Loft Insulation Case Study — Rodent Proofing, Ventilation and a Full 300mm Replacement, Stoke Gifford

The problem

The customer contacted us about rats in the loft. By the time we surveyed it, the roof space had been used by rodents for some time and the insulation across the ceiling joists had been disturbed, dragged about and contaminated.

Insulation in that condition cannot simply be topped up. Anything left in place would have continued to hold contamination and would not have performed properly once covered over.

The loft also had very little working ventilation. Without a clear airflow path through the roof space, moisture from the house below has nowhere to go, which is how damp and condensation problems usually start.

Our assessment

We recommended a full strip-out rather than a top-up, so that none of the contaminated material stayed in the loft.

Once the loft was clear, the entry points rodents had been using needed proofing, and ventilation needed to be introduced at the eaves so the roof space could breathe properly.

Only then was it worth putting new insulation down, finishing with a full 300mm layer of Knauf mineral wool across the loft floor.

The installation

The first stage was removing every piece of the old insulation, along with the debris and offcuts that had built up across the joists. All of it was bagged and taken away rather than being disturbed further inside the property.

With the loft floor clear, the team worked around the perimeter and the roof structure, proofing the gaps rodents had been getting in through. Mesh was fitted between the rafters at the eaves, sized so that it closes the gap without blocking the airflow path.

Ventilation was then added so that air can move through the roof space rather than sitting still above the ceiling.

Finally, a fresh 300mm layer of Knauf mineral wool was laid between and across the ceiling joists, giving an even depth across the loft floor.

The result

The loft was left clean, proofed and ventilated, with all of the contaminated insulation gone rather than covered over.

The eaves are now closed to rodents while still allowing air to move through the roof space, and the ceiling has a full, even 300mm layer of Knauf mineral wool above it.

The loft is also far easier to inspect in future, which matters after a rodent problem — it is straightforward to check whether anything has returned.