The loft in our old farm house has been converted at some point by a previous owner, however its absolutely freezing up there in winter and so we need to do something about it.
I've done some investigation and found that when then did the renovations previously they seem to have used ~25mm polystyrene sheets behind the plasterboard and that's it!. Also they haven't ensured an airtight seal around where the insulation/plasterboard meet the purlins/beams so we get draughts everywhere. Especially as there's a soil stack which runs internally (boxed in) from the loft eaves space and so the cold outside air uses that as a chimney and actually travels down through all the floors and come out in gaps in the ceilings below. (exposed beam ceilings with plasterboard in between)
I think realistically the only course of action it to rip it all out and do it again from scratch.
Because its an old farmhouse the rafters are not like modern 6x2 or 8x2 instead they are only around 70mm in depth and the roof is tiled with pantiles and has a bitumen membrane underneath it. Therefore i think my only real option is to put 25mm celotex sheets between the rafters which would maintain a ~50mm air gap between the membrane and the celotex and then i can over insulate on top of the rafters with thicker celotex sheets a further 50mm/75mm. The reason for not putting another 100mm on top is that the attic has exposed beams/purlins so if the insulation is too thick we would loose a lot of these features. So i think its going to be a slight compromise between the level of insulation achieved whilst still retaining some of the aesthetics. However i believe as long as we ensure air tightness with the insulation and eliminate the external draughts i think that is going to make the world of difference.
I would welcome those with experiences thoughts as to whether there's anything I've obviously missed or misunderstood before we embark on this.
Thanks
I've done some investigation and found that when then did the renovations previously they seem to have used ~25mm polystyrene sheets behind the plasterboard and that's it!. Also they haven't ensured an airtight seal around where the insulation/plasterboard meet the purlins/beams so we get draughts everywhere. Especially as there's a soil stack which runs internally (boxed in) from the loft eaves space and so the cold outside air uses that as a chimney and actually travels down through all the floors and come out in gaps in the ceilings below. (exposed beam ceilings with plasterboard in between)
I think realistically the only course of action it to rip it all out and do it again from scratch.
Because its an old farmhouse the rafters are not like modern 6x2 or 8x2 instead they are only around 70mm in depth and the roof is tiled with pantiles and has a bitumen membrane underneath it. Therefore i think my only real option is to put 25mm celotex sheets between the rafters which would maintain a ~50mm air gap between the membrane and the celotex and then i can over insulate on top of the rafters with thicker celotex sheets a further 50mm/75mm. The reason for not putting another 100mm on top is that the attic has exposed beams/purlins so if the insulation is too thick we would loose a lot of these features. So i think its going to be a slight compromise between the level of insulation achieved whilst still retaining some of the aesthetics. However i believe as long as we ensure air tightness with the insulation and eliminate the external draughts i think that is going to make the world of difference.
I would welcome those with experiences thoughts as to whether there's anything I've obviously missed or misunderstood before we embark on this.
Thanks
