Flat Roof Insulation
At Building Supplies Online we stock the Kingspan range of Flat Roof Insulation
Flat roof insulation needs to be installed whilst the flat roof is being constructed or renovated, without insulation, a flat roof will lose lots of heat and the materials used for the roof will deteriorate. Flat roofs need to be fully insulated to pass the building regulation rules and be signed off when finished. Flat roof insulation also gives fire resistance and helps minimise noise transfer.
The flat roof insulation goes above the roof deck level. Firstly you would lay rigid insulating boards on top of the waterproof roof membrane, followed by a vapour layer to control moisture and condensation. After that the flat roof insulation goes on top, then another layer of plywood or OSB board, finally, followed by the outer layer of asphalt or roofing felt.
The type of flat roof insulation used depends on whether the finished roof will need to be walked on or not. Insulation board is the strongest and best for load bearing, so this type will be the best if you need to be able to walk on your roof whether for maintenance or as a roof terrace. For roofs that won't need to be walked upon, flat roof insulation can be of a softer, less solid type that will still give good insulating properties.
When planning your flat roof you need to ensure that you allow for channelling of rainwater so that you don't get pools of water forming which can cause damage. To achieve this you can use the flat roof insulation material in several layers to form a tapered effect, which will channel water off of the roof.
Most flat roofs are now "warm roofs" which means the flat roof insulation is installed with a waterproof layer either side of it. "Cold roofs" where the layer of flat roof insulation goes under the waterproof layer, used to be popular but are now not used due to problems with condensation.
Flat Roof Insulation Guidelines
The Kingspan TR26 Flat Roof Insulation is designed for flat roofs waterproofed with mechanically fixed single-ply waterproofing. It has zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP). Manufactured with a blowing, TR26 is a High-performance rigid thermoset polyisocyanurate (PIR) insulant. Insulation is needed to reduce heat loss in the winter and control excessive heat during the summer. This will help to conserve energy and ensure comfort is maintained within the building. Insulation can also help to reduce condensation and depending on the type of insulation used, contribute to acoustic insulation.
What is a U value of a flat roof?
To comply with Part L of the building regulations 2010, all roofs except those in unheated buildings should be thermally insulated to a maximum U-value of 0.18 W/m²K.
A lower U-value means better flat roof insulation, therefor U-value requirements usually specify a maximum value.
U-value calculations take into account the thermal resistivity and thickness of the flat roof insulation.
the rate of heat transmission through a unit area for each degree of temperature difference from inside to outside the building. The rate of heat transmission through a unit area for each degree of temperature difference from inside to outside the building is known as Thermal Resistance.
For a warm flat roof:
Flat roof insulation should be able to withstand extremes of UV light and temperature without deterioration in thermal performance.
Your Flat Roof insulation should be able to resist pressure from any potential foot traffic and suitable and durable for external use.
Your Flat Roof Insulation should be able to provide support and protection to the weatherproofing membrane and moisture resistant.
Your Flat Roof Insulation should be capable of withstanding loads during construction and future maintenance.