<b><b>Andrew Leech asks brick and block manufacturers about their plans for the new challenges in Parts L &amp;&amp; E and what's in store to meet the demands of greater prefabrication</b></b><br><b><b></b></b><br> Now that an acceptable U-value of 0.35 for walls has been formally announced for Part L of the Building Regulations, brick and block manufacturers are heaving a sigh of relief. Although none of them doubted that they could meet, within reason, whatever the final calculation might be, they knew that a 0.30 figure - as first proposed - would be a tough call. Of course, the implications of changes to Part E (noise) are still to be resolved but this will hopefully be less problematical. <p></p><p><b><b>Pre-fab challenge</b></b><br> Now they can concentrate their full attention on meeting the demands for greater prefabrication to combat, amongst other things, a skilled labour shortage, declining workmanship standards and generally the economics of the building process. Already there are a number of prefabricated or fast-track systems at the disposal of UK housebuilders. Many enable the shell of a dwelling to be constructed quickly on site enabling internal fit-out to proceed with minimal delay. And some larger housebuilders have invested in factories to manufacture part prefabricated …