The ultimate guide to solid wall insulation

solid wall insulation

You may have considered insulating your cavity walls to save money on your heating charges. But did you know that solid walls can also be insulated?

Insulating solid walls is a good idea since they leak as much as 45% of the heat from your home, according to one study. Insulation on the inside or outside of your walls is both feasible and beneficial.

In this article, we’ll cover all you need to know about solid wall insulation, including what it is and how to do it (or pay a professional to do it!).

First of all: what is a solid wall? 

Solid walls are walls that are completely solid all the way through. They’re a bit more difficult to insulate than cavity walls (which have space within), but it can be done! nIt’s thought that over 8 million homes in the United Kingdom have solid walls.

How can I tell if my home has solid walls?

If your house was constructed prior to 1920, it is likely to have solid exterior walls rather than cavity walls, which were only introduced in the 1920s. You may also tell whether or not a brick-built property has solid external walls by measuring their thickness. Do so by taking measurements of an external doorway or window. If a wall is less than 10 inches thick, it is almost certainly solid.

Cavity walls can be as thick as 3 feet, but they are extremely rare. If you reside in timber or steel-framed house, this will be yet another story, and the insulation recommendations outlined in this article may not apply to you. Instead, go through our information on cavity wall insulation to discover everything you need to know.

What is solid wall insulation? 

Adding an extra layer of insulation to your wall, therefore making it more difficult for heat to pass through, is the goal of solid wall insulation. This keeps the heat inside, so you don’t have to turn your heating as high or keep it on as long. You’ll be saving money on your utility bills right away!

Cavity walls may be quickly and inexpensively insulated, while solid wall insulation is a bit pricier. However, while the start-up costs are higher, the heating expense savings will be greater!

Just so you know: we’re only talking about insulating your house’s external walls when we use the term “solid wall insulation.” This refers to rooms that have one side exposed to the outside world and the other covered (letting air in from the outside). Internal solid wall insulation, as this implies, means insulating your external walls’ inside. When we talk about external solid wall insulation, we mean exactly the same thing.

Internal solid wall insulation

Internally, solid walls can be insulated in a number of ways. You may attach rigid boards to the wall or construct a separate stud wall and fill the gap with insulating material (such as mineral wool).

Solid wall insulation types

Rigid insulation boards

The boards are fixed to the wall using ribbons of plastic or adhesive, or fitted to battens if the walls are lumpy and uneven. They’re generally secured with plastic ties or adhesive. The installer will add additional fixings to ensure that the boards stay in place and that the gaps between them are sealed.

Stud walls

Metal or wood frames are used to hold up drywall panels, which are then attached to the solid wall. The insulating material is inserted between the studwork frame and the wall after being plastered. It can then be painted or floral wallpaper to give it a unique appearance! Alternatively, rigid insulation boards could be used instead, making your insulation even more efficient while also lowering your running costs. However, keep in mind that this might affect the size of your room.

Benefits of internal solid wall insulation

Internal insulation is usually less expensive than external insulation, and it’s easier to install. There is no need for scaffolding, and it doesn’t alter the outside appearance or character of your property; therefore, it’s more suitable for visually appealing buildings and period properties. It’s also better suited for flats and maisonettes since you can’t easily utilize external insulation on one unit in a block! Internal insulation may even be acceptable in conservation areas where there are often strict limitations on what kind of modifications you can make to the outside aesthetic of your home.

What are the disadvantages of internal solid wall insulation?

You’ll need to deal with any damp issues before you start, since rising or penetrating damp can negate the benefits of your insulation. It will reduce the room’s size by about 4 inches; it will bring the wall in by about four inches

After that, you’ll have to re-lay the carpet and replace all of the fixtures and fittings you removed. If the wall’s surface is uneven and bumpy (as it often is in older structures, particularly in rural locations), it will need to be levelled with plaster or rendered before applying hard insulation boards.

If you utilize hard boards, it’s possible that your walls aren’t strong enough to support heavier things like washbasins, kitchen units, or heaters. However, if you want to install special attachments, stud wall insulation should be durable enough to handle these fixtures.

It might damage or mask period features.

External solid wall insulation

If you want to insulate your house on the outside, an installer will apply a layer of insulation to the wall using mechanical fasteners and glue. They’ll then cover it with protective coats of render or cladding. Render is typically less expensive than cladding, but it isn’t as versatile.

If the surface of your wall is solid enough to support the insulating material, it will be installed. However, if the existing render is outdated and rippled, it must be removed. This might make everything a bit more challenging

If you own a historic home or want to make your house more beautiful, you might consider hiring an architect or installer for bespoke insulation. They can utilize a number of different materials, including oak weatherboarding, stone, glass, and terracotta tiles.

Before work begins, make sure there are no rising or intrusive damp in the walls. External wall insulation will hide damp patches for a time, but the underlying issues will inevitably worsen.

Benefits of external solid wall insulation

It’s less disruptive because the task takes place outside your home, but your gas, electricity, or water may be disconnected for a time, and your garden might suffer some damage!

