow could also be increased around the wetted timbers by removing floorboards adjacent to wet walls, ‘if properly carried out, these corrective measures alone will control an outbreak of rot’ (BRE, 345. P11). Reducing the level of moisture in the property to below 40% will stop wet rot as it thrives on a high moisture content, where as the moisture content would have to be reduced to below 20% to stop dry rot thriving.
Before any secondary control measures are carried out it is important to establish the full extent of the decay and establish the size and significance of the outbreak. If there is infected timber found it should be removed extending a further 300-500mm into the apparently sound timber where dry rot is present. If dry rot is present in brickwork it must be ensured that all debris that has the possibility of being infected is completely removed. All remaining sound timber should be sprayed and treated using spray and the infected timber should be replaced with seasoned and treated timber. To be immune from attack, the measured moisture content of timber must be maintained below about 22%, and preferably below 20%. There are a number of methods for treating timber for rot, such as: Surface Spray Treatment – the treatment is sprayed onto the surface of the timber, Paste Treatment – the treatment is applied to the timber in the form of a paste and Fluid Injection – holes are drilled into the timber and fluid treatment is then injected into the timber.
Overall there are a number of issues that may have caused the original defect in the property such as a leak, damp, a problem with the gutters or rainwater goods, however the remedy must be found to the original problem or it may recur. It is also important to look for signs of insect attack on the damp timber, as timber is more vulnerable to attack if it is damp or weakened by fungal decay although dry timber is also at risk. I also know from previous experience that the rot may be coming for the property adjacent; it may be that the rot has travelled through the party wall, especially if it is dry rot, as it can penetrate through bricks and mortar and therefore travel, therefore this will need investigated. The issue of the springing in the suspended timber floor will need addressed; I would repair and replace the joists only after all the other issues have been addressed. It may also be that there is not adequate ventilation under the suspended timber and this issue should be addressed.
