Damp proof tanking vs membranes
Discussion
This is a call for rational PH advice, as the damp course companies I have had in are all giving different advice. It is as if they are competing religious beliefs, each one claiming the other is outdated and/or useless.
My house is partially underground but has been remarkably dry for the past 20 years (excepting the flooding incident below), ie no rising or penetrating damp.
We have recently stripped of all the plaster after a flood and are now getting conflicting advice on what to do next:
1) Reinsert a chemical damp course agaisnt rising damp, place membrance on the walls agaisnt penetrating damp and then stud, board and skim. (this is what we had before the flood).
OR
2) Insert an underground tanking stystem from the floor to up above ground level, dab board and skim.
Twelvety???????????????????????????
My house is partially underground but has been remarkably dry for the past 20 years (excepting the flooding incident below), ie no rising or penetrating damp.
We have recently stripped of all the plaster after a flood and are now getting conflicting advice on what to do next:
1) Reinsert a chemical damp course agaisnt rising damp, place membrance on the walls agaisnt penetrating damp and then stud, board and skim. (this is what we had before the flood).
OR
2) Insert an underground tanking stystem from the floor to up above ground level, dab board and skim.
Twelvety???????????????????????????
xllifts said:
Tanking dab & board, its the only way to gtee that water will not get in from outside, it makes a complete jointless waterproof lining of the basement.As the title says its made a room like a tank, water can't get in, or out.
HTH
Hopefully both 20 or 25 year guarantees underpinned by insurance.HTH
'Tanking is best' is what the guy is telling me, and it seems simpler and longer lasting solution (but probably more expensive). He also suggested not doing one wall which the others had wanted to do, saying it was damp which may be a ploy but it makes me trust him (old salesman's trick).
He was warning against the systems that use 'active' of channel water systems that try to move the water away on the basis that they have to be installed and maintrained in top notch order and have implications for the floors you can lay.
He also said that Chemical DPCs shouldn't be used with coursed rubble buildings because of the unknown cavities and general loose materials which can render the chemical DPC less effective as you don;t treat everything, no mattter how much you pump in.
Could be just lies as I know nowt and he knows it.
Imran-vx said:
My house is partially underground but has been remarkably dry for the past 20 years (excepting the flooding incident below), ie no rising or penetrating damp.
This appears to be the critical statement to me.If the flooding was from outside (rain or river) then the best would be an exterior tanking system combined with a french drain.
If the flooding was from the inside you need to let the below ground walls breath through the plaster and would be best speaking to British Gypsum directly.
Like the poster above I think that the Imran-vx joke has worn a bit thin unless everytime people see you post you want them to think &@$*
Are you able to dig down to the foundations on the outside? Our basement is 2/3 below ground level and I absolutely wanted to prevent damp (music studio). I dug down outside 300mm below the inside floor level and placed on the outside wall:
1)2 layers of cement morter with hydrofuge liquid.
2)2 layers of special hydrofuge morter (ParexLanko 221-the sort of thing you put on the inside of swimming pools)
3)2 layers of bitumen (Sika)
4)Drainage composite (Delta Drain by delta membranes.com)
5)Gravel and a drainage pipe at the base going to a soakaway.
I have no humidity in my basement. At all.
There are lots of gadgety solutions but at the end of the day the best way to have a dry basement is to stop the water getting in. The only real way way is to protect the walls from the OUTSIDE. If the water can get into the walls, it's already too late.
Try this link, lots of useful info and a forum:
http://www.pavingexpert.com/forum01.htm
1)2 layers of cement morter with hydrofuge liquid.
2)2 layers of special hydrofuge morter (ParexLanko 221-the sort of thing you put on the inside of swimming pools)
3)2 layers of bitumen (Sika)
4)Drainage composite (Delta Drain by delta membranes.com)
5)Gravel and a drainage pipe at the base going to a soakaway.
I have no humidity in my basement. At all.
There are lots of gadgety solutions but at the end of the day the best way to have a dry basement is to stop the water getting in. The only real way way is to protect the walls from the OUTSIDE. If the water can get into the walls, it's already too late.
