Mullion windows

[Heathland]

My parents what to upgrade their windows,trouble is they are mullion windows,its not listed but want to keep it looking the same,so they are looking for companies that do replacement double glazing sealed units to fit,but they are finding it difficult finding companies that do it.
Thought I'd ask on here for any recommendations

 

[phillipe]

My parents what to upgrade their windows,trouble is they are mullion windows,its not listed but want to keep it looking the same,so they are looking for companies that do replacement double glazing sealed units to fit,but they are finding it difficult finding companies that do it.
Thought I'd ask on here for any recommendations View attachment 640040

@renewablejohn has some experience with this type of installation

 

[Nearly]

@JLTate

If you're not careful there will be more frame than glass.

 

[milkloss]

Might it be wise to fit a unit inside the window aperture where it is a square hole? Not sure it would be pretty from the inside but would preserve the originals.

 

[Lincs Lass]

Have you tryed James Oliver in Lincoln

 

[Lincs Lass]

https://www.caststoneuk.co.uk/products/windows-doors/mullions

 

[JLTate]

Internet is hopeless due to the weather and on phone so apologies if my message makes little sense.

As much as I hate it have you thought about secondary glazing?

What's the condition of the current frames?

 

[Turra farmer]

Blairs Windows will make to match , we have fitted similar to schools made by them

 

[suffolksmallholder]

They look like Crittall windows. https://www.crittall-windows.co.uk/ The company is still producing & may be able to give you some sensible advice.
SS

 

[Heathland]

Might it be wise to fit a unit inside the window aperture where it is a square hole? Not sure it would be pretty from the inside but would preserve the originals.

They have secondary glazing up stairs and its a pain to clean as they are very awkard.Mothers not getting any younger!
They have had a quote from Vale windows in Grantham (bronzed windows) holy.
Just to replace the window above the opening middle window they are looking at £1200 each, and there is 6 WTF and that doesn't include VAT.
So thanks
@suffolksmallholder
@JLTate
@Lincs Lass
@Turra farmer

 

[renewablejohn]

@JLTate

If you're not careful there will be more frame than glass.

Not if you put the glass direct into the stone mullion which we have done with triple glazing and mimics the original pane we still have.

 

[renewablejohn]

This is our windows prior to pointing with burnt mastic which then hides the triple glazing spacer bars.

 

[milkloss]

This is our windows prior to pointing with burnt mastic which then hides the triple glazing spacer bars.View attachment 640268

Burnt mastic? What’s that?

 

[renewablejohn]

They have secondary glazing up stairs and its a pain to clean as they are very awkard.Mothers not getting any younger!
They have had a quote from Vale windows in Grantham (bronzed windows) holy.
Just to replace the window above the opening middle window they are looking at £1200 each, and there is 6 WTF and that doesn't include VAT.
So thanks
@suffolksmallholder
@JLTate
@Lincs Lass
@Turra farmer

At that price I hope they dont have 82 windows like us.

 

[Heathland]

@renewablejohn
Parents windows are like you said, the glass is embedded in the stone,the difficult bit is the arched windows at the top,don't suppose you could let me know who did yours,could you?

 

[renewablejohn]

Burnt mastic? What’s that?

I had never heard of it until the Listed Building Officer suggested it instead of using Lime Mortar. Its a traditional sealant used around windows and window frames.

Boiled Linseed Oil and Burnt Sand.

 

[renewablejohn]

@renewablejohn
Parents windows are like you said, the glass is embedded in the stone,the difficult bit is the arched windows at the top,don't suppose you could let me know who did yours,could you?

My local glass company (Mayfield Glass) measured up the window holes and placed the order with Redituff in St Helens to make the units. All 4-16-4-16-4 Argon filled units with self clean outer and thermal inner coating. Arched windows not a problem so long as you can do a template for the glass cutters to work to. Measurement is critical as the 3g units cannot be altered once manufactured and stone is not as forgiving as wood for alterations.

 

[Pond digger]

Do you get trouble with condensation with your stone mullion windows?
Would you have them in a new build? I believe there is a method of sandwiching insulation between a two-part mullion to prevent cold bridging, but there’s little available info. Stone mullions always look well I think.

 

[renewablejohn]

Do you get trouble with condensation with your stone mullion windows?
Would you have them in a new build? I believe there is a method of sandwiching insulation between a two-part mullion to prevent cold bridging, but there’s little available info. Stone mullions always look well I think.

No problem at all with condensation but then we do have MVHR system which the LBO insisted on to protect the fabric of the building due to the Listing and the fact non of the windows are opening. Trying to cut down on pollen and dust as wife suffers from asthma. Would certainly put in a new build. Fixing method between mullion and 3g glaze unit is using Soudal Flexiform with a lead barrier between the glaze unit and the foam as the foam can react with the glazing unit spacer bars. Foam trimmed flush with glazing unit then burnt mastic used either side to hide glazing bar and make it look like the glass has been put in with (sandstone looking) putty into the stone mullion.

 

[Heathland]

@renewablejohn
I noticed you said non of your windows open,the trouble is the middle windows open on my parents house and its finding opening window frames which are narrow enough and inkeeping,the company that quoted was also concerned about the window aperture being narrow to escape in case of fire, was anything said about your windows as they don't open?
Also did you do all the work yourself,sorry for all the questions.