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A model roof

By community archaeologist Alexis Haslam

On 29 April of this year, our Dissecting the dirt students were invited to participate in an incredibly exciting project which took place in our roof space above the Tudor arch and museum. With funding from the John Lyon’s Charity we were able to undertake a laser scanning workshop in a part of the Palace which is rarely seen but that I personally find very exciting. AOC Archaeology led the workshop, and the four-person team of Becky Haslam, Esther Hamilton, Rafael Solar Rocha and Juan Chacon duly arrived on the Saturday morning to set up the session and transport the equipment into the often cramped confines of our Tudor roof.

The morning started for our students with an introductory lecture on the history of the roof-space and a discussion on the different methods of three-dimensional recording. These recording systems are becoming more commonplace in the world of archaeology, with photogrammetry and laser scanning being the most commonly used. By scanning an archaeological excavation, archaeologists can now produce accurate three dimensional models of the site. These models provide an incredibly useful resource, especially if the site is due to be destroyed and features such as the remains of ancient buildings are not going to be retained or displayed.

We thought that the roof space would be an excellent area to scan due to the fact that it is inaccessible and not open to the general public. Although we do occasionally have Open House days when visitors can view our great hall roof or the Laudian wood panelling in the south side of the courtyard, the roofspace on the western side of the courtyard is rarely entered, even by Palace staff. This is a shame because the surviving late 15th century carpentry elements are truly fantastic.

The courtyard roof was largely replaced by Bishop Blomfield in the mid-19th century, but lifting and removing the original Tudor timbers was clearly a demanding task. Although the timbers are almost completely gone along the northern and southern sides of the courtyard, many elements remain along the western side. This was presumably because it was simpler to build the new roof over the skeletal remains of the Tudor timberwork. These remains include the principal rafters, purlins and wind braces as well as the remnants of the ordinary rafters, many of which have been sawn down. Interestingly, whilst modern rafters are generally laid on edge, in the Tudor period they were laid flatways, with the broader edge resting on the purlins. Sectional divisions are also present with queen posts and collar beams. In several instances the daub panelling which once defined sub-divided rooms within the roof are also present. These sub-divided rooms are alluded to in the Parliamentary Survey of 1647 although it is unknown when they finally went out of use.

Although we know from dendrochronological dating that the courtyard was built between 1493 and 1495, the vast majority of the roof is constructed from elm which cannot be tree ring dated in the same way as oak. Fulham is known to have been dense with elm trees in the Tudor period and it is likely that the Bishop used his own timber in the construction process. The quality of the carpentry is on proud display here though, with mortise and tenon joints neatly fitting together and held firmly in place with wooden dowels without a nail in sight. Rather strangely there are very few visible carpenter’s marks. These were symbols and figures carved into the timber by the carpenters in the workshop so that they could easily be assembled on site during the construction process; rather like a modern flat pack piece of furniture.

Returning to the session itself the students were then invited into the roof-space to observe the scanning process in action and to understand how it works. The AOC team were using a scanner known as a Trimble and they needed to set up several points (or stations) along the length of the roof-space in order to produce the model. Once in position on each station the scanner spins and, using eye-safe lasers, measures the distance from the scanner to the surfaces present within the roof. These measurements take the form of multiple points which generate what is known as a point cloud which, when combined with other point clouds, creates the 3 dimensional model. As the scanning process took place the data was gradually fed back to a tablet which the students were able to observe and watch the basic 3D model begin to take shape.

Further training also took place in the form of a photogrammetry session in the north side of the courtyard roof. Photogrammetry is another means of 3D modelling which involves taking numerous high resolution photographs of an object or area from various different angles. These photographs are then developed using specific software packages which are able to create accurate 3D models from the available images using known points and measurements. Throughout the process the students were encouraged to think about how 3 dimensional model could be useful to archaeologists and how storyboards could be developed to both describe the process and present the subjects of the scans to the general public.

With all of the data processed we now have our 3D model of the roof-space which we are placing up on our website as part of the Festival of Archaeology 2023. Interestingly, our Young Archaeologists’ Club was taken on a tour of the Tower of London as part of the Festival on the 12th of July. We were able to see the remains of the late 15th to early 16th century Assay House of the Royal Mint which lie beneath Legges Mount, an area of the Tower which is not currently open to the general public. Historic Royal Palaces have also laser scanned these remains and it was great to see that Fulham Palace is also using the latest technology available to digitally preserve its historic remains.

The Palace would like to pass on our thanks to the John Lyon’s Charity for enabling young people to take part in this fantastic project which will hopefully have a lasting legacy at the Palace. We would also like to thank AOC for all of their hard work on the day and for the production of the model which are very pleased with.

3D modelling of the roof space, courtesy of AOC.