How To Insulate A Warm Flat Roof

In the case of a flat roof insulation is usually either a rigid board above the deck or a mineral glass wool quilt immediately above the underdrawn ceiling depending on the type of roof design and construction.

How to insulate a warm flat roof.

With a warm roof the usual process is to split the insulation into two layers. It also lets hot air escape in the summer. Insulation is placed in between the joists underneath the roof surface above. Insulation material is placed on top of the roof rather than in between the ceiling and the decking.

Both these variants require different approaches to insulation which will be covered in this guide. The only point of putting the insulation on top of the waterproof membrane is when you can t take it off as when for example it is bitumen. Insulation can either be put below the weather proof membrane which is called a warm roof deck construction or above the waterproof membrane which is called an inverted warm deck. Then install r 30 fiberglass batts between the rafters.

The correct method for a flat roof is under the current regulations to have a warm roof. Add an additional layer of osb over the sheathing. How to insulate a flat roof. If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of the tiles or slates with an 80mm board running across the rafters.

In a nutshell you would sandwich 130mm of solid insulation between two decks allowing to place a vapour barrier on top of the first deck. It should be installed on tapered 2x furring strips in order to slope the surface of the roof to drains. When a homeowner really needs to cut down on costs some contractors may suggest the following. Like other roofs insulating a flat one requires ample ventilation a vapor barrier and sealed bypasses.

You would only do this however if replacing the roof covering on top and you have the height above the roof to do this. Proper ventilation in flat roofs. Occasionally some ask for a new warm roof such as an insulated flat roof however the majority just want a.