guess what - another damp question

[brianos]

There are a lot of threads on topic of damp. Wasn't sure which to add my damp question to so thought I'd create a new one! not sure what the etiquette is..

quick recap - I bought a 320 year old house. A damp proof company recommended £20ks worth of DPC and impervious membrane slurry. I almost committed to that strategy for the entire ground floor until I found this website.
After a best attempts to understand damp causes and remediation, I decided that DPC and membrane just wasn't the right thing. Instead - address the more likely source of water and use breathable plaster on internal walls. My house appears to have a cement render on the outside which I understand means that breathable internal walls therefore even more critical. And, throwing in a sprinkle of consistent heating and ventilation.

So, I'm taking it wall by wall and trying to decide what the best approach is for each. i.e. whether I need to take it right back to original stone, or whether I can just chip back until I find super dry render and patch it up from there with breathable lime. Also, I've got one wall which I'm not sure if/how I can address the source and so wondering if I need to resort to the damp proof membrane slurry.

So, wall number one. What's your name and where do you come from? I've whacked this plaster with a hammer and its sounds fine and it looks dry. It looks like its suffered from damp but I'm not sure. The paint is crumbly and a few bits of plaster have broken away. So, not sure what the remediation needs to be other than scraping it back until no more bits fall off and then re-plaster it?






And, Wall #2, You're kind of similar but you've got some black mould around you. This wall was covered with wall units so it may just be condensation that has resulted in this? again, I thought, chip it back until all crappy bits fallen off, and then skim with plaster and job done. One plasterer I had said to chip it back to stone, and up to 1.2metre throughout the room and re-plaster. Which feels like overkill surely









Right, Onto Wall #3 which is where it gets interesting, and where it looks nasty and what folks might actually say is a proper damp issue. As you can see from below, it certainly looks wet. Its also wet to touch. The outside ground level is approx 2 to 3 feet from the window sill which coincides with the start of the damp in that corner (actually, its wet to that level all along the wall). So, the possible causes are (numbered in red in the pic)

1. outside ground level being higher than inside. Not sure what I can do about that.
2. This gulley massively overflows when its heavy rain. It literally cant take all the water. I wonder if a bigger one would resolve that issue? In addition, Ive spoken to a guttering specialist who reckons we could reduce the amount of water going to that corner by redirecting the flow round the other side of property. The water just spews out onto the stones in that corner.
3. This is a waste water outlet from a bathroom upstairs. I have no idea if leaking or no.. its a possibility
4. The pointing in general around that area is poor but wouldnt that have cause

Do you think 1 and 2 alone would be sufficient to cause the state of the wall?

so.. whats the best way to address this last wall #3? in this instance, would tanking it with membrane and slurry be an exception to the rule? (in addition to trying to address the rainwater issue)








I've got pics of a bunch of other walls but I thought this was enough to be getting on with!!

Best
Brian

 

[malcolm]

That's a long question to try to answer. It's good that you aren't thinking about DPCs and tanking as that will make things worse. Breathability is much spoken about and that's based on the very simple idea that if more water gets into a wall than can get out again the wall will become wet. There isn't normally a lot of water getting into walls so just making sure the wall is breathable should prevent it from getting damp.

Occasionally you can get too much water coming in. Leaky or overflowing drainage and high exterior ground levels would need sorting first.

Pink plaster is gypsom. It's not all that breathable and very often it is on top of cement or something even less breathable. Lime would be much better and with breathable paints would go a long way towards fixing the problem. It's a lot better to send excess water outside rather than have it inside so concrete render and plastic paints outside are a bad plan, and people are less likely to paint a nice looking exterior in magnolia emulsion so the breathability will last longer.

Probably worth searching some of those topics on the forum - there's a lot of good information on here.

 

[brianos]

Thanks Malcolm, yes, too long a question on reflection. Allow me to narrow it down.

You stated 'Occasionally you can get too much water coming in. Leaky or overflowing drainage and high exterior ground levels would need sorting first.". So, on my wall #3 described above. Its 4 foot below ground level and there is nothing I can do about that, is it then an option to use a waterproof membrane/slurry against that wall?

cheers!

 

[a twig]

Search on here for “Zebcolm trench” for ideas how to reduce exterior ground level which might work for you, might not work for all 4ft but would at least help

 

[housewinnie]

Outside kitchen wall. You could put a water butt in and then run a hose from the tap away. Not pretty but a fix that has worked for us

 

[DampedOut]

@brianos Nice photos and post. I'm curious to see what happens next, please keep us updated.

For what it's worth, my experience has been that any fix that starts from the forum's golden rule – prevent and release trapped moisture and water vapour – leads to a solid improvement.

Anything that seals water out typically seals water in behind it and I'd avoid that. I'd say no to waterproof membrane or slurry. Waterproofing/sealing fixes are false solutions that store up trouble for the future. Malcolm and A Twig are giving great advice (as always!).

Looking at your jobs ahead, I'd deal with exterior ground level first because if you tackle downpipes and then lower the ground level, you'll have to extend the downpipes again. A Zebcolm trench could work in addition to a lower exterior ground level. I also like Housewinnie's solution because it's temporary and you get water for the garden during dry spells. Double-win!

