Narrow (10mm) residual cavity with Partial Fill IKO Enertherm Alu CW insulation boards with butt joints

[PGBuild]

I hope this message finds you well. We recently built a house using partial-fill IKO Enertherm Alu CW insulation boards with butt joints into the cavity. According to the product's BBA certification, a 50mm residual cavity is recommended; however, we have left only a 10mm residual cavity. This issue has been flagged by building regulations, and we have been asked to provide details on how we intend to rectify it.

 

Existing Wall Composition:
Inner Layer: 100mm Thermolite block
Middle Layer: 100mm Partial-fill insulation board
Residual Gap: 10mm
Outer Layer: 100mm External wall

I am strongly against taking down the external wall to replace the insulation boards with tongue-and-groove panels or creating a new external wall with a 50mm gap.

Understanding the Issue: After consulting with experienced builders and insulation experts, I identified two primary concerns due to the reduced cavity:
>Reduced cavity could adversely affect the insulation's effectiveness.
>Increased risk of moisture issues within the wall.

Using partial-fill cavity wall insulation typically leaves a 50mm gap between the insulation layer and the outer leaf of the wall, acting as a barrier to prevent external moisture from reaching the internal leaf. To remediate the issue without removing the external wall, I propose the following options. I kindly request your review of the potential impacts and any additional suggestions you may have.

 

Option 1:
Additional Insulation: Consider adding a thin layer of insulation on the internal leaf to compensate for the reduced cavity and enhance insulation effectiveness.

Masonry Creme Application: Apply a cutting-edge, one-coat masonry creme, such as Emperor Masonry Creme, which dries clear and provides invisible protection. This product has been independently tested by a United Kingdom Accredited Testing Laboratory (UKAS) and awarded four certifications, including:
EAD 040083-00-0404 (external thermal insulation composite)
EAD 090062-00-0404 (25-year hygrothermal performance)
BS EN ISO 12572 (water vapor resistance)
BS EN ISO 7783:2011 (water vapor diffusion)

 

Option 2:
Non-Invasive Foam: Use non-invasive foam to fill the 10mm residual cavity in the current cavity wall.

Potential Benefits:
Improved Insulation: Filling the cavity with foam can significantly enhance the wall's insulation performance, reducing heat loss and potentially lowering energy bills.

Reduced Air Infiltration: Foam can help seal any small gaps or cracks within the cavity, minimizing air infiltration and improving overall energy efficiency.

Moisture Control: Foam can reduce the risk of moisture condensation within the cavity, depending on the specific type of foam and the overall wall construction.

Additionally, apply the masonry creme on the external wall as suggested in Option 1.

 

Option 3:
Building Inspector Consultation: Confirm with the building inspector if they are satisfied with the existing cavity insulation solution. If the inspector agrees, consider the following:

Internal Adjustment: Remove the internal dot and dab and replace it with Speedline plasterboard with the same U-value as required by building regulations.

External Wall Insulation: Add external wall insulation with the same U-value as required by building regulations.

[nod]

It’s a shocking mistake 

Id ask BC what they would accept before doing anything Then push it on to the builder to sort out 

[PGBuild]

Thanks for the response. Yes, I plan to present these options to the BC officer to get his opinion. 

 

The main concerns with the reduced cavity are its potential to adversely affect the insulation's effectiveness and increase the risk of moisture issues within the wall. These issues can arise not only due to the narrow gap but also from several other factors, such as poor installation, so any of the options above should resolve the issue. 

 

BC agreed that the insulation has been installed to a good standard. 

[Russell griffiths]

Who specified this insulation?

and who said 100mm cavity, has it been built to the drawing. 

[nod]

1 hour ago, PGBuild said:

Thanks for the response. Yes, I plan to present these options to the BC officer to get his opinion. 

 

The main concerns with the reduced cavity are its potential to adversely affect the insulation's effectiveness and increase the risk of moisture issues within the wall. These issues can arise not only due to the narrow gap but also from several other factors, such as poor installation, so any of the options above should resolve the issue. 

 

BC agreed that the insulation has been installed to a good standard. 

To fit the insulation with such a small margin Must have been a hell of a task in its self and time consuming 

[PGBuild]

You are correct. We are planning to remove some bricks to check the actual gap, which should be at least 15 to 20mm. Photos taken during the installation confirm there are gaps, but it is clear that the issue lies in the fact that the gap is not 50mm. Any gap below 25mm is not ideal.

 

[Canski]

13 minutes ago, nod said:

To fit the insulation with such a small margin Must have been a hell of a task in its self and time consuming 

Just the same as that white Cavity Therm T@G shite.

Edited January 27 by Canski