Horse Guards is an illustrious historic building located in the City of Westminster, London, between Whitehall and Horse Guards Parade. The Grade 1 listed building was built in the mid-18th century, as a barracks and stables for the Household Cavalry, later becoming an important military headquarters.
The Palladian-style building is constructed of Portland Stone and Welsh Slate roofs. In March 2021, we were appointed by our client Amey Defence Services to undertake an ongoing and evolving schedule of reactive investigation/survey and repair of leaks.
Our scope of work included:
- Repairs include leadwork, gutters, and outlets involving liquid systems, which are non-destructive and overlay the original structure.
- Replacement of broken & slipped slates with reclaimed Welsh slate to match.
- Liquid waterproofing reline to lead gutter and clean, prime and line the lead gutter.
- Repointing of lead flashing on the chimney
Using highly specialised and bespoke techniques, we tested and investigated the source of water ingress and leaks across the roofs. As part of the external testing, a rope access survey was undertaken to investigate the cause of leaks into the roof area above the outer stable arches.
Signs of damp and extensive staining were also visible around the window frames. Cracks were visible in the modillion and the lead flashing on top of the cornice. The cornice was raised in one section of the roof above the damage. Having collated all of the information related to the defects, including location, type, size, severity and many more metrics, we were able to provide the client with a holistic view of the property’s condition, highlighting all tested
issues. The recommendations of remedial works to restore the well-being of the buildings for each elevation (north and south) were provided, along with costings.
Our experienced craftsmen carried out repairs to the roof and gutters on the south and north elevations of the building, cleaning and removing any loose material and debris.
New liquid liner was installed, and the ends of the gutter were recoated. We used a flexible liquid system to seal the gaps in the lead and cover the step flashing.
Given the conservation status of the building, the system was chosen based
specifically on the suitability for lead and a colour matching the surrounding areas.
Gaps had appeared between the Welsh slates due to slippage and movement which allowed water ingress into the offices below. To tackle the issue of missing /loose tiles and slates, reclaimed Welsh slates were reinstalled and the loose slates were pinned and refixed.
With the conservation philosophy of English Heritage and Historic England at the heart of our approach, we used minimal intervention and techniques aligned to the history and the future repair requirements of the iconic Horse
Guards building.
Project challenges
Being a building with unique access challenges and historical defects, it was essential that each elevation of the building was surveyed to ensure we collated the key data and information for existing defects.
Since Horse Guards is a Grade I listed building, the specific repair requirements with regards to listed building consent and conservation had to be carefully considered.
Because of the site layout, achieving safe access to inspect all areas was an issue.
The south elevation pitch roof had multiple slipped and missing slates. As an ageing building, the amount of slipped and missing slates suggested the damage to the trusses and joists from water intrusion was considerable.
• Historic cracks and failed repairs including failed joints and cracks in the stonework and lead flashing.
