Cavity wall insulation can be done incorrectly

When installed correctly, cavity wall insulation is a fantastic way to help lower your energy bills. The insulation will slow the movement of heat across the wall and therefore your home will stay warm longer once you put your heating on, meaning you need to use less energy to keep your home at a comfortable temperature. It is for this reason the Government have traditionally been keen to promote the measure – after loft insulation, cavity wall insulation is the second most cost-effective energy saving solution.

In some cases though, cavity wall insulation simply isn’t the answer – the good news is that it can be rectified, the bad news is that there is a cost.

Why would you remove cavity wall insulation?

In the 1980s, building regulations stipulated that insulation should be installed during the construction of new buildings. As soon as these regulations came into play, it became clear there were a huge number of slightly older properties that could also benefit from this type of insulation; however the only way to get the insulation into the cavity once the property was built was to inject it. Since the materials were cheap and the installation process was relatively simple, the Government really pushed the measure. Thousands of small installer companies popped up, knowing they could install the insulation in people’s homes and be well paid for the work.

As a result, any property with an unfilled cavity was targeted, regardless whether it was suitable or not – so obviously issues occurred. Some of these issues are laid out below:

1. The insulation material used was unsuitable – e.g. urea-formaldehyde. The problems with this insulating product were two-fold: Firstly, it breaks down, releasing (carcinogenic) formaldehyde into the home. Secondly, when the insulation breaks down it falls down the cavity, meaning walls higher up no longer benefit from the insulation.
2. When cavity walls were first introduced in the 1930s, the cavity’s sole purpose was to prevent water crossing the wall from outside to inside, causing damp in the home. As a result the early cavities were very thin – insulation could cause bridges between the two skins of brick, allowing water to cross and leading to damp issues in the home.
3. The insulation was installed incorrectly. When the cavity wall installer puts the cavity wall insulation in the gap between the two skins of brick, the wall needs to be drilled in various places to allow an even distribution of the insulation. If the distances between the drilled holes were incorrect, then the insulation would not meet leading to cold spots.
4. Another issue was corner-cutting. Since installers are paid per m2 of wall, they need to do the jobs as quick as possible. When beads are injected into the cavity wall they are injected with a uPVC glue which binds all the beads together. The problem is that doing this properly – injecting the glue with the beads – takes about 3 times longer than installing the beads alone. Some installers wouldn’t bother, as they were looking to maximise profits by doing multiple jobs in the same day. This often led to beads ‘settling’ in the bottom of the cavity, meaning there was no real insulating impact on the upper parts of the wall.
5. Until the development of new technology, cavity wall insulation wasn’t suitable for every property. If a wall is privy to driving rain for instance, the cavity is required to prevent ingress of water into the home. If these walls were retrofitted with old-fashioned types of cavity wall insulation, it could quickly lead to damp issues – this is most prevalent in coastal regions.
6. Another example of a wall being unsuitable is when we hear of timber frame properties having had cavity wall insulation installed. These properties should never have cavity wall insulation installed. However an untrained or untrustworthy installer may have installed anyway to make sure they get paid for the job. We get several phone calls a month from homes who are in this situation and are trying to sell their properties, but are finding it impossible since mortgage companies won’t allow prospective buyers to get a mortgage on the property until the cavity wall insulation is removed.
7. The final reason is when someone has just bought a property previously installed with cavity wall insulation. In some cases, the insulation causes allergies for the new homeowner and again this needs to be removed despite the energy savings resulting from the installed cavity wall insulation.

How to get rid of unwanted cavity wall insulation

If you can relate to any of the above, then it is relatively easy to get the offending cavity wall insulation removed – bricks at the bottom of the wall are removed and the insulation is simply sucked out, leaving the cavity completely clear.

The cost of getting cavity wall insulation removed is £21 – £22 / m² depending on the material that was used in the first place, therefore for a semi-detached (which is 80m²) the price will be approximately £1,680 + VAT @ 20%. For a bigger detached property (so roughly 120m²) the price to remove the cavity wall insulation would be a £2,520 + VAT @ 20%.

Where to look for draughts

1. Gaps around pipe entrances
2. Gaps around vent installations

Pipes and vents are areas that you may over look when considering draught proofing your home. Draught proofing these areas is easily done, affordable and effective.

How do I draught proof pipes and vents?

