Rodent Infestations – Identifying and Reporting.

Original Article
June 10th, 2018


by Sava Technical Team & Phil Parnham MRICS, Director, BlueBox Partners
At Sava, we handle complaints on behalf of surveyors on a regular basis and from direct experience know that homeowners are not best pleased if they move into a property to find they’re sharing it with unwanted house guests. We’re focusing predominantly on rat and mice infestations as these species have adapted well to the human environment, have health implications, are common pests and can cause much upset if found in the home.

We have seen cases where homeowners have been woken by the sounds of rats crawling in their loft space and others who claimed it was “too embarrassing to invite people over to their new home”. While this could be construed as an overreaction, it’s certainly true that rodents can pose a health hazard, particularly for vulnerable members of the community. Those at risk include the elderly, the very young, people with a disability and those with health problems. It’s worth noting that rodents are among the most successful animals on earth, largely due to their ability to adapt to their environment, their natural intelligence and reproductive abilities.

Current legislation

There are various pieces of legislation relating to the control of rodents within a property:
•    The Prevention of Damage by Pests Act 1949 means that a local authority has a duty to ensure, so far as practicable, that their district is kept free from rats and mice. They must carry out inspections, destroy rats and mice on relevant land, keep that land free from rats and mice (so far as practicable) and enforce the duties of owners and occupiers of land.
•    The Building Act 1984 covers Building Regulations and the sections applicable to pest control are:
o    To secure the health, safety, welfare and convenience of persons in or about buildings and of others who may be affected by buildings or matters connected with buildings.
o    To prevent waste, undue consumption, misuse or contamination of water and to further the protection or enhancement of the environment.
o    To make regulations with respect to the design and construction of buildings, demolition of buildings, and the provision of services, fittings and equipment in or in connection with buildings
•    Section 83 of the Public Health Act 1936 covers cleansing of filthy or verminous premises. Local authorities have the power to give notice on the owner or occupier of the premises requiring them to remedy the condition of the premises.
•    Section 82 of the Environmental Protection Act 1990 explains summary proceedings by persons aggrieved by statutory nuisances. If the infestation is considered a ‘statutory nuisance’, tenants may be able to bring a prosecution to the landlord or agent under this act.
•    The Destructive Imported Animals Act 1932 and the Wildlife and Countryside Act 1981 mean it is illegal to release the grey squirrel into the wild.

Explaining rats
There are two species of rat in the UK: the brown rat, also known as the Norway rat, common rat or sewer rat (Rattus norvegicus) and the black rat, also known as the ship rat (Rattus rattus). The brown rat usually eats around one tenth of its body weight every day. Wild rats are opportunist omnivorous eaters, meaning they eat whatever they can find (including breakfast cereal) but typically, their diet consists of grains, fruits, vegetables, seeds and nuts. In suitable conditions, the brown rat can breed throughout the year and the female can produce up to five litters during this time. The gestation period is 21 days and one litter can result in up to 14 rats. The population can grow from 2 to 15 000 in just one year. The average life span of a brown rat is two to three years, while the average lifespan of a black rat is one year.

Explaining mice
Mice are a common pest, but usually more troublesome around autumn and winter. The two types of mice are: the house mouse (Mus domesticus) and the field mouse, also known as wood mice and yellow-necked mice (Apodemus spp). Like the rat, mice are omnivorous but prefer to eat grains, fruits and seeds.

Explaining squirrels
The grey squirrel may be a familiar animal in the United Kingdom but isn’t a native species. It was introduced from North America during the late 19th century. Since then, the grey squirrel has displaced the native red squirrel across most of England and Wales, although the latter has managed to hang on in parts of Scotland, Ireland, Cumbria, Northumberland and on the Isle of Wight. Grey squirrels (Sciurus carolinensis) are regarded as a pest species in the UK while the red squirrel (Sciurus vulgaris) is a fully protected species. Grey squirrels can enter domestic property in search of food and shelter and, because of their size, can cause considerable damage to properties, including dislodging roof tiles.

Figure 1 shows a grey squirrel coming out of a broken fascia board, and the damage caused.

Figure 2 shows the grey squirrel trying to re-enter the property after a mesh panel was fixed by a pest controller.  

Hazards and risks
Rodents present hazards and risks to both people and property. This is common knowledge and the reason why people want to urgently rectify any infestations found on their property.  

Rats and mice can spread many diseases, such as salmonellosis, Weil’s disease, leptospirosis, rat bite fever, hantavirus and plague. The diseases can be contracted by humans from direct contact with rodent faeces, urine, blood or saliva, inhalation of air contaminated by rodent faeces and urine, ingestion of contaminated food/water or from bites or scratches by a rodent.

Damage and financial impact
All rodents have a pair of incisor teeth in the upper and lower jaws that continually grow. They use these to gnaw at the fabric of the homes they inhabit. Because of these sharp teeth, rats and mice can cause damage to the building fabric. They can gnaw through electrical wires and plumbing and therefore cause flooding and fires in homes. They can also damage woodwork, such as skirting boards and cupboard doors and while the damage itself might not be large, the only remedy could be to completely replace the damaged entity. They can also damage possessions by gnawing through soft furnishings, paper or books.
For obvious reasons, the damage caused by rodents can have a significant financial impact on owners and occupiers, if it isn’t controlled quickly.

Contamination of water tanks
Rodents can also contaminate stored water (for example, cold water storage tanks, feed and expansion tanks). This can be through their droppings or, in the worst cases, when they drown. We know of one case where a squirrel’s decomposing body blocked the outlet of the central heating system, which had to be flushed clear and the F&E tank replaced.

