| This article is about installing paving flags around an | | | | If the original ground around the pool is high enough |
| in-ground swimming pool. From an aesthetic point of | | | | and hard enough 150mm thick concrete slabs |
| view the pool itself is a small area of water that | | | | reinforced by a high tensile mesh reinforcement |
| reflects the colours of the overhead sky and the | | | | should be installed. They should be supported at one |
| pool walls and floor. It is the paving and landscaping | | | | end by the pool wall and at the other end by the |
| that makes or mars the appearance of a swimming | | | | ground around the pool that was not dug out so at |
| pool and so it is worthwhile taking lots of care and | | | | they span across the gap between the back of the |
| trouble to get it right. | | | | pool walls. Then subsidence is reduced to virtually |
| So what is the most important thing about the | | | | zero. |
| design of paving around a new swimming pool? The | | | | If the surrounding ground is to low or too soft the |
| obvious answer is that it needs to look good but | | | | levels need to be built up to support the outer ends |
| that is the wrong answer! The right answer is that it | | | | of the concrete slabs. This can be done with the pool |
| needs to be structurally stable. If it is not it may look | | | | excavation arisings in thin layers not exceeding |
| good for a few weeks but when it starts to settle - | | | | 150mm in thickness. Ideally these layers should be |
| as so many do - the whole pool will look dilapidated | | | | leveled and tracked in with a digger weighing at least |
| and neglected. The old truism in all the building trades | | | | 2.75 tonnes and the upper levels immediately below |
| that the preparation is the most important part of | | | | the slabs should be compacted with a roller or |
| the process is never truer then when applied to | | | | compactor. |
| paving around a pool. | | | | If the excavation arisings are unsuitable because of a |
| Not only is the support structure the most important | | | | high silt or clay content gravel or crushed rock fill |
| part it is also normally the most costly. In practice | | | | may need to be brought in. |
| most in-ground pools will have a gap up to 500 mm | | | | When the pool walls are not strong enough to |
| wide between the outside of the pool walls and the | | | | support these reinforced concrete slabs they can be |
| edge of the original excavation for the pool | | | | supported by concrete block piers that are installed |
| installation. The backfilling to this gap can crucially | | | | at right angles to the pool wall and 2 metres apart. |
| affect the stability of the pool walls but I will deal | | | | This adds a lot to the cost of the pool and is one of |
| with this in another article. | | | | the reasons why kit pools are really a waste of |
| The main issue from the pool paving viewpoint is that | | | | money. |
| this gap is never backfilled with properly compacted | | | | Most pools will have concrete or re-constituted |
| soil for all kinds of reasons. So when it rains and this | | | | coping stones (margelles in France). The best practice |
| backfill settles there should be a structure in place | | | | is to ensure that the top surface of the surrounding |
| that supports the paving - otherwise it will subside. | | | | paving flags are installed flush with the top of the |
| With many kit pools, the pool walls are not strong | | | | coping stones so there is no step that can be a trip |
| enough to support the weight of the structure | | | | hazard. |
| needed to span across this gap and so subsidence is | | | | Most paving flag layers prefer to lay the paving flags |
| inevitable. Because of this many pool builders do not | | | | on a bed of wet mortar that is about 50 mm thick. |
| recommend the installation of paving around their | | | | The paving flags should be at least 35 mm thick |
| pools until at least two winters have passed after | | | | because thinner ones will break up under low |
| backfilling around the pool has been completed. But | | | | temperature freezing conditions in Europe and the |
| who wants to wait two years to get their pool | | | | northern US. The top of the paving flags and the |
| looking good? | | | | coping stones will be flush if the top of the |
| Heavy pool walls, like concrete block walls , can easily | | | | reinforced concrete slabs is set 85mm below the top |
| be designed to support reinforced concrete slabs | | | | of the coping stone level. |
| that bridge across this gap. So the best bet is to build | | | | Just remember that the paving around the pool will |
| a pool with walls that can support reinforced | | | | make or mar the appearance of the pool. The cost |
| concrete slabs that in turn support the paving flags. | | | | of doing it properly should be less than 10% of the |
| These concrete slabs should be installed with a slope | | | | pool cost so there is no excuse if it is not done |
| of about 1 in 50 away from the pool edge to ensure | | | | properly. |
| that rainwater drains away from the pool. | | | | |