Frequently Asked Questions

Rigid polyurethane (PUR) and polyisocyanaurate (PIR) boards are widely used in the construction industry to provide technically advanced thermal insulation. Specifying the right board for the application is vital to meet today’s increasingly stringent building regulations. Martin Oxley, Technical Manager at EcoTherm, provides answers to ten frequently asked questions about choosing and using insulation boards.

What thickness of insulation board do I need?

Unfortunately, there is no one simple answer to this question as it really depends on various key factors. Firstly, there’s the matter of where the insulation board is going to be used in the building envelope, for example in a cavity wall or in a pitched or flat roof. You also need to consider which other building materials will be in contact with the insulation as this will also determine thickness. At EcoTherm, our technical team is always happy to advise on this important aspect of specification.

What compressive strength should I be looking for in a board?

We would recommend using a board that exceeds 140KPa when tested to BS EN 826: 1996.

Are there any environmental standards I should check for?

At a time when there is a universal call for increased effort to protect the environment, it’s important to check that the insulation boards you buy are manufactured from CFC and HCFC free grades of raw materials which ensure zero Ozone Depletion Potential (Zero ODP). EcoTherm boards, for example, have a Global Warming Potential (GWP) factor of 3, which comfortably surpasses the target value of 5.

What about U values?

EcoTherm boards do not have a specific U value, but you can calculate the elemental U value i.e. wall / floor / roof by dividing the sum total of the resistances of the building element into the number 1.

My boards have got wet – what do I do now?

Dry your boards before using them by natural means only. Do not use direct heat, such as a naked flame to dry the boards. Do not lay the boards in temperatures of less than 5oC as condensation may occur. If work is interrupted, the laid boards must be protected to prevent water penetration. Store the boards clear of the ground, ideally under cover, and never in areas subjected to high elevated temperatures or close to sources of ignition.

How do I cut insulation boards?

They can be cut with a sharp knife or a fine toothed saw. As a responsible company, we recommend that users take a sensible approach to the cutting of boards with strict regard for health, safety and environmental standards.

What is the typical temperature resistance of insulation boards?

For our boards, we recommend that for a long duration of extreme temperatures then -50oC to +110oC are not exceeded.

What about durability?

If the polyurethane board has been correctly applied then it has an indefinite life and will deliver design insulation values for the lifetime of the building. However this does, of course, depend upon the method of application, supporting structure and conditions of use.

Can foil / foil boards be used under a screed in a flooring application?

Yes, and EcoTherm Floor-Therm is ideal for this application. We recommend placing a sheet of polythene (1000 gauge / 0.25 mm) over the insulation before pouring your screed. This helps to protect the foil surface of the insulation from the alkalinity / dampness of the screed and prevents it entering the joints between the boards.

Can you full fill a wall cavity with PUR board?

NO! Polyurethane board is not designed for a full fill cavity and requires a minimum 25mm cavity from the external brick / block course.