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Drayton Hall temporary stabilization

Temporary stabilization
Each of the panels was light enough that only two people were needed to install them. Once the panels were lifted onto the rails of the scaffolding, the supporting legs were added below.
Nine stabilizing units were built at a cost of approximately $500 total. Each unit consisted of 4 telescoping legs which supported a 4' X 6' sheet of one-eighth inch padded lauan plywood. This in turn was covered with Tyvek paper to reduce the possibility of staining or discoloration, which might be transferred from the wood or the padding to the white plaster surface.  

To create each unit, legs were manufactured using four-foot lengths of dowel with a 1-inch diameter. In order to create the telescoping feature for the legs, 10 foot lengths of rigid conduit were purchased which had a 1 inch interior diameter allowing the conduit to slip over the top of the dowel. At the base of each section of conduit two small holes were drilled which allowed screws to be driven into the dowel, once the leg had been extended. This ensured that an extended leg would remain in place. 16 inch bases were created using oriented strand board (OSB) to keep costs down. To the center of each of these bases was attached the dowel using a 2" X 4" X 4"  plate with a one inch hole drilled in the center into which the dowel was inserted.
temp stabilization
A map of each of the 9 supporting panels which were raised to the ceiling while the floor was repaired above showing their relationship to the mapped 1991 detachment.
At four locations on the lauan sheet, short 10” lengths of dowel were attached in a similar fashion as the longer four foot lengths on the bases. By inserting these short lengths of dowel into the conduit at the top the entire 4 foot X 6 foot sheet could be easily raised into place by sliding the conduit upward over the lower doweled bases. The advantage of this simple design was that each leg had an infinite number of potential locations which allowed for fine adjustment. Each sheet was raised into place and lightly pressed to the surface so that the padding was compressed evenly across the plaster surface. The raised sheets of padded lauan were intended to support the plaster in place as well as reduce the vibration from above by distributing it through the one inch layer of foam padding.

Manufacturing took the longest time requiring two people working for three days, however installation was extremely quick taking only a matter of two hours to install all nine panels. These panels were very successful in a number of different ways, the most significant being that no plaster was lost during the floor reinstallation. Other significant features of this stabilization method was its low cost as well as its ease of installation. An additional benefit was that each telescoping leg was later used with a padded cushion during the treatment phase to introduce isolated pressure to the treated areas while the grout had time to set.
adding screws to the legs
Once the panels had been raised tight to the ceiling, screws were added to the legs, through holes drilled in the conduit, keeping  the panels in place.
A decision was made early in the project that some form of temporary stabilization was needed during the structural retrofit above, in order to secure both the damaged and sound plaster before treatment was carried out. Knowing that stabilization was required, it was quickly understood that the function of this stabilization was not to hold the entire floor system in place but instead simply to prevent plaster from further detaching from the lath by limiting vibration associated with the retrofit of the floor. The other need for this stabilization was to hold in place, small sections of the ceiling which may decome detached, as a way to prevent them from severe damaged associated with falling.  The strength of the support system needed only to be based on potetial detached areas and in almost every case did not need to address the issue of catastrophic failure, from large scale problems.
Even installed, the temporary stabilization still allowed for easy access around the great hall.
As had been identified in the documentation phase of the project, the problems associated with the ceiling were not consistent across the entire surface and as such not all areas of the ceiling needed to be stabilized.  Identifying locations for stabilization, as well as determining a method for fabricating the stabilization was based on a set of variables which included the following:
  • Present known condition of the plaster
  • Type of work required to install the flooring above
  • Present use of the first floor for public tours
  • Cost and ease of installation

The temporary stabilization also needed to be easy to remove and reinstall, and in fact was taken down and reinstalled for a fund raising event. Additionally the choice for the materials for constructing the system was based on cost and availability as well as ease of construction. All materials were purchased locally and each unit was built on site using basic construction equipment. The system was designed to be adjustable to address the variations between the floor and ceiling. Since both the floor and ceiling were not level or coplanar a flexible unit was critical.