uPVC double glazing issues

[AnthonyL]

A few issues that I hope to have sorted before the winter so advice and suggestions welcomed:

1) Kitchen window has internal condensation (ie inside the sealed unit) as well as doesn't shut tightly meaning outside sounds come in - SWMBO has run gaffa tape around the edges.

This same window was an issue when we first moved here in 2015 and on my sister's recommendation the glazing was replaced, supposedly with Pilkington K, Argon filled and anti-rattle inserts and the fitting adjusted accordingly. I don't understand how it could have gone wrong again if done properly and what to look out for if I get it done again.

2) The main bedroom window gets very misted over on the inside (room side) when there is cold weather, or even this morning as it was a bit cool.

The problem has worsened since I've been supplied with a CPAP + humidifer.

Is it practical to retrofit trickle vents? They would need to have good sound control as the birds can be quite noisy.

I'm not sure I'm up to doing this stuff myself but need to know what to ask and what to check.

[Theo]

You can buy the sealed units yourself and DIY:

and others. It doesn't look super complicated if access isn't awkward (either the beads are on the inside, or on the outside of a ground floor window). You need the gasket and a few packers to get the window level, especially on opening windows, but that seems to be it really.

Not sure what might have happened to the old one. Not shutting can just be due to uPVC thermal expansion (especially in hot weather, direct sunlight).

You can, if there is sufficient space in the frame (eg if they were originally an option). Look for 'acoustic' vents which have better soundproofing.

Theo

[Tricky Dicky]

Installing trickle vents is easy if you can do it in openers as these can be removed. The usual thing is to router out a number of slots on both sides but if you do not have a router then chain drilling a number of holes will probably achieve the same.

I bought these from this seller recently to repair a damaged one.

Richard

[RJH]

In my case I think the wrong packers were used, failing to support the unit properly and eventually breaking the seal. The fact it was top hinge opening won't have helped.

Also, I gather blocked drainage points can cause water to sit in the frame, eventually rotting the seal.

Can't see how, very odd.

That really isn't going to work in any event. Best deal with the cause of condensation.

[Tim+]

Um, CPAP + humidifier. I’m gonna assume that the OP needs these. A dehumidifier might be the answer.

Tim

[RJH]

Oh, sorry OP, yes, misread your post. Agreed, a dehumidifier may well help out.

[AnthonyL]

The CPAP needs added humidity as I'm a mouth breather and my throat is like a rasp in the morning without a bit of added moisture.

The windows suffered condensation before the CPAP but obviously worse since. It is the rear large bedroom window of a bungalow which has extensions either side to the rear and then a 40' rise to the top of a well treed back garden. I suspect that cool morning air gets trapped as it cannot get around the sides of the bungalow. Opening the windows a little works, but the birds in the trees are noisy. No other part of the bungalow has this issue and I can't think that it can be anything other than warm breath on the inside. It's not every morning and that may be dependent not just on temperature but the direction of any breeze/wind.

[AnthonyL]

It's just a side opening window, approx 1100mm (h) x 600mm (w). Fortunately the beads are on the inside as it is the south, front garden/street facing window of a bungalow, though there is a bit of tree shade. Not sure that given the problems that I'm up for a d-i-y and maybe a bit of extra expertise is warranted.

[AnthonyL]

Side hinge on an 1100mm (h) x 600mm (w) window. I have no idea about packers such is my ignorance.

Good point thanks, another item to check out.

[Theo]

The condensation is because the humid air is hitting the cold inside surface. Ventilation isn't really going to help if you intentionally have a (hygrostatic) humidifier running - if the humidifier is targeting say 60% humidity, ventilation will let some of it escape but if the RH were to fall to say 50%, the humidifier will kick in to bring it back to 60%. If there is a way to turn off the humidifier early (eg in the middle of the night) it would prevent it fighting with ventilation. You could also try turning down the humidification - maybe you can cope with a lower RH?

Cooling the room would help a bit, since you would get to the target RH by adding less water to the air. So you could try turning down any heating.

It could be worse investigating improving the U-value of the glass, eg going to triple glazing. You may be able to do that by replacing the sealed unit and keeping the frame (depends whether you can get a sealed unit of the same thickness). With a better U-value the inside glass would be warmer, causing less condensation to form.

If the condensation is on the frame not the glass, it may be the frame is actually the cold bridge and would ideally need replacing.

Theo

[Tim+]

I doubt very much if it’s any sort of hygrostatic humidifier as it’s only humidifying the inhaled air, not the whole room. Could be a simple Venturi effect humidifier or an ultrasonic one.

A dehumidifier in the room won’t change the output of the humidifier to any great degree.

Tim

[Brian Gaff]

The usual issue with windows that keep on failing in my experience is a twist in the installation. I have also noticed that Upvc seems not to like to be in windows in sun traps, where it warps and does not close very easily. I guess it depends on the design. I get condensation on some windows, but I also remember the old single glazed windows and the problems they had. My windows have no vents either, as they are older than that. I'm not convinced that these actually do that much myself. If something is colder it will always be where the moisture condenses. Brian

[AnthonyL]

Indeed, it's just a small container of water over which the air passes on its way to me.

But of course it now adds another 300mL of water vapour to the closed bedroom during the course of the night.

[Animal]

Misting within can be solved by drilling a tiny hole in the outer pane at the bottom & covering it with something porous to keep out insects. Fine mesh, epoxy & sand or twinwall closure tape are candidates.

RH is far too high then. As you can't omit the humidifier, ventilate or dehumiliate.

[AnthonyL]

Bit the bullet yesterday and took the double glaze unit out. First observation, contrary to what I had said earlier the beading is on the outside, not good on a front facing bungalow window. Double checked all around the property and the problematic bedroom window is also externally beaded, as it one other window at the back but that is within a brick/uPVC porch with beading on the inside.

A blue packer fell out during the process, but it looks as if there are two packers in a "L" configuration at the bottom left and a mirror on the top right.

There are drainage holes in the top and underneath of the bottom rail

- but - although they are clear when I poured water onto the bottom rail it just sat there. Presumably not a good sign and a bit inexplicable.

The sealed unit has moisture inside and discolouration on the base. It seems wrapped all around the circumference with some sort of tape which seems in good condition.

I've sort of put it all back together but not well. I feel now that the whole window and not just the opening part ought be replaced by someone competent and aware of the exposure to the south facing sun.

Don't know whether to play a bit dumb (not hard :) ) and get someone out and see what they say or be very direct and tell them the issues I know. I'm disappointed that the guy that replaced the sealed unit 5 years ago did not mention the security risk of external beading.

[Andrew]

Externally beaded uPVC windows can use double sided security tape to fix the glazing into the frame, but it depends on the frame design.

If it is a side-hinged casement then the glass is the bracing for the frame, just like a timber door or gate would have one or more diagonal struts acting in *compression*, so the glass unit should have two packers at the bottom to carry the weight, then one at the top and two at the side, top and bottom such that the diagonal of the glass is in compression and stop the frame sagging. This requires the non hinge side of the frame to be gently levered up to get the packers to fit snuggly top and opposite bottom.

[Andrew]

Oh and there are YouTube videos showing how to take a DG unit apart and remake it with fresh dessicant and sealant.

[AnthonyL]

Interesting, and I'll be interested to see what the specialists say when I get them out.

Yes it is a side hinges casement and I'm still confused as to how there is no apparent drainage.

So that's two installers who have skimped or are ignorant - the original fitters before I bought the house and the one that "fixed" the problem 5 years ago.

It's supposed to be Argon filled.

Thanks very much for your input - I feel that the project is beyond my skill set even if I am now more educated.