Primary Causes of Damage to Drains
Unfortunately, on occasion it is necessary to carry out essential repair work to your drains.
Damage to the system can occur for a number of reasons including:-
Root ingress - One of the primary causes of blockages in the UK is root ingress; this occurs when tree roots have gained access to the pipe through cracks and joints and continue to grow within the pipe, causing obstructions and further damage.
General wear and tear - Over time pipes can deteriorate, causing weakness within the pipe walls leading to the collapse of the pipe.
Ground movement - Movement of the surrounding ground can apply force to the pipes which can lead to cracks, dislodged joints and total collapse of pipes. The cause of this is generally due to the changes of moisture content within the ground, which has an effect on the volume of the soil / clay. For example, flooding, or drying out of the ground. This cause is more consistent with older properties, as clay and subsoil was typically used for surrounding and backfilling of pipework, as opposed to modern properties, where pipework is surrounded with gravel, alleviating the problem to some extent.
Freeze Thaw - Another reason for damage to drains is freezing and thawing. The ground contains a large amount of water; in cold weather this water can freeze causing expansion, subsequently the ground may heave upwards. As the ground thaws in the warmer weather, the earth will settle back down. This cycle of freezing and thawing can cause the pipework to sag, which over time can result in a complete collapse.
Indications that you have a damaged drain:-
- Foul smell, to front, rear, or inside your property
- Drains backing up - ie overflowing manholes, external gulleys overflowing, toilet water not flushing away
- Localised wet patches or boggy ground around your property
- Sinkholes - depressions in the ground around your property
- Cracked walls or floors within or to the outside of your property
What to do
If you suspect that your system has sustained damage, we would suggest that the first port of call is to identify who is responsible for the maintenance of the drain. Generally speaking, you are responsible for the drains within the boundary of your property, and the local water authority are responsible for the drains and sewers outside of the boundary, although if drains are shared with other properties this can be a little more complicated - see diagram below to give you a general idea. In the event that the issue is within an area of local authority responsibility, they will be compelled to carry out the necessary repair; however, should you, the property owner fall responsible, you will need to organise for the repair work to be carried out yourself. This can be costly, so it is worth checking your insurance cover, as you may be protected. Our advice would be to approach local drainage companies, who can be found advertising online.
A good drainage company will usually carry out a cctv camera survey, (this is also likely to be required if you are making an insurance claim). The camera survey will reveal the exact condition of the pipes and will accurately pinpoint the location of the problem. From here, the drainage company will offer its recommendations for repair, and provide you with a quote or estimate for carrying out the work. Where possible, get a fixed price quotation, although it must be appreciated that this is sometimes not feasible due to unknown ground conditions and the extent of what will be required to achieve a robust repair.
Some drainage companies can also offer to manage the insurance claim on your behalf.
Methods of repair
Drain relining (Cured-in-place) - Drain relining is a process or repairing the pipe from within the pipework itself, removing the need to excavate and replace the pipework, offering substantial cost savings. It involves inserting a strong internal lining sock into the affected pipe, that is then expanded and bonded to the internal walls of the existing pipe with a strong resin. The resin helps to fill cracks and joints and creates a smoother, stronger pipe within the pipe. Many contractors can offer this service, and the process is normally complete within a few hours, dependant on the extent of the work required.
Drain relining (Slip Lining) – Slip lining is the oldest process of trenchless pipe repair, and involves a rigid tube being inserted as one single piece or separate segments. Slip-line tubes are normally made from HDPE or fibreglass.
Excavation and replacement - in situations where relining is not possible or the extent of the damage is too severe, the only option may be to excavate and replace a section of the pipework. Many factors can affect the cost of this option. For example, if the pipework is below a patio, block paved or tarmacked driveway, the cost of reinstatement on completion of the repair will have an effect.
Typically the contractor will initially identify the location of the problem, excavate down to the top of the pipe, hand dig around the pipe, remove the damaged section, cut back the pipes to a clean face, install a new section of pipe, surround the pipe with gravel material, backfill the excavation and reinstate the surface.
Sometimes, if only a minor repair is required, it may be possible to carry out the repair work yourself. Although we always recommend consulting with a professional, should you wish to go ahead, you may find our guidance videos useful (coming soon).
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