Windows and The Great Fire of London


We could also have called this article;

How are old windows different to new windows?

and What to look out for with regard to old windows?


1stAssociated can provide help and advice with regard to building surveys, structural surveys, independent valuations, property surveys, structural reports, engineers reports, specific defects report, home buyers reports or any other property matters. As you can see from this article we use lots of sketches and photos in our reports as the feedback we have from our clients is that the sketches and photos help them understand the reports.

We, of course, like to meet you at the property during the survey and we are more than happy to talk to you about the reports.

Please free phone 0800 298 5424 for a friendly chat with one of our surveyors.

The Great Fire of London

The Great Fire of London in 1666 was really a turning point in window design. Prior to this date window sills were almost unheard of however after The Great Fire of London one of the key elements that was deemed to cause the fire to spread was the fact that the fires could transfer from one level to the next.

This resulted, for those that do not know, allegedly from a fire in a bakery in Pudding Lane and the burning down of over thirteen thousand buildings including many churches and town halls. Although it has been said for a long time that there were next to no casualties from what we understand this was because many of the poor that died simply could not be accounted for in a fashion that we would record today.

We have written an article on The Great Fire of London and fires which we would refer you to the articles:

The Great Fire Of London


From fire marks to James Braid Wood, the Surveyor who set up the Fire Brigade


After the 1666 Great Fire of London in 1667 The London Building Act initially required window sills to be compulsory, prior to this window's had either been flush or a small window sill. We would add that whilst this legislation came into being in 1709 in our experience often it took some time before everyone complied with the legislation and indeed the farther away you travelled from London the less likely the compliance would be carried out with any haste.

The window of this era was either the casement metal window or sliding sash window.

1709 the London Building Act required 100mm (4 inches deep or more) window sill and the setting back of the window. Any older window you see with a window sill of 100mm (4 inches deep or more) is likely to have been built after The Great Fire of London.

Such was the fear of fire that a second London Building Act was added in 1774 which specifically looked at recessing the timber window frame into the brickwork.

This affectively means that part of the window frame is hidden.




A few thoughts on sliding sash windows

We have heard that the word window is meant to come from the old English word literally meaning eye hole.

Sliding sash window defined

This is two windows known as sashes that overhang each other slightly sliding up and down originally using a set of weights. Sliding sash windows are normally in a vertical manner although they can be horizontal and literally slide sideways (we have heard that these are the older style windows often referred to as York windows or Yorkshire sash windows).

There is much argument with regard to the sliding sash window as to when it was invented and who made them first. Up until fairly recently it was considered that they were invented in the Netherlands in the late 17th century however it is equally argued that the sliding sash window was invented in the early 17th century in central England .

In addition there is the French theory that sliding sash windows came from France as the word sash comes from the French word chassis (meaning frame).

These windows are most popular in the Georgian, Regency, Victorian and Edwardian eras.

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Design features that make the sash window long lasting

A sliding sash window is hung from the top corners rather than by the side of the window as with a casement window therefore it is not affected by its own weight and does not distort. Many of these windows are literally hundreds of years old and are so popular that many older windows were removed and replaced by sliding sash windows particularly during the Georgian period when this window really is a standard feature of Georgian design.

The problems with sliding sash windows

An interesting point was made in an article that we were reading recently with regard to sliding sash windows was that they do not really have that many problems considering that many of them are decades old. The problems they do have are more to do with lack of maintenance.

The thought surely has to be what other windows have lasted so long? Certainly a modern aluminium window or plastic window we would not expect to last a hundred years many are replaced after ten or twenty years.

Badly maintained sliding sash window

A badly maintained sliding sash window will have loose or rattling sashes that through the various seasons can be draughty or rattle when windy. This type of problem can normally be reduced by carrying out a full refurbishment of the windows however they are single glazed windows and therefore will always be draughtier than a modern double glazed unit. However, we would add that many modern double glazed houses are suffering from condensation due to the lack of air movement in them.

Wet Rot

We have come across problems with wet rot in more modern sliding sash windows however we find in older windows the quality of the timber is generally so good that unless they really have not been redecorated for some time and wet rot has set in even the bare exposed timber is reasonably good.

Repairing beautiful sliding sash windows with plastic!

There is a limit to the amount of repair work you can carry out to any timber window – it always gets to a point where it is better to splice in new timber than to continually try to repair wet rot.

The plastic double glazing window myth

There are many arguments for and against plastic windows, one of the best that we have seen is that plastic windows generally have a life of ten to twenty years; double glazing units within them often fail after twenty years and need replacing.

Plastic double glazed windows do not actually save that much money with regard to pounds through the window. It is said that 10% of heat travels through a typical single glazed window; this is reduced and halved by a double glazed window. A fuel bill of £500 a year with double glazing at a 5% saving will save you £25 per year, typical costs of double glazing are between £2500 and £6000 which means even when buying the cheapest double glazing windows it would take a hundred years to get the costs back with the extra money spent.

Of course you could argue that it is more pleasant to sit in front of windows that are not draughty!

We do like the look of sliding sash windows and we have seen secondary glazing used very successfully to minimise draughts. It really is a personal choice unless the building is Listed or in a Conservation area when you have to keep the window.

Other articles that you may find helpful on our website are:-

Problems with roof windows, roof lights, sky lights and light tunnels

Property eras and common problems

Condensation problems

Independent professional advice on property

If you truly do want an independent expert opinion from a surveyor with regard to structural surveys, building surveys, structural reports, engineers reports, defects report, including things such as cracks, dampness, condensation, foundation problems, etc, dilapidations, home buyers reports or any other property matters please contact 0800 298 5424 for a surveyor to give you a call back.

Independent professional advice on commercial property

If you have a commercial property, be it leasehold or freehold, then you may wish to look at our Dilapidations Website at and for Disputes go to our Disputes Help site

Useful articles

We hope you found the article of use and if you have any experiences that you feel should be added to this article that would benefit others, or you feel that some of the information that we have put is wrong then please do not hesitate to contact us (we are only human).

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