How to Insulate an Old House or Property

Old roof insulation

No matter how much you appreciate your old house, the draughty windows and thin walls are always a concern. Staying warm in your old house becomes nearly impossible when the temperature drops.

In England, three-fifths of assessed homes have low energy efficiency ratings. A recent Office for National Statistics analysis showed that only 12% of homes built before 1900 have good energy efficiency ratings. That being said, home insulation is now a must rather than a nice-to-have thing. But when it comes to old houses, insulation can be tricky.

Not to worry, we’re here to explain how to insulate an old house or property.

Assessing Your Old House for Insulation Needs

Before you go ahead with insulating your old house, you need to assess the whole property’s insulation. 

1. The Age of Your Home

The age of your property plays a significant role in determining the level of insulation needed. For example, older homes built before 1920 often have little or no insulation. That’s because it wasn’t required by building regulations. 

Additionally, people used to invest in fireplaces, and the fuel wasn’t expensive, so insulation wasn’t a huge concern.

If your home was built between 1920 and 1990, you likely have a space between the inner and outer walls. In that case, you should look into cavity wall insulation, which we’ll discuss shortly.

2. Wall Type

The structure of your walls is another crucial aspect of thermal insulation. As we mentioned, you can easily know which type of wall you have if you know when your house was built.

Generally speaking, there are two main types of walls: cavity walls and solid walls. So, what’s the difference?

Cavity Walls

Cavity walls were developed to solve dampness issues in the first half of the 20th century. They consist of two layers of brick and a gap between them. The gap width ranges from 20mm up to 100mm. As such, they’re much wider than traditional brick walls.

To make sure you have cavity walls, check any exposed brickwork. You may have a cavity wall if the bricks are all equal in length. Another way to go around this is to measure the width of your wall. You probably have a cavity wall if it’s more than 270mm.

Fortunately, insulating cavity walls isn’t a daunting task, and it’s fairly cheap. All you have to do is fill the gaps between the bricks with an insulating material. 

There are many types of insulating material. You can use fibreglass insulation as an affordable option or opt for the more expensive polystyrene bead insulation, which performs better.

Solid Walls

As the name suggests, a solid brick wall is two bricks wide. Each row of bricks is interlocking, creating a 9-inch brick wall. These are the types of walls in houses built before 1920. 

Since these walls don’t have any insulation gaps, they don’t have any insulation properties. So, the only solution is to add internal or external insulation.

You can simply identify these types of walls by inspecting the brickwork of your house. You probably have a solid wall if you find a mix of short and long bricks. 

You can also measure the wall width if your property is rendered. If the width is less than 260mm, chances are you have a solid wall.

Dealing with solid walls isn’t as simple as insulating cavity walls. The process is expensive, time-consuming, and may require planning permission. 

Internal and External Wall Insulation

There are two ways to insulate a solid wall: internal and external wall insulation.

External wall insulation involves changing the appearance of your house completely. That’s because board insulation is installed around the exterior walls of your house, and then a breathable render is added. 

Moreover, depending on where you live, you might need planning permission to go on with external insulation. If you didn’t get permission, internal wall insulation might be sufficient.

Note there’s some funding available for solid wall insulation. However, you might have to contribute too.

Internal wall insulation is all about creating a lining on the inside of your house’s exterior wall. You can do this by constructing a stud wall or attaching insulation boards to the wall. After that, add a vapour barrier and a render to cover the insulation.

The main problem with internal wall insulation is that you give up some space from inside your home. That’s when thermal-resistant thin insulation boards come in handy as they conserve space in your house. 

3. Loft and Floors

When assessing your home for insulation needs, checking the loft is crucial. That’s because around a quarter of the heat is usually lost through roofs.

Fortunately, checking and insulating roofs is easy. First, you need to understand what the regulations suggest. Currently, the recommended depth for loft insulation is 270mm. 

Years ago, the recommended depth was 100mm and then 200mm. So, even if your loft is insulated, it’s likely that you’ll need to add more insulation.

To access your attic, check the existing insulation and measure the depth using a tape measure. 

After that, measure the spacing between joists. Start from the middle of one joist and measure to the middle of the next. Usually, the distance is either 400 or 600mm. This will give you an idea of the needed insulation width.

Regarding floors, check the underside of the ground floor through an access hatch or cellar to see if you need more insulation. You should probably install insulation if you have elevated timber floors and a space underneath. That’s because a lot of heat is lost through floors.

4. Draughts

Have you ever felt a sudden chill in your home in cold weather? Sometimes, it’s just an open window, but in old homes, draughts can come from many sources in your home.

That’s why inspecting your house for draughts is crucial to saving energy and money. Here’s what you need to check.

1. Windows

The first thing you need to check is your windows. If you have double glazing, your windows shouldn’t be leaking. However, you might need to replace your windows if you find any mists or condensation between glass panes.

You should also check if your windows are closing properly. That’s because windows that don’t close well are a good spot for draughts. Adding a strip of insulation might help, but it would be best to repair your window if it doesn’t close properly.

2. Doors

If your house is old, your external doors probably perform poorly when stopping draughts. Carefully inspect your doors for any gaps that can let in draughts. 

