Supplying Timber Issue 9 0 - Autumn 2025 - Flipbook - Page 71
———— TIMBER KNOWLEDGE SHEET ————
larger frames cost more. Some
manufacturers o昀昀er their own
standard window sizes, although
no set standard for window
size exists in the UK, meaning
bespoke options are necessary
- especially for restoration
projects.
Pivot hung
Popular in the 1960s and 1970s,
where a simple centre pivot
allows the sash to turn through
180 degrees giving a 90%
openable area.
Colour and 昀椀nish
Timber windows can use a wide
variety of possible 昀椀nishes, from
stains to show o昀昀 natural timber
grain to matte paint cover. A
factory 昀椀nish with preservative
treatment before sanding,
followed by a base coat and two
topcoats will ensure maximum
performance and durability.
Other types
Multi-light windows mix di昀昀erent
opening windows into one. For
example, a side-hung sash with
a top-hung vent and direct
glazed window below. Other
combinations may include a
projecting casement and 昀椀xedlight window, or tilt and turn and
昀椀xed-light.
Installation
Whether installing fully factory昀椀nished and glazed windows, or
timber windows with a primer
or base coat stain which require
glazing, they still need careful
handling and storage:
Speci昀椀cation
A number of factors can
determine the appropriate
choice of timber window:
•
•
Species
Engineered softwood timber,
in particular Pine or redwood
(Pinus sylvestris ) is frequently
used for windows for dwellings.
Recognised for its durability
and natural strength, natural
tannins in the timber reduce the
likelihood of rot over time, while
engineered laminated sections
prevent warping.
Oak (Quercus spp.) has
historically been the timber of
choice for windows, although
its high density makes it more
costly.
•
Check the delivery complies
with the order and there is no
damage
Where possible store
windows upright in clean, dry
and covered conditions
If outside, stack on level
bearers and cover with
a tarpaulin; do not use
•
•
•
When 昀椀tting windows:
• Use durable packings
between windows and the
structure to avoid distortion
to the frames
• Take care with packings to
sash windows not to distort
the sliding mechanism
• Damp proo昀椀ng should be
昀椀tted in accordance with
building regulations
• For 昀椀xing to the structure and
gap sealing, use specialised
proprietary 昀椀xings and
foams, in accordance with the
manufacturer’s instructions.
Avoid projecting timber sills and
use stone, brick or tile sub-sills
which allow the windows to be
recessed to provide protection
for the window and brickwork
(a requirement of Approved
Document L of the Building
Regulations).
You can explore all our
Timber Knowledge Sheets at
www.timberdevelopment.uk
Size
The size of a timber window
impacts overall costs, as
SUPPLYING TIMBER
71
polythene as it can cause
condensation
Store in the sequence of use
Use spacers between frames
with projecting sills or
hardware
Do not lift frames by their
昀椀ttings.
AUTUMN 2025
TIMBER KNOWLEDGE
50% openable area. Often
required for older buildings and
conservation projects where
like-for-like replacements are
needed. Both sashes open
by sliding within the frame.
External access is required for
redecoration and cleaning.
