Double Glazed Sash Windows
Double Glazing Original Sash Windows
In recent times sash window companies who restore, repair, and replace windows have started to double original windows. There are many advantages to double glazing your original sash windows and that is you keep the originals and save a large amount on complete replacement sash windows. In fact once a sash window draught proofing system has been incorporated and they have been fully decorated it is possible to achieve savings on entire replacements of up to 50 percent. When considering a house of twenty sash windows may cost £25,00 – £30,000 to entirely replace this represents an excellent saving.
The original sash windows are removed from frame and then rebated deeper and wider to hide the edge of the double glazed unit which is unsightly. This can only be done with sashes carrying a certain thickness. To check your sashes are wide enough for this service you should contact any specialist who carries this service out. If the sashes are over one and a half inches then it’s likely that we can work with your existing.
Once sashes are rebated the units are then offered to make sure they fit. They are then bedded in with a silicone and externally where would have originally been putty is replaced with a neat glazing bead. Not only will this improve the look of your original sashes internally (black of putty badly glazed over the years) it will give them a perfect uniform look externally too. Once decorated nicely from even ten yards you would be hard pressed to tell if they are entire replacements or not.
Lead sash weights are then used in place of your original cast iron as lead provides density which cast iron does not have. The advantage to this although expensive is that you can retain full travel on your sashes. If you were to pursue the use of cast iron the weight would have to be so long typically that by the time you lift your sash a foot or two the weight will hit the bottom of the box internally thus stopping any further ‘gravity’ and travel.
Another significant factor is that by having double glazed sashes your are effectively nearly doubling the weight of the windows and as such it is important that a sash cord design to take the strain of the extra weight is used. If this is not the case you will find the standard sash cords installed will not carry the normal lifespan you would expect.
Some sash windows may have intricate glazing bar. The modern standard is to remove the glazing bar and have one sealed unit within each sash.The reason for this is that the edge of a sealed unit would be visable if we are to maintain a slim ornate glazing bar. Once the glass is installed we then laminate the internal section of glazing bar to the glass and make a custom external glazing bar to match our glazing bead. If this is difficult to understand or your struggling to envisage this we are happy to send you pictures as you require.
When carrying out this type of work we use a 4mm soft coat – 8mm air spacer argon filled – 4mm thermal glass. This is the most modern and up to date technology and provides a U-Value that would satisfy complete replacement easily. So there really is’nt many reasons not to use your existing joiney. We will be happy to look through with you and advise best how to install you double glazed sash windows units.