Damp proofing and plastering

Status
Not open for further replies.

flynnyman

Well-Known Member
probably the most mis diagnosed subject in the building industry or the biggest con, forget what types of plasters are gonna be used for a start and solve the damp problem, plasters or cements cannot fix a damp problem. sometimes its just a case of opening the windows, unblocking vents or puttin the heating on, maybe fix a gutter or remove anything thats bridging a dpc, seal your windows properly but an interesting subject which i will add more to.
 

warriorupnorth

Private Member
Types off damp
Rising damp:- caused by capillary action through the substrate when there is no physical barrier ie DPC (damp proof course) or in the event of a breakdown in the existing barrier. There are many ways of rectifying this , some of which are not always credible, and there are many things you should check prior to contemplating a new dpc course ie: Bridging, sealants around window and door frames, pointing and masonry, gutters and fallpipes, overflows,etc etc etc.
1.Injection of fluids or cream, probably the most com on type of replacement DPC and widely used
2 Insertion of a physical barrier ie: Pvc membrane, which requires removal of masonry or substrate to physically insert the barrier ( Time consuming and very impracticable compared to modern day methods)
3 Osmosis probably the most contentious methods of curing rising damp , but basically means running a small electrical current through anode's at certain points at dpc height.
4 Breather vents, another contentious form of curing damp , by means of the installation of a porous (usually clay) vent spaced at certain intervals along dpc line.
5 Tanking (yes i know this does not stop the damp from rising) but rising damp generally stops rising when it gets to a metre in height (gravity and evaporation etc) so tanking is now generally accepted as the method of preventing damp from entering you dwelling , this is mainly due to the problems associated with party walls, chimney breasts etc where guarantying success with injection of fluids and creams is nigh impossible.
These are few of the options available and not always necessary
Penetrating damp
Often mistaken for rising damp and the usual causes are listed above ie: badly pointed or perished mortar, leaking gutters or constantly running overflows etc
The normal methods of combating this are re-pointing/rendering and fixing leaking gutters etc etc etc
Do not seal using the brush on spray on proprietary sealers as this prevents the structure from breathing.
Condensation this in my opinion covers 70% of all the so called rising damp problems i've been
called too , so many time has missus Smith called me and said "i have rising damp in my bedroom bathroom , kitchen " and 70% of the time it's due to condensation you should see there faces when i tell to leave a window open, but then when i tell em the alternative's which they have to pay for it's
" okay just leave a window open eh"
I have only touched on the problems of Damp, Causes and Methods etc but hopefully this will give you a small insight into the related problems of damp etc and that's without even starting on the subject of
hygroscopic salts!! but that's enough for me for today , time for a beer.
There will no doubts be other post's tellin me where i've gone wrong or what i've missed out but as stated this was only intended as a small taster for those of you wanting to dip your toes into such a contentious subject and i couldn't leave it all to BIGSEGS, Flinny, Church etc
 
B

bigsegs

Guest
And all this before we've even reached the subject of plastering damp walls..
or more to the point - Plastering walls that USED to have a damp problem, now rectified, but that isnt to say there isnt water left in the wall, which contains salt..
onto round 2 then..
 
B

bigsegs

Guest
but a lot of damp proofing companies hack off up to a metre high, inject the dpc (using whatever method) then plaster it back up..
what are they doing that isnt normal mate?
 

flynnyman

Well-Known Member
bigsegs said:
but a lot of damp proofing companies hack off up to a metre high, inject the dpc (using whatever method) then plaster it back up..
what are they doing that isnt normal mate?

advising them to open a window...:)
 

warriorupnorth

Private Member
bigsegs said:
but a lot of damp proofing companies hack off up to a metre high, inject the dpc (using whatever method) then plaster it back up..
what are they doing that isnt normal mate?
It's become the the norm though eh , but i suppose once plastered back up it forces any moisture the other way and hopefully outside , like i said very contentious subject this eh !! Flinny
 
B

bigsegs

Guest
;D ;D APART from damp which isnt damp ???
whats all this 3:1 waterproofer/salt repellant, salt neutraliser, limelite, guarantees, bridging and 'for gods sake dont paint it' all about then?
 

warriorupnorth

Private Member
i Know it's a fecking nightmare, don't think theres a chemical that can neutralise salts really cos it can't penetrate deep enough to do any good , your supposed to physically remove visible salts, poulticing then use sacrificial mortars and plasters and re treat until it's at a less destructive level ??? ???
 
