Breeze behind plasterboard
Discussion
Hello all,
We moved into a new house last year which has a single storey extension on one side built roughly twenty years ago (the house is thirty years old). The whole house including the extension is cavity wall construction and I'm pretty sure the cavity is not insulated.
I noticed during the winter that the extension was exceptionally cold and the plasterboard wall seemed very cold to the touch.
During the spring I cut a hole in the plasterboard to fit a pattress box and noticed a fairly significant breeze behind the plasterboard. I'm wondering if the outside air is somehow circumventing the cavity and getting inside the inner wall.
Before I get a roofer to take the roof off the extension to check the construction can anybody make any suggestions of why this might be the case please?
We moved into a new house last year which has a single storey extension on one side built roughly twenty years ago (the house is thirty years old). The whole house including the extension is cavity wall construction and I'm pretty sure the cavity is not insulated.
I noticed during the winter that the extension was exceptionally cold and the plasterboard wall seemed very cold to the touch.
During the spring I cut a hole in the plasterboard to fit a pattress box and noticed a fairly significant breeze behind the plasterboard. I'm wondering if the outside air is somehow circumventing the cavity and getting inside the inner wall.
Before I get a roofer to take the roof off the extension to check the construction can anybody make any suggestions of why this might be the case please?
battered said:
Yes. Air is blowing through the soffit vents and into the cavity. There is no or no adequate seal between the inner leaf and the ceiling so the cold air is blowing from the roof void to the space between the inner leaf and the plasterboard.
Id wager there are gaps in the perp joints letting the air throughHowever, 20 years old you would expect there to be some insulation in the cavity
V8RX7 said:
Can you get in the roof void ?
If not you could drill a series of small holes and use expanding foam to form a seal - ideal if you can hide them behind coving.
No, unfortunately there isn't a void really, the ceiling slopes internally as well as externally if you see what I mean. Another reason why I think it's cold as there can't be much insulation in the roof at all.If not you could drill a series of small holes and use expanding foam to form a seal - ideal if you can hide them behind coving.
Spudler said:
A Roofer or builder should be able to easily sort this.
As mentioned the cavity is open at the top and the soffit is probably vented.
Remove bottom couple rows of tiles and close of cavity with a cement board or similar. Use either a sealant or non expanding foam.
I could be way off here, but if it's been built with the expectation that air will circulate then is it a good idea to seal it up?As mentioned the cavity is open at the top and the soffit is probably vented.
Remove bottom couple rows of tiles and close of cavity with a cement board or similar. Use either a sealant or non expanding foam.
Our house, crap built late 60's job, is generally draughty but it's dry. Neighbour's retired builder father was horrified at the idea of putting cavity wall insulation in. Other people have laughed at that, but we've had it surveyed by 3 firms and none would do it.
We have a similar problem, our house 30 years old too. We had cavity wall insulation put in when we moved in 5 years ago but still get a breeze behind the plasterboard.
I've found the culprit to be gaps around the windows which breaches the cavity wall and insulation. Modern houses have a cavity closer in place here to stop breezes. I've managed to solve this by drilling a series of holes in the plasterboard about 1 inch back from the window and squirting expanding foam into the void (don't forget to do the same underneath the window sill).
This has stopped the breezes and has made a real difference in room temperature. You can also feel the difference in temperature of the plasterboard in a window that has been insulated and one that hasn't.
I've found the culprit to be gaps around the windows which breaches the cavity wall and insulation. Modern houses have a cavity closer in place here to stop breezes. I've managed to solve this by drilling a series of holes in the plasterboard about 1 inch back from the window and squirting expanding foam into the void (don't forget to do the same underneath the window sill).
This has stopped the breezes and has made a real difference in room temperature. You can also feel the difference in temperature of the plasterboard in a window that has been insulated and one that hasn't.
Sheepshanks said:
I could be way off here, but if it's been built with the expectation that air will circulate then is it a good idea to seal it up?
Our house, crap built late 60's job, is generally draughty but it's dry. Neighbour's retired builder father was horrified at the idea of putting cavity wall insulation in. Other people have laughed at that, but we've had it surveyed by 3 firms and none would do it.
Not way off, but sealing off the top of the cavity, as it should have been from new, won't affect air circulating from the soffits into the roof space, if done properly. One possible problem OP, is your house detached? If not, depending on how it's built, there could be a continuous cavity twixt you and your neighbor; sealing just the top of your cavity might not cure anything. Worth bearing in mind. Don't be scared of cavity insulation either.Our house, crap built late 60's job, is generally draughty but it's dry. Neighbour's retired builder father was horrified at the idea of putting cavity wall insulation in. Other people have laughed at that, but we've had it surveyed by 3 firms and none would do it.
