We have a 1830's mid terrace which has a cellar. House is rendered externall
and no cavity wall. We're getting damp walls directly above the
cellar(kitchen), salt in the bricks also. It's rising damp.
We've just stripped the wallpaper and found the plaster in the whole house
is decades old and just falls off so time to do something.
It's been suggested to us to dry line the damp walls and use insulated
plasterboard....Is this is a good idea?
- Isn't the wood going to rot been fixing to a damp wall? we're just had
part of the cellar entrance collapse because of 2 rotten beams which were
both againt damp walls.
- And aren't we merely covering up the damp? and boxing it in.
I wouldn't pre-judge the "rising damp" issue. It may even be falling
damp, where water works its way down inside the masonry until it reaches
a barrier of some kind. This can be a dpc injection or some other
misguided attempt to deal with rising damp. Problems with the roof can
often produce symptoms much lower down, especially on internal walls.
I think I'd start by removing all the plaster. This will make it easier
for you, or whoever you're getting to do the work, to see what's really
going on. Easily said when you're not trying to live in the place at the
same time :-)
Most of the posts above have in essence got it mostly right. Lets take
each problem separately:
This is not a habitable space. It is not neccessary for it to be dry.
It "should" be well ventilated from front to rear by means of the sub-
floor ventilation for your suspended timber floors. No doubt some
plonker in the 1950s has put in a solid floor rear addition to obtruct
this but hopefully not. So .....either respect the original purpose
and design of the structure (assuming it is still there and functional
with respect to subfloor vents) and only store non-cellulosic (wood-
based) materials down there that cannot be harmed (or put such items
on protected surfaces such as raised bricks with a dpc ) or make the
area "habitable" ie able to store materials safely. To do this you
will have to tank it. Tanking can be done in a whole variety of ways -
sand:cement render applied to the walls with special additives such as
SIKA No 1, cementitious paints, followed by render, dry lining
systems with sump pumps or not as the case may be etc etc. These are
all pretty expensive ways to get a dry cellar and I would be amazed
that most people would consider it worth it for storage. It is really
only worth it if you do a digout and can get some light in and
literally make the area habitiable. I presume this is not in the plan.
Above the cellar:
You allege rising damp. I endorse the other posts on this urging not
to jump to this conclusion without evidence.
DPCs have been required by building regs since 1886 or thereabouts.
Your plaster will not deteriorate by age alone. You may well be right
and it is rising damp but check and make sure it is not a bridged dpc,
lateral penetration falling down etc etc.
If the plaster is "falling off" in the whole house, that is NOT rising
damp, which only affects the area within a metre or so of the ground.
You need to establish why it is falling off elsewhere and what the
cause is becausee that will not be age related. If you have to replace
it, the post who said to wait for a while and see if there is any
other source of water coming in is correct.
If you do need a DPC (as it likely) then it should be injected into
the mortar of the walls (not the bricks) and is generally 150mm above
the external ground level and below the internal floor level. There is
a BS to cover DPCs and the BWPDA (now the PCA) which defines how to
inject dpcs properly.
Walls and insulation
Separate the issues of dry lining and insulation
Generally I do not like this in that it does not allow for easy
hanging of pictures, is less "substantial" more easily damaged, sounds
hollow, and is difficulte for other fixings but, sure, it is quicker,
cheaper and inherently better insulated than solid plaster. Solid
plaster is traditional and you can have a proper lime plaster which is
made from lime putty (NOT bagged lime) and sand (purist, correct and
expensive) or what is now traditional a sand cement plaster. I would
avoid like the plague any gypsum- based "renovating" plasters although
a cement-based one (Limelite) would be acceptable.
Insulation boards are generally urethane based insulation (as in roof
insualtion for hot roofs such as TP10) with plasterboard bonded on the
outside. Thicknesses vary from 100 down to 17mm (reveal board). most
poeple do not like to lose 2" off the size of all rooms but it is a
VERY good investment to make on external walls in a Victorian terrace
house if you can overcome the junction with the cornices etc. I am
doing this in my present project and being a cheapskate I have bought
roof insulation and fixing 50 mm board to the existing plaster (or in
one case brick) using both mechanical fixings (the ones for external
insulation) stainless steel screws and penny washers plus wall board
adhesisve (used for dabs) which I will put on "a la tiling" method
with a serated trowel. With both mechanical and glue fixing I am
hopeful that the insutalion will stick! That done I will put on 12.5mm
plaster board also with glue and plasterbord nails. That done I will
bond scrim and set it.
Hope this helps
Either you need to employ an excellent independent damp specialist or
become one yourself!
Reading the bazillions of posts about it on here, and on period
property, and lots of googling will get you most of the way.
Reliably diagnosing these problems from limited information is very
tricky, so you may get diverging but equally valid responses to your
Sounds like the render _may_ have been an attempt to treat the
symptoms, and _may_ have added to the problem.
Usually the solution is 'holistic', that is a number of measures
instead of just one.
Also often all aspects of the building and it's past and present use
need to be considered.
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