With winter around the corner, we will no doubt see plenty of rainfall and it is this intensity that can often cause problems for buildings and the land around them.
For existing buildings the key is often good maintenance. Here are a few tips from our technical team to help prevent any problems:
Gutters
Ensure that gutters are in good order. Downpipes should not be blocked and connect to drainage gulley’s that are also free from blockages. Overhanging vegetation can cause blockages and material build up in gutters. This reduces the ability of rainwater goods to drain water, causing overspill, and if left, damage to the external envelope.
Drainage and landscaping
The land around properties can be affected to a greater or lesser extent dependent upon a number of factors, not least the natural geology. Stiff clays for example do not allow water to drain through easily, whereas gravels do. Landscaping can also affect drainage: hard landscaping cause’s run-off whereas soft finishes generally facilitate drainage.
When planning any landscaping of garden, drive or path areas consider drainage and where water might run off to. Provision of drainage channels at abutments with walls are essential to avoid splash back and the risk of running water saturating the external walls.
For new build properties, and particularly complex properties on sloping sites land, drainage must be considered, particularly where trying to achieve Building Regulations for accessibility or if a property has a basement.
Basements
We frequently see basement accommodation installed using the best products, but if those products are badly finished at ground level, the waterproofing and basement can become inundated not due to groundwater, but due to rainwater by-passing seals and DPC’s. There are other requirements for basements which must be considered, and reference should be made to our Technical Standards.
Penetrating water
We often see other details that can affect the integrity of a property. Properly installed cavity trays over openings (within the cavity) with weep-holes enable water penetrating the outer leaf to be captured and drained away to the external face of walls. Windows and doors need to be protected and cills properly positioned to prevent water running off and into the wrong areas. Particular thought must also be given to the aforementioned accessible areas, ramps and steps need to be constructed to shed water.
Roofs
Finally the roof: zero fall flat roofs can be problematic, although some manufacturers suggest zero falls, reference should be made to BS 6229 which recommends a minimum finished fall of 1:80, this enables quick drainage and reduces the risk of ponding. Pitched roofs also need to be carefully considered, reference can be made to Regulation H3 of the Building Regulations and the associated guidance which provides details of how to calculate sizes of rainwater downpipes and gutters as well as other information to ensure good provision is made.
Good building and site drainage is essential and as stated more-so than ever, get it wrong and there can be short term and long term issues for both property occupier and other involved in property.