It won’t reduce the size of any of your rooms.

It may help to improve the look of your home’s outside walls by allowing you to choose whatever finish you desire.

It can improve the soundproofing and weather resistance of your home.

It seals cracks and gaps in masonry, reducing drafts.

Because the insulating material is applied continuously, without any gaps, there’s less of a chance that “cold spots” on the inside of the walls will cause condensation and mould.

What are the disadvantages of external insulation?

It’s not cost-effective to do it yourself, so you’ll probably want to schedule it for the same time as other external work on your home to save money.

It’s not suitable for properties with a history or characters. All external pipes and other attachments, such as satellite dishes or security lights, will need to be removed and replaced. You may have to extend window ledges or roof eaves to make room for the extra thickness of your outside wall. It might prevent ancient walls from breathing naturally in a historical home

Solid wall insulation costs

How much does external solid wall insulation cost?

The cost of insulating solid walls externally ranges from £100 to £200 per square meter. It may range from £8,000 for a modest flat to £22,000 for a large detached house3. With that in mind, it might take several years to recover your investment. However, costs can differ considerably based on how much work needs to be done and whether installers have easy access.

How much does internal solid wall insulation cost?

The average cost for internal walls in a typical semi-detached house in the UK is £7,400. This is obviously far less than the cost of external wall insulation, but it would take a long time to make back your investment.

How could I reduce the costs of solid wall insulation without compromising on quality?

If you’re trying to cut costs, consider insulating a wall while you do other building or decorating work. When it comes to redecorating, internal insulation is an excellent addition. If you’re going to replace your kitchen or bathroom and install solar PV panels, for example, external insulation will be less expensive. You may save money by doing one room at a time.

It’s worth seeking a quotation for any work you’re doing since it’ll almost certainly be less expensive than doing the two tasks separately.

Solid wall insulation installation

DIY solid wall insulation

Internal wall insulation may be done by an expert DIYer. But external solid masonry surface (SMS) should only be installed by a professionally trained installer. If you do try internal wall insulation, keep all of your receipts for the materials and take photographs of each stage of the installation. You’ll need them if you want to get an Energy Performance Certificate if you sell or rent your property in the future.

Before you begin, be sure there is no damp in the walls you’re going to insulate. Insulating the walls may actually make the damp problem worse.

How do I choose an insulation installer?

When it comes to choosing a roofing company, the same precautions apply as with any other building project: get several quotations from professional installers. You may look for specialist firms on the main trade association sites. The National Insulation Association (NIA) (for either internal or external work) or the Insulated Render & Cladding Association (INCA) (for exterior insulation) are two examples.

What sort of guarantee can I expect?

Ask if the installer offers a 25-year warranty from SWIGA (Solid Wall Insulation Guarantee Agency) before giving them the go-ahead to begin working. This will provide you with 25 years of coverage for faulty materials, design, or execution. Also make sure they’re using BBA-certified products and materials.

Will I need to get planning permission, or comply with any building regulations?

You won’t need planning permission, but you may require a building warrant. The local Building Control Office should be contacted to obtain approval. Check to see if they’re going to do it; if they aren’t, make sure you contact the Building Control Office before any work begins.

Contact your local council to see whether there are any specific rules or permissions that apply to your home. You may require listed building permission if your property is a listed building. There will almost certainly be limitations on what you can do to alter the appearance of your home since it is in a conservation or world heritage area.

Do you want to install extra insulation on your roof? If you live in a flat in a complex with several owners, you’ll need permission from each of them. Do you want to build an addition to your house? Check out our guide to green loft conversions for ideas.

Is it okay to use “non-breathable” insulation materials in my home?

In traditional solid-wall construction, “breathable” or “vapour permeable” insulation is typically the best option. These allow air to move freely and prevent moisture from accumulating. If you decide to utilize non-breathable (or vapour impermeable) materials for whatever reason, find out what measures you must take to keep your rooms fresh and dry.

More ideas to help you insulate your home

Our user guides provide you with a slew of options for further boosting the insulation in your home’s roof, loft, walls, windows, and doors. For some great energy-efficient design inspiration, check out our guide to Passive Houses’ incredible “hyper-insulated” homes

Cavity wall insulation

Insulating your cavity walls might be a very cost-effective approach to keep heat in your house while also reducing your energy expenses. Read our guide on cavity wall insulation for further information.

Roof and loft insulation

We lose a large amount of our body heat through our heads, and so does your roof! In uninsulated homes, as much as a fifth of the heat escapes through the roof5. Filling your loft with insulation may be a very cost-effective method to keep warm and save money on your energy bills. Learn more about roof and loft insulation in our guide.

Draught-proofing windows and doors

Draught-proofing your home’s windows and doors may save you between £25 and £50 each year on heating costs, not to mention the environmental benefits. Learn more in our guide to draught-proofing windows and doors.

If you’re interested in learning more about solid wall insulation, why not contact DBI today for a quote?

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