House is detached so no worries there.
Once I have this problem sorted I'll be looking at cavity insulation, renewed loft insulation, sealing the roof from birds (currently nesting in the loft) and finding a way to block the conservatory off in the winter as it's currently totally open to the kitchen, maybe just a thick curtain.
House has some serious thermal problems that I want to sort before next winter. New thermostat is also on the cards.
Once I have this problem sorted I'll be looking at cavity insulation, renewed loft insulation, sealing the roof from birds (currently nesting in the loft) and finding a way to block the conservatory off in the winter as it's currently totally open to the kitchen, maybe just a thick curtain.
House has some serious thermal problems that I want to sort before next winter. New thermostat is also on the cards.
Well that didn't go according to plan.
The roofers came yesterday to sort it and appeared to have something completely different in mind to me. I was expecting them to take the bottom few rows of tiles off along with the batten and felt and then block off the gap at the top of the plasterboard between the plasterboard and the inner skin wall, putting new felt and battens back afterwards.
They were expecting to stuff rockwool in to the roof void underneath the felt effectively blocking off the vent under the soffit and preventing the air flow through the roof.
The guys who turned up to do the job (not the same guy who came and looked previously) suggested that what they were expecting to do was a bad idea as it could cause damp/mould. Sounds fair, but it wasn't what I actually wanted. They couldn't seem to get their heads around what I wanted them to do, even when they took a small section of the roof off and confirmed, as I had suspected, that the plasterboard to wall gap was open to the roof space at the top.
They were convinced (and may be correct) that this opening wouldn't be causing my problem provided that the air isn't getting in to the plasterboard-wall gap lower down and creating a chimney effect.
So now I'm really only left with the idea of getting cavity wall insulation and hoping that will block off any air flow in to the lower part of the plasterboard-wall gap and thus prevent the cold air circulating through.
Having done some reading on cavity wall insulation it seems to be a very thorny issue with people having strong feelings both for and against.
Sorry for the long post, any other suggestions on where I go from here?
They did confirm that the ceiling at least has kingspan so is mildly insulated.
The roofers came yesterday to sort it and appeared to have something completely different in mind to me. I was expecting them to take the bottom few rows of tiles off along with the batten and felt and then block off the gap at the top of the plasterboard between the plasterboard and the inner skin wall, putting new felt and battens back afterwards.
They were expecting to stuff rockwool in to the roof void underneath the felt effectively blocking off the vent under the soffit and preventing the air flow through the roof.
The guys who turned up to do the job (not the same guy who came and looked previously) suggested that what they were expecting to do was a bad idea as it could cause damp/mould. Sounds fair, but it wasn't what I actually wanted. They couldn't seem to get their heads around what I wanted them to do, even when they took a small section of the roof off and confirmed, as I had suspected, that the plasterboard to wall gap was open to the roof space at the top.
They were convinced (and may be correct) that this opening wouldn't be causing my problem provided that the air isn't getting in to the plasterboard-wall gap lower down and creating a chimney effect.
So now I'm really only left with the idea of getting cavity wall insulation and hoping that will block off any air flow in to the lower part of the plasterboard-wall gap and thus prevent the cold air circulating through.
Having done some reading on cavity wall insulation it seems to be a very thorny issue with people having strong feelings both for and against.
Sorry for the long post, any other suggestions on where I go from here?
They did confirm that the ceiling at least has kingspan so is mildly insulated.
skahigh said:
and confirmed, as I had suspected, that the plasterboard to wall gap was open to the roof space at the top.
They were convinced (and may be correct) that this opening wouldn't be causing my problem provided that the air isn't getting in to the plasterboard-wall gap lower down and creating a chimney effect
But air does get in lower down - typically behind kitchen units and at floor level.They were convinced (and may be correct) that this opening wouldn't be causing my problem provided that the air isn't getting in to the plasterboard-wall gap lower down and creating a chimney effect
You know those dirty marks you see on cream carpets around the edge of rooms...
If you google about modern house builds and air testing - dabbed walls are seen as a significant cause of poor performance, they are supposed to create a solid line of dab - but never do
V8RX7 said:
But air does get in lower down - typically behind kitchen units and at floor level.
You know those dirty marks you see on cream carpets around the edge of rooms...
If you google about modern house builds and air testing - dabbed walls are seen as a significant cause of poor performance, they are supposed to create a solid line of dab - but never do
Which suggests that to prevent significant heat loss straight up in the to the roof ventilation I really need to take the plasterboard off and put insulation in the spaces between the battens (it's not dot and dab). You know those dirty marks you see on cream carpets around the edge of rooms...
If you google about modern house builds and air testing - dabbed walls are seen as a significant cause of poor performance, they are supposed to create a solid line of dab - but never do
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