UKH

Rich world problems...

We've had some timber frame triple glazed window units installed recently on a hard-to-reach aspect of 2nd floor, floor-to-ceiling size, made bespoke to replace a juliet balcony door and surrounding panes that had started rotting and leaking (you might expect more than 20yrs from Nordan, but there it is). The replacement was not cheap. I'd like them to not need any serious attention for a couple of decades at least.

After installation and removal of the scaffolding outside, it was soon obvious that the new window frame was not water tight: expanding damp patch on the inside of the frame, after heavy rain and wind. I had queried before they were put in that they didn't appear to have any external gasket or seal around the glass in the frame, but was told this was fine. To solve this, the firm who made them came back and squoosheed a bead of silicone along the outside bottom of the glass. I'm not convinced this has actually done the job since it seems to be letting in water again.

I don't actually know how windows are made, if what we have is a proper job just minus a final bit of silicone that can be easily rectified. So I've a couple of totally basic questions for someone who does: 

1. What is the standard way that you would set a glass pane in a timber frame - would you build in some sort of seal or gasket when making the whole thing up in the workshop? Would this be visible? (I can't see anything in this case - just seems to be wood against glass)

2. Assuming yes to the above: If the original seal was not put in place, or done badly at the time the frame was made, would retro-adding a silicone strip to the outside be an acceptable long-term solution? (assuming it was done properly - I suspect it's still leaking in this case). I don't want to have to think about re-doing it every few years as the silicone perishes in UV and the elements - something we might only notice when it has started letting water into the frame again. Getting to the outside of this window is a major faff, not an easy ladder job for a DIY bodger.

3. Removing and re-doing these particular windows would be big palaver and expense (for someone) - scaffolding, etc. In light of all the above, is that something we should be discussing with our main contractor? Or would it be more reasonable to just make sure that a silicone seal is done properly on the outside and leave it at that?

Thanks...

I'm none of those tradies, but I've renovated a fair bit, the glass cassette should sit in a rubber gasket, which is the right size for the frame housing, so water etc can't blow or run in, it should be flush, smooth and with no space to even squirt a bit of silicon seal into. Sounds like the glass/gasket/frame aren't matching in their dimensions. 

Ditto, no trade here but I do know that when replacing a failed double glazed unit into a timber frame you'd use something like this:

https://www.reddiseals.com/product/butyl-tape-sealant/

Not just window abutting timber.

another point is that if you have gone to the trouble of adding triple glazing - presumably for energ efficiency purposes?  [ie:  more than external noise reduction].  Then the air tightness around the edge of the window is key to the energy efficiency improvement.  It will not be anywhere near air tight if it is glass sitting on wood.

Done a fair bit of glazing and window restoration as well as leak investigations so seen plenty issues and variations.

Obviously they done a shit job if it's leaking already. Slapping some mastic is a very bad sign of a bodge job being bodged further to rectify.

I'd ask for a detailed drawing of how the windows were fitted and run that through a third party who will be able to point to the problem, then either get the original company to satisfactorily rectify that problem or countercharge them for the third party to do the job.

If you got some photos we can try to armchair diagnose what the issue could be, as it's hard to figure out from the description and there is countless ways of doing windows 

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It's a good while since I detailed timber windows but on an externally beaded frame I'd expect butyl tape between the back of the glass and the timber rebate. On the outside, I'd have a thin compressible gasket / profile, then the external bead pinned in place. I wouldn't expect a silicone seal to be applied, even retrospectively. 

One question though, aren't the windows inward opening if you have a Juliet balcony? I'm trying to figure out why you'd have fixed lights onto one thereby creating a maintenance issue.

Edit: the dg unit should be raised on plastic shims off the cill frame so it's not sitting on any water that does happen to get past the external beads.

 Hard to Comment without seeing the particular 

 No windows should not leak 

 Stone building ingress of water from somewhere else like I’ve damp courses in head above window 

 You have totally ruled out condensation 

 It’s a long time since I’ve set a double glazed unit into timber but non-setting glazing compound was the normal 

Some systems on here from a long-established glazing product manufacturer:

https://hodgsonsealants.com/technical/

hth

Have the installers issued you a Fensa certificate for this work? Not anything I know much about but hard to see how the installation meets regulations. 

I'm not a glazier / joiner / architect, but I can tell a bodge when I hear it...

Putting silicone round something that's already leaking isn't going to fix it in the long term.  I think they're going to need to remove and refit. 

For what it's worth I've been fitting and glazing since 1991. I've not fitted too many timber windows but we used to get our frames from a company that sprayed them in booths with a very specific method of fitting. The method was a roll of butyl tape, noted quite rightly by another poster above.

No silicone was to be used on a timber frame as it's a similar issue that cement mortar does to stone as opposed to brick, it doesn't work. Either your frame is leaking between the stone and the edge of the frame or the glass isn't sealed properly.

Feel free to message me privately and I'll forward my contact details back to see if I can advise better as some questions I have might shed more light.

