I’m just starting the task of fixing up the boy’s bedroom/nursery, which is in the attic. It’s an old house (1816) with solid stone walls and tiled roof. The attic has previously been converted to living space, but I’m rapidly finding out that this was done in a less-than-satisfactory manner. Basically, the interior face of the stone walls have been painted with some kind of tar substance, then rockwool insulation in plastic bags placed against the wall and held in place by MDF boards, which are the room walls. The tar has prevented the roof space “breathing” and any moisture formed has worked its way around the insulation plastic and onto the MDF, and the whole lot is a bit rotten and mouldy.

I’m wondering what the best way to tackle this is. Was going to see about steam-cleaning the tar off to clean the inner surface of the stone wall, using that foam-backed plasterboard to re-wall the room, and plywood to replace the shagged floorboards. Does this seem the most sensible idea, or am I totally out of my depth here? The plasterboard manufacturer suggests using adhesive foam to mount the boards, but I’m unsure if having anything touching the stonework is such a good idea given this is what appears to have caused the problems in the first place….

😕

if it was me I’d just build partition walls with insulation slabs int he voids and insulated plasterboard for the walls. Leave a void between stone walls and the partition to allow air to circulate and make sure there’s ventilation to the void available.

I am not a builder/damp expert but suspect any works of this type are notifiable even if you are replacing a previous bodge…

I’d not even considered that wwaswas. Local council, I presume?

building control.

Mine were quite helpful when I phoned up for a chat about some work I wanted to do. Talk them through what you plan and see if they think it’s covered.

I do get fed up on here with the constant ring building control for every screw you use at home but in this case wwas is right. The worry with any loft conversion in my mind is fire especially if its going to be a space for the young un. You need to protect the room/shaft with fire doors etc, access egress via top opening skylight etc.
I know it all sounds a bit doom merchant but ill designed loft spaces can definitely be death traps where fire is concerned.

in this case wwas is right

*breathes sigh of relief*

Just to give some background I have an old house that was very damp, and has been pretty much rebuilt.

Personally I wouldn’t worry about the breath-ability if wall is above two meters, as you won’t be pulling up water from the ground.

You need to first find out where the damp is coming from, as it won’t be due to the walls pulling up water that far.

So I would check the gutters are clear, fascia (if you have them) aren’t rotten and aren’t allowing water into the roof space and your roof is water tight (no broken slates/tiles).

If its all good, then the damp could be due to condensation.

If it is condensation you could seal the wall with a SBR and cement slurry then baton the wall out fit insulation then add insulating plasterboard that way the temperature difference shouldn’t be a problem.

If you are tight on space on the walls you could use SBR/cement slurry + limelight then normal multi finish but that will cost a lot more.

If you get someone in to advise and they suggest delta membrane get another opinion as they are just selling you something you don’t need or want.

Regarding the tar, our house is 1820 and we had the same problem.

The builders used a needle gun to strip it off, reckoned it made light work of a nasty job…

http://www.jewson.co.uk/tool-hire/power-tools/needle-guns/

The wall in question is a gable end with chimney. I’m thinking the flashings are duff, but until we get up there it’s only a guess. The chimney could also do with repointing, but The tiles look in decent nick, so I’m not overly concerned with the roof leaking.

if it was me I’d just build partition walls with insulation slabs int he voids and insulated plasterboard for the walls. Leave a void between stone walls and the partition to allow air to circulate and make sure there’s ventilation to the void available.

This isn’t a bad idea.

Battening out is not the best way to deal with a solid wall. Yes, it will be warm but it is necessary to allow moisture to travel through the wall. If not you will have damp problems behind the boards which will encourage bad mold spores that you cannot see but will potentially give health issues. It will also have a detrimental affect on the infrastructure of the building.

A solid wall ideally needs to use lime mortar/render inside and out. Insulation can be achieved by using hemp lime inside.

Solid wall buildings are not really compatible with modern building materials.

Rich.

I know it all sounds a bit doom merchant

not at all, too many iffy loft conversions out there & people not considering the fire consequences so good point well made