Try this link, lots of useful info and a forum:
http://www.pavingexpert.com/forum01.htm
Edited by driller on Monday 10th September 23:19
Parrot of Doom said:
Impossible to give a good answer without knowing the ground level, what the wall is made from, what kind of mortar is used, if theres any external render, bitumen, etc.
We are about 1.5 meters underground. No possibility of exposing the outer wall as it is the neighbours' drive. The wall is old coursed rubble stone with I presume, a lime mortar but looks like significant repointing took place in cement in the 1980's.Both damp companies are reputable, one is a large regional and the other a smaller company with 30 years experience who specialise in tanking (which may explain his preference but he said the type of construction we have is unsuitable for chemical DPC). I am not sure if I said but the existing state is that they had injected a chemical DPC into all the joints in the stone at 100m intervals vertically and horizontally up to 1.5 meters, then bitumen painted it.
The recent water entry was as the result of a blocked drain during the storms and water came in at floor level at just one point (which is the level of the blocked drain) but then ran through the ground floor. I have since had the drain excavated, cleaned and a new acessible drain cover put on so (hopefully) the source problem has been dealt with.
The other temptation for going with tanking is that they say that we won't have to wait 2 months for the walls to dry as we will with a traditional DPC and board/skim approach. At the moment we are living in the utility room and dining room with no kitchen or downstairs toilet so the desire to get on and finish is great!
xllifts said:
He sounds like he knows his stuff, if he's any good he'll be a member of bwpda.co.uk you can also check his advice on this site very informative.
But he's right about the chemical dpc.
HTH
I agree, he does sound like he knows his stuff. Not many people would check the possible wall construction included loose fill.But he's right about the chemical dpc.
HTH
mrmaggit said:
xllifts said:
He sounds like he knows his stuff, if he's any good he'll be a member of bwpda.co.uk you can also check his advice on this site very informative.
But he's right about the chemical dpc.
HTH
I agree, he does sound like he knows his stuff. Not many people would check the possible wall construction included loose fill.But he's right about the chemical dpc.
HTH
Chemical DPC will be useless. This is really to stop rising damp. Not water petetration from behind, in time the plasterboard will stain and start to come away due to damp building up within the void.
You defo need to tank, but think about having the floor done too. I would use a cavity drain membrame. follow the link. clicky here
If you only do the walls, the water will find a way out of the bottom of the tanking on the walls. Remember, ground water is always there, and can come with a pressure that could blow your tanking off the wall.
It's defo worth spending the money to get the job done right now.
You defo need to tank, but think about having the floor done too. I would use a cavity drain membrame. follow the link. clicky here
If you only do the walls, the water will find a way out of the bottom of the tanking on the walls. Remember, ground water is always there, and can come with a pressure that could blow your tanking off the wall.
It's defo worth spending the money to get the job done right now.
nowt said:
Chemical DPC will be useless. This is really to stop rising damp. Not water petetration from behind, in time the plasterboard will stain and start to come away due to damp building up within the void.
You defo need to tank, but think about having the floor done too. I would use a cavity drain membrame. follow the link. clicky here
If you only do the walls, the water will find a way out of the bottom of the tanking on the walls. Remember, ground water is always there, and can come with a pressure that could blow your tanking off the wall.
It's defo worth spending the money to get the job done right now.
I am beginning to feel more and more like a hobbit. 'Basement living' doesn't seem to sum it up somehow. We still have large 8 foot tall sash windows, just the lower third of the room is below ground. The floor is a poured bitumne which they are sugesting they seal to the tanking to make a fully waterprrof seal. Oddly, the only sign of dampness is a slightly damp stonework at about 3 feet below ground.You defo need to tank, but think about having the floor done too. I would use a cavity drain membrame. follow the link. clicky here
If you only do the walls, the water will find a way out of the bottom of the tanking on the walls. Remember, ground water is always there, and can come with a pressure that could blow your tanking off the wall.
It's defo worth spending the money to get the job done right now.
Had the quote today. Tanking comes in about £200 more than the chemical DPC version, BUT their warranty is only their own and not backed by an insurance company should they go bust. Alos the warranty on the underground tanking is just 10 years compared to 30 years on the above grounhd tanking and slurry work. I called the company who tell me that this shortended warranty is because the system is German and legislation in Germany dictates the length of warranty. Doesn't sound quite right to me.
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