I am thing of dry lining a north facing bedroom in a flat which is
suffering from condensation. Can you get vapour barrier polystrene
backed plaster board which I could just grip fill to the wall or do I
need a breathable air gap, or does the polystrene act as a vapour
barrier on its own.
Thanks

Steve Jones

"Stephen Jones" wrote in message
om...
I am thing of dry lining a north facing bedroom in a flat which is
suffering from condensation. Can you get vapour barrier polystrene
backed plaster board

Almost - you can get vapour barrier Kingspan backed plasterboard which is
twice as good.


which I could just grip fill to the wall or do I
need a breathable air gap, or does the polystrene act as a vapour
barrier on its own.

Although the vapour barrier stops condensation from the occupants, there may
still be some moisture ingress from outside (lots if you've got an old
house) and so a small air gap and an airbrick near the floor will keep
everything dry.

"Mike" wrote in message ...
"Stephen Jones" wrote in message
om...
I am thing of dry lining a north facing bedroom in a flat which is
suffering from condensation. Can you get vapour barrier polystrene
backed plaster board

Almost - you can get vapour barrier Kingspan backed plasterboard which is
twice as good.


which I could just grip fill to the wall or do I
need a breathable air gap, or does the polystrene act as a vapour
barrier on its own.

Although the vapour barrier stops condensation from the occupants, there may
still be some moisture ingress from outside (lots if you've got an old
house) and so a small air gap and an airbrick near the floor will keep
everything dry.

So the air brick is behind the plaster board and vents the area behind
the plaster board, doesn't go directly into the room? Do you require
holes in the plaster boad to allow the free flow of air, if so does
this not let condensation behind it. I was thinking of plasterboarding
down to skirting board. Would gripfill allow enough of a air gap
behind the plaster board ?

Thanks

"Stephen Jones" wrote in message
om...
I am thing of dry lining a north facing bedroom in a flat which is
suffering from condensation. Can you get vapour barrier polystrene
backed plaster board

Almost - you can get vapour barrier Kingspan backed plasterboard which
is
twice as good.

which I could just grip fill to the wall or do I
need a breathable air gap, or does the polystrene act as a vapour
barrier on its own.

Although the vapour barrier stops condensation from the occupants, there
may
still be some moisture ingress from outside (lots if you've got an old
house) and so a small air gap and an airbrick near the floor will keep
everything dry.

So the air brick is behind the plaster board and vents the area behind
the plaster board, doesn't go directly into the room?

Yes. It's purely to remove moisture from the enclosed area. With no
ventilation at all this area would gradually become damp and cause decay to
any wooded joists above and below and possibly to the bricks.


Do you require holes in the plaster boad to allow the free flow of air, if
so does
this not let condensation behind it.

That's a different issue - the room needs ventilation to normal building
regs practices but whether that is done through the plasterboard or windows
is up to you. But I wouldn't allow any air from the room to reach behind
the plasterboard.


I was thinking of plasterboarding
down to skirting board. Would gripfill allow enough of a air gap
behind the plaster board ?
Plaster adhesive is much cheaper - £6/25kg

Thanks

On 24 Feb 2005 03:48:59 -0800, (Stephen Jones)
wrote:



So the air brick is behind the plaster board and vents the area behind
the plaster board, doesn't go directly into the room? Do you require
holes in the plaster boad to allow the free flow of air, if so does
this not let condensation behind it. I was thinking of plasterboarding
down to skirting board. Would gripfill allow enough of a air gap
behind the plaster board ?

Unless you have vissably damp walls I wouldnt waste any time on that,
just attach the boards with plasterboard adhesive applied to the walls
then after your join filler has dried paint drywall sealer as the
vapour barrier. Thats what I did. I dont think the insulated boards
are vapour sealed unless the maufacturer specificaly states it. Also
drywall sealer gives a much nicer finish especialy on the joins than
applying paint straight to the boards.

