<b><b>Andrew Leech finds the implications of changes to Part L of the Building Regulations (thermal insulation), plus adjustments to Part B (fire safety), are not as painful as most window manufacturers had expected</b></b><br><b>Both PVCu and timber window manufacturers have taken Part L in their stride. Steel and aluminium still have a number of issues to address, but are getting there.</b><br><b>As far as Part B is concerned, and the requirement for a minimum 628mm emergency exit window in every habitable room, Cotswold Architectural Products - a leading window stay manufacturer - reports that demand has doubled. The firm is being used as much in the replacement market as for new build. </b><br><b><b>The material debate </b></b><br> Overall the PVCu perception of the changes to Part L is that they provide a further opportunity to steel a march on timber, which seems to be doing &amp;"very nicely thank you&amp;". <p></p><p>By the time the new Part L is fully implemented next February, or thereabouts, the plastics boys aim to have cornered 80% of the windows and French doors market, according to one manufacturer, Speed Frame. On the other hand, Kevin Cubbage, director of the British Woodworking Federation, is in no doubt that &amp;"we have …