Breathable Roof Felt WRONG Underlay Felt Explained Part 1

>> YOUR LINK HERE: ___ http://youtube.com/watch?v=ePhwCO8qkh8

Video 2 will be coming mid-December and I will like it here. • • 00:00 Introduction • 00:23 Naming of each type • 01:51 Breathable or vapour -permeable • 02:25 Should you vent? • 03:23 Vapour and breathable test • • Pitched roof underlays Explained. Part 1 I conduct many roof surveys and often find that the wrong sarking felt—also called underfelt—has been used. The term breathable is frequently misused when advertising underlays for pitched roofs. Generally speaking, a pitched roof underlay is vapour open or vapour permeable, but it is not breathable. Despite this, you’ll find it advertised all over the internet and in many roofing suppliers as breathable. This is a complete misunderstanding of what these materials actually do. • Many customers and roofing contractors seem unable to grasp the difference between breathable and vapour open, so let's clarify the terms. • Types of Underlays • Original Underlays (High Resistance - HR) • The original underlays were completely airtight and vapour-tight. This means they did not allow air or vapour to pass through them. These are known as high resistance (HR) underlays. • Vapour Permeable Underlays (Low Resistance - LR) • The next category consists of vapour permeable underlays, which are often called sarking or underfelt. These are vapour-permeable but not breathable. They are airtight or air-closed and fall under the category of low resistance (LR) underlays. • Air-Open Vapour Permeable Underlays (Low Resistance - LR) • There is also a new category of underlays that are low resistance (LR) but are air-open and sometimes referred to as breathable. This can create confusion, but it’s important to understand that while they are air-open, they still belong to the LR category. • Common Misunderstanding • The biggest misunderstanding is that many people assume vapour-open LR underlays are breathable, which leads to improper installation. Many times, these underlays are installed without adequate roof ventilation, which is incorrect. This can lead to interstitial condensation—essentially causing the roof to sweat and potentially rot from the inside out. • In this video, I aim to explain the different types of underlays available, and how to use them correctly. I will be releasing another video soon, where I will share photographs of poorly installed underlays and explain the consequences of incorrect installation. • Steven Dickinson • London Flat Roofing • 07802300099 • [email protected] • #londonflatroofing • #londonroofsurveyor • #steveroofer • Storm-damaged roofs in London • Roof surveys • Roof surveyor • London Roof surveys and inspections • Roof consultancy • Roof consultancy and roof condition reports • Domestic roof survey • Flat roof condition report • Independent roof surveyor • Leak detection roofing

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