Above & Beyond

Gold Balls galore!

For the first time in many years, all four of the Palace's iconic gilded spheres are gleaming once again! The final sphere, above the Great Hall, was completed this month, marking the first time all four have been newly gilded at the same time.

The gilding works were carried out by John Naysmith of Oxford Ironmongery, who has restored each of our other spheres over the last 4 years. We have four in total! Before any gilding could begin, a small hole was drilled to allow an endoscope inspection of the sphere's internal structure. Once the condition had been assessed, failed joints were repaired and the surface carefully prepared. The metalwork was sanded back, primed and coated with an enamel base before specialist gilding adhesive, known as size, was applied. Finally, the delicate sheets of gold leaf were laid using a gilding brush to create the brilliant finish seen today.

The beginning of the end!

This month marks a major milestone in the roof restoration project as scaffolding begins to come down from the front of the Palace. Removing the scaffold is a carefully planned operation, requiring close coordination between our teams, contractors and event organisers to ensure the Palace can continue welcoming visitors and hosting events safely throughout the process.

The project has been delivered in two phases. Phase 1 includes the Great Hall, part of the Heights roof and the Gallery roofs. As the first areas to undergo restoration, they are now the first to be completed. Before the scaffold can be removed completely, our consultants carry out a detailed snagging process, inspecting the works to identify any defects or adjustments required before works are formally signed off.

Add you name to Britain's Greatest Palace!

This month the Sign a Slate campaign launched, led by the Philanthropy team, the campaign allows you to sign a roof slate which will be put on the Saloon roof as part of the restoration works.
Blenheim Palace is more than a building; it is a living piece of Britain’s heritage. Our roof restoration is the most ambitious project in our history - a £12 million undertaking to safeguard the Palace and its collections for centuries ahead. By signing a roof slate, you help protect priceless treasures and ensure that Blenheim Palace continues to inspire generations to come.  

World-Class Views

Kelly, Head of Built Heritage, recently attended the Historic Houses Association AGM, where President Jason Lindsay highlighted our scaffold visitor platform as an exemplar of world-class public engagement during major conservation works. This recognition is especially meaningful, as it shows how heritage conservation can be both carefully protected and openly shared with the public.

So far, more than 55,000 visitors have taken the opportunity to step up and enjoy truly once-in-a-lifetime views, seeing conservation in action from a perspective rarely available to the public.

This recognition is a testament to the dedication and collaboration of the entire tea.  We can’t wait to welcome you back up again after Christmas.

Knowledge is power

This month, Kelly (Head of Built Heritage) and Edward Lewis (Donald Insall Practice Director) hosted over 200 professionals in our first batch of Knowledge Exchanges.

We were joined by architects, heritage leaders, construction industry professional, estate and building managers and many more across the entire month. These Knowledge Exchanges were designed to be collaborative series not only for us to share the highs and challenges of delivering a vast project in sensitive surroundings but also to hear and learn from other professionals across the country doing similar things! We have found this series invaluable, and we hope to host some more in the new year after the Christmas period.

From Roof to Roots

A wonderful connection to the Palace’s living history: Our Clerk of Works, Chris Monaghan, met a local gentleman whose father had worked on the roofs back in the 1960s.

Evidence of those earlier repairs was still visible, in the form of patchwork to the lead gutters. Today, the challenge is scale: around an acre of roof is currently served by just six downpipes, so our design team undertook some complex work to carefully increase the gutter capacity. Although the gutters themselves are undercover, the scaffolding has been fitted with a temporary roof system that channels rainwater into four large tanks, with a combined capacity of around 38,000 litres. So far, more than 200,000 litres of rainwater have been collected, that’s roughly 1,330 standard bathtubs worth of water!

Unique unveilings!

We have uncovered probably the only bit of original roof with sarking boards underneath the steeper pitched Housemaids House.

The industrial revolution, quarrying efficiencies and the canal and subsequently train networks resulted in slate becoming significantly cheaper than lead. Although lead production peaked in the 19^th century it remained prohibitively expensive due to more demanding process of finding and processing ore, and the weight lead for transport purposes, and of course it had other markets i.e. military use. In the 18^th and 19^th centuries many of the nation’s grandest buildings sold their lead when it reached end of life, and replaced it with slate, including Westminster Hall, Chatsworth, and of course Blenheim.

A closer look above

Whilst access was available Opus were on site for just over week, to make a start on investigations to the Saloon ceiling.

This started with just visual inspections using torches and handheld lights, from there they photographed for record keeping purposes. Using sponges and water, a small area was water cleaned to remove particulate matter. The image below shows the effect of water and sponges in just a small area of the Saloon ceiling. Opus will be back in September to push on with Phase 1 of the works.

Wrapped and ready!

After approximately a year of designing and around 137 days of construction, the scaffolding is complete.

Allen and Foxworthy have worked at great speed and efficiency to complete the scaffolding. This will be its final form until around April 2026. With the scaffolding complete, a safe work environment has been created for the roof works. The scaffolding itself is a feat of engineering, with over approximately 70,000 scaffold fittings and around 31 miles of scaffold tubes.

