Planning the Swimming Pool Decking

This page describes how reinforced concrete slabs should be used to support the paving and decking around a UK swimming pool. These slabs carry the paving flags across the backfilled gap between the back of the pool walls and the ground around the original pool excavation so that they do not subside. It is designed to help choose between paving flags and timber decking and describes how the decking around a pool should be supported in the same way as the paving flags.

Decking is softer aesthetically

The first question that needs to be answered is when decking should be used in place of paving flags. Decking is softer aesthetically and gives the appearance of not being a form of hard landscaping – which of course it is!

If the pool is to be installed in the middle of a landscaped garden decking may be a better answer then paving flags. However if it is intended to have meals on the area around the pool then fully grouted paving flags are best because food that is dropped can be properly cleaned up.

Another alternative is to have paving flags just at the Roman End where the sitting / eating area is and to surround the other 3 sides of the pool with decking.

Cheap decking is dangerous

When decking is being considered, the type of decking should be taken into account because of the cost involved. When decking is being used around a swimming pool where people will be walking with bare feet DECKING THAT CAN SPLINTER MUST NOT BE USED.

This more or less rules out cheap softwood decking and the more expensive exotic hardwoods have to be used in most circumstances. So do not make the choice between paving and decking until you have confirmed the cost and availability of appropriate decking material.

Decking must be supported by reinforced concrete slabs

Decking should be supported by the same type of reinforced concrete slabs that are recommended for paving slabs.

Many so-called experts will recommend that decking can be installed on lots of small pad footings and softwood timber framing. Well it can be – but it is very likely to be more costly and the likelihood of settlement is high. There is just no point in buying very costly decking and then supporting it in a way that will allow it to settle

You may also think that this is a very costly way of supporting timber decking. In practice it is not because you will find that if individual support pads are used for the decking, they are very time consuming to install at exactly the right level. The timber framework will also need to be made in treated softwood, and even when treated, this will eventually need to be replaced before the costly hardwood decking starts to deteriorate.

There is one fundamental difference between installing decking for subsequently covering with either paving slabs or decking – the top level of the concrete slabs.
Hardwood decking is normally 30 or 35 mm thick and should be screwed down onto hardwood bearers 75 x 50 mm in size. These are leveled up on mortar pads and then fixed down by plugging and screwing into the underlying concrete slabs.

This requires the supporting concrete slabs to be kept 120 below the top level of the adjacent coping stones if a step is to be avoided. It is also very important to make sure that these slabs have a surface slope away from the pool of at least 1 in 50 in order to shed rainwater. The hardwood bearers also need to be supported by packer plates so that rainwater can run beneath them.

Decking will be more expensive than paving flags

In most circumstances properly installed decking will be more expensive than paving flags and so an over-riding aesthetic consideration might be the only reason why it would be installed.