Insulating solid brick wall (internal)

[andy2626]

hi

i am currently insulating the walls in my house, my neighbor tells me he
done so in the following way

First putting a breathable membrane on the wall, then screwing battens at 600mm spacings then filling the gaps with 25mm polystyrene and screwing plasterboard to cover

I have done this in one room put have not yet skimmed

since starting i have looked into the methods and now i am unsure which way to go,

my first question is should i put the breathable membrane on first or after the insulation

is breathable membrane classed at a vapor barrier or am i using the wrong stuff.

and while we're on the subject of the walls what are your thoughts on blocking up vents, people say don't but its like having a windows open, not good in winter

i would be very gratefully for your time and any input

Thanks

 

[noseall]

You have not yet described the wall construction in your house.

Could you elaborate?

 

[andy2626]

the house is 1930s semi 9" double brick wall no cavity

does that help

 

[ajrobb]

You might want to read Refurbishing dwellings – a summary of best practice.

You'll get somewhat different advice from Heritage House.

The breathable membrane is NOT vapour proof. Consider duplex plasterboard (foil backed) to introduce a VPL at the warm surface.

Air vents are a solid walled house's main protection against condensation and are needed to keep the walls dry. Modern trickle vents do the same but to a lesser degree for sealed, insulated rooms. Mechanical heat recovery ventilation can be used to recover most of the heat lost through ventilation.

 

[stuart45]

The vapour barrier should go on the warm side of the insulation, not against the wall.

 

[ajrobb]

If you stripped the plaster from the bricks before putting up the breathable membrane, the membrane against the brick will help prevent cold drafts through the brickwork from forcing their way around the insulation. The polystyrene board might provide a degree of VPL, depending on how tightly it was fitted between the battens.

25mm of insulation is not much compared to modern building regulations but could still cut heat loss through the walls by some 70%.

I think 9" brick walls are traditionally called 'single brick' because that is the length of a brick. A 4" wall would be a half brick.

 

[stuart45]

This site might help.
http://www.feta.co.uk/rva/downloads/gpg155.pdf

 

[andy2626]

thanks everyone, some very useful links and info.

I just need to have a good think on the best form of ventilation, i like the thought of mechanical heat recovery im guessing thats sum kind of heat exchange, sounds expensive

Any more info on ventilation systems would be great thanks

 

[ajrobb]

Any more info on ventilation systems would be great thanks

Another thread has lately made good comments about the Nuair Drimaster system. There is no explicit heat recovery but it draws air from the loft, filters it and pumps it into the landing. The humidity controls can be completely automatic on the 2000. The DriMaster 2000 can also be used with the EcoHeatEx unit for heat recovery.

 

[andy2626]

thanks everyone for all your info