In the UK, 2003 saw the introduction of Document L which is a new set of regulations
for replacement windows. Theses changes have caused some confusion
within the construction industry; even some building inspectors are unsure
of the details.
Replacement Sashes
The new regulations only apply to 'new or replacement windows' and therefore
replacement sashes are not subject to these new requirements. Replacement
sashes are simply a repair to an existing window and so can be supplied
either single or double glazed. Authentic replica sashes do not require
any local authority planning permissions or FENSA certification.
Replacement Windows
Complete window replacements do however require compliance, with some
exceptions for conservation areas and listed properties.
All new windows must now meet minimum thermal standards, expressed as
a 'U' Value. To achieve the required U value in the case of new sash
windows then they must be double glazed, incorporating a low 'E' glass
with an Argon gas filled void. The size of the void between the panes
must also be increased, likewise several changes must also be made to the
window construction. Inevitably these additional requirements have
significantly increased the cost of replacing whole windows, making repair
work the preferred option when possible.
We are not a FENSA registered company as the majority of our
work is restoration and not replacement. Currently building
permissions must be obtained by the home owner, from the local authority,
for any complete replacement window required.
