Thermal Insulation

Internal gutter systems have to thermally comply with Parts L2 and J as they are classed as part of the roof construction. However, Kingspan recommend a U-value of 0.35W/m²K which provides pre-melt drainage in the event of snow fall and ice formation. This facilitates drainage of the roof system under winter conditions. Additionally analysis of condensation risk f-factor and thermal bridge heat loss Psi Value (Y) is necessary. These values are then built into the Alpha value (a) whole building heat loss calculation.
Insurer approved Loss Prevention Certification Board (LPCB) or Factory Mutual (FM) insulation board should be incorporated to prevent risk of fire development, propagation or spread.

Durability

All gutters are subjected to severe corrosive conditions due to frequency of wetting, accumulation of debris and dirt, which can retain water and moisture for extended periods. Internal gutters are used as walkways during and after construction and are subject to periodic cleaning, therefore, any protective coating systems have to be resistant to damage.

Gutter replacement is disruptive and expensive as it involves stripping out elements and possible replacement of the roof system.

Therefore, overall lifetime durability for internal gutters should be 30 years, this includes periodic maintenance.

Protective Coatings

External gutters - Galvanised substrate - S220GD + ZA to BS EN 10214:1992
    - internal coating 200 micron Plastisol.

Internal gutters - Galvanised substrate - Fe P02G Z600 BS EN10143:1993
    - single ply membrane

    - internal coating 200 micron Plastisol.

Site Installation

Site installation of gutter systems is a high risk activity which requires specific Health & Safety and CDM procedures and method statements.

Maintenance

It is important to recognise that the performance of all gutter systems will deteriorate in time because of leaves, silt and other debris. The system should be designed with appropriate safety factors to allow for this, depending on risk of accumulation and frequency of maintenance. BS 5427 recommends regular scheduled inspections which should be at least once per year in most locations.