Bas

On Thu, 24 Feb 2005 19:44:12 -0000, "Mike" wrote:

Yes. It's purely to remove moisture from the enclosed area. With no
ventilation at all this area would gradually become damp and cause decay to
any wooded joists above and below and possibly to the bricks.


Small amounts of moisture will safely pass through the maisonary and
evaporate to the outside as its no doubt currently doing on the
uninsulated walls. The only probelms I can see would be if there is
rising damp or if the outside is treated with something like a water
proof render in which case I wouldnt bother at all especialy if its a
cavity wall as there would be a risk of rusting the ties.

BaSiL

"basil" wrote in message
...
So the air brick is behind the plaster board and vents the area behind
the plaster board, doesn't go directly into the room? Do you require
holes in the plaster boad to allow the free flow of air, if so does
this not let condensation behind it. I was thinking of plasterboarding
down to skirting board. Would gripfill allow enough of a air gap
behind the plaster board ?

Unless you have vissably damp walls I wouldnt waste any time on that,
just attach the boards with plasterboard adhesive applied to the walls
then after your join filler has dried paint drywall sealer as the
vapour barrier. Thats what I did. I dont think the insulated boards
are vapour sealed unless the maufacturer specificaly states it.

Have you checked behind them ? I would bet that the damp is building up
quite nicely in a puddle on the floor as that is exactly what I found when I
removed poorly installed lining in my property.

"basil" wrote in message
...
On Thu, 24 Feb 2005 19:44:12 -0000, "Mike" wrote:

Yes. It's purely to remove moisture from the enclosed area. With no
ventilation at all this area would gradually become damp and cause decay
to
any wooded joists above and below and possibly to the bricks.


Small amounts of moisture will safely pass through the maisonary and
evaporate to the outside as its no doubt currently doing on the
uninsulated walls.

You can probably rely on this on south facing walls in protected areas but
for a north facing wall exposed to heavy rain the overall averaged effect
over the year will be water ingress, not egress.

On Fri, 25 Feb 2005 09:16:23 -0000, "Mike" wrote:



You can probably rely on this on south facing walls in protected areas but
for a north facing wall exposed to heavy rain the overall averaged effect
over the year will be water ingress, not egress.


Is this just a theory of yours or can you point us to some resources
to back it up?

I see a brick wall after heavy rain and it looks soaked, then a few
hours latter it looks dry and not from evaporation to the inside. If
the phenomonem you describe is correct wouldnt you see wall paper
peeling off north facing externanal walls and salts appearing on
crumbling plaster? and conversly that not happening on south facing
walls? I havnt heard of that.

On Fri, 25 Feb 2005 09:14:56 -0000, "Mike" wrote:



Have you checked behind them ? I would bet that the damp is building up
quite nicely in a puddle on the floor as that is exactly what I found when I
removed poorly installed lining in my property.



Quick check on my "poorly installed lining", no its dry as a bone!

The puddles you have seen sound exactly like you get with
condensatiion. The vapour hits the dew point in within the insulation,
condenses out and drips to the floor.

I used to get condensation on the North wall in the room I lined. But
now obvously not now. So the wall is dryer for being lined.

"basil" wrote in message
...
On Fri, 25 Feb 2005 09:16:23 -0000, "Mike" wrote:



You can probably rely on this on south facing walls in protected areas but
for a north facing wall exposed to heavy rain the overall averaged effect
over the year will be water ingress, not egress.


Is this just a theory of yours or can you point us to some resources
to back it up?

I see a brick wall after heavy rain and it looks soaked, then a few
hours latter it looks dry and not from evaporation to the inside. If
the phenomonem you describe is correct wouldnt you see wall paper
peeling off north facing externanal walls and salts appearing on
crumbling plaster? and conversly that not happening on south facing
walls? I havnt heard of that.
Sun and rain destroy pretty much anything over the years and, because our
prevailing weather comes from south west, walls facing that way cop it far
more than north or east facing.

Stuart Noble wrote:

"basil" wrote in message
...

On Fri, 25 Feb 2005 09:16:23 -0000, "Mike" wrote:



You can probably rely on this on south facing walls in protected areas but
for a north facing wall exposed to heavy rain the overall averaged effect
over the year will be water ingress, not egress.


Is this just a theory of yours or can you point us to some resources
to back it up?

I see a brick wall after heavy rain and it looks soaked, then a few
hours latter it looks dry and not from evaporation to the inside. If
the phenomonem you describe is correct wouldnt you see wall paper
peeling off north facing externanal walls and salts appearing on
crumbling plaster? and conversly that not happening on south facing
walls? I havnt heard of that.

Sun and rain destroy pretty much anything over the years and, because our
prevailing weather comes from south west, walls facing that way cop it far
more than north or east facing.


In my case, not so. I think my problem is wet walls freezing - on the
north west side of the house in deep shade. This messes up the render
and paint surface. Must put some sealer in those patches next summer and
repaint..

In my case, not so. I think my problem is wet walls freezing - on the
north west side of the house in deep shade. This messes up the render and
paint surface. Must put some sealer in those patches next summer and
repaint..
The pliolite products made by Johnstones and others are a *huge* improvement
over water based masonry paint. I can't say for sure that it's totally cured
my penetrating damp, but the signs are good. Can be applied in damp and cold
conditions too, so no need to wait for summer :-)

The walls are solid walls. I have noticed that in the bathroom the
radiator is under the window and no damp. In all the other problem
rooms radiators are on internal walls. Do you think it would help if
the radiators where moved under the windows. Also if I add some room
vents what height above floor should they be?

Thanks

The walls are solid walls. I have noticed that in the bathroom the
radiator is under the window and no damp. In all the other problem
rooms radiators are on internal walls. Do you think it would help if
the radiators where moved under the windows. Also if I add some room
vents what height above floor should they be?

Thanks
Post a follow-up

Unless you have vissably damp walls I wouldnt waste any time on that,
just attach the boards with plasterboard adhesive applied to the walls
then after your join filler has dried paint drywall sealer as the
vapour barrier. Thats what I did. I dont think the insulated boards
are vapour sealed unless the maufacturer specificaly states it. Also
drywall sealer gives a much nicer finish especialy on the joins than
applying paint straight to the boards.

Bas

Did you use standard plaster board or was it insulated, if insulated
what thicknes and what was its trade name etc

Thanks for the advice

Steve

On 28 Feb 2005 09:28:55 -0800, (Stephen Jones)
wrote:



Did you use standard plaster board or was it insulated, if insulated
what thicknes and what was its trade name etc

I used
http://www.knaufdrywall.co.uk/theman...?category_id=2

As much for sound insulation as anything. As there are better and
cheaper laminate boards for thermal insulation I wouldnt recomend it
unless you need sound insulation.

This looks good:

http://www.insulation.kingspan.com/n...dry_lining.htm
http://www.lafargeplasterboard.co.uk.../therm_res.htm

Without a vapour seal it will make your problems worse, and to make a
neat job around the window frames and skirting and any coving etc will
be demanding. If your ceilings are 2.4m hight ( quite likely for
you) the adhesive dabs method is more tricky.

I replied to your other thread too.

Basil

"Stephen Jones" wrote in message
om...
The walls are solid walls. I have noticed that in the bathroom the
radiator is under the window and no damp. In all the other problem
rooms radiators are on internal walls.

Is the bathroom upstairs and all the problem rooms downstairs ? More likely
but obviously I don't know your house.

Also if I add some room vents what height above floor should they be?

Million dollar question. I've had four sheets of Kingspan blocking a wall
in a corridor all winter to identify the dampest parts. But my problem is
probably a lot more harder to solve than yours (that part of house is 17xx).
A foot from the floor is usually adequate.