How To Insulate A Warm Flat Roof

Like other roofs insulating a flat one requires ample ventilation a vapor barrier and sealed bypasses.

How to insulate a warm flat roof.

Many times i answer the phone and customers ask me to give a price for a new flat roof. Ventilation is necessary to allow moisture accumulated inside to escape. You would only do this however if replacing the roof covering on top and you have the height above the roof to do this. Both these variants require different approaches to insulation which will be covered in this guide.

How to insulate a flat roof. 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. The correct method for a flat roof is under the current regulations to have a warm roof. It also lets hot air escape in the summer.

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 material is placed on top of the roof rather than in between the ceiling and the decking. With a warm roof the usual process is to split the insulation into two layers. Occasionally some ask for a new warm roof such as an insulated flat roof however the majority just want a.

When a homeowner really needs to cut down on costs some contractors may suggest the following. It should be installed on tapered 2x furring strips in order to slope the surface of the roof to drains. Proper ventilation in flat roofs. 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.

Add an additional layer of osb over the sheathing. Then install r 30 fiberglass batts between the rafters. 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.