Gaps may be found in the area where pipes pass through walls and floorboards; draught proofing these areas is a simple but effective way of stemming the heat loss flow. Foam-based fillers are simple and great for draught proofing irregular gaps like the ones caused by pipes.

Air bricks and bathroom vents

A word of caution: there are some areas that should never be blocked off or insulated. Air bricks are there for a reason – to prevent your floorboards and wooden supports from rotting. A constant flow of air is needed to prevent damp from entering the property and running havoc. When you get floor insulation done professionally, these air bricks are kept free to allow air into the area, so it is essential not to block this off.

The same goes for vents in the bathroom, as damp can easily build up in these humid rooms without adequate ventilation. So remember, draught proofing is great, but allow your home breathing space!

Key points before you start

Insulating the rafter space will give you a warm loft. This means insulating between or below the sloping beams that form the construction and support a sloping roof. The rafters are joined together by a horizontal ridge board at the top and tied together by ceiling joists at the bottom.

Having chosen to insulate your rafters and potentially use the loft space as an extension of your living area, you need to be aware of some safety features before you read on:

1. Ensure if you are placing heavy objects or walking in the loft space you have fix boards to your joists, otherwise there is a danger you may fall through the ceiling.
2. Be aware of pipes and electrical cables.
3. Making the loft warm is not a substitute for a full professional conversion.

Insulating your rafters as a DIY job

There are two ways you can do this as a DIY job:

• Insulating between the rafters
• Insulating below the rafters

DIY loft insulation

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Preparing the loft space ready to insulate

Before you get to the business-end of installing the product you need to make sure you have prepared the workspace in the loft and have also bought the right quantity of materials. There is a quick step-by-step guide below on what you should do before you begin any work:

• Clean the rafter space by vacuuming between them, removing any dust that may have settled there over time.
• Make sure you pay attention to any cracks, dry rot or damage to the rafters and the roof membrane. If it looks unsafe to work, stop what you are doing and immediately seek professional help to repair these areas.
• Check the wiring is ok.
• Ensure a good level of lighting in the loft to provide decent visibility to help you do the work.
• Ensure you have boards laid out on the joists, as you will be moving around the loft and transferring your body weight onto the ceiling below.

Once you have all the space figured out you will need to do an equipment check.  Here is what we recommend you find before starting:

• Tough pair of scissors
• Measuring tape
• Protective overalls and gloves when handling rock or glass wool
• Safety goggles
• A disposable mask
• Safety helmet

If you are handling insulation boards then you may also require the following:

• A saw
• Drill
• Nail gun
• Wooden battens

Measuring the size of your rafter coverage

After you have cleared bulky objects, you will be able to see the area more clearly. When measuring your loft space here is a simple guide:

• Take a measuring device (tape measure or a laser measure) and measure the rafter area – this can be done by measuring from the apex of the roof down to where the sloping roof meets the horizontal joists and multiplying by the breadth of the roof.
• Take into consideration the thickness you want to insulate – it is recommended you insulate to at least 100mm to get the optimal performance
• Measure the width of your rafters – this is important if you are thinking of insulating below the rafters
• Write down these measurements on a piece of paper and then take them with you to a DIY shop to buy the insulation or order the materials online.

DIY rafter insulation

Before you apply the insulating material you will need to measure and leave a space of about 50mm between the roof (breathable membrane or tiled) and your insulating material so air can travel freely through, otherwise you could have issues with condensation and damp.

The depth of rafter will obviously influence the thickness of insulation you can fit between them, but you can always extend the rafter by attaching a wooden extension to it, since the more insulation you can fit in place, the warmer the loft space will be.

• When handling wool, ensure you take enough rolls with you into your loft space. Use scissors to cut through the packaging and lay out the material. You will need to start at the top, stapling the wool material to the sides of rafters on each side. Carry on fixing the material until you have the whole space covered. You will need to have your dimensions correctly mapped out as you need to have material that covers the width of the rafter space.
• Make sure the insulation is 50mm below the actual roof, which can be done using the battens as your measuring gauge for the breathable area between the roof and the insulating material.
• Depending how deep your rafter is you may be able to fit two layers of 100mm thick wool insulation. To ensure bits don’t fall off you can then attach a layer of netting that will ensure the material is further supported from the forces of gravity.
• At this point, if you are bothered about aesthetics you can fix a thin layer of plasterboard to the bottom of the rafters (with the material already snuggly fitted between them), and paint over it. Although you will lose you some headroom, it does improve the visuals of the place.