Fear, stress and embarrassment
As well as physical hazards, such as damage to the building, rodents can cause a lot of stress to homeowners and tenants through both fear and/or embarrassment. For some, a fear of much smaller mammal might seem irrational, but fear of rats and mice (clinically known as musophobia) is one of the most common specific phobias. It can cause extreme anxiety, shortness of breath, sweating, nausea or shaking. A rodent infestation can also be socially embarrassing, causing homeowners to avoid inviting friends and family overdue to the noises made by the rodents in the loft or under the floorboards.  

Identifying factors of rats and mice
If rats, mice or squirrels are in residence during an inspection, there could be repercussions if it’s wrongly reported. Surveyors should be aware of the factors that indicate that rats or mice could be in a building:

•    Droppings
Rat droppings are usually found in specific locations rather than all over the area they inhabit. This means that they’re not immediately apparent, while mice droppings are usually scattered randomly. It is also common to find rodent droppings on the benching of inspection chambers. Ensure you check all accessible areas for droppings. Rats and mice can produce between 40 and 80 droppings per night, and they’re usually dark brown in colour and shaped like a grain of rice, but slightly larger for rats. If the droppings are shiny, it indicates that they are fresh, and the rodent is nearby, further suggesting the problem is active and ongoing.  
•    Urine odour
Rodents urinate frequently, giving off a strong ammonia-like smell. Keep this in mind when carrying out an inspection as it can help to establish the presence of a rodent problem. As well as a strong smell, their urine also contains minerals such as calcium, which dries to leave a chalky residue.
•    Rub marks
Due to poor eyesight, rats and mice tend to use the same routes. In doing so, they leave behind dirt and grease from their bodies.
•    Scratching noises
Scratching noises are more likely to be heard at night when rodents are more active. Brown rats may be heard in the loft, while mice access smaller areas, such as between partition walls, under floorboards, in false ceilings, cellars and lofts. It is possible for young rats to access these areas also.
•    Access holes
Brown rats excel at digging and create extensive burrowing systems, so they can take shelter, nest and store food. Rat burrows are usually situated next to solid objects or structures, while mice holes are more hidden. Mice are likely to find their way in and around the homes they inhabit through openings that already exist, such as the gaps around the drain pipes under the kitchen or bathroom sink.    
•    Nests
Rats usually nest in their burrows. Be aware that nests can also be found in lofts, under eaves and in cavity walls. They use any materials they can find, such as insulation or cardboard to shred up and use for their nest. Mice will also use soft material for nesting, which can be found in places such as lofts, suspended ceilings, cavity walls, under floorboards, behind fridges and in airing cupboards.
•    Footprints
In lesser-used areas of the property where dust may have accumulated, you might find footprints and tail marks, which can help identify whether rodents are present.
•    Water source
As rodents need access to water, rat and mice runs are likely to be found near a water source, such as a leak or a water tank.

 Reporting on infestations
If you notice evidence of a rodent infestation, you must make a clear record in your site notes and tell your client. Although there is no strict rule regarding where to locate the issue, we think you should report the matter in the element it mostly affects. For example: roof space, floors (where you notice the problem in the void), drainage or in the grounds (where you notice general signs outside). The main clause should then be cross-referenced in the ‘risks to people’ section of the report, where the possible risk to health should be mentioned.

Here is a typical clause for a HomeBuyer Report:
F1 Roof space/structure
Evidence of rodent infestation was seen in the roof space. This included:
Rodent droppings near the loft hatch;
Piles of chewed material; and
Damage to adjacent timbers.

This is a risk to the health of the occupants and could result in further damage to the building (see J3)
Condition Rating 3 (further investigations)
Rodent infestations can spread diseases and illness, result in damage to the building through their incessant gnawing and are often unsettling for occupants. You should ask an appropriately qualified person to inspect the problem and provide a report together with a quotation before you commit to the purchase.

Case study

We recently settled a claim due to a rat infestation discovered in the loft and cavity walls by new owners after moving into their property.

The claimants had a Home Condition Survey completed, and the surveyor failed to detect the presence of rats. There was, however, evidence of rat droppings in the loft space from the date of inspection, so it was not possible to defend the report. A without prejudice offer was made to the claimants to bring the matter to a swift and amicable resolution. It was important to resolve the matter as quickly as possible due to the risk of the rats causing more damage to the property. Before the claimants contacted the surveyor about the issue, they attempted to resolve it themselves with bait and traps. They also contacted the water company and arranged a full drainage inspection with CCTV to see if there were any cracks in the pipes. This inspection confirmed there were no cracks or apparent issues with the pipes and this was not the entry point for the rodents. The claimants wanted the costs already incurred, as well as the quote obtained by the pest control company to eradicate the rats, clean the area, install new loft insulation and for installation of cavity wall insulation. The amount the claimants were seeking was excessive on the basis that claims of this nature are assessed on the basis of ‘diminution of market value’. We were able, therefore, to reduce the claim amount by around 50%.
What can we take from this case?

It is important to utilise best practice to avoid missing anything important in the condition report. We never found out exactly how the rats were entering the property, however, if you identify any holes or damage in the fabric of the building under inspection, or areas where rodents can potentially enter the property, extra vigilance is necessary. It is also good practice to include a seller’s questionnaire, which includes a section asking the seller if they are aware of any issues that may affect the decision of any potential buyer. In this case, in our response to the claimants, we included that we considered it highly likely that the previous vendors of the property would have been aware of the issue but failed to disclose it to the sellers at the time of the sale. Therefore, it was our view that the claim should be re-directed to the vendors.