DPC help

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beddy said:
i'm not on either side, i can see where flynnys coming from but on the other hand, if its not rising damp what is it
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first of all, i reckon every discussion on this topic should begin with a definition of exactly what 'rising damp' is... or in flynnys case, exactly what the 'idea' of rising damp is...
people call anything showing symptoms of damp near the bottom half of the wall 'rising damp' whether its salts, dark patches or mildew.... thats half the problem imo...

back to sherlock holmes again for me...
 
flynnyman said:
Its true you will not find proof of RD anywhere I challenge you to find me solid proof and i will change my mind :)
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i had one year before last, not sure but i reckon i popped it on here and we had some discussion on it, hydrostatic pressure was mentioned...
old, old house...
floor been re-concreted..
damp been 'treated' before on one wall by hacking off and re-rendering 3:1 - hard as f'ck... im guessing waterproofer..
this walls a 9" party wall, no the other side wasnt built at a later date (trust me, checked) BUT the floor level on the other side WAS about 12" higher...
now, the (new, well 10 year old) concrete didnt have a break, went right up to the brickwork, couldnt find a membrane..
couldnt find a dpc either...
removed the skirting and its rendered to the floor, dont forget its rock hard very resistant to the passage of water..
the PROBLEM was, the new render was a metre high, dead on...
above the render was a line of damp about 300mm wide/high on ONE side of the wall only...
other side WASNT bridged - checked....
they'd had a bathroom leak in the past, 2 years ago, i repaired some of the plaster in the hallway due to this leak - bone dry...

question - how did the damp get to be where it was? absolutely no sign of damp on the other side, the 'higher floor' side...

had me scratchring my head to come up with anything other than 'rising damp' or water/moisture soaking 'up' the wall from the dodgy floor levels and manifesting itself ABOVE the waterproof render... must have happened after the 'treatment' or they'd have hacked off 1300 wouldnt they?

p.s. once i'd hacked off the 'bridge' behind the skirting board (thats how i know how hard the render was) the perps in the bricks behind were pure mush, i raked some out with a pen... funnily enough, the floor looked dry :RpS_bored:
 
beddy said:
thats a different story bubbles, plasterboard is extremely pourous
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Yeah, that's my point beddy - I was using plasterboard as an analogy, as it will have very similar properties to plaster stuck to a wall. I think I know where flynny is coming from with the brick reference, but when a bridge has been made through a wall and the water reaches the plaster, it WILL rise, so the point is - as far as OUR trade goes - rising damp DOES exist...............along with DPC companies to scare the crap out of the punters:RpS_thumbup:
 
Fyynnman argument is base on that brickie who built a wall and stood in water for a period of time only for the water to rise 2". Damp just not about water soaking up brick walls. It's more to do with a moisture content so what flynn is saying has some merit to it. Where I live the town is built on marsh land hence we get east marsh west etc. What I have seen ,is brick work pissed wet up to 5' high in some cases on internal walls. Like chris said some firms will inject walls even when they are dry it is a gravy train for some. Were I grew up there use to be a old brick pit this mostley supplied most of the pre 1920 housing stock of bricks it use to flood every month to high tides as it was only 100 yards from the sea . some times these bricks could be weeks under salt water before they was even laid. Also I have seen a least 20 different brick shapes some with 10 holes and some with 2 big holes this is all to do with the morter bond I would think. I also noted were morter beds which had fly ash mixed into the lime these building never seem to have mojor problems. That's it me done on dpc problems.
 
good.. worked then...
big deep subject is damp, worth getting into if only so's you know what not to do and what youre potentially looking at when pricing work up...
i'm always finding out little snippets... like 'diffusion' - gotta go an figure that out now..:rolleyes)
 
p.s. that link of flynnys is actually a bloody informative read for the novice and the expert alike...
 
It's riseing moisture what ever that is going to look at a job at tea time party wall showing signs of something not rising damp but something?.
Flynnyman are you the lad Ive seen who always wears his baseball cap back to front and you drive a large van.
 
henry said:
It's riseing moisture what ever that is going to look at a job at tea time party wall showing signs of something not rising damp but something?.
Flynnyman are you the lad Ive seen who always wears his baseball cap back to front and you drive a large van.
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No mate im the guy on the push bike with a bucket on either side of my handlebars and a darby across the front OH and a bob marley dreadlock and hat set up ;)



Na its not me :)
 
If you was you are the guy with dreadlocks I was on a job last year and you was working across the road from me in old waltham sunningdale
 
Called tonight to look at a moisture patches on the party wall of a terrace house. What it showed was paint bubbleing in different places and height along this party wall. What would you do.
 
not enough info there mate but for the star prize ill say condensation...
give us another clue? anything in front of it like a settee? highest point of bubbling paint? lowest point? leaky rad upstairs? or downstairs? age of paint and any plastering works? condition of skirting board? type of room ventilation? bathroom upstairs with a leaky pan connector with water tracking along joists barely perceptible but over a period of time....
youve got to eliminate possibilities...
then charge em for the diagnosis, scrape the paint off and tell em to repaint it... :RpS_blink:
 