Installing rigid boards

• Your rigid boards will need to be cut to fit the gaps between the rafters. When they are cut ensure there is a relatively tight fit between the edges so that it could be stapled to the rafters. The wooden battens that sit further in the rafter will act as an automatic stabiliser, so the boards could easily sit on top of them.
• Again make sure you select the right thickness of the material so you fill as much of the rafter gap as possible. To ensure you don’t have bits flying off you can get sheets of see-through film and staple it to the underside of the rafters.
• Using rigid boards as opposed to wool is a much more precise process, as the cuttings need to be almost perfect to snugly fit rather than the wool, where your material can be folded and moulded to fit into the rafter space. If you are in doubt please consult a professional.
• When you use solid insulation board to create a warm loft the key thing to remember is ventilation – you must keep a 50mm gap between the roof and the rigid insulation board. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. If there is no vapour layer it might result in damp issues, since the warm air may condense in the loft space on cold surfaces. Water and timber don’t work too well together and it could result in the timbers rotting.
• The best way to achieve the gap is to attach some dowel batons on the inside of the rafters so you can then butt the insulation board up to them ensuring the 50mm gap is still in place. If you measure the thickness of the rafter, then less the 50mm gap – this is the thickness of the rigid board you want to put between the rafters. By doing this the insulation board will then not protrude out past the outside edge of the rafters, which means that you can then very simply attach more insulation boards, fixing them directly to the rafters to achieve the required depth of insulation.

What materials can you use to insulate below the rafters?

If you have shallow rafters or just don’t care about losing the headroom, then fixing material on the underside of the rafters is the much easier way to insulate at rafter level. Here you don’t have issues with condensation or worrying about leaving a gap in the roof membrane.

Installing rigid boards

• Your rigid boards will need to be cut with some logic so that you can move from one side of the roof to the other. Insulation boards come in different sizes, and as long as you figure out a plan as to how you will cover the rafter space then you should be fine.
• You need to nail them to the underside of the rafters to ensure they can be fixed. You can use a nail gun or a conventional hammer and nails to do this. If you are using a nail gun, ensure that you handle it with care.
• At this point you may also decide that it is sensible to do this as a lone ranger. Having someone there holding the material in place while you fix the edges will ensure the process is more efficient. In addition having a fresh pair of eyes and hands means you always have a second opinion during this process.
• At the end you may want to put a decorative finish by covering with a thin layer of plasterboard and painting a finish.

Installing reflective foil

The reflective foil installation is the easiest of the processes, however the thermal insulation result is the poorest.

• Unroll the material and start on one side of the loft. Staple the foil to the underside of the rafter, ensuring as you roll-out the material you staple to all the rafters. You will eventually get to the other side of the room having covered a level with this insulating material.

• You either now move onto the other direction of the loft or you position the foil below or above the level you have just insulated. The idea is that by the end of the process you would have covered the whole loft space.

Why should I draught-proof my chimney?

Even after completely draught-proofing your windows, doors and floors, you may still be left with a large area of concern in the shape of the chimney stack. A lot of heat can be lost through an uninsulated chimney. Unless your chimney is never used, you need to choose a temporary draught-proofing solution that can be removed as and when you want to light the fire.

Draught-proofing chimneys with a Chimney Sheep

Draught proofing chimneys with chimney balloons

There is a really easy solution to prevent these draughts, which does not involve permanently boarding up your fireplace or blocking your chimney. You can use a chimney balloon.

A chimney balloon is essentially a balloon that you inflate in your chimney that creates a snug fit, thereby preventing hot air escaping up out of the chimney or cold air dropping down it, helping to prevent draughts in your home.

You position the balloon up in the lower regions of the chimney stack and then inflate it, which holds it in place. The balloon is designed to stop the majority of airflow, but it will still allow a little ventilation so you don’t have any damp issues.

Can you draught proof a chimney with anything else?

You can obviously opt to draught proof your chimney by simply stuffing plastic bags up it – the issue with this is twofold. Firstly, if you forget it is there and light the fire, you can actually cause a chimney fire. The second is that it will be far more difficult to ensure that you are stopping all the draughts. We have also come across people insulating their chimneys using tea towels and newspaper in the past – which again as flammable materials are a really bad idea. If you were to forget the chimney balloon was up the chimney when you light the fire, it would simply wilt and fall from the chimney – but it would not cause a fire – hence from a safety point of view, this is why we always advise them!

