Lath and plaster cavity a significant cause of heat loss?

[BarumMike]

All of our internal walls are lath and plaster with the usual cavity behind. I had naïvely thought that this would contribute to keeping the heat in.  However having been up in the loft spaces I realise that the cavity behind the lath and plaster opens into these very cold voids.  I suppose there are streams of cold air from the roof voids circulating down into the lath and plaster cavities while air warmed by conduction across the lath and plaster escapes upwards into the roof voids.  So my practical question is, should I completely or partially close off the openings into the lath and plaster cavities in the roof spaces?  Assuming there is no obvious reason to worry about internal damp.

 

Does anyone have a view or know of research on this issue?  

 

 

[Tom]

Hi Mike - welcome to the forum.

Sounds like whatever you can do to reduce convection currents would help. Perhaps some rockwool pushed in from the top? This would still be vapour permeable which is always a good idea with old houses.

Tom

[ProDave]

Yes this is all pretty normal stuff.  This is the period property version of the "plasterboard tent".  As you rightly say cold air from the loft fills the void.

 

You should be aiming to fill the top of that gap to the loft all the way round, but it will usually be a miserable job and parts of it particularly in the eaves may be hard to reach.