Home Home Improvement What Is Internal Wall Insulation? How To Insulate It?

What Is Internal Wall Insulation? How To Insulate It?

internal wall insulation
Sue installing the Earthwool insulation in the attic roof; shortly afterward she fixed wooden battens to the furring channels so that we can affix lengths of tounge-and-groove pine.

What is the definition of internal wall insulation?

Internal wall insulation is applying insulation to the inside face of external walls to optimize the property’s thermal efficiency.

The most popular (though not always the most effective) form of installation is constructing a new stud wall to which insulation can indeed be added.

On the other hand, internal wall insulation can be inconvenient because it necessitates the removal and reinstallation of objects such as switches, radiators, and kitchen units, so make sure it is the ideal insulation choice for your home. Because it’s critical to create an impermeable layer, difficult locations like exposes & floor voids demand extra attention.

How much does it cost to insulate internal walls?

Internal wall insulation is typically priced between £40 and £50 per m2 — but it can cost more than £100 per m2 when a new stud wall is constructed. Internal wall insulation costs vary based on the type of insulation chosen and the existing wall’s condition.

Under the country’s ECO initiative, funds are offered for interior wall insulation for concrete walls for qualified families. Internal wall insulating is far less expensive than external wall insulating, often less than half the cost.

What Are Building Codes Involved in Internal Wall Insulation?

The Building Regulations specify certain airtightness & heat loss conditions that must be met for your property to be considered compliant. The rate during which heat (in watts) is lost over each square meter of a material’s surface is measured by its U value. A lower number indicates better thermal efficiency.

  • Due to the cavity ties, an uninsulated concrete slab will have a U value of roughly 1.5W/m2 and a significant level of cold bridging.
  • A solid 225mm stone wall will have a 1.9W/m2 rating.
  • A solid stone wall will be between 1.7 and 1.4 W/m2 (depending on the thickness)
  • A maximal U value of 0.3W/m2 is required by current building regulations, with a practical value of 0.2W/m2. To achieve that U value for solid walls, at least 100mm of insulating material must be installed (Celotex, Kingspan, or similar).

Improved airtightness has been shown to influence energy loss more than insulating strongly. The solid portions of the wall will be essentially airtight by nature, but gaps, cracks, and passageways can provide a challenge. These can be found inaccessible and inaccessible wall portions, such as basement voids underneath the ground level and the first-floor ceiling. The airtight barrier can be formed by applying insulation to the wall, but the advantage will be diminished by up to 50% if the insulation is not done correctly.

Does Internal Wall Insulation cause dampness?

The dew temperature is when moisture in the air condenses and condenses as water. Interior wall insulation will keep the wall at the exterior ambient temperature, causing the dew point to be drawn to the internal surface.

Moisture can be collected by the insulation & appear as wet spots on the plasterboard if the moisture content is too near the actual structure’s internal surface.

A moisture control layer will be required to assist prevent damp penetration. An insulated wall’s inside surface will likely be warmer, lowering the likelihood of condensate developing. Still, there will be spots – including where an external wall contacts an internal wall – where condensation will occur.

Condensation is a real possibility in those places, especially in high-level corners. Generally, overcoming this, upgrading the insulation to encompass the cold bridging.

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What is the best way to install internal wall insulation?

Internal wall insulation can be installed in three ways (plus one alternate approach that we’ll go over), but the procedure is essentially the same across all three:

  • Examine the wall’s condition and make any necessary repairs.
  • Inquire with the recommended insulation manufacturer about where the dew point will happen with the desired insulation thickness.
  • Choose the most effective strategy from the three options (as below)
  • Determine how to handle reveals, floor voids, and other cold bridges.
  • Remove any electrical outlets, light switches, curtains rails, radiator, pipes, skirtings, covings, kitchen cupboards, fitted wardrobes, and other items fixed towards the walls to be insulated.
  • Carry out any wall preparation work (i.e., knocking off old plaster if damaged)
  • If necessary, construct a new stud wall and/or install insulation.
  • To finish, seal the joints and skim the plasterboard.
  • Reinstall smart switches, plug sockets, and other electrical components.
  • Attach the insulation to the wall immediately

The insulation can be fastened immediately to the wall in the first installation option. Insulation attached to beadboard and a vapor barrier is available from Kingspan & Celotex in products specifically intended for this procedure.


This procedure can be efficient and quick if the wall is somewhat flat and in good shape. Boards can be fastened to the wall with a unique adhesive designed for the job. If necessary, mechanical fasteners (screws) can be employed. To ensure consistency of the vapor barrier, gaps between boards at the walls and floors borders should be sealed with mastic & taped over them before plaster skim.

  • Putting up a wall batten
  • Battening on the wall is the second choice. There are two approaches to this:
  • Battens are fastened to the wall to create an equal insulation installation.
  • Alternatively, the ‘warm batten’ approach involves fastening the plasterboard over the insulating. Battens of 25x50mm would be used in both cases.
  • Build a new stud wall.
  • Option three is putting up a new stud wall, usually 100mm thick, inside the existing one, with a 40mm gap between them. This choice takes up much more room on the floor than the others.
  • Apply insulating plaster to the walls

The fourth alternative for interior wall insulation is insulating cement directly on the wall. This is especially beneficial on stone walls, where airflow is critical. A hemp or cork-lime mix (with the hemp or cork providing protection) or layer upon layer of lime plaster sandwiched between two, a cork or wood fiberboard would be used.

Do your internal walls have insulation?

Interior walls are typically not insulated during construction. Internal wall insulation is seldom needed, as opposed to external walls, which must adhere to municipal and state building requirements. This is because inside insulation may still affect your home’s energy efficiency, even if it has a considerably smaller effect.

Is damping a result of interior wall insulation?

When appropriately placed, internal wall insulation won’t lead to water. It shouldn’t be positioned if there is a damp issue since rising or penetrating moisture would be evident. This implies that you might need to reinstall if the problem isn’t fixed.

Benefits of Internal Wall Insulation

Energy Efficiency

Internal wall insulation can help to improve the energy efficiency of your home significantly. By reducing heat loss through the walls, your heating system will not have to work as hard to maintain a comfortable temperature. This can result in lower energy bills and a reduction in your carbon footprint.

Improved Comfort

Internal wall insulation can make a noticeable difference in your home’s comfort levels. By reducing heat loss, your home will be more evenly heated, with fewer cold spots. This can make a big difference, particularly in older homes where walls are often thin and poorly insulated.

Reduced Noise Pollution

Internal wall insulation can also help reduce noise pollution outside the home. This can make a big difference if you live in a busy area or have noisy neighbors. Reducing noise penetration through the walls will make your home quieter, more peaceful, and more comfortable.