Penetrating Damp Specialists

Do you think your property has a penetrating damp problem? Penetrating damp has various tell tale signs that differ from other types of damp.

Rentokil Property Care are experts in dealing with damp problems, and have a number of qualified surveyors who can help provide answers and solutions to stop the problem from returning.

If your property is experiencing problems with penetrating damp, we are here to help find the root cause of the problem, with decades of experience working with homes and businesses across the country.

Penetrating damp is when moisture external to a property, and typically rainwater, enters a building's structure from the outside through building defects or because the structure is below ground level. Under NHBC guidelines, this may be as little as two bricks below ground level. Over time it can cause damp patches, mould growth, deterioration of plasterwork and cause structural damage and fungal decay.

Many properties across the United Kingdom are of solid wall construction, which means they are susceptible to penetrating damp as the moisture is not prevented from entering by the cavity break. This means moisture can pass straight through to internal surfaces.

Unlike rising damp, penetrating damp will damage a property at various stories, and can appear on walls and ceilings. High external ground levels can cause penetrating damp, especially for properties with below ground spaces like basements or cellars.

Typically penetrating damp is more noticeable after periods of rainfall, or during the winter months. Because penetrating damp is often caused by building defects or a lack of regular maintenance, simple fixes or small remedial repairs from a local builder may be all that is required, rather than specialist damp proofing. A specialist damp and timber survey can provide answers to the root cause of a damp problem affecting your property.

Penetrating damp is often caused by building defects that allow rainwater to penetrate into the fabric of the property, usually through cracks, failed pointing, faulty guttering and roof coverings. Blocked drains or burst pipes will also allow water to pool around a property, which can penetrate internally and cause problems.

Penetrating damp can also be caused by spalled brickwork as over time the external face of the masonry is exposed to frost damage, causing it to fall away. Sometimes masonry is porous, and unable to stop rainwater from penetrating inside.

High ground levels externally that bridge existing damp proof courses will also allow moisture to penetrate internally. This is common in below ground spaces like basements and cellars, or properties that are built into hills.

Basements and below ground areas can be converted into habitable living space through specialist waterproofing techniques.

Penetrating damp has some identifying features that are similar to other forms of damp, which can make correctly identifying the source of the problem difficult if you are unsure what to look out for.

If you are worried about a penetrating damp problem, and would like specialist advice from a qualified professional, Rentokil Property Care have a number of CSRT/CSTDB qualified surveyors who can get to the root cause of your problem, and provide you with recommendations and long term solutions.

Here are some ways to spot penetrating damp, both internally and externally:

Cavity wall insulation is not the cause of damp problems, but if it has been installed incorrectly or affected by building defects, it can exacerbate damp problems. Cracks in brickwork, missing mortar or defective roof coverings can result in water ingress into the cavity, resulting in the insulation becoming wet and contributing towards penetrating damp problems internally.

If you have cavity wall insulation and have noticed damp walls on the inside of your property, it is worthwhile having the exterior of your property surveyed to understand where the moisture is coming from.

Rising damp occurs when there is the upward movement of moisture through capillary action, affecting walls on the ground floor of a property. This means it can only occur just above ground level, normally reaching a height of one metre above skirting board level.

Because the source of moisture that causes penetrating damp can be from building defects as well as high ground levels, this means that penetrating damp can affect both walls and ceilings anywhere throughout a building, on any floor.

Accurate diagnosis is key in order to fully understand the source of moisture causing the problem in your property. Misdiagnosis may lead to the wrong treatments being carried out, which will not solve the problem, leading to more costly repairs in the future.

While penetrating damp can often be prevented by regular maintenance outside your property, if left over time, timbers exposed to moisture can suffer from issues such as wet rot, dry rot and woodworm problems. 

Timber decay in the form of wet rot is a common problem caused by penetrating damp, weakening the structural integrity of timbers such as joists and beams. This can cause timber to become weak and spongy, and eventually lead to collapse.

Penetrating damp can also cause structural damage to masonry, causing cracks to form, mortar to deteriorate and brickwork to spall.

Internally, mould can create an unhealthy environment for occupants.

This makes it important to deal with a penetrating damp problem as quickly as possible. A professional damp survey can help provide answers on the source of the problem, and provide recommendations for treatment, if necessary.

The first step in fixing a penetrating damp problem is understanding where the moisture is originating from. This means you will need to check for damp patches internally, and the corresponding location externally, to understand what the problem might be.

Often damp problems are more complex than they appear, which is why it is recommended to have a damp and timber survey carried out by a professional surveyor, typically with a CSRT or CSTDB qualification. They will be able to find the root cause of the damp, assess the extent of damage to masonry, plasterwork and affected timber, and provide their findings in an easy to understand survey report, with recommendations for treatments, where required.

The first step in fixing a penetrating damp problem is to identify the source of the moisture.

A professional surveyor will be able to thoroughly investigate your property, and once the source of moisture has been identified, timber has been assessed and the external elevations and internal wall surfaces inspected, you will receive a survey report highlighting their findings.

This will also detail any penetrating damp repairs necessary, but often penetrating damp can be prevented by regular ongoing maintenance or minor remedial repairs from a local builder or roofer.

Building defects that often cause penetrating damp that need to be addressed:

• Defective or missing mortar
• Porous or spalled brickwork or stonework
• Cracks or damage in external renders
• Defective rainwater goods such as guttering and downpipes
• Visible damage to roof flashings, tiles or chimney breasts

For penetrating damp caused by high ground levels, elements of structural waterproofing may be required, whilst damaged timber affected by wet rot, dry rot or woodworm may also need to be addressed. Masonry protection creams can be used to create a waterproof barrier on porous masonry walls, helping prevent penetrating damp caused by wind driven rain.

If you choose to go ahead with remedial repairs, our experienced technicians will keep you informed on the processes involved, while taking care of your property from start to finish.

They will repair your property to the highest industry standards, and will come prepared with protective floor coverings, Hilti dust extraction units and vacuums in order to keep your property clean and tidy. Where possible they will cover surfaces with dust sheets in order to keep disruption to a minimum.

The costs of fixing a penetrating damp problem can vary depending on the source of the moisture, and extent of the damage. Sometimes it can be solved by simply removing blockages from drains or guttering, but in other cases it can cause damage to internal plasterwork and severe damage to structural timber. A professional damp survey can help provide answers on the extent of the problem, and costs of repairs.

Often home insurance policies will not cover penetrating damp as it is considered a wear and tear issue as it can be prevented by regular inspections and maintenance of your property. It is always worth checking with your insurance provider before carrying out repairs.

If incorrect DIY repairs are carried out you could invalidate your insurance policy. It is always recommended to use a professional to accurately diagnose the type of damp affecting your property, and investigate the full extent of damage.

Rentokil Property Care has been working in peoples homes and businesses for over 70 years, correctly identifying property issues and providing long term solutions.

We are experts in property preservation, and can provide you with personalised advice for damp problems affecting your property.