Is This Insulation Installed Correctly?

[Gareth790]

I’m looking for some help and advice. I live in a new build and we have a problem with condensation, mould and damp plasterboard around the bedroom windows in the winter. It doesn’t matter what we do inside the house or even if the windows are left slightly open. Once the temperature drops the issue is there.

There wasn’t any filler in the gaps between the window frames so I’ve filled and resealed those but the problem persists. I was told it could be inadequate insulation so I’ve put an inspection camera through the plaster board. I’ll upload the pictures. They essentially show the plasterboard then a cavity, a foil membrane then what is going on behind that between the studs. To my admittedly untrained eye there doesn’t seem to be enough insulation to be effective and I assumed that there wouldn’t be a cavity between the plasterboard and the membrane.

Could this be causing the issue? Any help and advice from people in the know would be greatly appreciated.

 

[freddiemercurystwin]

Those photos are useless, are the neighbours houses the same?

 

[Gareth790]

Those photos are useless, are the neighbours houses the same?

It varies. Some neighbours have the same problem with excessive condensation and mould around the windows, some also have mould up in the corners of the external walls in the bedrooms and some don’t have either of these issues.

 

[catlad]

Some pictures of the windows would be useful.

 

[Gareth790]

Some pictures of the windows would be useful.

When the temperature drops enough the condensation covers that full bottom window pane and has been as high as half way up the vertical pane.

 

[blup]

Pics arent bad for an inspection camera, always difficult to get the perspective right. Maybe you could fill the full cavity with insulation but protect the inner wall/window edge from moisture ingress by foam and dpc bent back between window and reveal.

 

[RandomGrinch]

I’m looking for some help and advice. I live in a new build

How new is this "new build"?

Some neighbours have the same problem with excessive condensation and mould around the windows,

if multiple neighbours have similar issues, this may be something you can go back to the developers, or NHBC with, as a group, for increased leverage?

 

[Gareth790]

Pics arent bad for an inspection camera, always difficult to get the perspective right. Maybe you could fill the full cavity with insulation but protect the inner wall/window edge from moisture ingress by foam and dpc bent back between window and reveal.

So taking the plaster board off and going from there? Do you know why there’s a cavity between the plaster board and the membrane/insulation?

 

[Gareth790]

How new is this "new build"?

if multiple neighbours have similar issues, this may be something you can go back to the developers, or NHBC with, as a group, for increased leverage?

Around 8-9 years. We had loads of problems with the company that built them. They eventually signed the house off themselves without addressing a good number of the issues we’d raised and said we’d told them to. The work that they did do around snagging issues wasn’t up to the standards of a first time DIYer. Because these issues were raised within the two year period the NHBC we likely bump us back to the builders as it’s on them to rectify and they’re an absolute nightmare to deal with. A good portion of my neighbours felt intimidated by them so they wouldn’t want to get back into it.

 

[blup]

So taking the plaster board off and going from there? Do you know why there’s a cavity between the plaster board and the membrane/insulation?

No, my guess is it is specced where a cavity closer is used, the absence of which is maybe a cause of moisture getting through.

 

[robinbanks]

Do you know why there’s a cavity between the plaster board and the membrane/insulation?

Two reasons; it forms a service void in which to run pipes and wires, and the foil face of the insulation improves its effectiveness by reflecting radiant heat, but it cannot do that when in thermal contact with another material; it needs an air gap

As to your problem - absent any leaks, your lifestyle generates too much moisture for the house to cope with. Solving it may be a mix of approaches but chiefly comes down to

* don't put as much moisture into the air (don't dry washing inside the house, only outside or in a tumble drier that condenses or vents properly, don't shower for long periods with the bathroom door open and no extract, don't boil pans of water excessively without using extract to world, don't use bottle gas fires, these are examples, not an exhaustive list)
* ensure the house air is ventilated effectively - installing an MVHR system is the gold standard for that, most other approaches are a compromise that loses large amounts of your paid-for heat to the world
* keep your house at a temperature where the surfaces are above the 14 degrees C at which condensation is likely to form on them. Insulation plays a big part in this, of course, but you may also find places where poor finishing detail (holes in the insulation layer) is letting cold world air into the service void behind the plasterboard, so the effectiveness of the insulation is diminished and the plasterboard becomes a cold surface that effectively dehumidifies your house as moist air condenses on it. Honestly, the house bashers that throw up most modern new builds do not give a crap about careful detailing to ensure the insulation is well installed, continuous in nature and has gaps properly sealed. If it's a choice between doing it quick and making mistakes that are easy to hide from the inspector and doing it properly , there is more profit in the former

 

[RandomGrinch]

Insulation plays a big part in this, of course, but you may also find places where poor finishing detail (holes in the insulation layer) is letting cold world air into the service void behind the plasterboard, so the effectiveness of the insulation is diminished

Just to add, an IR camera may help to find these sorts of issues.
Some local authorities and energy suppliers have schemes to lend them out.

 

[Gareth790]

Two reasons; it forms a service void in which to run pipes and wires, and the foil face of the insulation improves its effectiveness by reflecting radiant heat, but it cannot do that when in thermal contact with another material; it needs an air gap

As to your problem - absent any leaks, your lifestyle generates too much moisture for the house to cope with. Solving it may be a mix of approaches but chiefly comes down to

* don't put as much moisture into the air (don't dry washing inside the house, only outside or in a tumble drier that condenses or vents properly, don't shower for long periods with the bathroom door open and no extract, don't boil pans of water excessively without using extract to world, don't use bottle gas fires, these are examples, not an exhaustive list)
* ensure the house air is ventilated effectively - installing an MVHR system is the gold standard for that, most other approaches are a compromise that loses large amounts of your paid-for heat to the world
* keep your house at a temperature where the surfaces are above the 14 degrees C at which condensation is likely to form on them. Insulation plays a big part in this, of course, but you may also find places where poor finishing detail (holes in the insulation layer) is letting cold world air into the service void behind the plasterboard, so the effectiveness of the insulation is diminished and the plasterboard becomes a cold surface that effectively dehumidifies your house as moist air condenses on it. Honestly, the house bashers that throw up most modern new builds do not give a crap about careful detailing to ensure the insulation is well installed, continuous in nature and has gaps properly sealed. If it's a choice between doing it quick and making mistakes that are easy to hide from the inspector and doing it properly , there is more profit in the former

Cheers for this. I’m already doing all of your first points so I’ll see if keeping the rooms from dropping below 14degrees helps and hope it doesn’t dent the wallet too much. I suspect from what you’ve explained that there’s a continuous cold airflow in the service void. When I’ve painted the bedrooms the placement of the battens behind the plasterboard becomes visible as those sections dry at a much slower rate. I had assumed that it was the studs that I could see and they were possibly sodden from being open to the elements before they put the roof on.

 

[robinbanks]

Note that it's not the centre of the room that needs to be maintained at 14+.. if you're getting draughts that cool the plasterboard you can end up with cold surfaces in a warm room, the warm room air has lots of moisture in, the cool surface condenses it..

The IR camera is a good call. I bought one years ago that clips on the back of an iPhone but they're also something you can hire .. eBay for a flir one.. it'll likely sell for what you pay for it when you're done