Chimney cowls are also a great way of ensuring maximum efficiency while also keeping out nesting birds and debris.

Why should I insulate my loft hatch?

Your loft hatch can cause cold draughts to enter the living space of your home, especially if you have a cold loft space (i.e. insulated at joist level rather than rafter level).

Draught-proofing the loft hatch should be done at the same time as insulating the loft space to ensure you gain the maximum savings on your energy bills.

How to draught-proof a loft hatch

First of all: be careful. If you intend to insulate the loft and draught-proof the hatch yourself, it is imperative you take safety seriously. You must take care whenever you work up a ladder and if you feel unsafe or not entirely comfortable undertaking this then please use a certified installer.

There tend to be two types of loft hatch:

1. The hatch rests on the frame of the loft entrance.
2. The loft hatch is hinged and will swing down when opened.

Insulating the top of your loft hatch

Once you have insulated your loft space and you have draught-proofed the loft hatch, creating a seal to stop cold air entering the main house and hot air escaping, it is also worth insulating the top of the loft hatch as a final step. This is fairly simple process; essentially you just need to attach the insulation to the top of the loft hatch.

How do I do this?

What is floor insulation?

Insulating a floor means adding an insulating material beneath the floorboards, thereby reducing heat escaping through the floor into the ground. Approximately 15% of heat is lost from a house via this route. Insulation also acts to prevent draughts coming up through the floorboards. In addition the household should also consider insulating the gaps between the skirting boards and the floor, which also helps in reducing draughts.

Floor insulation is most commonly done when putting a new floor in place, but most floors can be retrofitted with insulating material, and this will make a large saving to your overall heating bill. Depending on how confident you are with DIY, it is possible to install floor insulation yourself.

DIY floor insulation

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Benefits

• Filling the gap between the skirting boards and the floor can save about £25, recouped within the year (assuming a £20 material cost).
• Since the insulation will slow the movement of heat through the floor, the home will feel more comfortable and warmer in the winter, but cooler in the summer months.
• You can reduce your carbon footprint by about 240kg per year by installing floor insulation and almost 100kg if you fill the gaps between the floor and skirting boards.
• According to the Energy Saving Trust, installing floor insulation underneath a wood surface saves about £60 per year, which would mean a payback of 2 years based on recouping the material costs (approximately £100).

Limitations of floor insulation

• If you are wishing to installing the floor insulation as a DIY project, you will need to move furnishings and potentially remove carpets and floorboards.
• Additional costs may add up, if once you remove the floorboards, you discover that some are rotten, therefore the overall insulation costs may be higher than previously predicted.

Cost of floor insulation

• Professional installation costs start at £770, dependant on the size of the floor space installation.
• DIY Cost for wooden floor insulation cost approximately £100 and it will cost about £20 to buy the materials to fill the gaps between the floor and the skirting boards.

Installing floor insulation

Interested in having floor insulation installed? The Green Homes Grant is a Government run scheme lasting until March 2022. The scheme offers grants up to £10,000, under-floor insulation is a primary measure that can be installed utilizing the scheme.

If you are interested in the Green Homes Grant, we advise looking in to this on the Government website.

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What type of floor do I have?

Most floors in the UK are either solid (concrete) or suspended (usually timber floorboards). Solid floors don’t really tend to have draught issues associated with them, but suspended timber floors are definitely worth tackling.

The first step is to identify which type of floor you have. You can find out by pulling up the corner of your carpet, or looking for air bricks on the outside of the property at the bottom of the walls – these will signify a suspended timber floor.

Where to look for draughts:

1. In between floorboards
2. Around skirting boards

How do I draught-proof floorboards?

The gaps in between stripped floorboards may add up to the size of a small window; therefore draught-proofing your floor is essential and can shed pounds from your energy bill, paying for itself in less than 12 months. With so many products on the market, it is important to select one that will provide you with the best outcome for your specific requirements.

The first thing to assess when considering whether to draught-proof your floorboards is what the required finish is. For example the methods used to draught-proof floorboards under a carpet are different to those used to draught-proof stripped floorboards. It should be noted that even though carpet will help with draught-proofing, it is not 100% effective, and additional measures can still help.

How do I draught-proof stripped floorboards?

