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Insulating Walls In Old Houses

Insulating Walls In Old Houses

Insulating an old house from the inside. The idea of making an old building more comfortable, energy efficient and fit for purpose of modern living can be a challenge, especially if you are trying to retain period features. 

In UK, one in four homes is made up from solid walls. Out of 25 million of total home stock, that’s 6.25 million of properties with solid walls that could be improved in terms of energy efficiency and comfort of living.

As Home Logic Team is committed to finding the best solutions and advice on the topic, we gathered a few tips on how to best deal with insulating walls in an old home, be it a classic and widely desired Georgian dwelling or draught prone Victorian terraced house.

What type of wall?

It is important that we understand, insulating walls will depend on many variables. The main factors to take under consideration will be:

  •  material from which the wall was built, for example, stone, brick or timber
  • how old the wall is
  • the structure of the wall (cavity or solid)

In UK, houses built before 1920s are likely to have solid walls. Houses built after that time, will most likely be constructed from cavity walls.

  • Cavity walls comprise two layers of wall with a gap in between; the outside layer is made up of a regular pattern brick, and the inside layer is made up of concrete block or brick.
  • Solid walls are single layer structures; there is no gap or cavity inside, and are likely to be made up of alternating pattern brick or stone.

Dry means Warm

Before starting the process of insulating walls in old homes, there’s one condition  – the walls must be completely dry to proceed. It is even fair to say that a thick brick wall (no less than 9inches), as long as it is dry, it provides a great insulation from the cold of the outside. The thicker the wall, the warmer the house – simple.

The problem starts as soon as a cement rendering is applied on the outside walls and gypsum plaster on the inside of those external walls. The original wall sandwiched  between plaster and cement will trap atmospheric moisture in the pores of the stone, which then conducts the heat rapidly making a house very cold and damp quickly.

Think of your house as a giant storage heater. Mass of the solid walls, when dry and heated, will stay hot and will release heat throughout the day and at night to keep the interior cosy.

This is the concept that justifies large tiled concrete heaters that were commonly installed in buildings from more than a century ago.

Back in the days people were relying on so called “thermal mass value” of the walls and the homes were supposed to be heated 24/7. Modern times developed different solutions for new builds but what about these amazing period homes that we love to live in for their character features? Do we have to go back to old fire stoves that will have to be on all day? Read on.

Insulating Walls in Old Houses: Your Options

Now that we have identified that insulating walls in old houses comes down to insulating a solid wall rather than a cavity wall, we can explore our options.

Inefficient damp proofing

Old buildings with solid walls are likely to have been treated with some sort of damp proofing in the past: gypsum plastering inside and cement on the outside are very popular.

Unfortunately, they block a natural “breathing action” of the building, and instead of sorting, they escalate damp problem even more by causing an inter-layer condensation to form. This means a lot of moisture stored in the mass of the building and, if cold enough, it will conduct heat rapidly out from the house.

All impermeable insulating materials must be removed from a solid wall, for the building to pass the air rather than moisture through the pores of the brick or stone and transport it out.

The solid walls  will work again as an insulator, or a basis for more advanced insulating systems specifically designed to match the nature of solid walls.

Listed period buildings

Another factor to consider is whether you have any restrictions in regards to insulating the outside of your property. If you live in a grade listed building, you may be restricted by planning permission or conservation restraints in terms of insulating the building. If you can’t change the outside, internal insulation will suffice. In reverse, if you are unable to alternate the inside, suitable outside insulation solutions are also available.

Once this preparation has been finished, you  can do the following:

  • apply new heating systems that work for solid wall house (under floor heating)
  • invest in double and triple glazed windows (replicas of original styles are now allowed)
  • insulate with innovative insulation systems like Home Logic Spray Foam

If you only decide to change your heating system in your period property, you will be relying on the outside temperatures to turn your heat controls up and down accordingly. You must be prepared for paying more for your energy bills

In other words, you will need to consider some sort of insulation to go with it. Insulating walls in old houses using rigid boards, stud walls with mineral wool on the inside, or plaster boards on the outside won’t work because they are non permeable materials and will create a imbalance in natural heat transfer of the solid walls, in other words, it will distort the U Value.

Why Home Logic Spray Foam Insulation Systems?

With all the research and feedback from installers available, Spray Foam is the most efficient solution for insulating solid walls in old houses to date. The benefits include:

  • it has a porous, open cell structure that enables for the solid walls to expel the excess moisture out
  • it is an airtight yet permeable, eco-friendly material which improves the quality of the inside air
  • eliminates draughts and cold spots
  • it will allow for the period building to be even more effective at storing the heat in its solid wall mass
  • is perfect to control elements in cold and wet climates to prevent structural damage
  • only a thin layer can be applied so no period features are lost
  • it takes minimum amount of space from the inside
  • it doesn’t take a long time to install
  • causes a minimum disruption for home owners during install process
  • makes an old property a comfortable space to live in

If you live in a period home with solid walls, you may need a combination of open and closed-cell spray foam to effectively insulate your property. Why not give one of Home Logic Experts a call on 0800 1700 636.

Learn more about Home Logic Spray Foam Insulation here.

To check spray foam insulation product details & to obtain an instant quote, try out our online estimator