The two classic types of flat roof designs are the warm flat roof and the cold flat roof.
Hybrid warm deck flat roof.
Flat roof design guide.
The roof itself is therefore kept warm.
A hybrid cold flat roof is one where at least 2 3rds of the insulation is above the roof deck or joists.
Designed specified and constructed correctly a warm roof will keep the roof structure at the same temperature as the building s interior eliminating the possibility of condensation occurring and ensuring the roof performs for the life of the building.
Ventilation is not needed in a warm roof.
In each case the name refers to the position of the insulation in relation to the roof deck.
However the presence of insulation below the deck in a hybrid roof brings the dew point down potentially threatening the roof structure and spaces below it.
In a warm roof construction with no height restrictions insulation levels can ensure that no condensation occurs within the build up.
Traditionally flat roof constructions fall in to two camps.
There are design differences for each type.
However this is a general guide and could change depending upon the building use location and humidity class.
In the case of a flat roof insulation is usually either a rigid board above the deck or a mineral glass wool quilt immediately.
In the case of a flat roof insulation is usually in the form of either a rigid board above the deck or a fibrous quilt immediately above the ceiling depending on the type of roof construction.
Hybrid cold flat roof.
In this context the term hybrid flat roof refers to a timber flat roof construction that is insulated both between and over the joists.
In terms of the thermal design of a flat roof what are the options and the best practices of flat roof build ups.
Flat roofs are among the simplest construction elements that can feature in a building.
Warm cold and inverted.
The recognised flat roof build ups for best design practices are.
No insulation is on top.
Flat roofing solutions the xtratherm range of high performance insulation boards provides the ideal technically advanced solution for flat roof projects.
By majority the rule of thumb is that in a domestic house not flats approximately a third of the total thermal performance of insulation can be placed below the deck with two thirds above the deck sometimes this is called a hybrid warm roof.
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Xtratherm manufactures an extensive range of high performance pir flat roof insulation boards that include tapered insulation providing comprehensive technically advanced solutions for all.
A cold roof is where all of the insulation is placed either between and under or completely under the joists or deck.
There are three recognised designs of flat roof construction.
Single ply pvc no backing flat roof board hybrid 25 hybrid 25 is a laminated flat roof insulation board with our jablite flat roof board factory bonded to a 25mm thick fibre faced pir panel.
In addition there s a third type the warm flat roof with airflow that s essentially a hybrid version of the warm flat roof and the cold flat roof.
Easily the most frequently asked question to the celotex technical centre is with reference to hybrid flat roofs.
