Flat Roof Insulation

About

Insulating a flat roof correctly is one of the most important decisions in any roofing project. The right roof insulation board , correctly specified for the deck type and waterproofing system, will deliver consistent thermal performance, prevent condensation and protect the building fabric for the life of the roof. Get it wrong and you risk poor thermal performance, moisture problems and premature failure of the waterproofing system above. At Insulation UK we stock a comprehensive range of flat roof insulation boards from three of the UK's most trusted manufacturers — Kingspan, Recticel and Tekwarm Roofdek — covering warm deck construction across timber, concrete and steel substrates, and compatible with torch-on felt, single ply membrane and built-up felt waterproofing systems. Understanding Flat Roof Construction Types There are two principal approaches to flat roof construction, and the insulation strategy differs significantly between them. In a warm deck roof — the most widely used modern approach — the insulation is installed immediately above the structural deck and below the waterproofing membrane, usually with a vapour control layer between the deck and the insulation. This places the insulation on the warm side of the deck, keeping the structure at a comparable temperature to the room below, eliminating the risk of condensation forming within the roof build-up and removing the need for ventilation. Warm deck construction is the standard approach for new build and refurbishment flat roof projects in the UK and is the type of construction our flat roof insulation boards are designed for. In an inverted warm deck roof, the insulation is installed above the waterproofing membrane rather than below it, protecting the membrane from temperature extremes and UV exposure. This requires the use of extruded polystyrene (XPS) insulation boards — the only material with the compressive strength, water resistance and long-term thermal performance required for this appli