Book - School of Science and Technology

Atypical construction features 39InsulationScreedBoardingBattenBoardingSaddle clipDPC Fibre mat JoistsUrethane board(a) (b) (c)Figure 2.8 Methods of applying insulation to floorsby driving rain, of the outer skin of the wall construction. Once a cavity has been filled,there is apparently no known method for clearing it completely!Flat and sloping roofsAs has been noted previously, attack upon the energy loss through factory roofs was thetarget of early legislation. Methods of insulation more appropriate to the present day areshown in Figure 2.7.FloorsIt has been noted earlier that the heat loss from a solid floor on earth will occur largelyaround the perimeter. It follows, therefore, that provision of insulation overall may not benecessary and that a horizontal strip about 1 m wide laid at the exposed edge of the floor,as Figure 2.8(a), will be adequate.For a timber floor suspended above an enclosed but ventilated air space, insulation isbest applied not too far below the actual flooring. One method is to lay an insulating mator quilt, over the joists and under battens, with a supporting membrane of plastic nettingas Figure 2.8(b). Another uses rigid urethane boards, push-fitted between the joists andsecured by means of saddle clips as Figure 2.8(c). Some means of access to any piping orwiring below the insulation must not be forgotten.ApplicationIt is now appropriate to reconsider the earlier example of conduction heat loss in the light ofpossible improvement to the thermal characteristics of the structural elements. For instance,the floor might be covered internally by laminated panels of 25 mm EPS and 9 mm ply andthe roof might be covered externally with 65 mm high density mineral fibre finished withroofing felt and asphalt. The walls might be backed up with a 100 mm medium weightconcrete block, thus forming a cavity which could contain a 50 mm glass fibre batt:the internal finish could be plasterboard on battens. As to the windows, those existingmight be replaced with double glazing in a metal frame having a thermal barrier. Thus,assuming the same temperature difference as before (22 K), the calculation would be revisedas follows: