Polystyrene insulated plasterboard



Members online

#1
Hi everyone I'm looking at using polystyrene to insulate an extension we have to turn it into a bedroom. It is currently a finished room but it is cold and suffers from black mold. It is built with brick and the light weight blocks and then plastered. I will be looking at using polystyrene that isn't stuck to the plasterboard as it's cheaper to buy them separately. The walls look pretty straight but how do I fix it all to the wall properly? Do I need to batten the walls and put the insulation against the wall between the battens? Do I batten and glue the polystyrene to the plasterboard and screw over the batten leaving a gap between the wall and the polystyrene? Do I dot and dab straight to the wall or screw straight to the wall or when I skim the joints will they crack? The plasterboard and polystyrene are both 2400 ×1200. Complete diyer here. Thanks in advance. Danny
 

Nicm

Well-Known Member
#4
Hi everyone I'm looking at using polystyrene to insulate an extension we have to turn it into a bedroom. It is currently a finished room but it is cold and suffers from black mold. It is built with brick and the light weight blocks and then plastered. I will be looking at using polystyrene that isn't stuck to the plasterboard as it's cheaper to buy them separately. The walls look pretty straight but how do I fix it all to the wall properly? Do I need to batten the walls and put the insulation against the wall between the battens? Do I batten and glue the polystyrene to the plasterboard and screw over the batten leaving a gap between the wall and the polystyrene? Do I dot and dab straight to the wall or screw straight to the wall or when I skim the joints will they crack? The plasterboard and polystyrene are both 2400 ×1200. Complete diyer here. Thanks in advance. Danny
Hire a local pro and pay him well for a good job.
 

Tinytom

Well-Known Member
#5
Hi everyone I'm looking at using polystyrene to insulate an extension we have to turn it into a bedroom. It is currently a finished room but it is cold and suffers from black mold. It is built with brick and the light weight blocks and then plastered. I will be looking at using polystyrene that isn't stuck to the plasterboard as it's cheaper to buy them separately. The walls look pretty straight but how do I fix it all to the wall properly? Do I need to batten the walls and put the insulation against the wall between the battens? Do I batten and glue the polystyrene to the plasterboard and screw over the batten leaving a gap between the wall and the polystyrene? Do I dot and dab straight to the wall or screw straight to the wall or when I skim the joints will they crack? The plasterboard and polystyrene are both 2400 ×1200. Complete diyer here. Thanks in advance. Danny
First off I’d find out the reason why your getting black mould.
How old is the extension? I’m guessing it’s not that old and it’s got a cavity, is the cavity clean, could be bridging across dirty wall ties causing the mould
Is there ventilation in there? If the builder has used cheapest windows possible there may be no trickle vents causing stale air.
Is it a flat roof? Is it leaking into the cavity or behind the dot and dab?
Has the lead fell out where the extension meets existing wall? (If it’s constructed that way)
Is there heating in there? If not look at either extending your central heating into that room or fit an electric radiator.
Post up some pictures of you want one of us to have a proper guess as to what it is, where abouts are you based? Someone may be able to quote you for required works
 
#6
Hi guys yes it's got a cavity but apparently it's not very wide. We had somebody come to look at ventilation and they said it didn't need it we just need to insulate it and fit a radiator. He suggested insulated plasterboard as the cheapest and easiest way to do it. It's only going mouldy due to lack of use as it's too cold in winter. Waiting on quotes for a proper radiator fitting. Just wondering if the polystyrene backed plasterboard will fit straight to the existing plasterwork or do I need to fit buttons. The battons I have are 38mm deep so would I be better using 25mm polystyrene or fit loft insulation between the battons and the plasterboard so there is no gap in there?
 

Arti

Private Member
#7
Mould is a condensation issue due to a lack of ventilation. Get someone in who knows his oinions before wasting a load of money on materials you might not need
 
#8
Had a ventilation company in we used for rest of house and they fitted an extractor in bathroom and supply vent at top of stairs. He said the existing vents would work in this room simply by cutting the door short at the bottom and fitting a radiator and insulating the room. There is no damp or anything just a bit of black mould due to not using or heating the room. The outside door will be getting removed and rebricked.
 

Topspread16

Well-Known Member
#9
Had a ventilation company in we used for rest of house and they fitted an extractor in bathroom and supply vent at top of stairs. He said the existing vents would work in this room simply by cutting the door short at the bottom and fitting a radiator and insulating the room. There is no damp or anything just a bit of black mould due to not using or heating the room. The outside door will be getting removed and rebricked.
Its not a room you dry clothes in is it?
 
#10
Its not a room you dry clothes in is it?
No the moisture will be coming in through the door which is coming out and getting bricked up. The walls are dry and pretty straight being plastered over the breeze block. Just wanting to know best way of insulating and olasterboarding over the existing plaster. Now thinking batten and put loft insulation in between the plaster and new plasterboard
 

raggles

Private Member
#11
I have stopped using epf insulation in walls and ceilings because they reduce the life span of the pvc coating\insulation around your electrical wires. Basically the ep f leeches polymers from the pvc making it brittle so, what seems like a cheap way to insulate can turn out to be very expensive in the long run. Save your pennies and buy non epf insulation
 
#12
I have stopped using epf insulation in walls and ceilings because they reduce the life span of the pvc coating\insulation around your electrical wires. Basically the ep f leeches polymers from the pvc making it brittle so, what seems like a cheap way to insulate can turn out to be very expensive in the long run. Save your pennies and buy non epf insulation
What's epf?