You create a warm roof, or a cold roof, simply by applying the layers of the roof in a different order. Namely the insulation layers. In a cold roof, the insulation is applied between the rafters, but in a warm roof, the insulation is applied on top of the existing roof surface.
What's better warm roof or cold roof?
A warm roof is the easiest and most cost effective type of insulation and is an ideal choice for pitched roofs. On some flat roof extensions and balconies, a warm roof would increase the height and isn’t possible, in this scenario you should choose a cold roof insulation.
What are the advantages of a warm roof?
Advantages of Warm Roof Insulation on the entire roof structure keeps all the components in the roof space at the same temperature. Therefore, there is reduced thermal bridging which prevents heat loss from the living room. Houses with warm roofs are less expensive to keep warm than those with cold roofs.
What is warm deck roof?
Warm deck roof: The insulation in a warm deck roof is installed immediately below the roof membrane on top of the roof deck, usually with a vapour control layer underneath the insulation. … This then means that the roof void or deck are at a similar temperature to the room below.Can you turn a cold roof into a warm roof?
Cold bridging occurs when there is a continuous path created through the insulation. If an existing cold roof is to be refurbished, consideration should be given to converting the design to a warm roof, or incorporating new insulation into the roofing system to improve thermal performance.
Does warm roof need ventilation?
A warm flat roof usually does not require ventilation. What space do I need to allow for the ventilation? To ensure sufficient ventilation, enough space must be provided to allow for the movement of air, preventing the risk of condensation forming within the roof.
Does cold roof need ventilation?
Cold Roofs A cold roof is where all of the insulation is placed either between and under or completely under the joists or deck. No insulation is on top. In this way the roof itself is kept cold. You only need ventilation in a cold roof.
What are cold roofs?
A cold roof implies that the attic is not within the conditioned space of the home. Instead, the attic has insulation on the floor that separates air between the conditioned and attic spaces. For this type of roof, you’ll need to have proper soffit vents, a ridge or gable vent, and ventilation baffles.What is cold deck flat roof?
Cold deck flat roofs Older roofs are typically built with a timber under deck providing the support for both the waterproof covering above and the thermal insulation below. With a traditional roof insulation is likely to consist of mineral wool sheets suspended below the deck.
What is warm deck flat roof?A warm flat roof or a built-up roof (BUR) is one where all the insulation is above the joists/deck, making them part of the warm fabric of the building. The insulation is immediately below the waterproofing layer. The vapour control layer is above the decking but below the insulation.
Article first time published onCan you put insulation between joists on a warm roof?
Why you can’t just insulate between the rafters The general advice we give is that you should always insulate between and above the rafters (warm roof) or between and under the rafters (cold roof).
How much does it cost to insulate a warm roof?
When insulating one, you’re aiming for a value of 0.25 W/m2K or less. To achieve this, you should insulate your flat roof with insulation boards totalling around 150mm thickness.
Do I need a Vapour barrier on a cold flat roof?
If it is not a habitable space or as per the old design for flat cold roofs then you would use foil backed plasterboard which acts as a VB. ideally you need to ventilate the roof and have a 50mm air gap above your insulation.
Does a warm roof need a Vapour barrier?
Warm deck flat roofs can be constructed on most modern construction material types such as concrete, timber and timber based sheets. … A vapour barrier will then need to be installed to reduce condensation in the roof structure.
How do you vent a cold roof on a deck?
The cold deck roof as shown above has the insulation at ceiling level and must have a ventilated cavity of at least 50mm. The cavity must be ventilated on two opposing sides by a continuous ventilation gap of 25mm. A vapour control layer is required on the warm side of the insulation to combat condensation.
How do you vent a roof without soffit?
To ventilate your attic without soffits you can use gable vents, eyebrow vents, a venting drip edge, a shingle-over intake vent, wind turbines, or power vents. All are good alternatives if you cannot install soffit vents; however, a very important factor for good ventilation is good insulation.
What is a hybrid roof?
What is a hybrid or compact roof? A hybrid or compact roof combines elements of both warm and cold roof construction. You install the insulation both directly above and directly below the roof deck, but there is no ventilated cavity. Typical hybrid or compact roof.
What is cold deck construction?
A cold deck is constructed as follows: The insulation material is placed immediately above the ceiling between the rafters. The 18mm roof grade deck is then fixed on top of the rafters leaving suitable air flow between the insulation and the deck.
Are cold roofs banned in Scotland?
Cold flat roofs are found in many homes around the UK, though they are not recommended these days and are actually banned in Scotland. … Warm deck roofs also help reduce the risk of condensation build-up, with any water vapour entering the roof having no cold surface on which to settle.
Can I insulate the underside of my roof?
Open-cell spray polyurethane foam or closed-cell spray polyurethane foam (ccSPF) insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in all climate zones (see Figure 1).
Should roof rafters be insulated?
Insulating between rafters will do no good, because the attic should be ventilated, and the rafter insulation would be between two unheated spaces. You can add insulation to the floor; the more the merrier. … Moisture buildup in the attic is a concern because it can condense into water, often causing mold.
Which roof insulation is the best?
One of the most common and effective ways to insulate your roof is with polyurethane spray foam. This spray-applied plastic is known to be highly effective for sealing any cracks as well as resisting wind and heat. The foam is applied to the underside of your roof deck and directly onto the slates and tiles.
How much space do you need between roof and insulation?
A minimum 2-inch air space is then provided as an “over-roof” to carry away any moisture that escapes up through joints in the insulation. The ventilation space also helps keep the underside of the over-roof surface cold, thus avoiding snow melting and forming ice dams.
How do I stop condensation on my cold roof?
The cold deck solution There are two forms of flat roof construction which can reduce the risk of condensation forming. Essentially, thermal insulation can either be placed above or below the structural roof deck or waterproofing layer.
Where does the vapour barrier go on a cold flat roof?
A vapour barrier should also be placed on the warm side of the insulation, i.e. between the insulation and the ceiling finish. The roof should also have ventilation openings of at least equal to a 25mm continuous gap running the full length of the eaves on two opposite sides.
Do flat roofs cause condensation?
Condensation is never good news for a flat roof. This is especially so if it occurs within the roof’s structure itself as this can lead to decay in the roof timbers which is very difficult to spot. It can also reduce thermal insulation performance which can be a particular problem during winter.
Can you screw through Vapour barrier?
1 Answer. Typically, nothing is done. That puncture should be at a tight connection of drywall to stud, where airflow is impeded by the pressure of the screw holding the drywall and vapor barrier to the stud.
Is Vapour Barrier same as DPM?
Damp Proof Membranes (DPMs) A Damp Proof Membrane or DPM is a waterproof barrier that’s introduced between your sub floor and your wood floor. … Vapour Barriers A vapour barrier is a damp proofing product that is attached to a wood floor underlay and is intended to reduce the passage of moisture.
What is the difference between a Vapour barrier and a breathable membrane?
The answers in the names: vapour control layer stops water vapour getting into the wall from the inside of the structure. Breather membrane keeps water from getting into the wall from the outside but allows any water vapour that is in there to escape.
