Remedial work to existing buildings

The photo on the right was sent in by a building control officer who was called out when a builder uncovered work on site.

The proposal was to change a window opening into a new doorway. Having stripped away the plasterboard the builder was a bit shocked to find an unclosed cavity, no wall ties and a lack of insulation.

The opening also had a concrete lintel over the window spanning onto the internal blockwork.

Following discussion with the owner of the house it became apparent that the window had been added over a weekend several years ago when they had extended into a former outside toilet and coal store.

There had been just a single brick wall and ‘a friend of the family’ had added the internal block wall and the concrete lintel over a former doorway bridging the cavity to form the window head.

The new room had always been cold and needed constant attention to clean down mould growth around the top of the window.

After propping the masonry over the opening, the concrete lintel was replaced with a steel insulated lintel to remove the cold bridge. Retro wall ties with a dry resin fix were inserted at 225mm, centred vertically up the reveals; the full height of the wall reveals forming the new doorway.

Additional ties were also added to the remainder of the internal block wall.

Finally, insulation and cavity closers were added to the exposed sections of the cavity wall to prevent cold bridging before fixing the plasterboard.

The home owner was delighted with the end result and, although it cost a little more for the extra work, the room was much warmer with no signs of condensation.

They were also looking into having the cavity wall insulation injected into the rest of the house walls.

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^{Please Note: Every care was taken to ensure the information was correct at the time of publication. Any written guidance provided does not replace the user’s professional judgement. It is the responsibility of the dutyholder or person carrying out the work to ensure compliance with relevant building regulations or applicable technical standards.}

^{This article was reviewed and updated on 10 August 2023}