Major rebuild of a bay window

This bay required extensive refurbishment. Cutting out of most of the bottom 20% , new windows, removal and repair of all the leaded glass before re-fitting.
and the introduction of secondary glazing into the leaded windows – the lead came had perished. New cills.
Was it worth it? well an 8 light timber bay made to measure worked out at over £12.000 this project came to under £7.000

Significantly reduce heat loss and save money

A single clear window film that reduces thermal loss to such an extent that your single glazed windows will now perform BETTER than a double glazed unit.
A Double glazed unit has a ‘U’ value of between 3 and 1.8 this depends on the type of gas used to fill the cavity between the glass. A Treble glazed unit has a ‘U’ value of between 1.5 and .9 again depending on the type of gas used to fill the cavities. Using a low ‘E’ E means low emissivity, energy saving film on single glazed windows reduces the ‘U’ value down to 1.14 this is lower than double glazed units.

The lower the U value the better the thermal insulation

The film is totally clear and can be fitted to all types of glass with the exception of laminate glass and obscure glass where the pattern is on the inside. The film can be fitted without the removal of glass and the addition of extra weights in sash windows and is suitable for listed buildings and buildings in conservation areas where double glazing is not permitted.
Another benefit is that it has a 99% UV rejection so your curtains, soft furnishings and flooring will not fade in summer light. It is a completely clear film from both sides which will not alter the appearance or light levels.

A thermal shield against heat loss in winter through the glass thus reducing the amount of energy required to heat a room which in turn means lower energy bills. An investment that will pay for itself .

If you combine this with the addition of brush seal draught excluders to your windows you will reduce heat loss even further. Fitting the film alone will not reduce draughts through ill-fitting windows or doors. See my notes on draught proofing on this website a combination of both film and draught excluders will transform the window into a high performance barrier against the outside elements.

Your question answered

What is it?

A heavy Duty totally clear window film that will be as efficient as double glazing in keeping the cold out and the heat in your home, It will pay for itself given the current cost of energy almost within months.

How does it work?

By using a ‘low E’ coating that reflects heat back into the room and prevents cold temperatures passing through the glass into the room.

How does it compare to double glazing?

As good if not better than double glazing depending on the gas used to fill the cavity of the double glazed unit. The film has a ‘U’ value of 1.14 a double glazed unit has a ‘U’ value of between 1 and 3. The lower the ‘U’ number the more efficient it is at keeping the cold out.

Is it cheaper than double glazing?

Yes, about 70% cheaper than double glazing retrofitted into wooden windows and 90+% cheaper than having your single glazed windows removed and double glazed windows installed.

How messy is it to install?

No mess No dust and installed in 1 day to an average bay window.


It cannot be fitted onto laminate glass or obscure glass where the rough or patterned side is on the inside of the property. It cannot be fitted when the surface temperature of the glass is below 2degrees. It cannot be fitted onto cracked glass.


10 year guarantee against peeling or cracking.

Can it be cleaned?

Yes, use a soft damp cloth but no chemical cleaning solvents.

What about the summer?

99% UV rejection so no fading of fabrics.

Wooden flannels and slips

A Collins window that could be salvaged with timber slips and a flannel. Once all the rot had been identified and machined out leaving exposed sound wood I could go about fitting the replacement parts.

This can become a lengthy project depending on the rot present and it is not always economically viable to do this. The only exception would be if a window or door was from a grade 1 listed property.

However this was economically viable and cost less than half that of a replacement window.

Removal of Collins windows

After the removal of the old windows and prior to the installation of the new replacements the cills in part needed to be replaced. It is usually the external component of the cill that needs to be replaced as this is the bit that is exposed to the elements.

There are occasions where the rot has travelled beyond this exposed part and continues under the window and into the internal components of a cill. This is often caused by ill fitting windows where the bottom rail sits on the cill and capillary action occurs.

Unless the window is opened on a regular basis the water sits and rot eventually takes hold.

