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Surveyors should adhere closely to these instructions. Failure to do so may result in delays or increased costs. 


Information to get before survey

To avoid wasted time (especially going to properties whose windows are incompatible with Gecko panes), before organising a survey, ensure you have the following customer information:

  1. Full name
  2. Email address
  3. Mobile number
  4. Address (full address if interested in survey/installation)
  5. Number of windows to be upgraded (to determine survey possibility and cost)
  6. Are windows timber-framed? (ALMOST all of our orders are, but a few aren’t)
  7. Does glass meet frame at 90 degrees? Occasionally there are beads in the way. See How to Measure for details.
  8. Are windows Georgian style (many small panes – 6 over 6 or similar) or Victorian (fewer big ones – 1 over 1, 2 over 2 etc).
  9. ONLY IF GEORGIAN style:
    1. Ask if they might be original (in which case they will be over 150 years old) or if they have been replaced relatively recently to owner’s knowledge (in which case much less likely to suffer from moisture ingress)
    2. Advise that Gecko Panes can work great with Georgian windows, but occasionally a few seem to let a bit of moisture into the cavity from outside.  If so you just have to leave the Gecko Pane open at the top very slightly so the moisture can evaporate. The Gecko Pane still cuts heat loss as normal. We suggest installing in a single window first to see if you’re OK.   
  10. Are there any arched or shaped panes? We can’t do arched or shaped panes if they’re the top sash in a vertically sliding sash window. Contact Gecko Glazing for advice on other shaped panes. 

We advise collecting the information in a survey spreadsheet in readiness for a survey (click here). 


Equipment needed

  • Tablet or laptop able to open this survey template OR print out this template. Directly entering measurements into the survey spreadsheet reduces errors and typos and accelerates order fulfilment. If using the Word template, surveyors should fill in spreadsheet before sending to Gecko Glazing.  
  • Laser measure. ONLY use blue (professional) Bosch laser measures (NOT GLM 30 though, which is less accurate). The cheapest adequate model is the Bosch GLM 40 PROFESSIONAL. Used ones are often available on Ebay. Gecko glazing have a stock, so contact us if you can’t source.
  • Spare laser measure batteries 
  • Gatortape top reader measure. These are an excellent alternative even for large panes if your batteries run out. Available to surveyors at cost price from Gecko Glazing. Also use this to check your laser measure remains well calibrated (even Bosch ones). 
  • Stepladder 
  • White, brown, black and grey Gecko pane sample(s) to show customers, but also to check for clearance between glass and window furniture)
  • Leaflets
  • Shoe covers


How to survey

Before commencing survey

  • Put on shoe covers
  • Ask if the customer has any questions
  • Show product sample
  • Show how Gecko pane will look in window. 
  • Summarise how Gecko pane works and key benefits.
    • By trapping layer of air, heat loss is cut by nearly 50%
    • Easily installed and removed
    • No damage to windows. No obstruction of window opening/closing
    • Reduces external noise
    • Much better than replacing windows. Preserves historic window fabric and far cheaper than timber replacements.
    • Reduces condensation BUT will get a little misting on cold days (due to moist air trapped in cavity. This will go as day warms). For -Georgian- windows, if exterior woodwork not in great shape, might need to ocasionally wipe away moisture or, better, get exterior frame refurbished.  
  • Ask the client to show you rooms to survey and ask if you’re free to walk around to measure, where to begin and if OK to begin. 

Frames widths can vary from top to bottom and heights from left to right without a problem as the sponge surround on Gecko panes allows for it. Panes with sides smaller than 65cm can vary by up to 4mm altogether (i.e. a width or height can vary by 4mm over it’s length) and larger panes by up to 6mm. An extra couple of mm can be accomodated by trimming sponge if necessary. Only extremely rarely are panes more warped than this. 

That said, great care must be taken to avoid measurement errors by following these guidelines. Replacing ill-fitting panes due to measurements errors is time-consuming and costly.  