B

bigsegs

Guest
Nightmare indeed... :'(
Heres what we used to do, triton damp proofing chemicals spec..
3:1 plastering sand : ordinary portland cement, 1/2 litre of waterproofer per 25kg cement. The waterproofer had to be 'triton' waterproofer which contained a salt repellant (apparently, blue goo we used to call it, smelt no different from any other waterproofer though, acidic, bit like lemon sherbert)
Usually went on in one coat internally..
No bridging of dpc injection (dont render to the floor basically)
Skim it next day with multi or board finish.
Do not paint for minimum 6 months.
If it got a scratch coat there was to be no waterproofer in the float coat.
Any deviation from the mix/method invalidated their product guarantee.
There was the odd callback but 99% of the time it was just visible salts, no water marks and it just got painted with 'salt neutraliser' - smells like batery acid, once scraped off obviously..
If it were a major callback it was usually a building made out of sandstone and rubble and the dpc process was 'injection mortar'... probably would have been better off acro'ing, yanking a line of stone out and sticking some engineering bricks in but thats a damp proofers problem really, not a plasterers..
Now I must have heard another 3 or 4 different mixes/methods/materials..
anybody?
 
M

mrspoon

Guest
well ive jsut got back from my parents new apartment in cyprus and guess what, theres damp problems ::) and theres lots and lots of sandstone too, happy days :-\ the whole site is the same!
 

richardbrown

Private Member
Build a stud wall in front of the damp wall using foil back board with the boards 3 inchs from the floor, fit plastic skirting and lay a vinyl floor, I usually throw in a mop and bucket to sweeten the deal .

Rich

edit : more modern methods include the use of insulating board (cellotex) and a vapour barrier to stop condensation forming behind the board but just as good a method as any..
 

richardbrown

Private Member
richardbrown said:
Build a stud wall in front of the damp wall using foil back board with the boards 3 inchs from the floor, fit plastic skirting and lay a vinyl floor, I usually throw in a mop and bucket to sweeten the deal .

Rich

edit : more modern methods include the use of insulating board (cellotex) and a vapour barrier to stop condensation forming behind the board but just as good a method as any..

I was only joking :(

Rich
 
B

bigsegs

Guest
still better than hacking off and re-rendering a wall that hasnt been sorted though..
 
B

bigsegs

Guest
yeh ive red similar aricles before..
first thing i spotted with that article..
the 'buy now' button.. nuff said on that one..

rising damp (or rising dampness as jeff puts it) is caused by the breakdown or non existence of the dpc or 'damp proof course', its a layer of impenetrable material built into the mortar joint just below internal floor level

this is built into every building (dwellings that is, not necassarily barns and the like, which tend to be thrown together by bog arabs) for the sole purpose of stopping water from rising up out of the ground and soaking into the porous substrates we build homes out of via capillary action..

dip a piece of blotting paper into a spillage of water and what happens?
anything porous will do exactly the same thing...

however it HAS always confused me how people always state that 'damp will only rise up to a metre'..
why should this be? does it think to itself 'well, a metres high enuff, if they cant spot me by now doing my evil deed im wasting my time!'

remember the mercury barometer from school? (if you cant, ask your teenage kids)
you take a thin hollow tube, fill it with mercury, seal one end and dip the other end in a bath of mercury.. it measures atmosperic pressure..
1 bar (roughly atmospheric pressure i.e. the weight of air 1cm2 rising up to space) will 'weigh' the same as roughly 76cm of mercury.. i.e. air pressure can only hold up 76 cm of mercury in this long thin hollow tube...

Now... replace the mercury with water, a lot less dense (less heavy) and what happens?

air pressure could hold up more than 15 METRES of water...
I dont actually think this has much to do wth capillary action in building substrates but it is the source of my confusion regarding damps apparent inability to rise further than a metre.. maybe early 'damp proofers' all had a bad back?

I do understand though that these 'damp meters' were invented purely for the purpose of ripping people off... they dont work (well they do but if youve actually got rising damp(ness) then believe me you'll see it long before you think about getting the 'damp proofers' in..

bit of a 'rogue traders' this article.. probably where they got their idea the other week..
 
B

bigsegs

Guest
incidentally...
the chemicals used to combat the phenomenom work in the following way..
holes are drilled in either the brick or the mortar joint..
if theyre in the brick, the chemical is silicon based, its injected under high pressure (very high pressure) into the brick until little beads of 'sweat' are seen to form on the surface of the brick... silicon being inpenetrable to water, bit like wd40..
if theyre in the mortar joint then a cream/gel is pumped in, not very much pressure is needed, a mastic gun will do. what happens is the cream dissolves within the water within the joint and tracks (via capillary action, yes use the forces of nature against itself) into and along the mortar joint and wherever it comes into contact with water it 'crystalises' and forms an impenetrable barrier..
or thats the theory anyway.. theres no real way of checking to see if its worked other than letting it dry out for as long as possible and plastering it back up and waiting to see if it comes back..
or if you havent hacked any plaster off... draw a pencil line around the perimeter or along the topmost edge of the 'damp line' and wait to see if it recedes..
problem with this method is it might well recede during dry weather, then come back during wet weather..

did someone mention that damp was a nightmare somewhere in this thread?
 