There are many products that fill the gaps between the floorboards, helping to prevent draughts. These come in the form of tube-like rolls (such as DraughtEx) that are easily pushed into the spaces between floorboards, assuming that the correct and accurate diameters have previously been taken into account. This is a quick, easy and relatively cheap way of draught-proofing your floorboards effectively. However, difficulties may arise if you have an older floor with uneven gaps between the floorboards that may require you to buy additional rolls of different sizes.

Alternatives to the tube-like rolls, which are pushed into floorboard gaps, are thin V-shaped, one-size-fits-all, plastic lengths that spring apart when pushed into place using a credit card. When in position, this innovative method is invisible and effectively stops draughts. The issue here is that if they pop out they could then potentially trip you up; make sure they are fitted as per the instructions to prevent this from happening.

How do I draught-proof floorboards under a carpet?

A carpet fitted over your floorboards helps reduce draughts; however there are further steps you can take if you are searching for optimal draught-proofing. If you are on a small budget, then the traditional technique of papier-mâché may be the best option. However, while this provides a cheap and effective solution and covers the potentially draughty gaps in between the floorboards, it does take a lot more time than shop-bought fixes. For a more efficient, but costlier method of draught proofing underneath your carpet, you can apply a gunned silicone sealant to the gaps between the floorboards provided the gaps aren’t enormous!

Using thicker underlay below the carpet is also an effective way to stop the draughts and insulate the floorboards.

The most effective way to stop draughts coming up through the floorboards is unfortunately also the most costly and time consuming. This involves lifting up the floorboards and applying insulation between the joists – details of how to do this can be found on our ffloor insulation pages.

How do I draught-proof the skirting board?

Even with successfully draught-proofed floorboards, you may still lose heat through the skirting board area. In order to maximise efficiency you can draught-proof this area using wooden beadings, which can be applied to skirting boards where they meet the floor. The wooden beadings come in a variety of shapes and they help bridge the gap that allows draughts.

Draught-proofing this area may also be achieved through silicone-based gunned sealants that can equally block the gap between the floor and the wall; again you may need to use a combination of both the wooden beadings and the sealant if the gaps between the floor and the skirting board are particularly large.

Where should I look for draughts?

1. Around the door frame
2. The keyhole
3. The letterbox

Obviously draught proofing external doors should be the priority, since this will stop cold outside air entering the property; but doors that separate cold rooms from warm rooms should also be draught-proofed to prevent the unwanted circulation of air between the two. This maybe the case if you have a spare room that you do not heat during the winter to help save on your energy bills.

How can I draught-proof around the door frame?

The first step is to fit a brush strip to the bottom of the door frame, as this is where the largest gap tends to be between the door and the frame. Most draught excluders are screwed in place, so first you need to measure the length of the bottom of the door. It is important to measure the door when it is closed, as the fixed brush strip may otherwise stop the door shutting. The brush strip then needs to be cut to length using a hacksaw. Once it has been cut to length, screw the brush strip in place, ensuring that the bristles of the brush reach the floor as this is what is going to stop the draughts.

A hinged flap draught excluder may also be used as it works on a similar principle; however instead of brushes this method relies on a flexible strip to prevent draughts.

Around the sides and the top of the door you can use a foam strip or brush strips to minimise draughts. The foam strips tend to come attached with a self-adhesive surface, so prior to fitting them to the door, you need to clean the door surface with soapy water (and let it dry) to ensure the foam strip sticks properly.

Gunned silicone sealant may also be used in the draught proofing of doors. This is the cheapest solution to draught proofing around the edges and at the top of the door It is absolutely key that a release agent is first applied to areas of the door that you don’t want the sealant to attach too. By applying the releasing agent in the correct places, the closed door can actually be used as a temporary mould for the sealant before it sets.

Installing Cavity Wall Insulation

How can I draught-proof a keyhole?

Draughts may also enter the property via keyholes within doors. These draughts are easily prevented by installing an escutcheon plate (essentially a metal disc that is attached at the top of the key hole). This will swing open allowing you to insert the key and swing shut again to stop draughts.

How can I draught proof letterboxes?

Standard letterboxes produce a surprisingly large draught. We recommend installing something like the Ecoflap letterbox as it is 100% effective, easy to install and is low cost. It is a simple method of draught proofing and completely stops any potential heat loss through the letterbox. You attach the bracket to the inside of the door so it also works as an anti break-in feature.

Installing new doors

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