On 6 Feb, 20:17, "Tim Smith" wrote:
Hi Everyone,



Got a few queries that Im hoping someone might be able to help with...

Im starting to renovate the dining room in our house. When we moved in 4yrs
ago the survey picked up a bit of damp in the walls either side of the
mantel piece. The damp was repaired and although I didnt watch what they
did, the visible outcome was a two new patches of plaster

Determine if this is render or gypsum
Probable cause of damp was likely to be hygroscopic salts from fossil
fuel burning but may have been other sources
If gypsum consider seriously replacing in sand cement with silicatious
water proofer

from floor level
upto the height of the mantel on either side of the fireplace.

Now - we've had the fireplace removed and Im decorating in preparation for
the installation of a hole in the wall electric fire.

First question - having removd the skirting board, there was what looked
like expanding foam that the damp people put in when replacing the skirting
board. Is this likely to have been for any particular reason
Nothing to do with damp per se - more likely to be cheap and cheerful
gap filling
could be they are plonkers and tried to "glue" it with foam - I have
seen that done!


or may they
have just used it to fix the skirting?
It depends if you are talking about glue or foam
difficult tocomment without seeing


The plaster doesnt go right down to
the floor

Quite right
that is good practice
maybe they are ok
reason is to stop bridging

so this may have been to keep the skirting vertical

no


this there is
no solid fixing - is this likely to be correct?


not sure if you mean a timber ground or nails

timber grounds ( a solid fixing into which you put screw or nail)
should not be used
you can use glues or screws or skewed nails

I use a dpm and screws with Fischer type or Rawl type fixings

Secondly, with regard to the fireplace, the fitter who came to do first part
of the fireplace install, bricked up the bottom of the original grate
opening to create a "hole" in the wall about 50cm up from the floor. Im
doing the plaster work around this new brickwork.

make sure it is render not plaster

Questions

1. There is a series of holes around the outside wall in the bricks just
above the floorboard level (floorboards have a 50cm cavity beneath them to
hte ground). Im presuming that these holes form the dampproof course. Is
this correct?

It may well be correct that it is holes for a dpc but they are in the
wrong place
Look up BWPDA Code or Practice or BS Standard for correct location of
dpc
If they are angled down at a steep angle you may just be ok

2. The fitter, bricked up from floor level (just below the level of the
holes in the bricks eitehr side of the opening) to the height of the hole -
should he have put something in here with regard to stopping damp

Yes normally a physical dpc but you are not alllowed anything
combustible too near a fire and I cannot visualise what has been done


or does
this not matter as this is merely the front of "proper" chimney opening?
dont understand - send a piccy or put one on line


3. Where the hearth was there is a concrete slab which (on looking under the
floor) is supported on bricks going down to the soil under the floor. As
this slab was slightly below the floor level, I levelled it using levelling
compound. Now a small area of the levelling compound near where it meets the
wall (and to agree the new bit of wall the fitter built) is showing signs of
being damp - they are a darker colour but not physcially damp.

How do you know
use a meter to be sure
If it is coloured it is likely to be wicking damp
damp may be from below or water from recent works
eitther way there should not be any link

use SBR and SIKA No 1 in the mix and redo that bit or put in a dpm

As the
concrete slab is below the dampproof course, Im assuming that this is to be
expected - is that the case?


yes but it will be bridging unless isloated or replaced
consider merits of rebuilding it on insulation?


4. I was intending painting with waterproof floor paint

Not a bad idea if it is proper dpm
modern equivalent of Syntha prufe or an epoxy resin
~Woulnt bother with teh polythene


and putting some
polythene down before carpet goes down. Is this the best course of action?
Alternatively, I can take out the levlling compound i put in, and put a
layer of a waterproof membrane underneath some new levelling compound?

Just make the new leveling compound water proof as suggeseted?

Chris G





Many many thanks for your thoughts...

Tim