A layer in time

Careful removal of the roof coverings has started – Climb up to the Viewing Platform to witness what is revealed!

Our goal is to retain as much of the timbers, slates and lead as possible. Working from the ridge level downwards, all ridge slates are removed carefully using a specialist tool called a slaters rip. Good quality Welsh Slate can often be re-used after over 100 years on a roof. The percentage of salvage will be dependent on a number of factors, such as the number of nail holes and their size. Each slate is visually examined and can also be struck to see if it still ‘rings true’. Once the roof slates are removed, the sarking boards are removed. All structural timbers will be retained, but some of the substrate/ boards might be replaced if they are very worn. A wooden wedge or thin pry bar is carefully inserted at a joint, and the board is gradually lifted along its length.  

Surveying Centuries in Stone

DIA have been on site conducting detailed stone surveys of every elevation, cataloguing the condition of each individual stone.

Using a precise tagging system, they’ve identified the exact intervention needed. From full block replacements and intricate indent repairs to repointing, repining, mortar stabilisation and surface consolidation.

It’s painstaking work, and up close, the variations in the masonry are both beautiful and revealing. Each mark, crack, and weathered edge tells a story of time, craftsmanship, and history. While the façade may still look great from afar, this survey has shown just how much work is needed to preserve the Palace for generations to come.

Breathtaking in more ways than one

Experience once in a lifetime view from our viewing platform. It’s 109 steps to the top, but the reward is spectacular!

As part of our commitment to sharing this restoration journey, the scaffolding has been specially adapted to include a one-of-a-kind viewing platform. The viewing platform provides stunning Capability Brown views beyond the Great Court, stretching towards the famous Column of Victory. Unique viewing pockets give a peek into the Palace’s East and West wings.

Preserving Masterpieces

The urgent conservation of two nationally significant paintings by Sir James Thornhill and Louis Laguerre are located in the Great Hall and Saloon. Identified as heritage at risk, this has been made possible thanks to a £250,000 grant from The National Lottery Heritage Fund, which provided the necessary support to preserve these important artworks for future generations.

Find out more...

Happy Anniversary to us

75 Years ago, Blenheim Palace first opened its doors to the public to raise funds for essential spot repairs to the roof.

These repairs are now at the end of their life and this latest vital project ensures the preservation of the architecture and safeguards its heritage for generations to come. To honour the milestone, we welcomed staff, visitors and the local community to recreate the original iconic queue photo taken on the opening day in April 1950. A snapshot of the past perfectly reimagined for the present, thank you for being part of Blenheim’s story thus far!

Contractor awarded

Following a fair and thorough tender process, we are pleased to announce that DBR have been awarded the opportunity to be the contractor for our big roof project.

They are specialists in quality historic building conservation and have worked on projects such as Wakehurst Place, Hampton Court Palace and Elizabeth Tower. Last month, alongside our architects, Donald Insall Associates, DBR were recognised for their work in the second phase of the repair and conservation project at Westminster Hall. They won the Europa Nostra Award in the Conservation and Adaptive Reuse category. The Europa Nostra Awards are Europe's highest honour in the heritage field.

We are so excited to have them on board!

End of RIBA Stage 4

RIBA Stage 4, also known as the ‘Technical Design’ stage, is a pivotal transition where the vision for the project starts to materialise in a physical sense.

At the end of RIBA Stage 4, the tendering process is a critical phase. This phase is about much more than just picking a contractor; it is about finding a competent contractor who shares the Blenheim vision and understands the project objectives. They can confidently face the challenges and risks that this project will bring, all whilst considering our guests, visitors and staff.

Dusk to dawn

Bat Emergence & Re-entry Surveys (BERS) help to determine which species of bat are present, how many, and the type of roost (e.g. maternity, non-breeding, hibernation, etc.).

After the preliminary surveys in November established the presence of bats, a bat emergence survey is required to observe and record bats emerging or re-entering from the roofs. BERS surveys should be conducted from May to September, and Emergence surveys are undertaken 15 minutes before sunset and last for up to two hours after sunset. Re-entry surveys start two hours before sunrise and last until sunrise or for 15 minutes after sunrise, depending on the level of bat activity.

Down the drain

Nearly an acre of the roof is only serviced by six downpipes which have very limited access, so a CCTV survey is required to survey the historic rainwater drainage serving the roofs.

The exact routes, conditions and sizes of the down pipers are unknown, so CCTV surveys are important to provide a clear picture and can also identify issues such as cracks, splits and displaced joints before they cause problems. Water ingress is one of the key contributing factors to the deterioration of the roofscapes.

Safety First!

Stone fall from a height is the highest priority due to the health and safety risk posed. Getting up high to remove it safely is paramount.

Mobile elevated working platform (MEWP) surveys were undertaken of the south elevation on 23rd, 24th and 26^th April 2024, to survey the high-level stonework in more detail as well as to undertake emergency removal of stone at risk of falling. Significant pieces of stone and decorative detailing were loose and came away very easily. The survey focused on the decorative detailing of the capitals and modillions, which are high risk items.

