The creation of a new gymnasium and three classroom blocks at a London school have seen the engineered timber systems provided by B & K Structures prove their worth: from an aesthetic as well as a practical perspective.
The work at the Preston Manor School has been carried out for the London Borough of Brent, on a design and build basis by Kier Construction Ltd; one of the country’s biggest contractors with vast experience of educational buildings.
As a result Kier opted to utilize an engineered timber solution of cross laminated panels (X-LAM) and awarded the contract for its design, supply and erection to B & K Structures of Derby.
The construction combines B & K Structures’ X-LAM, produced in a variety of dimensions, with Glulam beams thus providing long span support in specific areas.
In total 860 cubic metres of X-LAM panels were supplied, with a further 26 cubic metres of Glulam being used. The erection of the structure was undertaken during the summer of 2011.
Aside from the normal challenges associated with educational projects by the academic year, Brent was keen to invest the funding available within a relatively short time period. And while the Kier project team - which also included HLM Architects and structural engineering consultant, MG Partnership - considered a number of innovative solutions – they favoured the use of cross-laminated timber as the principal solution for a number of reasons.
In addition to being a largely prefabricated off-site solution, using X-LAM and Glulam in this manner avoids the need for internal columns within the rooms, while the sustainably sourced timber locks in carbon and therefore contributes to the Preston Manor School project’s aim of achieving a BREEAM Excellent rating. X-LAM is furthermore inherently fire resistant and provides good thermal properties.
HLM Architects incorporated clerestory windows into the design which gives the main building its distinctive roofline, and promotes natural cross ventilation: saving energy on mechanical plant and creating a healthy learning environment.
The Project Architect for HLM, Mr Philip Grant, comments: “Using the B & K Structures prefabricated system allowed us to keep to what was a very tight programme; and they did an excellent job engineering the design in ensuring everything worked in the final analysis. Being that everything is precision cut also enabled us to achieve very good airtightness readings, which of course is critical to the energy performance and a BREEAM Excellent rating.”
While externally the structure has been clad with larch boarding at low level, and an insulated render above, internally large areas of the X-LAM have been left exposed. Philip Grant explains saying: “We have had to install plasterboard linings in a lot of the teaching areas, though this was primarily for acoustic control, otherwise we would have left a lot more of the timber exposed.”
B & K Structures’ X-LAM elements are produced from European softwoods such as spruce (European White Wood) and have PEFC or FSC accreditation offering full chain of custody when required, it uses three, five, or seven lamella layers of finger jointed timber boards, bonded at 90 degrees to the layer below in each case.
Strength will vary depending on the overall thickness, which rises from 66 to 341 mm, but the construction allows the panels to span in two directions and offer very good stability even at extremely high temperatures.
Fire resistance periods of generally 30 or 60 minutes can be accommodated comfortably.