Ok it's the party wall when entering the house which have the staircase in the entrance hall. Front porch showed damp patches about 1' high hallway rad boxed in them wood rad covers about 2' high along wall odd mosture patches. Cup under stairs same as hall. Kitchen cooker on party wall this wall had
paint blistering about 3' high in line with cooking rings , back entrance lobby, wall, just felt damp.
 
ill guess again, next doors hallway backs onto this hallway yes? so does the cupboard and kitchen?
rads not gonna be working properly, walls gonna be cold, not enough ventilation, kitchen making tons of moisture, rest of house kept reasonably warm in comparison...
doesnt necessarily have to have black spotty mildew to be condensation...

if not, any sign of salts in the bubbly paint?
timber floor? is it vented properly? ill be gobsmacked if theres a vent under the front door, there should be technically, but theyve usually got a step built
be a good idea to have the skirting off and check for bridging / gaps between wall and floor (cold draught) - lower half of wall always gonna be colder than the top half but it helps to keep it as warm as possible... if its old 9" skirt like a lot of these houses your gonna have to be destructive and make some work for yourself, especially trying to match it again and it'll prolly turn out to be fine but you have to discuss that with the customer....

I'd still plump for condensation...

various ways to combat condensation from trickle vents to loft mounted forced air ventilation/extraction, insulation not really being an option down the hallway cos the doors gonna be tight up the wall yes?
remove the rad cover, turn the valves up a bit, draughtproof the door (yes, keep some heat in) and install a passivent in the fanlight above
cupboard - vent it best you can
kitchen - 6" fan and trickle vents in the window and door
tell em to scrape all the paint off and repaint with anti condensation paint, or just matt... shiny surface always gonna attract water wheras a matt surface can soak it up and evaporate... once moistures got through silk its a hard job getting out again cos it soaks into a wider area... i dont even know if anti condensation paint does what it says on the tin or it just inhibits mould growth to be honest?
if you can get hold of some of that insulated wallpaper that'll prolly cure it...
 
He is s an old friend of mine his home is spot on he is joiner come window fitter, vents fitted to doors and windows he seems to think the damp is comeing through the party wall from next door. He went on to say they just bodge there house up he also said over the years he has had 2 dpc done. I think your on the right track here chris.
 
only way i can think of proving it maybe stand a mirror or piece of glass against the affected walls and monitor em at strategic times of day for condensation... e.g. first thing in the morning, after the shower/bath has been used, washing machines been running, or a meals been cooked..
it should work like a condensation magnet once its reached the ambient temperature, do a control by using other pieces of glass in other rooms against other walls...
might just work? being a window fitter he should have no worries getting hold of bits of glass...
dont forget warm air carries moisture, but it needs a cold surface to deposit it on otherwise it'll hang onto it... thats how dehumidifiers work...
 
henry said:
Called tonight to look at a moisture patches on the party wall of a terrace house. What it showed was paint bubbleing in different places and height along this party wall. What would you do.
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I bet you what you want its been patched before and they have used a gypsum backing coat :)
 
flynny you do get rising damp and your half right the true passage of rising damp is threw the mortar beds not brickwork thats why you inject into the mortar bed not the brick
 
kevmc said:
flynny you do get rising damp and your half right the true passage of rising damp is threw the mortar beds not brickwork thats why you inject into the mortar bed not the brick
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Why would the damp go up rather than just out the otherside which would be easier for the water?
 
You can still buy fluid for injecting into the brick and still drill the bricks with a 10mm hole.
 
Would it? what if the other sides already wet, like it's holding as much water as saturation point allows?
 
why only an inch john? surely if theres a constant supply of water, albeit small and slow, the mortar will keep sucking it up, you've seen how quickly it sucks it in when you wet a wall down to plaster it.
 
I think flynny reckons that it's air-bourne moisture that condenses on the walls and the water finds it's way to the bottom of the wall and 'appears' to be rising. Could be!............ Right flynny?:-)
 
beddy said:
why only an inch john? surely if theres a constant supply of water, albeit small and slow, the mortar will keep sucking it up, you've seen how quickly it sucks it in when you wet a wall down to plaster it.
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The water will suck in but if you wet a wall down to plaster it like you say will the water run down or up?
 
down off the bricks. not off the mortar though. try this then. get a block of sand and cement say 2ft square, let it fully dry out then place it in a gorilla tub with a few inches of water in. i bet it would soak up as much water as it could
 
then as the water rises up the mortar, the dry plaster sucks some of the water out of the mortar, causing damp. possible?
 
Ok steve i need you to get a 2ft block of mortar to try it out for us lol so what your sayin is when you wet the walls down the water runs down the bricks but up the mortar?
 
no the water soaks into the mortar. i'm just trying to understand how it works mate, not saying ive got the answers. ok maybe 2ft square is a little big, 18 inches square? lol
 
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