The cills have a 4.5 degree fall from window to edge. Rot can also travel up to effect frames as was the case with the octagonal window. The glazing beads had to be removed as they had deteriorated. Broken putty being the cause of the rot in the glazing
beads as well as the frame itself. A timber flannel was introduced onto the frame and glazing beads replaced. A particular feature of Collins windows are the parliament hinges which allow the windows to be fully opened flush to the brickwork.

I spent considerable time searching on the internet for replacements but couldn’t find ones that were exact in design and more crucially size. I imagine that Collins must have had a job lot made specifically for these windows. Close inspection suggested that they were indeed made in a foundry rather than on a factory production line. So replacing one of the two hinges to any given window cannot be undertaken. I had to replace both as the projection on a modern replacement does not match the original. The original projection being 121mm ( 4 3/4″) . The closest projection I could find was 114mm ( 4″ ) . Original hinges appeared to be made from cast iron with a high percentage of steel although this may be a guess rather than a fact as this is not my area of expertise. Lime based mortar was then applied to the underneath of the cills and at the ends. Again this too had to be right. I found a supplier who matches colour in premixed lime mortar so that once it’s set it will marry into the rest of the property. Several properties close by had patched mortar that did not match and it did not look right.

Finally after 350 hours of manufacturing , replacement of cills , repairs and installation of replacement windows I could finally stand back and feel confident that these windows are good for another 70 years.

Herbert Collins Architect

Herbert Collins 1885-1975 was a British architect.
He designed many suburban developments in Southampton primarily but not exclusively around the Highfield and Basset Green area of Southampton.
Distinctive in their design and built during the 1920s and 1930s. Today their uniqueness is closely guarded with no deviation from the original design allowed and quite rightly so.
There are some subtle but distinctive features from a joiner’s perspective within the design of these windows and the exterior joinery.
Whilst manufacturing I noted that the internal part to the glazing beads and frame has a 1.5 degree taper from the face to the base of the rebate. Incorporating a 4.8mm radi (3/16″ ) roundover moulding.
The combination of these two features produce a 8 or 6 light window which is aesthetically less bulky and lighter in appearance than would normally be the case.

The 4.8mm round over also features on the edge of the central meeting stiles along with a 4.8 mm rounded grove set back 10mm. Glazing bars are 25.5mm wide, reducing to 24.75mm on the face ie;
1.5degrees. Glazing rebate depth is 16mm x 10mm. The bottom rail on an 8 light is 80mm (3 1/8″ ) wide and 70mm (2 3/4″) wide on a 6 light. Stiles are 44mm (1 3/4″) wide on both the 6 and 8 light windows along with thet top rail. Overall they are 35mm (1 3/8″) thick.

Before manufacturing commences I need to take apart one of the windows to extract the various components. Layers of paint often have to be scrapped away to get to the original timber so that accurate measurements can be taken.
Next a rod sometimes called a cartoon is set out onto a piece of board or length of timber usually a piece of 8×1″.This is basically a full size plan incorporating all the mouldings and the position of components in relation to each other. The rod is an essential part of the manufacturing process, get this wrong and everything else will be wrong.

I do remember the rod loft during my apprenticeship where long lengths of board were set out on equally long work benches with sometimes complex ‘ works of art’ being drawn up. There were even full size rods set up onto a white washed floor displaying the sheer at set intervals of a yacht with datum lines. There was one particular old hand who after a lifetime of setting up could undertake this freehand. My understanding is that this can now be done on a computer alas these skills may be lost in the coming years.

Finally machining can now commence referencing the rod periodically to ensure accuracy.

A solution to Double Glazing in wooden windows

Some exciting developments have been made in Double Glazing technology. And finally a solution to retrofitting traditional single glazed wooden windows with a double glazed unit has been developed. It is now possible to have a 6.7mm or a 7.7mm clear double glazed unit. The statistics are impressive.It’s actually better at insulating homes than double or triple glazing with an impressive unbeatable U value of 0.7. The higher the ‘U’ value the less its insulating properties.It’s also better at sound reduction than double or triple glazing with a sound reduction of 35db. The higher the ‘db’ number the better it is at sound insulation.Also the internal pane temperature outperforms double and triple glazed units.