General points

  • We can do arched or shaped panes, but not if they are the top sash of vertically sliding sash windows (as per one of the panes below). We’re still developing a system for those.  Contact us for advice on how to measure for and deal with shaped windows (

  • The interior of window frames must a) meet the glass at 90 degrees and b) be 12mm wide where it does so. (i.e. frames must not have a ‘bead’ or other shape between the frame and glass, or be too narrow for a Gecko pane to fit). The vast majority timber frames meet these conditions:

  • Iron glazing bars: Occasionally windows can have these a frame mid points which preclude fitting Gecko panes.
  • Check the state of window frames, and note state of cleanliness and repair on survey sheet. Usually Gecko panes work well even with tatty window frames, but customers should consider refurbishing frames in disrepair, as repainting at least every 7 years prolongs the life of windows, avoids expensive repairs and ensures that Gecko panes work well.
  • When preparing quotes, it’s also necessary to know if the frames are particularly dirty (especially if mouldy) as extra time will be needed for cleaning, so ensure to note this on the survey sheet. 
  • In particular, as Georgian windows (those with multiple small panes in each sash) can be poorly sealed and allow moisture ingress. The below are examples of typical Georgian “6 over 6” windows. 

  • If possible check outside frames. If sashes are not ground floor, they can normally be ‘swung in’ using hinges to the side of the sash to allow observation. Check for cracks in window paint and putty and that paint overlaps the glass by 1-2mm. If not, suggest re-painting in the not too distant future. In pictures below, paint overlaps glass, but otherwise has lots of cracks, indicating a poor state of repair and water ingress.


  • Even if the paintwork is reasonable, bubbling in the paint or, crucially, a lack of overlap of paint on glass can indicate that sealing is poor:


  • Examples of excellent frame paint work, with a uniform overlap of paint and glass all round panes and no cracks in putty are as follows. This doesn’t mean moisture ingress will not be a problem!

  • Maximum sizes: Currently, Gecko panes can have a maximum longest dimension of 1.7 m and must be smaller than about 1.5 square metres overall. We’ve sometimes made larger panes (up to 1.95 square metres and up to 1.9m long), and we’re working on versions for larger panes, so check back with us if in doubt.

For each pane, check that there is 11mm between glass and handles, closers or other furniture (use sample pane to check). If not, the furniture will have to be moved or replaced during installation. Mention this to the customer. 

On the survey sheet, add a note for each pane requiring furniture movement/replacement (e.g. “painted over window closer to be replaced”). This helps installers estimate installation time and ensures they bring replacements. 

Also note if any furniture must be removed temporarily (e.g. if there is a closer at the bottom of the sash and a ring pull at the top, one must be removed temporarily to allow installation).

Check for clearance 11mm

For all panes, measure the width a quarter of the way from the top and bottom, and the height a quarter of the way from each side. Always take two measurements of width and height to avoid errors and ensure a good fit in warped panes.

To measure accurately

  1. In the survey sheet, give each room, window and pane a title, such as “Living Room, Bay Window, bottom left”.
  2. Check your first laser measurement with a tape measure to ensure that the laser is working correctly. Gloss paint or direct bright sunlight can affect laser accuracy. If the laser takes longer to settle upon a reading, or successive readings differ significantly, it may indicate low laser accuracy. In these conditions, check measurements with a top reader tape measure (ideally a Gatortape), and potentially use the tape measure for the survey instead.
  3. Enter the measurements into the survey excel sheet or the print out version.
  4. Add any other observations/notes, such as poor window conditions or frame furniture that needs to be removed during the installation. Always note whether window furniture to be moved is painted over. These can increase installation time significantly (circa 30 mins per item). 
  5. Note the colour required and check with the customer.

Key messages for customers post survey

  • Mention whether any window furniture will require to be replaced/moved
  • Advise of colour options you suggest: white; brown; grey; black
  • Mention that Gecko panes (like all secondary glazing) can sometimes get internal misting on very cold days, due to moisture trapped in the cavity, but that this goes as the weather warms
  • Only if any windows are Georgian, suggest a single window (not single pane) initially, ideally North-facing (as these benefit most) to see if moisture ingress occurs. If it does the customer can decide if they’re happy to vent ocassionally and therefore to get more Gecko Panes. Note that moisture ingress is more common in windows that get direct sunlight. 
  • Explain next steps and lead times (detailed quote to follow, with cost for professional or DIY installation) 
  • Explain whether DIY installation is unrealistic (lots of painted over furniture to remove or inaccessible panes) 
  • Leave a flyer with the client 
  • Ensure survey notes highlight whether a discount is to be applied.

How to send survey data to Gecko Glazing

  • If the printed out version of the survey sheet was used, transfer data to the spreadsheet version before sending to Gecko Glazing. It is easier for the surveying company to ensure accurate transcription of all data (e.g. if hand-writing is unclear). 
  • Send completed surveys to We will provide a detailed quote within 24h. 
  • Once received, prepare your quote for the customer. 

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