Warm Roof Construction.

The construction of a roof over a swimming pool is significantly more complex than a similar construction over a domestic dwelling or ancillary building. The condition is further exacerbated if an automatic cover is not installed. Uncovered pools are common in commercial situations but less common at a domestic level. If you are designing a warm roof over an uncovered domestic pool extreme caution is advised and it is prudent to engage a checking consultant to verify that your proposed detail accords with good practice and the various standards. In our experience designers have been caught out in the following ways:-

A) Simply installing the wrong type of roof construction for the wrong environment.

B) Failure to take on board the importance of penetrations through a vapour check.

C) Failure to co-ordinate the roof design at key junctions, allowing vapour to permeate from one roof void into another.

D) Not checking the construction drawings.


Anyone responsible for designing a warm roof should familiarise themselves with the basic scientific principles behind interstitial condensation. It is not intended to provide an exhaustive resume of this well understood topic here, suffice to say that moisture penetrates out at the dew point and when that dew point is within the fabric of a building catastrophic consequences can ensue. The images below illustrate an uncovered domestic pool after only c. 15 years of life. Left unchecked this roof would have experienced extreme structural failure and probably collapsed within 2-3 years. The cost of rectification was circa 200,000.00.

Typical Section.

The attached typical section has been used on countless of our indoor pool designs with subtle variations to suit the site conditions. Its strengths are the integration of a continuous vapour check which has a well understood resistance to vapour pressure and meets the target of vapour resistance level of 43000 MNsg NB: not all products hit this level. Its weaknesses principally revolve around the risk of cracking if inadequate fixings are used and its inability to accommodate any penetration for lights, ducts etc [ lights can be recessed into the plasterboard ceiling without compromising the VB ]. It also inevitably results in a fat fascia and soffit detail which needs to be reconciled against any planning drawings.

Mono Reflex 275 PDF »

Specimen Warm Roof Detail PDF »

Specimen Warm Roof Eaves Detail PDF »

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