The valuessingle glazingslimline double glazingdouble glazingtriple glazingnew 6.7mm
light transmission9080807180
sound reduction2931313235
internal pane temp with outside temp1c13.6c15.7c17.28c17.7c

This glass can also be fitted  into frames using putty which means that retro fitting into heritage windows is now possible.These double glazed units solve the problem of retrofitting and basically all that I have said and written about not being able to fit a double glazed unit into a wooden window without compromising the integrity of the window itself have now been overcome. I will say though that these units are not cheap but they do come with a 15yr guarantee which is in itself way ahead of conventional d/g units.                                                                                

16th Century windows

16th Century windows
Its nice to come accross such delights. The customer asked for a survey of these windows and I was suprissed at their condition some areas require a bit of attention particulary on the Oriel window which has a established mini forest of foilage hanging down. This will have to be removed.Repairs were undertaken in the 1950s and you can see the ‘slips’ put into place where rot or damage has occured. With a build date of around 1550 these windows made from English Oak stand as testimant to the durable caracteristics of timber and in particular Oak windows.I was informed that the leaded glass dates from the mid 1600s. It could be the case that prior to the instalation of the leaded lights oiled cloth may have been used as a weather proof curtain which was the case in many buildings of that period.   

A stained glass window in Southampton.

A particularly tricky project with possible issues arising from the stained glass segments falling out or worse still breaking.
The stained glass itself is in a very ‘tired’ condition with the lead cames shot and the cement between the cames and glass cracked or missing. This is in addition to the rotten timber windows.
Normally I would take out the windows and glass and rebuild but that would entail something in the region of 200 hours labour. The windows also have not been opened for at least 30years and I was not going to attempt opening them.After some thought I decided to tape up the glass inside and out and then tackle the repair of the timber. Taking my time using specialist cutting blades set on a very high speed to reduce vibration I replaced the rotten timber with new. Thankfully it worked.

On a separate note I advised the customer to insure these as an extra on their household insurance as the replacement costs would be somewhere in the region of £20,000 if the worst was to happen and a house fire destroyed the whole lot. Lead has a low melting point. 

Box Sash Diamond Lights

I came across this beauty whilst stopping for lunch in the west country on my way down to Cornwall. I have described this as a Box Sash Diamond Light which is something I have never seen before. The Diamond design is not unusual in fixed and opening windows but in a sash window it is. There would be a considerable amount of work involved in manufacturing and glazing of this window sadly now in a poor state of repair.

Box Sash Diamond Lights

My guess is that eventually it will be replaced by a plastic unit, the building itself did not appear to be unusual or of historic importance so its probably not a listed building or window. I did knock on the door hoping someone would answer and throw some light on the subject but no one was in. So I stood in the public car park around the back of the building lodged between a parked car and an opening in a fence and done my best to take this image without drawing attention to myself. I did wonder what would I say if challenged by the police I would probably try and draw their attention to the design and aesthetics of this window and my website. They may come to a different conclusion! My wife incidentally wanted nothing to do with me at this point.

Yorkshire lights

A popular choice in late 19th and early 20th century buildings in the North of the UK, it is uncommon to see an example of the Yorkshire Light window in the South.
My understanding is that the design originated as the name suggests in and around Yorkshire. Openings for windows were often wider than their height due to dwellings in the North often being squat in comparison to dwellings further South. This no doubt was due to being exposed to the elements particularly on hill sides. A traditional sliding sash window requires height to be able to accommodate the weights and pully wheels to operate up and down.
This example required new shoes -the sliding windows run along Oak or metal runners fixed to the cill and housed in a rebate cut to the underside of the bottom rail, known as a plough groove . I also added draught brush seals set into carriers that eliminated draughts and reduced outside traffic noise.
In an edition of The Practical Woodworker dated 1929 it describes this style of window as being ‘very satisfactory in every sense’
I agree. They are a pleasure to operate pleasing to the eye and function without fuss. The customer had no idea of their rarity in the city of Southampton and was pleased with the end result. My only other experience of Yorkshire Lights in this part of the world would be a row of farm cottages that I worked on many years ago north of Winchester.

An opener damaged by wet rot

An opener extensively damaged by wet rot. The bottom one third of the window was completely rotten due to wet rot. 

