Advice on draughty sash windows

Hi @Chipcity

The guy is on eBay, but don’t be put off by that because I’ve used him a few times and the service has been spot-on every time.

The window in this link doesn’t have the deeper bottom rail but you can specify that on the order form.

I’d be happy to help you understand any of the jargon or features if you want.

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Sorry @DevonishForester , I’ve had a good look on Lewisham’s planning pages but I can’t find it. I’m sure it used to be on there. I’ll have a dig through my old paperwork to see if I’ve still got a hard copy that I printed-off a few years ago.

Lewisham’s rigid wooden-over-UPVC argument was, I’m sure, based upon seeing some poor attempts at replicating the essential look and aesthetics of an old window but all UPVC sliding sash windows are not the same!

I think he might be the same person as I spoke to him on the phone and his prices are great. The windows are synseal evolve. My builder recently fitted 4 for me, purchased from fascia place, but I intend to buy more from this chap.

There’s some great advice and recommendations here. @moderators can these become a category in recommendations?

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Yep, Colin’s the man!
And the EU lady who I’ve dealt with on the phone is so helpful.
Great firm.

Good idea. Perhaps we could add a heading to the recommendations page for general “neighbourly advice” topics like this.

You should be technically able to edit the recommendations page yourself (it’s a wiki topic) and I’d encourage established members to do so. Only condition is that the topics listed there are for general recommendation lists, as opposed to recommendations for individual companies.

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Yes, there are some excellent UPVC sash replacements. I would be interested to hear from anyone in the conservation area who has navigated this with Lewisham Planning.

Historic Windows Guidance.pdf (193.7 KB)

This is a few years old, but was sent to us when we were looking to replace rotten windows.


Perhaps the insistence on wooden sash replacement should be assisted with a grant?
As modern sash windows are excellent replicas, coupled with ease of cleaning and sound and heat insulation. Difficult but surely conservation of energy trumps draughts and maintenance and without a trained eye no apparent difference.

I should add that some changes are ridiculous with outward openings and ‘georgian’ panels and certainly see a point of view where totally incongruous windows are fitted. Maybe the planners should have a recommended design/supplier?

I agree with you @Wynell .
On the planning part, at least their guidelines should stipulate minimum ‘heritage’ design features such as ovolo glazing bars, deep bottom rails and run-through horns?

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Thank you @Sandinista, this document is the one I was looking for - but it really winds me up!
Yes, in an ideal world (where slow-grown softwood and craftsmanship cost the same, relatively speaking, as it did back in the early-1900s) people would all be able to afford to do like-for-like replacements - but they can’t. So, as preserving the look and the character of an area can essentially be achieved by using a modern, less-expensive material and manufacturing process, I find it really annoying that many local authorities are still digging their heels in on this.


Since this topic has evolved into a slightly more general discussion of windows and seems as good a place as any to ask, can anyone advise on “soundproof” windows? The recent re-introduction of fast Thameslink services (I live near the rail line) has me contemplating trying to improve soundproofing but having looked online I’m not quite clear whether you need specialist windows or whether decent double-glazing should do the job. Is there a rating system for sound-proofing and is there a stage where you are paying significantly more for only marginal gains - i.e. what is the sweet spot in terms of cost to significant (but not necessarily complete) sound-proofing?

Any thoughts, experience or recommendations appreciated.

We used Magnaglaze for our sash windows. They supply precut polycarbonate panels with magnetic stripes on the edges. You offer up the panels to the frame and the result is that you really can’t see the secondary glazing and the sound and heat insulation are excellent. They also make a version for people who want to open their sash windows.

Our builder told us that the heat loss through the cracks in floor boards greatly exceeds heat loss through draft y windows
We had insulation installed under the floor boards and it made a huge difference to temperature and comfort.

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Real soundproofing costs a packet, I believe the recommendation for glazing is a 75-100mm air gap. Which due to thermal activity then reduces the effectiveness of heat insulation.
There is laminated glass which is a sandwich where the inner section is a plastic film vibration reducing feature.

Basically its cost v benefit

Hi, thank you for details and it looks good especially his feedback on eBay.

May I ask, did you replace or repair? It would be helpful to hear from someone in the conservation area who secured permission to replace timber with UPVC.

The Historic Windows Guidance sounds rigid:

“If the original window does need to be replaced, it should be in the original style and material. It should be replaced exactly ‘like for like’”

Strangely the document also says --" Depending on age and style of the building, the glazed area of the sashes can be subdivided with glazing bars into smaller panes." Surely subdividing the the window into smaller panes would make greater visible change than good quality UPVC sash replacement?

Another thing is, I’ve seen some pretty amateurish-looking wooden replacement sash windows that aren’t as good as these UPVC ones.
I have a feeling that the existing guidance is old and, due to the advent of these sympathetically-designed UPVC replacements, needs to be updated .

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Hi there - we replaced our windows, as they were in pretty bad nick and we wanted to double glaze. They’re not actually sash windows though - we have quite large casement windows with Georgian bars, so it was a big (and expensive) job. Ours are timber.

Try this: It worked for my sashes and you can take out in the summer and re-use in the winter. Cheap as well. But depends on how bad yours are, obviously.

Also, if you have any cracks or rotten timber in the sashes, definitely look at

I had bad timber decay in two of mine and thought I was looking at new sashes or at least a major repair, but was put on to this by a sash specialist I rang, but who was too busy to help. Worked perfectly and saved me hundreds.

My advice is shop around. The main company in this area, which I won’t name, is grossly over priced in my opinion. But they have a waiting list / a lot of business so I guess they are doing something right.

But as someone said above, we thought it was the windows, but in reality most of the coldness was actually coming from the floorboards. But you need to have airflow under the house to prevent damp etc. So it’s a balance.