Sliding Sash - should they be 'stopped'

[paulbandler]

I have recently taken delivery of a set of sliding sash windows bought from a specialist supplier after much investigation and angst regarding their cost. Unfortunately during their installation they have become damaged by someone sliding the lower sash up to its limit and the catches on the lower sash colliding with the top of the inner frame and indeed scratching the top rail of upper window. This happened on 2 out of the the 2 sliders installed so far! (3 more to go).

Now while the installer (not the supplier) regrets the damage and indicates that it can probably be made good with some filler it seems to me something of a design fault that there isn't some kind of 'stop' lower catches colliding so readily with the upper frame.

Now I've tried to raise this question with the supplier but as yet they're not being very co-operative, so I thought that I might find some 'sliding sash' construction or use experience on this site that could tell me whether this is a general problem with sliding sash that needs to be avoided by careful use, or whether it is indeed a design fault with these windows perhaps?

Thanks in advance for any advice about what is 'normal' for sliding sash.

 

[essexbearhunter]

The cam or quadrant arm systems used on many traditional sashes as a locking device are simple and elegant. Additionally, its design pulls the inner and outer sash together to create a good seal.

Failure to turn the cam plate/arm fully out of the way (rather than just clearing the retainer on the outer window) before raising the window, inevitably leads to marking on the next surface that it contacts.

The obvious options would be:

1/ to have the retainer on the upper sash so close to the lower sash that it would not unlock until the cam was rotated fully clear. The negative of this is the probable marking caused by having the retainer this close.

2/ to use a Brighton catch which uses a pivoting bolt and hand nut rather than a cam. This is not as elegant and clumsy operation might still allow marking if the arm fell back.
http://www.tbks.co.uk/?state=displa...finitions=&session=1198602063XXXUU2oT0ZH1JInw

3/ not having the closer on the meeting rails at all. However, security bolts with a removable key that go through the vertical parts of the frame could still mark if incompletely dis-engaged.

Stopper blocks would only work if you never lowered the top sash. This would remove a major ventilation advantage of the sash design.

Your solution is really to get your builders to fully rotate the cam/arm out of the way before they push the windows up. If you can't be sure of this, temporarily remove the rotating half of the catch until the builders have finished fitting them.

Hope this comes in time to save the rest of yr windows.

Seasons greetings

Ian

 

[paulbandler]

Your solution is really to get your builders to fully rotate the cam/arm out of the way

Thanks for the helpful suggestions, but actually even fully rotating the arm doesn't prevent it from coming into contact with the inner framework attached to the frame head which is what has done most damage - we have relatively neat semi-circular gashes out of these sections where the cam on the bottom sash has collided with them.

 

[Moo]

Most of my sashes are a bit manky where the catches are. It's the sort of wear and tear that happens over a few centuries.

 

[NT]

Its a design issue with sashes, but damage only results from careless use or counterbalance failure. A competent installer should not cause this damage imho. There is no shortage of sash windows that have been in use over a century and are not marked/damaged in this way.

As a means to avoid further damage I'd remove the catches on the not yet fitted ones, and argue over the damage with the installer later.


NT

 

[Nemesis]

I'd seek out also more suitable catches. They should not foul any other part of the sash when sliding, not at any point, if chosen correctly. They should slide freely up and down and pass each other without any fouling. The retainer should be fitted so that it does not protrude beyond the wood, the part with the moving mechanism ditto - when the 'arm' is sprung back it should be contained in such a way it does not protrude either. It's not a design issue when properly installed and the correct type of fastener chosen.

The wood can be filled, scratched glass it's not so simple to remove the damage.




http://www.historic-scotland.gov.uk/sashcase.pdf

http://tinyurl.com/3cqf5x

 

[biffvernon]

Paul, are they double glazed? With dg there's less room for the catch. With a sideways swinging fastener with a round knob on the end, I sometimes grind the knob down to an oval to give an extra couple of millimetres.

 

[Nemesis]

But even with dg, the catch, if chosen correctly, should not protrude and should not foul the wood.

The sliding bits on sashes should be able to pass each other - all the ones we have ever had have.

There's a pic in the gallery part of this site of a very slim design of catch:

http://www.germanwindows.co.uk/gallery.html

 

[NT]

"The sliding bits on sashes should be able to pass each other - all the ones we have ever had have."

If they couldnt, the windows wouldnt open far. What type of catch do you propose that will never foul, even when left in the wrong position when the window is opened?


NT

 

[Nemesis]

So there isn't a problem, it's just someone didn't operate the catches correctly?

Design fault yes, but maybe not with the windows. Or the catches.

We have had catches with springs so that there was no 'in between'.

A pic would help - of the type and placing of catches, and the damage.

If most of the damage is to the inner frame not the sliding part, I presume that there are no horns?

 

[paulbandler]

Thanks for the further comments guys - I'd not checked back since new year so appologies for not following up before.

Yes they are double glazed.

I'll take a couple of photo's later and get them displayed here for your review, as I really am interested in getting to the bottom of this - from what I can tell even with care these windows are very vulnerable to further damage.

 

[paulbandler]

shows the damage most graphically where the cam has collided with some force with the top inner frame.

In

and

I'm attempting to show how close the cam comes to the top inner frame (this is from an undamaged one yet to be installed).

In

you can see how the cam has scratched the top transom of the upper sash before gashing the top inner frame.

Sad to see on brand new timber sash's no...?

 

[biffvernon]

Surround the picture's URL by the [img ][/img ] tags thus:

 

[biffvernon]

Maybe it would be better to use a slimmer type of fastener such as this:

This is the sort that I grind the round knob to an oval to gain another millimetre!