My preference is a warm roof construction with grp. If you are upgrading the roof to meet current thermal requirements then the thickness of insulation will vary depending on its thermal conductivity. edit too slow. If you want a speedy reply from a manufacturer contact Xtratherm with your proposed roof construction and ask them to specify the minimum insulation thickness for your target u value. Condensation; This is the … This vapour check and airtight membrane should always be laid on the warm side of the insulation. I'm about to have my flat roof re-covered because its at the end of its service life. The insulation is below the deck, but above the plasterboard. Flat roof – there are three options available: warm deck, cold deck or inverted roof. cold, heat and rain for the entire service life of the build - ing. The right roof solution ensures lifetime perform - ance without degradation. Flat Roof Insulation … National Energy Foundation SuperHomes is coordinated by the Like funky monkey, I’d favour a warm roof design that should deal with cold bridging. Sedum roof covering 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. They’re generally pretty good at recommending products if you give them the u-value you need to achieve, and the build-up you’ve got/want. And how? Ventilated cold roof or warm roof with insulation boards atop sheathing which serves to raise the dew point above the structural members of the roof. It should be of the maximum available thickness. A note to consider before construction: if insulation is installed below the flat roof deck this is called a “cold” roof. The roof covering is then laid over the ply ; Cold deck: the thickness … Limited by guarantee Roofers at work are replacing 50mm with (I think) 160mm, but that’s on a concrete sub-roof There is no attic. From there, the flat roof system you choose will determine the materials you apply. Draught-proofing- a good thing? This makes them a great source of ideas to help you green your own home. Assumptions include: In practice, the depth of insulation that can be added is often determined by features such as flashings, kerbs and upstands. Powerdeck ® U. For more detailed guidance on roof insulation please google for the following Energy Saving Trust literature: Thanks to the Energy Saving Trust for the illustrations. It’s clear: Flat roofs have a promising future. Insulation of new flat roofs must satisfy Part L of the Building Regulations. It currently has an EDPM roof with no added external insulation as far as I know. There is only a small gap between this ceiling and a concrete roof (cold roof, felt covered). (Thickness varies according to the manufacturer's specifications). With an inverted warm roof construction, put ballast, usually graded pebbles or concrete paving slabs, on top of the insulation in order to keep the insulation down in the event of wind. Closed-cell polyurethane spray foam will prove ideal for thermal insulation of a flat roof. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof, just above the ceiling. insulating a solid wall You can see flat roof insulation at four open home events around the UK this month. It allows insulation … The simplest and cheapest roof insulation is the classic cold loft option. Cold Roof. Warm Roof vs Cold Roof. Insulation can also help to limit condensation and contribute to acoustic insulation (depending on the type of insulation used). Consequently, the roof construction and the sealing layer will shrimp or expand as … Flat concrete roofs are generally not ventilated since the ceiling internally is generally a plaster and skim coat directly to the underside of the cold concrete. You need to insulate a flat roof. There is no insulation at present, its a cold roof. Roofgiant Guide to Roof Insulation. •Cold Deck Flat Roof The thickness of insulation required will vary depending on the material you decide to use and the manufacturer’s specification. Flat roof design guide. Company Number: 2218531 In this case ventilation is required and the roof … Consider geography, budget and use for the roof to determine the best option. Additionally, attic condensation and leaks will make fiberboard wet. A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck. This method of insulation can also be used to upgrade the thermal performance of an existing roof … As has been said, they’re probably guessing there’s something there already. As I understood it, if we’re adding any insulation at all then it has to be to the current standard, ie. So all that lovely insulation doing nothing at all…twunts!!! cold deck: this is where the insulation is placed between the joists/rafters or in between