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September 2015

Question

I purchased a house in January mainly due to the fact that the property had an extensive back garden.When I was viewing the property, the weather was quite bad and I assumed that this was the reason why the garden was so boggy.

Having lived here for six months, the garden is still boggy and having discussed the issue with my neighbours, it would appear they are experiencing a similar situation. I imagine I need to install a drainage system.

Essentially what I am looking for is advice on this process. What is involved, will it cause much disruption during installation, will it be quick and effective and is it costly?

Answer

 The issue here is that the ground is retaining water. This is either due to the fact the ground is low-lying and most of the surface water is draining to this area or alternatively the ground conditions have a poor natural drainage. If the issue is as a result of the former, ie low-lying ground, it can be extremely difficult to do anything about this as in effect the actual finished ground level is either at or very close to the water table, ie the water level within the ground. In instances such as this, you could effectively be in a flood plain.

Historically developers took appropriate account of such sites and generally avoided building on them. However the recent building boom and scarcity of land, coupled with poor planning decisions mean there have been some more recent developments in such a situation.

If this is the case, it can prove extremely difficult and expensive to solve the issue and you could find yourself having to artificially reduce the water table by incorporating a sump and pumping excess water away from the site.

While such scenarios exist, this is the less likely of the two situations.

It is more likely that the water lodging here is due to poor natural drainage and this can more often than not be addressed by improving the drainage. This will involve digging trenches, inserting perforated pipes and back-filling with gravel before reinstating the ground.

Whereas this is disruptive, it is relatively inexpensive, particularly if there is good access for machinery. If the access is poor, excavations may have to be done by hand and this tends to increase the costs.

The fact that your neighbour is experiencing a similar problem complicates the situation, because ideally the neighbour should also address the issue in their garden at the same time in order to be fully effective.

It would be necessary to undertake a specific site survey to identify the ground levels and/or soil type to decide on remedial works required. Your local chartered building surveyor will be able to assist you in this regard.

Val O’Brien is a Chartered Building Surveyor and a member of the Society of Chartered Surveyors Ireland.