The window although under a thatch overhang so set back by around 2ft (600mm) from the rain had suffered. I couldn’t work out why this was the case.

When I visited the customer to look at the job I thought perhaps there was a damp problem with the wall a traditional lath or perhaps an issue with rain from above through the thatch but if that was the case then the rot would occur at the top of the window not at the bottom.

I rebuilt the bottom 30% of the window and then refitted.

It was then that it became apparent why it had rotted. A wheelie Bin was placed in front of the window which was removed on my initial visit. When I finished the job it was replaced and the customer informed me that that’s where it always lives. The thatch overhang which has no gutter was immediately above, in heavy rain the water pours off the roof and continues to drip long after it has stopped raining the water was hitting the bin lid and splashing back onto the window. The bin had to be found a new home.   

New lease of life for a neglected window

Having been advised by a local council listed building department that they had received a number of complaints about a run down property the customer finally took action.
I was advised that these windows had not been touched or opened since the 1970s. As you can see they are in a pretty poor state although surprisingly little rot was present.
All the glass had to be removed, and rebates raked out. The joints required gluing up and clamping. The glazing beads needed replacement partings -that’s the timber between the glass and putty that forms part of the glazing bead. All the various layers of paint had to be stripped, a tedious task.
In total 120hours were spent on this one box sash window and frame

The finest Gothic revivalist window

This is probably the finest example of a Gothic revivalist window that I have ever seen.
I came across this sash window whilst on a weekend break in Ely, Cambridgeshire. My reason for visiting this city-the second smallest in Britain, was to see the Cathedral and the Stained glass museum within.

finest example of gothic revival windows

This beauty is in the high street above a building society. The Tracery- that’s the timber elements that support the glass is truly extraordinary with its hidden intricate joints dividing the whole window into symmetrical perfection.
The Angel lights – the upper panes of glass on the curved window section, from what I can determine are a combination of fused and painted glass resulting in an outstanding visual display of colour and patterns. And to top it all the Crockets- the figurative carvings and frieze that adorns the frame. It does not get better than this.
I stood there for some time admiring this masterpiece of joinery and glazing. My wife does think that I am slightly odd to get so carried away with a window! But for me this is art.
I imagine it was made during the revivalist period for all things gothic say around 1820s /30s. I can only hazard a guess at the extraordinary effort that went into designing manufacturing and installation of this piece. All for the expression of love for a style called Gothic.
Sad to say that I can see areas that do require some work, particularly the putty which if left will continue to break down, crack and allow wet rot to take a hold. I do hope that someone is going to look after this for future generations to admire.

Another Gothic arch window
figurative carvings and frieze that adorns the frame
Carved rose details on the pediment

Leaded Windows repairs

This was a challenging project. The leaded windows had extensive rot to the bottom rail and both the left and right hand stiles. New windows were made.
Because of the long term exposure to high moisture laden timber frames the lead cames around the edge of the glass had deteriorated and fell apart when they were removed. New edge came had to be soldered and each piece of glass recemented as these were leaking.
On top of that the bottom 20% of the actual frames and all the cills were very rotten. I did at one point question if I had taken on too much!
10 days later I stood back and felt pleased with the outcome. All in all this still worked out cheaper than replacement.
So this character property in Bitterne – Southampton built in 1912 managed to keep its original windows.


Leaded and stained glass window repairs

Window repairs with leaded glass edge.

An example of the service we offer in Southampton
repairing leaded windows

Leaded/ stained glass window repairs.
The method of making leaded or stained glass has changed little since its inception in the early part of the 11th century.
although technique and materials have advanced its nice to know that the basics remain the same today as they were applied back in the 1100s.

Old leaded window in need of repair

A common problem I encounter when removing the leaded glass from rotten windows is that the lead solder joints break or the edge came breaks as the putty is removed.
A came is the lead between each piece of glass.
Also I do come across some lead glass windows, particularly older examples where the lead came edging has perished.
Other issues encountered can be leaking lead joints and sagging lead came.
The lead glass shown here had broken joints and perished edging. Rather than taking the whole piece to bits and starting again – which is a time consuming job; tacking the broken joints and re-seating the glass with paste to prevent leaks and building up the areas of edge that have perished takes less time and results in a satisfactory repair.