B

bigsegs

Guest
one more thing for people reading this that think they may have a damp problem..
you can go to a hire centre and hire a multi lance injection pump and slicon injection chemical and do it yourself..
if you dont know what your doing however your probably wasting your time, but if youve done your homework youve got as much chance of curing the problem as a professional damp proofing outfit..

the difference is a properly registered proffesional (not dodgy) outfit will give you an 'insurance backed' (this means if the company goes pop youre still covered) guarantee lasting 30 years..

youll need this if when you come to sell your house and you state that youve had a chemical dpc installed, the buyers mortgage company will want it or the installation is technically worthless and will devalue your property..

on the other hand, if you do it yourself and it works, it wont get picked up by the surveyor and the problem will never arise..
 

flynnyman

Well-Known Member
bigsegs said:
yeh ive red similar aricles before..
first thing i spotted with that article..
the 'buy now' button.. nuff said on that one..

rising damp (or rising dampness as jeff puts it) is caused by the breakdown or non existence of the dpc or 'damp proof course', its a layer of impenetrable material built into the mortar joint just below internal floor level

this is built into every building (dwellings that is, not necassarily barns and the like, which tend to be thrown together by bog arabs) for the sole purpose of stopping water from rising up out of the ground and soaking into the porous substrates we build homes out of via capillary action..

dip a piece of blotting paper into a spillage of water and what happens?
anything porous will do exactly the same thing...

however it HAS always confused me how people always state that 'damp will only rise up to a metre'..
why should this be? does it think to itself 'well, a metres high enuff, if they cant spot me by now doing my evil deed im wasting my time!'

remember the mercury barometer from school? (if you cant, ask your teenage kids)
you take a thin hollow tube, fill it with mercury, seal one end and dip the other end in a bath of mercury.. it measures atmosperic pressure..
1 bar (roughly atmospheric pressure i.e. the weight of air 1cm2 rising up to space) will 'weigh' the same as roughly 76cm of mercury.. i.e. air pressure can only hold up 76 cm of mercury in this long thin hollow tube...

Now... replace the mercury with water, a lot less dense (less heavy) and what happens?

air pressure could hold up more than 15 METRES of water...
I dont actually think this has much to do wth capillary action in building substrates but it is the source of my confusion regarding damps apparent inability to rise further than a metre.. maybe early 'damp proofers' all had a bad back?

I do understand though that these 'damp meters' were invented purely for the purpose of ripping people off... they dont work (well they do but if youve actually got rising damp(ness) then believe me you'll see it long before you think about getting the 'damp proofers' in..

bit of a 'rogue traders' this article.. probably where they got their idea the other week..



it doesnt stop or start at a metre rising damp doesnt exist put a brick in a tray of water with an inch and watch it for the rest of your life and it wont rise above the brick also next time your next to a canal or a bridge that goes over water look for rising damp.........yep doesnt exist.
 
B

bigsegs

Guest
ive always wondered why they bother to put a strip of polythene dpc in new houses... or that silly membrane thy put in the floors?
must just be a throwback to the scaremongering of the damp proof rip off revolution when it actual fact its not needed at all? quick somebody tell all the builders :eek:
 

lucius

Well-Known Member
As Flinny says if you put a stack of bricks in half a bucket of water it wont rise very far so what that means i dont know, a mate of mine who specialised in damp proofing who unfotunately is dead now used to quote a mathmatical formula which allegdly proved that damp can only rise a meter unfortunately i cant remember it and i cant ask him.As i mentioned on another post ime not a fan of injecting as when ive pulled walls down that had been you can see that the sillicone has not fully penetrated the brick and as my old mate used to say its the render that holds it back thats why the spec is so stringent.As for guarranties yes you may need it for a sale but damp proof companies are notorious for disapearing and opening up under another name which invalidates the original guarrantee if you needed them back.
Lucius.
 
B

bigsegs

Guest
dunno bout formulas, ive no idea why damp only rises a metre but i have seen it higher down the sides of chimney breasts..
yes, injecting is very hit and miss, as i said before.. nightmare..
guarantees need to be insurance backed or theyre completely worthless.. the guarantee is backed by the insurance company not the firm carrying out the work.. check the small print..
silicon injection does work, but only if every single brick has full saturation.. one blown brick and the lance just gets pulled out and on to the next one.. trust me ive seen it done many times.. in which case theres a break in the dpc.. dodgy at best..
but as for rising damp not existing?
well..
 
Status
Not open for further replies.
Top