In reply to Thugitty Jugitty:

Fensa are useless and don't care about anything other than money.

Thanks all, some really helpful and detailed advice here. It's much appreciated!

Our main contractor totally agrees there's a problem and it's likely to be that the gasket/seal is just too thin for the slot, or otherwise poorly fitted within the frame. Hopefully they can remove the panes from the inside and replace the seals with something better. That's plan A anyway.

Ah, good question re the opening. The original juliet balcony door and surrounding glass was all totally knackered and unfixable (water ingress, rot, warping). We would never have chosen to have a door opening onto nothing but a grate - always seemed an odd idea to us - so since we had a blank slate we ditched the door idea and replaced the entire assembly with a new wooden frame with fixed panes, and just one outward-opening window in the middle.

Hi Dan, 

how the window sits in the frame, and what bedding system is used for the glazing does depend on the construction of the timber frames themselves. Do you happen to know if the frame is a fully bedded or vented construction?

realistically if they are revisiting to put a bead of silcone in it sounds to me like a ‘fully bedded’ glazing system that hasn’t been done correctly. Although this would be a serious omission to have no butyl tape/glazing tap as you say and also v unlikely. The glass would just fall out of the frame. Without photos it’s hard to tell but are you confident it’s the glazing against the timber causing the leak? A dry day, hard to come by recently! a garden hose and a mate may help confirm this. 

Ultimately if it is a fully bedded system that hasn’t been done correctly I’d be asking for a new window. Getting the glazing out without damaging it is hard and the likelihood of future leaks from the current bodge is high. Worse still if there is water in the glazing rebate on a fully bedded system it could freeze with obvious smashing consequences. 
 

Dan, without photos its hard to say for sure, but if your previous doors were rotten then maybe there is an inherent defect in the wall the doors / windows are set in?  Just replacing the doors / windows is unlikely to fix this.  Whats the construction of the wall they are set in - cavity brick, or timber frame with cladding?  Damp on the inside of the window frame could indicate poor detailing at roof level or a missing / improperly installed window lintel - both could cause water to track back inside the wall cavity and soak the window frame, giving the appearance of a leaky window.

Hi all, huge thanks again for all the thoughts and advice: UKC forums come up trumps with skilled and experienced folk.

A few photos here showing water ingress, some poorly fitting/loose seals, and an external shot looking down at the sill that shows the new silicone bead that's been added to the bottom of the external pane.

It's a timber frame, timber-clad house.

The original leak was in a similar bottom-of-frame location. The original windows on the house are timber with alu cladding. This is a particular weather-exposed part of the building, and it appears the seal around the cladding had failed at this point and water ingress had been ongoing for years - parts of the old frame underneath the cladding were waterlogged and rotten, and over time this seems to have resulted in the adjoining door warping and that sort of thing. When the old stuff was all removed, the fabric of the house itself seemed fine - so I'm pretty certain it's not a leak coming from elsewhere in the structure.

The new windows were delivered as raw wood: I painted the external face myself before they were fitted - several coats of a decent external wood paint, took a good couple of days at the pace I go. Would have preferred they'd been spray-painted in the workshop but that wasn't on offer. (inside is yet to be finished with varnish - it started leaking before I got onto that job).

At the time I painted them, I did query the apparent lack of beefy rubber gaskets as we have on all the other windows. On the outside in particular I can't see evidence of tape/seal. Inside there clearly is a thin strip of something, but as is evident from the pics it's not formed a tight seal all the way around all of the new panes. And there are a couple of small breaks in it.

I'm not best pleased that we have issues with the replacement, but at least the overall house renovation is not yet quite finished or indeed fully paid for, so we're still at the snagging stage. 

The current thinking is that it may be possible to remove the panes from the inside to redo the seal/gaskets. I note advice in this thread that this may not be the best plan. Removing and rebuilding the entire assembly would be a major job with scaffolding in an awkward location, besides the time and expense, so I can see why it's not been mooted in the first instance. But this is something I'll discuss with the joiners who made them and our main contractor.

Thanks again, all  

Looks like glass out and refit - properly 

Did you apply any wood preservative before painting 

if as it appears the leek is on the central pane at  the bottom it should  rule out damp  and roof  Ingres

However it points at condensation yes unlikely on triple 

and finally who ever was involved in the silicon can we get them out of building and construction maybe a new job directing fly’s on the muck heap

That silicone 🤦What's that meant to do?? That's just going to fill up from the top. Whoever came up with that idea is not someone you want near your house.

PS 

The outside photo   Has the beading that holds the glass in the frame got a slope away form the glass. It should have, a must .  

^ This. If the beading is a dry glaze, drainage system, I'd expect a wider, angled beading at the bottom with 2 drainage holes to allow the water to escape and the damp to breathe away from inside the glazing rebate. Other method is a traditional, sealed beading which can cause units to fail quicker and mist up.