Circular windows

A opportunity arose for me to undertake some circular work. The window in question had been re-glazed approximately 10years ago.
Unfortunately the glazier did not measure the bend correctly and had to fit the glass ‘off centre of the bend’. This resulted in the glass having to be forced against the rebate and pinned.In turn this meant that the glass was under pressure to spring back to its original form. There is a certain amount of give in curved glass but it will always want to return, just like a spring.
This pressure to spring back resulted in the glazing bead between the two pieces of glass to break at the joints. I suspect when the glazier formed a mould for the replacement glass he/she took measurements from the inside and did not include the depth of the rebate. The piece was 24mm short on the length, the precise depth of both rebates.
I fashioned a new mould by taking out the second piece of glass which fitted correctly and transferred this shape to a piece of plywood.
The glazing bead between the two pieces was repaired using Oak tenons that were slipped into mortices that I cut out and glued.
Once I had the replacement piece back from the manufactures’ it was a simple case of fitting.
There is always a moment of anxiety when offering up a bend but this one fitted like a glove.

Window Cill replacement

This started as a small area of rot in one of the corners. But once I started It became apparent that the whole cill had perished.
The exterior walls had been rendered and the interior walls plastered after the window had been fitted. It would have meant either a re- rendered exterior wall or a re-plastered interior wall if any attempt was made to remove the window frame, so replacement was not an option.
The property which is a grade 2 is situated 100meters from the beach. All new work was finished in a marine primer and marine grade paint will be used.

Sash window rescue

About ten years ago these two sash windows had double glazed units fitted after the original glass had been removed. Because the original rebates that the old glass sat in was not deep enough, the contractor machined them so that they became deeper and allowed the thicker units to be fitted. This meant that the joints were reduced and their strength compromised – these sash windows should not have had double glazed units fitted due to their construction; there is just not enough stock to be able to do this. Also the rebates were not painted prior to the glass being fitted which meant that the sealant used did not adhere to the timber. Add to this the inadequate timber beads, the end result was a weakened window at the joints and the opportunity for rot to take hold once water ingressed into the rebate, due to poor adhesion of the sealant. Also there was no throat (a groove that stops capillary action taking place) underneath the bottom rail.
Some sash windows can be successfully retro fitted with slimline double glazed units but not all; it depends very much on the thickness and width of the stiles (side members) and the top rail (meeting rail).
For those windows that are too slim or too narrow, single glazing remains the only option. After all, box sash windows manufactured in the early and mid part of the 20th century or earlier were not designed to accommodate such double glazed units, just like a car built in the 1970s was not designed to accommodate air bags or many other modern features we now take for granted.
This is where secondary glazing comes into its own, with or without brush seals on the parting and staff beads and along the meeting rail. As I have mentioned several times in previous posts, thick curtains will certainly help.
With these two sashes, I managed to replace the bottom rail and glazing bead, along with the bottom 1/3rd of the stiles. The question of weakened joints I have solved by using an adhesive as the sealant between the glass and the frame at the bottom of the rebate – not ideal because if these units need to be replaced once they blow and mist up (and all double glazed units are destined to do this, even if its years down the road) then removal may be a challenge. As you may guess, I am not a fan of double glazed units in timber windows. Normally you can strengthen joints by: 1. inserting a wooden slip, which can be seen in one of the images that accompany this post, 2. inserting a loose Tennon, or 3. inserting two wood screws that secure the stile to the rail, but on this occasion there is not enough stock to undertake any of these options.

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Scarfing in

An area of wet rot to a 1930s window appears to be the result of either water ingress past the putty or insufficient primer used when painting a previous repair. As you can see I  made  a cut out of the effected area leaving in the piece that has the interior moulding it may have been a whole new window if the wet rot had eaten away at the moulding.

A new piece was then added and fastened with glue and screws, timber plugs were used to plug the screw holes. Not entirely necessary but a far more professional finish. Once dry the window was re-hung and primed.