Meticulous Masonry Cleaning

Specialist masonry cleaning trials were undertaken to demonstrate results, manage expectations, and inform the specification.

Sensitive cleaning to remove surface contaminants has the potential to prolong the lifespan of the limestone.

Cliveden Conservation and Restorative Techniques were undertaking the trials, and Odgers Conservation Consultants provided onsite consultation.

-Thermotech Super-heated steam clean (150°C)

-Thermotech Wet-Air Abrasive clean (a fine abrasive clean)

-Laser cleaning

-2 applications of Sepiolite / 5% ammonium carbonate poultice

It will be critical to complete this cleaning sensitively to avoid disrupting the current appearance and character.

Roof Revelations

Our Structural Engineers – Clive and Harry from FW Haywood, surveyed the butterfly roof to review the existing structure and have found a high proportion of the original early 18th century structure in situ.

 During the surveys, the original roof structure (a lower hipped roof) was clearly visible below the later butterfly roof structure, and this provided an opportunity to not only to improve the detailing of this area but also to reinstate the original roof design.

Preserving paintings of national importance

A scaffold tower was built for a week of specialist inspection and analysis of the ceiling and wall paintings in the Saloon and Great Hall. Areas of the paint sampling were tested for chemical composition, colours and layers. This is a necessary investigation to inform the correct approach to conservation. The conservation of the paintings is a unique part of the project and will require the involvement of consultants who are specialists in the conservation of wall paintings and other decorated architectural surfaces.

Opus Conservation have been on site conducting these investigations. They bring an experience of wealth of experiences, having previously worked in Hampton Court Palace and The Royal Gallery in the House of Lords. Initial investigations show that the Saloon painting is a lot dirtier than the Great Hall painting due to the historical use of coal fires in the Saloon.

Reducing Risk

We have completed nearly 10 different survey types to date. From ecology to photogrammetry and hazardous materials. Surveys are essential for gathering comprehensive information, understanding our requirements, ensuring regulatory compliance, assessing feasibility, and managing potential risks. This information forms the foundation for the subsequent design development stages. The more that is known about the building, the more accurate planning and design can be.

Surveying also allows for a better understanding of the risks – collecting information about what we know about the building, what we need to know more about and what the impact will be of these risks. Whilst some of this data can be sought through desk studies, on-site surveying will often provide the most up to date and accurate information.

Careful considerations

Cliveden Conservation were on site to scope out areas for some trials in cleaning the stonework. Stone cleaning is being considered as an option to stabilise compromised stone, which would save significant future replacement costs and reduce health and safety risks.

Changes to the climate (increased rainwater and temperature fluctuations) and airborne pollution have caused a build up of sulphation crusts and salts on the surface of some stones. This surface grime is contributing to the decay of the stone. Carved work is particularly vulnerable to decay because it has a large surface area in relation to its volume, often with exposed fine edges. Through research and specialist discussions, a targeted and intelligent approach to stone cleaning emerged as a more cost and time efficient solution instead of adding new stone or replacing whole blocks.

Why Bats Matter

Did you know that in the UK, all bats and their roosts are legally protected? Meaning that a special licence is needed for any activities that may disturb them and their habitat. BSG Ecology were on site to conduct bat surveys, which involved an initial internal and external inspection to identify the potential for bats roosting or feeding. At the end of this survey, a report is written to explain not only if bats are there or not, but also how suitable the place is for bat habitation and next steps.

This is extremely important because if there are bats or signs of bat habitation, we have to apply for a mitigation license in order to start the works. After the initial surveys, BSG returned to set up bat monitors in the roofscapes that will provide evidence of the presence/absence of bats.

Reaching new heights

A Mobile Elevating Work Platform (MEWP) was brought onto site for a week to allow for some up-close inspections of the higher-level facades of both the North and South Porticos. The MEWP took the team to over 20 meters high!

During the week, the architects from DIA, surveyors from GBG conducted Ground Penetrating Radar (GPR) surveys and stone condition surveys. GPR is a non-invasive geophysical method that uses radar pulses to image the subsurface. GPR was used to identify embedded metalwork, fabric construction and locations/routes of embedded downpipe, allowing for the identification of potential conflicts and enabling effective planning.

Researchers from our Oxford University Heritage Innovation partnership team also took the opportunity to preliminary survey the stone types to give us an understanding of which quarries/beds the various stones have come from.

Meet the team

Our consultants were on site to get a closer look and discuss progress. Being on site to discuss the works is a vital part of the project as it allows for our consultants to see their areas of interest and report on progress to date any highlight any concerns to work through.

Project kickstart!

Our first official project meeting with our appointed architects, Donald Insall Architects. Kickstart meetings are a crucial moment when everyone involved gathers to set the project off in the right direction. Potential challenges are identified, roles and responsibilities are confirmed, and as the clients,  we can align our expectations with what the team can deliver.

Led by Practice Director Edward Lewis, the team from Donald Insall have worked on other significant listed buildings such as the Palace of Westminster, Kensington Palace, Hampton Court Palace, as well as many of the Oxford Colleges.