Floor Insulation Buyers Guide

Insulation, Membranes & Felts
Floor Insulation Buyers Guide

Why Do You Need Floor Insulation?

Quite simply, insulation prevents heat loss. If you have an older property in need of renovation, installing insulation in the floor will help to make it a more comfortable area to inhabit, it also improves the energy efficiency of the house.

It can also protect pipework and is an ideal way to prevent draughts. Floor insulation works in concert with your wall insulation to provide a much more energy efficient home. Even if you have solid concrete flooring, like most modern buildings do, adding a layer of insulation will further reduce the energy burden on your home. It stops moisture from accumulating and keeps you nice and warm during the winter!

The benefits of floor insulation are pretty clear. But which type of insulation do you need?

Best Types Of Floor Insulation

The type of insulation you decide to get will be determined by the type of floor you have. Most houses in the UK have a solid concrete floor, although many properties will have timber joists between floors. This allows draughts and moisture to travel through your house freely if they aren’t properly insulated.

Below, we take a look at some of the most popular types of insulation for use in flooring and the environments they are best used in.

  • Mineral wool: Best used in between the joists of a floor. Mineral wool is highly fire-resistant and acts as a fantastic noise barrier - ideal for busy family homes! Like all other insulation, it will reduce energy costs and is very versatile. This type of insulation can be installed in ceilings and walls as well as floors and also has an exceptional R-value, meaning it resists the flow of heat.

It does tend to be a bit pricier than some other options but has great insulation properties, acting as a barrier to heat loss, keeping you warm in winter and cool in the summer.

  • Fibreglass batt and roll: These are the most common insulation batts used to fill gaps in between joists. The reason it is so widely used is because of its convenience in design as well as its insulation properties. The material is more cost-effective than other options and can be easily shaped to fill in awkward gaps, stopping draughts.

Also effectively blocks sound and is fire resistant and is an eco-friendly choice, with a high percentage of recycled materials used in its construction.

  • Rigid foam board: This type of insulation comes in many forms and is ideal for use over concrete flooring, as an underlay before carpet or wooden flooring is placed on top.

Expanded polystyrene sheets (EPS) – Very cost-effective insulation material, EPS sheets have very low thermal conductivity and although it is an artificial product, it also means that it remains operational and retains its efficient properties throughout the entirety of its lifespan. Amazingly, EPS is 98% air, made from solid beads of polystyrene, you’ll find EPS insulation in almost every modern household.

Extruded polystyrene insulation (XPS) – Using a different manufacturing process than EPS foam, XPS provides many of the same benefits as EPS except that it is more resistant to moisture absorption, making it better for use in wet environments, and it also has a higher compression strength making it ideal for use when installing underfloor heating. Because of the extruded manufacturing process, these boards are not ideal for recycling and the emissions used in manufacturing are higher.

Polyisocyanurate (PIR) – PIR boards are lightweight, easy to handle and cut into shape. They offer an extremely low rate of moisture absorption and have typically fantastic insulation properties. PIR is manufactured in a more environmentally friendly way than other solid foam boards and can be recycled.

Types OF Floors

8 – 10 million UK homes have a suspended floor. These houses are usually older and built before 1930. A suspended floor is constructed with supported joists of timber beams or concrete and there will be a void underneath.

The most common type of flooring in the UK is concrete. The type of flooring you have will determine the insulation you need as well as affect the installation process.

Solid concrete – When installing insulation on concrete, you will first have to lay down a damp proof membrane or underlay. Then you can lay the insulation, before adding a layer of chipboard or concrete screed for moisture resistance. Once that is done, you can lay your flooring on top to finish.

The reason for this is to create a completely sealed system that draughts, and moisture cannot penetrate. You can also easily add an underfloor heating system on top of foam insulation.

If possible, install insulation under the concrete. Concrete is a fantastic insulator and is great at absorbing heat, but obviously, this option is not available to everyone!

Use XPS, EPS and PIR foam board to insulate concrete floors.

Suspended floor – When insulating a suspended floor, it will be a bit more complicated than a solid concrete floor. This is because you will need to inspect the joists, ensure there is no damage to them, replace them as necessary and then move on to insulating.

You can install insulation from above or below, whichever is more practical and suits you best. Using insulation slabs won’t be enough; the main aim is to make the floor as airtight as possible to eliminate draughts. Firstly, install a reinforced breathable membrane over the joists.

These membranes conform to the shape of the timber and provide support for your insulation as well as a barrier from moisture and draughts. Since older properties are sometimes not made perfectly, you may have to cut the membrane to fit flush with the walls.

When installing the insulation, mineral wool would be best to use. This is because it is easy to handle and fills any gaps well. Use can even use loose-fill insulation to ensure that there is a minimum amount of air penetration.

When selecting your insulation, be sure to measure the thickness needed. One of the major difficulties of insulating between joists is that you need to ensure the insulation is uniform throughout the room, which can be difficult with imprecise older buildings.

Things to Consider Before Getting Your Insulation

Insulation thickness – Be sure to measure the exact thickness of insulation you need. With suspended flooring, the depth is dictated by the timber. For solid floors, it is up to your judgement. Foam board comes in a variety of thicknesses, so consider the amount of room it will take up before deciding.

Cost – Every part of the house should be insulated including the loft. If you are embarking on a complete house renovation or only replacing the insulation in one room, you will need to decide which areas need higher cost insulation. Some areas of the home may not need the same quality of insulation as others. If, for instance, fire resistance or moisture absorbency is not a priority in certain rooms.

Here are the average costs for insulating floors in the UK:

Soundproofing – Insulation acts as a tremendous barrier against sound pollution as well as heat. If you live in a busy household or noisy city, consider using acoustic insulation, fibreglass or even blow-in cellulose insulation, as these are the best for insulating against sound.

Obviously, other things will also help with this, such as effective window glazing, but the sound dampening properties of insulation are well-known.

Hiring a professional or DIY – This depends on the confidence you have in your own skills and the size of the job at hand. If the insulation project is straightforward then insulating a room is a fairly simple task, as long as you follow each step carefully and slowly.

However, for larger areas, unforeseen circumstances and difficult to access areas, hiring a tradesperson might be the best option. A legitimate labourer will have years of experience and the know-how to deal with problems as they arise, and it will remove the stress from the job for you.

R-value – This is usually stated on the insulation or in its product description. Be sure to look for it and take note. The higher the R-value, the greater the ability of the insulation to resist the flow of heat through itself. Consider the yearly climate where you live, how cold it gets and how efficient your home is at retaining heat already. You can’t go wrong with a higher R-value, but you may not need it to be as high as possible.

Damp and draughts – Before you install insulation, check the space you intend to insulate for damp or draughts. Damp spaces could indicate a leak and will need to be dealt with before you lay the insulation, otherwise it could lead to damage over time. By finding any particularly draughty areas, you know where to make sure you have filled every nook and cranny possible. Consider obtaining some loose fill insulation for these hard-to-reach areas.

Allergens – Some insulation materials, such as fibreglass and rock wool, have been known to induce allergic reactions in people. Small particles of this insulation can break off and get into the air, causing rashes, irritation and itching. If you or any member of your family are sensitive to such things, there are anti-allergen insulation materials you can consider.

Insulating a floor is a laborious but straightforward task. Hopefully, this guide will have made it a little bit easier, helping to narrow down your choice of insulation and giving you a good idea of the best insulation for the job and some of the possible pitfalls for you to avoid.

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