Sash Window Replacement, Renovation and Upgrade FAQs

Listed below are questions we are often asked. Please take some time to look over these before submitting a general enquiry. We have answered here as concisely as we can to cover more topics without too much reading, with many of the questions covered in greater detail in the relevant areas of our website. There is also a customer service section at the bottom of the site with more detailed information.

Questions About Services

Newly manufactured sashes, pre-installed with double glazed units (IGU’s), made to fit your existing window case (surround). Typically, we make these to match the format of the existing windows.

A complete replacement comprises new sashes AND case (window surround). Replacing your whole window is usually only required when the existing case (surround) is beyond repair or if none is currently in situ.

You can replace your windows if your local council give permission. To receive consent, a Listed Building Application must be submitted. You can do this yourself or, we can do this on your behalf as part of your quotation.
With a simplex system, the lower sash can swing inward and allow access to clean and paint a window. This system is standard in sash and case windows on the first floor and above.
Yes, although we recommend you have your windows painted by professional tradespeople. If you wish to go down this route, it will need to be discussed at the time of your quotation and may affect your guarantee.
We usually require a minimum of six weeks lead-time for manufacturing, although there may be some flexibility depending on our schedule. Typically, manufacturing works are booked eight to ten weeks before fitting and refurbishments a bit sooner, depending on our planner.
We will try to match the colour of your interior woodwork as closely as we can. However, please be aware that it can be difficult to achieve an exact match. Through time, pine will darken when exposed to sunlight, so it’s often the case that it will appear lighter at first.
As part of the draught-proofing process, we replace the existing parting beads and baton rods with new timbers integrated with brush strips. We also install a strip into the meeting rails in the centre of the window. While installing this system will show a large improvement over windows without, draughts will not be stopped completely.

Questions On Glazing

As a general rule, they do not. Slimline units are typically either 14mm 4/6/4 or 12mm 4/4/4 and allow for installation to historic windows. They are seen as a compromise for local authorities so that double glazing does not affect the character of the building. Most councils will allow the installation of slimline units in conservation areas and listed buildings.

Our argon filled, warm edge spacer units have a u value of:

14mm (4/6/4) Units – U Value 2.0

16mm (4/8/4) Units – U Value 1.6

18mm (4/10/4) Units – U Value 1.4


Low E or low emissivity glass has a film on one side of the glass that improves thermal retention when used in a double glazed unit.

  • Low E glass helps reduce Energy Costs
  • Low E glass blocks infrared light from penetrating the glass from the outside
  • Low E Windows Reduce Destructive UV Rays. These coatings help reduce ultraviolet (UV) light
  • Low E glass has a slight blue/green tint to it
  • Low E Windows Do Not Block All Natural Light

Fineo is a new type of vacuum-sealed unit which offers a better U Value than standard units while retaining a thin profile. At the moment, it’s fairly expensive, but as popularity increases, prices will come down. These units are ideal for Georgian style multi-pane windows.

Fineo 8 (7.7mm thick) has a U Value of 0.7

Please see the Energlaze website here:

Not necessarily. Several factors cause condensation, and while double glazing will help, it may not eliminate it entirely. The ambient moisture levels in the property and outside temperature extremes are governing factors here. When possible, rooms should be well ventilated to allow air circulation.

Yes, although it depends on the dimensions of the existing sashes, primarily the astragals on multi-pane windows. The process is also quite destructive to the existing timbers and, the overall finish is not as neat as new sashes.

Toughened, also known as safety glass, has been heat-treated in a furnace to give it extra strength against impact. If any portion of a pane of glass is below 800mm from floor level, toughened glass is a requirement.

Questions On Works

Yes! Our fitters and painters will do their best to keep disruption to a minimum during works and allow access as needed.

If our fitters finish up at the end of the day and with a window incomplete, they will temporarily secure either the old windows or the replacements in position before leaving.

As a rule of thumb, windows take one day per fitter, and we usually have two fitters per job, depending on staffing levels. Painting usually takes slightly less time than fitting but can be impacted by inclement weather.