If you find any, you can simply seal them with brush strips or foam. Regarding internal doors, they naturally have large gaps, especially at the bottom. Draught excluders are handy to draught-proof these gaps.

3. Chimneys and Fireplaces

Chimneys and fireplaces are common in old houses. While they look authentic, unused chimneys can let in a lot of air. 

To stop this, use a cap on top of your chimneys or use chimney draught excluders. If these don’t get the job done, you might consider filling your whole fireplace. But this will cost a lot more.

4. Vents

The last thing you need to check is the vents. Unused vents like old gas fires are usually a source of draught and should be blocked up using vent covers or filled with foam. 

Be careful; some vents are useful and shouldn’t be blocked or covered. For example, vents in rooms that naturally have a lot of moisture, such as the kitchen and the bathroom. Such vents are meant to reduce moisture, so it makes no sense to block them.

If none of these are the culprit, then you may need to think carefully about the insulation you can add to your old home to improve your comfort levels. 

Different Methods to Insulate an Old House

Now that you understand your home’s insulation needs, it’s time to start insulating the different parts of your home. 

1. Insulating the Roof and the Attic

First things first, your house might be losing around 25% of heat through its roof and attic if they’re poorly insulated. On the bright side, insulating your roof or attic is easy, affordable, and super-effective.

To insulate your attic, seal any cracks or gaps that might be allowing air to travel through your ceiling into the attic. Use any sealant, such as foam, caulk, or weatherstripping. 

Gaps and leaks are usually found around pipes, exhaust fans, light fixtures, and chimneys. If there are any nearby windows, check them for gaps, too.

After sealing gaps and leaks, it’s time to start insulating the attic. Note that the insulation type varies depending on your roof type.

For example, if you have a flat roof, you can install polyurethane or mineral wool layers. Meanwhile, if the roof is sloped, we recommend using polyurethane spray foam as they’re easier to apply.

You can add a layer of Batt insulation over the attic flooring and to the underside of your roof between the rafters.

2. Insulating the Floor

Insulating your floor is a great way to save up to 10% in energy costs. Upper floors don’t usually need insulation, but ground walls, especially those above unheated spaces, could benefit from insulation.

If you’re living in an old house, you probably have suspended timber floors.

To insulate suspended timber floors, lift the floorboards, place a soft insulation material such as sheep’s wool or mineral wool, and support it by netting between the joists. 

Lifting floorboards can be complex, and you’ll most likely need professional help. That’s because damage can always happen even if the lifting is done right.

However, if you have to do this, we strongly recommend lifting only a few boards at a time to minimise damage. 

So, is there another way to go around this without risking floor damage? Yes, there is!

You’re in luck if you can access the suspended floors through a cellar or a hatch. In that case, floor insulation can be easily done as part of insulating your basement. 

All you have to do is insert a quilt-type insulation between the joists from below. Then, you can opt for netting to provide extra support for the insulation. 

If you need more insulation, you can add a tongue-and-groove wood fiberboard and fix it to the undersides of the joists.

3. Insulating Walls

Insulating walls is another decent way to improve your home’s energy efficiency. But as mentioned above, the process is quite complex and depends on your wall type.

You can easily insulate cavity walls by adding insulation material from outside. However, it’s not a DIY job. You’ll need to hire a specialist company to do it for you. You can find a reputable installer local to you with Insulation Advisor.

The installer will drill multiple holes in your wall and inject the insulation material, usually polystyrene beads, mineral wool, or polyurethane foam. 

Once the insulation material is in, the drilled holes are filled in the brickwork so they’re not noticeable.

If your house has solid walls, you must choose between external or internal insulation. 

1. External Wall Insulation

External wall insulation is done by fixing a layer of insulation material to the walls outside your house and then covering it with cladding or plasterwork. 

On the bright side, external insulation doesn’t reduce your home’s internal space. It also has other benefits, such as:

  • Filling any gaps or cracks in the brickwork, reducing draughts
  • Gives your outer walls a fresh appearance
  • This can be done without disrupting your household
  • Increases the lifespan of your outer walls

On the flip side, external wall insulation has the following downsides:

  • Usually needs planning permission
  • Alters the original appearance of the walls
  • More expensive than internal insulation

2. Internal Wall Insulation

Internal wall insulation can be done in two ways. The first is installing boards of insulation material to the wall. The second is to install a stud wall filled with insulation material like mineral wool.

This type of wall insulation is usually preferred for its affordability. However, it’s a bit disruptive to the household and reduces the floor area of the house since the insulation material is usually 100 mm.

How To Insulate An Old House: Wrap Up

While it may seem like an expensive and time-consuming job, insulating your house can be a lifesaver in terms of energy efficiency in the long term. 

To insulate your old house, start with your roof, as it’s usually the primary source of heat loss. Then, insulate the floors, especially those above unheated spaces like a garage. 

Next, determine whether you’ll use internal or external wall insulation. Finally, seal any sources of draughts around doors, windows, ceiling joints, and between floorboards.

Ready to get started? Compare insulation installers with us today, and we’ll help find the best deals local to you!

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