I noticed the inside tape sticking the glass to the frame is a foam tape that we used to use for externally glazed PVC windows back in the 90's, I'd still say that should be a butyl tape.

I'd be interested to know what glass you have on those triple glazed units. They look like proper spec 44mm units with the correct 16mm spacers but I would have expected a warm edge bar and a coating like Planitherm to get the best thermal advantages. I noticed the labels are still on the glass, I'd be curious to know what info they have on them other than the sizes. Hard to tell from those photos but they don't look like they have a tint to them which I'd expect if it was coated.

Lot of jargon there.

Blimey, that's a lot to take on board - thanks a lot for taking the time! Looks like plenty for us to raise with the builders here.

No, it doesn't. One more thing to add to our list! Thanks 

Wood preservative? No I didn't dammit! Three coats of paint...

Yeah, leak is on the bottom edge, definitely seems window-related. 

Not noticed any condensation since they've been fitted: this may be because they're not properly air tight I suppose...?

The silicone is a bodge isn't it! 

OK, your glass does have a coating on it as the label says, it's a soft coat which is a bit cheaper than the Planitherm but still works.

the 4/8/4/8/4 bit means,

4mm outer glass / 8mm air gap / 4mm middle glass / you get the idea. This gives an overall triple unit glazed thickness of 28mm. To get the best performance thermally you would need a 16mm air gap as less than that causes temp transfer due to the glass being too close together, air = heat, think down insulation. 44mm unit is as good as it gets but that would require a wider glazing rebate.

TLDR: They just gone a bit cheap with the glass, not a deal breaker and they will be able to fix the issue by reglazing it. Good luck.

Another thing to check with your main contractor is that the glazing and its frames (which are effectively acting as a barrier) comply with section 4.4.2 of the Scotland Government 2023 Domestic Technical Handbook:

"A protective barrier, and any wall, partition or fixed glazing accepted instead of a barrier should be secure, capable of resisting loads calculated in accordance with BS EN 1991-1- 1 and the associated PD 6688-1-1"

And also that the glazing complies with section 4.8.2:

"Glazing should be designed to resist human impact as set out in BS 6262-4: 2019, where all, or part, of a pane is: within 800 mm of floor level"

Good point. The OP said the glazing is on the 2nd floor so one of those layers of glazing should really be laminated, not just 'toughened'. At 4mm, it's not so if a person were to fall or be pushed against it and the glass breaks (into small pieces, as it's supposed to) they could just fall through the opening. Laminated glass would prevent this, as would a proper, physical barrier such as a rail. 

3 layers of toughened glass? Not a chance could a person fall through that and neither could a flying dining table. The fitters have covered that fine.

Safety - not something I'd considered. The old door arrangement had a metal rail outside but now we just have the frame and glass. I've got no concerns that anyone could fall through, it's very solid. But it does need to comply with the regs in case we ever want to sell the house. Will need to check that's been factored in.

I'm coming at this all a bit backwards. Should have established the spec etc beforehand. Think it's very clear I know nothing. 

Looks like they used PVC foam for sealing, (or at least it should be PVC). That's fine and it's the gold standard nowadays in new builds as it's superior to butyl tape and friday-afternoon-bodge-proof. (Usual mistake when rushing applying butyl taoe is to stretch it so it ends up too thin and won't seal).

There is only 1 thing to keep in mind when using PVC tape and which can go wrong, and that is that it has to compress a minimum of 30% for it to form a dependable seal.

In the photos it looks like it's not being compressed anything close to that, so likely causes are :

- Glass too thin for the frame (maybe ordered/delivered a glass that is not what it was specced to be. Did you check what you were quoted glass-wise against what was actually fitted)

- Frame too wide for the glass. (Made/measured wrong?)

- Foam tape too thin for the application, They are somewhat standard thickness and that gap already looks pretty wide, so this wasn't the original mistake, but could be a solution. However that gap will hold water in and rot the frames from the inner beading out unless fitted with some drainage or water control shizzle

P.S. As a temporary bodge, and assuming they used plastic packers to seat the glass, you can gently push the glass and making your way around it shove packers between frame and unit along the edges to push it forward and get good compression on the outside seal.

You'd probably get better performance with a decent quality double glazed window.

Regarding the leak, I'd get an independent, hopefully trustworthy installer to have a look because without looking inside we can't see what's going on. Good quality manufacturers give set installation instructions for their windows which can help ensure a decent installation as the warranty only kicks in if they're installed properly.

You'd probably be quite surprised how often glass fails. I've seen it happen several times - on almost new buildings - and with zero warning. Different spec. from what yours appears to be but I've also read some very detailed analytical reports and also been to large, international glass manufacturers' factories in the UK and abroad and seen the processes and tests. It's quite eye-opening what can happen unexpectedly.

It's very unlikely yours would ever fail but personally, I seriously doubt it's compliant with current regs. Good luck.

Edit: just remembered your opening light opens outwards. That right there isn't compliant on a 2nd floor window, sorry!