the ceiling joists in the case of a pitch roof. Inverted 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. The typical U-value of an existing, uninsulated flat roof is 1.5W/m2K. There are essentially two designs used in the construction of a flat roof to include insulation. It takes the form of reinforced bitumen sheeting or polyethylene laminated with metal foil to reflect the heat back in. The effective roof insulation layer may range in thickness … a u-value of 0.18 or better. See our flat roof insulation … Energy Saving Insulation. More realistically though, they are probably just making it up and have no real idea. However, through-ventilation must be maintained and the clear space between the top of the insulation and the deck must be at least 50mm (2ins… Given the costs of labour and all the other materials slightly thicker insulation doesn’t really make that much difference given it’s not a very large area. It’s unlikely that this design would be thermally efficient enough to meet the regulations, not without extra insulation under the joists. Lots of traditional flat roofs are of the ‘cold roof’ construction type. Warm deck: the type of insulation for this is usually of a rigid type and the thickness … Mastic asphalt is a further option, to be applied according to the guidance in BS 8218 and BS 8000: Part 4. Consider geography, budget and use for the roof to determine the best option. A cold roof has the insulation placed below the structural deck, which thus remains cold. Classifieds Rules If you're unsure as to the difference between warm roof insulation and cold roof insulation, keep reading. However, if the roof is not ventilated then it will require a breathable membrane between the insulation and structure. The topic ‘Insulation thickness when renovating a flat roof?’ is closed to new replies. Eurothane ® Eurodeck is a thermal insulation board for use in warm flat roofs under mechanically fixed single-ply membrane waterproofing systems. Cold roof Insulation is less expensive as there is a lot of space available with deeper insulation materials used. But where? Reg Charity Number: 298951 Cold deck (fig 1) This is the most common construction and can be the least thermally efficient. This may help with condensation, but causes such a loss of heat that it has been banned in Scotland. Login/cookie issues? This construction relies on a vapour control layer working effectively, and in tandem with a continuous ventilated airspace to disperse the water vapour to atmosphere before it reaches the cold deck and condenses. The thickness of the insulation will be governed by the depth of the joist and this may not allow sufficient insulation to meet the regulations. A green (sedum or grass) roof can also be put onto a flat roof, provided it can take the weight. Protexia Geofabric is one heavy duty all-in-one solution I have found to both the roof covering and filter membrane. On top of this goes the roof covering. The best way to deal with this is to add insulation. A cold flat roof is one where the insulation is between or between and below the roof joists. Registered in England and Wales. The typical U-value of an existing, uninsulated flat roof is 1.5W/m2K. I think it has to be 140mm, but the quotes so far have been for 90, 70 or 50(!) Are the regs not as strict as I thought? 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. Additionally, attic condensation and leaks will make fiberboard wet. The existing ceiling is sound but provides no insulation. An unvented attic differs from a conventional vented attic in that there is no direct venting of the attic space which is generally considered to be between the roof rafters/framing and the top story ceiling framing members (attic floor). When you insulate a flat roof it is important that moisture or air are kept well out, all around. Close attention must be paid to drainage patterns, to ensure no pools of water can gather. Inverted warm deck flat roof insulation – click to enlarge. You can choose this if you don’t want to use mineral wool, polyurethane (PUR), expanded polystyrene (EPS) or rigid polyisocyanurate (PIR). Insulation System for Flat Roofs & Balconies. Insulation (on a scale of diminishing returns) is a no-brainer. Building regulations. Moisture will be trapped inside, causing mold growth and further reducing its efficiency. It protects thermal insulation where there is a possibility of moisture entry, e.g. This means there is a vapour control layer in the ceiling and cross ventilation at the eaves or the top of the walls. When it comes to insulating a flat roof, there are two options. 