By Lance Anderson
The past several years of weak pool construction activity, especially in the U.S., has highlighted the value of identifying alternative revenue sources for pool industry professionals. Finding and fixing leaks in existing swimming pools has become an area of great interest as it provides pool builders with several options for specialization and many opportunities to generate revenue. One such opportunity is crack repair in concrete pool shells.
When dealing with a leaking concrete pool, the leak professional and customer are faced with several repair options, including simple topical repairs (performed while the pool remains filled), permanent crack injections or extensive concrete removal and structural re-engineering. Method selection should be based on the severity of the crack, permanence of the desired repair and customer budget.
What’s the problem?
A number of things can cause cracks; some are the result of poor workmanship or the materials used during construction. These cracks usually appear soon after construction and are generally not the leak professionals responsibility.
Cracks that develop in older pools and result in water loss, however, are a different story. The first step in any repair job is to try to understand what caused the problem in the first place, and determine if this force will continue causing crack movement in the future. If the crack, for instance is a result of a one-time event, such as an extremely cold winter or shell movement due to the pool being left empty for a long period of time, little additional movement should be expected. However, if it is caused by re-occurring ground expansion and contraction (e.g. soils that expand when moist and shrink when dry), continued crack movement should be anticipated and any repair should take this into consideration. The most serious problems result from ground conditions that are continuously undermined and are expected to continue degrading thus causing cracks to continue growing.
While some of these problems can be solved with tools and techniques available to the average leak professional, situations involving erosion or slope creep (where a pool may be built on a hillside and the supporting soil settles downhill) are generally handled by a structural or soil engineer.
Sometimes a bandage will do
The simplest and least expensive type of crack repair is a topical patch. These repairs are applied to the surface of the crack and can be made with a variety of epoxies and sealants, many of which can be applied underwater. Epoxy putty is a two-part material kneaded together by hand to form a clay-like substance leak professionals can work into cracks with their fingers. Epoxy putty can be applied underwater and easily matched to the pool surface. However, since it is non-flexible when cured, future crack movement will undermine the repair. These repairs often require annual attention.
Rubber- or silicone-based sealants can also be used for simple surface repairs. While some can be used underwater, most require the pool to be drained. When using these sealants, a leak professional should ‘v-cut’ the crack and apply a bead of sealant to the bottom of the ‘v.’ Plaster repair compounds are then used to fill the remainder of the ‘v’ and match the pool surface. This repair method is useful for hairline cracks that are too small to accept a fuller-bodied putty, such as an epoxy.