Draft / airflow issue behind insulated plasterboard (dot & dab) – advice needed

[bobbybobski98]

Hi all,

I’m looking for some advice following a recent kitchen refurbishment.

I’ve installed insulated plasterboard on an external wall using the dot and dab method. On installation, I followed guidance to leave a small gap at the bottom of the boards to prevent moisture wicking up into the plasterboard.

However, I’m now experiencing a strong cold draught coming down from the roof cavity, travelling behind the plasterboards, and exiting at floor level through that gap. It’s very noticeable in the kitchen.

I’d like to stop the draught but I’m conscious of not creating a moisture problem. I’m considering the following options and would welcome views on what’s best practice:

• Expanding foam:
  Can I use low-expansion foam to seal the gap at the bottom, or would that risk moisture transfer up into the plasterboard?
• Loft insulation:
  Would it be acceptable to stuff insulation (e.g. loft insultation) into the gap, particularly as it will be hidden under the kitchen cabinets by the skirting? Would this still allow enough breathability?
• Alternative approach:
  Is there a more appropriate way to block airflow at the base of dot-and-dab insulated boards without causing damp issues?

For context:

• External solid wall
• Gap currently left along the full length at floor level behind the kitchen cabinets
• Kitchen units and plinths will cover the area once finished

Any advice on how this should ideally be dealt with would be much appreciated. Happy to clarify anything if needed.

Thanks in advance.