25mm (3) 30mm (2) 40mm (1) 50mm (4) 56mm (1) 60mm (2) 70mm (2) 75mm (3) 76mm (1) 80mm (4) 90mm (2) 96mm (1) 100mm (4) 106mm (1) 110mm (1) 120mm (4) 126mm (1) 130mm (2) 136mm (1) 140mm (3) 150mm (4) 156mm (1) Filter by Width . 2 The Flat Roof 4 2.1 Types of Flat Roofs and Definitions 5 3 Advantages of the Inverted Roof System 7 3.1 Advantages of Styrodur® in Inverted Roofs 8 4 Application Notes 10 4.1 Substructure 10 4.2 Roof Waterproofing 10 4.3 Roof Drainage 10 4.4 Thermal Insulation Layer 11 4.5 Protective Layer 11 4.6 Protection … Flat Roof Insulation: Insulating a flat roof with timber deck insulated between and below joists - In the Mannok insulation range, there are a number of suitable insulation products for use in this particular type of roof construction. Insulating between the joists of your loft will keep your house warmer, but make the roof space above colder. Flat roof insulation £50 – £100 per m². Make sure that whoever does the work also carries out a condensation prediction/risk analysis. Insulating a flat roof with polyurethane foam — definite advantage. Flat roof. U value of a flat roof To comply with Part L of the building regulations 2010, all roofs to rooms (except those in unheated buildings) should be thermally insulated to a maximum U-value of of 0.18 W/m²K. Warm vs. Winter temperatures turn metal, clay, plastic and tile roofing cold. Contact Us the plasterboard. Kingspan website is good for literature with pretty pictures though, and there are tables in there showing how much insulation you’ll need to achieve a certain u value. They may be using different types of insulation, some of which won’t need to be as thick as others for the same u-value. This is easier to insulate and to maintain. 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’. Whether ballast or green roof is chosen, a filter membrane is a good idea just beneath it, to prevent dirt clogging up the drainage channels. This means that it is possible to use it in combination with all fibrous, organic insulating materials. Rigid PIR insulation boards, such as Mannok Therm Roof / MR boards, are generally the preferred roof insulation materials for flat roofs for a number of reasons.They are lightweight, easy to fit and come in a range of thicknesses. Forum Rules It has only 1-r value per inch and is always installed in 0.5 inch thickness. Premier Club These figures are approximate and vary according to the construction type and material used. Alternatively, cold flat roof insulation works by placing the insulation layer between or under the timber rafters. Cold flat roofs are typically avoided as you’d need to install ventilation, which can prove problematic for many reasons relating to space, labour costs, etc. This site uses cookies to personalise content and services and to provide social media features. See 'Options' below. If you are upgrading the roof to meet current thermal requirements then the thickness of insulation will vary depending on its thermal conductivity. Having Flat Roof Insulation Installed in these homes makes a huge difference in the heat flow into the home. Secondly, it’s important to understand how to keep it airtight and prevent condensation. Might want to think about if you have a moisture barrier behind your ceiling plasterboard too. We recommend a combination of Therm Roof insulation boards and Therm Flat Laminate-Kraft insulation … Expanded Polystyrene: While a great option for new flat roofs… The answer is especially important if the room below generates high levels of humidity like a bathroom. Creating a void between the old ceiling and new is better but ideally you need to eventually consider insulating the top of the concrete roof with solid insulation … And how? Achieving a U value of 0.20W/m² (meaning your roof will be better insulated than your walls) will need 120mm thickness of rigid foam or 200mm … © David Thorpe Jan 2013. There’s a few ways to go about it but I’d probably have most of the insulation on top with insulated plasterboard inside, but it may depend on which roof cladding system you go for. Ventilation is required for these roofs. There are two basic categories of roof design: A warm roof has the insulation above the structural deck, which is thus kept warm. Flat roofs, for example on extensions, bathrooms and dormer windows, are not the best of ideas. A product like pro clima INTELLOplus features humidity-variable diffusion resistance that is effective in most if not all climates. According to the Energy Saving Trust, a quarter of heat is lost through the roof in an uninsulated home. Entry is free. Flat roof. Easily identify what thickness of EcoTherm Insulation product you need to meet your project's U-value requirements.