There are probably multiple causes involved and as you eliminate them, one by one, you'll see changes. Sometimes they take effect over a long time like a couple of years. We removed the concrete facade on this house and it's taken about 2–3 years to see the full effect.

 

[brianos]

Search on here for “Zebcolm trench” for ideas how to reduce exterior ground level which might work for you, might not work for all 4ft but would at least help

Thanks Twig. Yes, are definitely going for a trench, however, we've selected one thats likely to be a cheaper version of the ZebColm'O'Matic500++ trench system (tm) (C)opyright.

 

[brianos]

Outside kitchen wall. You could put a water butt in and then run a hose from the tap away. Not pretty but a fix that has worked for us

That's a genius idea Housewinnie!
Not sure if I mentioned it previously but I did some tests and established that the soakaway is filling up after about 10 minutes of heavy rain! Plus, there are about 3 different roofs all feeding into the same soakaway.
So, we're going to do some redirection of one of the major roofs so it all goes to a different exit (out onto the road).
Regarding the soakaway being full, I'm not sure what to do. I guess its a case of find the old one and dig it up and refresh? I dont have money for that so maybe the patented HouseWinnieButtSystem (That doesn't sound right) will be a good solution for now.

 

[brianos]

@brianos Nice photos and post. I'm curious to see what happens next, please keep us updated.

For what it's worth, my experience has been that any fix that starts from the forum's golden rule – prevent and release trapped moisture and water vapour – leads to a solid improvement.

Anything that seals water out typically seals water in behind it and I'd avoid that. I'd say no to waterproof membrane or slurry. Waterproofing/sealing fixes are false solutions that store up trouble for the future. Malcolm and A Twig are giving great advice (as always!).

Looking at your jobs ahead, I'd deal with exterior ground level first because if you tackle downpipes and then lower the ground level, you'll have to extend the downpipes again. A Zebcolm trench could work in addition to a lower exterior ground level. I also like Housewinnie's solution because it's temporary and you get water for the garden during dry spells. Double-win!

There are probably multiple causes involved and as you eliminate them, one by one, you'll see changes. Sometimes they take effect over a long time like a couple of years. We removed the concrete facade on this house and it's taken about 2–3 years to see the full effect.

So, I chipped away the internal walls. The ones in the kitchen which is subterranean by about 4 foot (and where the downpipe is leaking to) was wet. I'm still unsure what to do here regarding damp proof membrane. Everyone here says dont do it, yet ever builder I've spoken to, including a 'Damp Detective' says, put a damp proof membrane in for those walls. Also, I'm uncertain if I will be succesfull in resolving the standing water issue outside on those raised walls!. So, Jury still out on that one.

In other news though, I chipped back a bunch of other walls which were supposedly 'sopping wet' according to a surveyor, and they all looked dry to me?! pictures attached. I'd appreciate your opinion on those walls? I was thinking that they'd be fine just to re-render in lime and let breathe

 

[housewinnie]

Our main roof drainage runs down the down pipe and meets a piece of large guttering placed at a slight angle then runs away onto the lawn. Works great. Just get a little creative amd get the water running away from the house.

 

[DampedOut]

So, I chipped away the internal walls. The ones in the kitchen which is subterranean by about 4 foot (and where the downpipe is leaking to) was wet. I'm still unsure what to do here regarding damp proof membrane. Everyone here says dont do it, yet ever builder I've spoken to, including a 'Damp Detective' says, put a damp proof membrane in for those walls. Also, I'm uncertain if I will be succesfull in resolving the standing water issue outside on those raised walls!. So, Jury still out on that one.

In other news though, I chipped back a bunch of other walls which were supposedly 'sopping wet' according to a surveyor, and they all looked dry to me?! pictures attached. I'd appreciate your opinion on those walls? I was thinking that they'd be fine just to re-render in lime and let breathe

I guess I'd like to ask: are you doing some of the work yourself then? Because if so, then you can give yourself a little permission to experiment and potentially re-do things or change tactics later. Why not do something that's reversible as a test? I'd take the cement off so long as the walls look and act stable, then lime, just like you said.

Outside, I think you will need to look at some kind of French drain or Zebcolm trench system to help direct the water where you want it and away from where you don't. A rain butt is still a great idea too.

I had a structural engineer by about a different kind of issue and he also suggested a damp proof membrane and dry lining for that problem. And then he said, "but then you'd just be chasing moisture elsewhere in the wall." Bit of a having your cake and eating it too, it felt like. I'm just saying that it is a standard offered solution, even by people who know it will cause trouble elsewhere. I'd stay away from it and see if you can solve in other ways.

 

[brianos]

I guess I'd like to ask: are you doing some of the work yourself then? Because if so, then you can give yourself a little permission to experiment and potentially re-do things or change tactics later. Why not do something that's reversible as a test? I'd take the cement off so long as the walls look and act stable, then lime, just like you said.

Outside, I think you will need to look at some kind of French drain or Zebcolm trench system to help direct the water where you want it and away from where you don't. A rain butt is still a great idea too.

I had a structural engineer by about a different kind of issue and he also suggested a damp proof membrane and dry lining for that problem. And then he said, "but then you'd just be chasing moisture elsewhere in the wall." Bit of a having your cake and eating it too, it felt like. I'm just saying that it is a standard offered solution, even by people who know it will cause trouble elsewhere. I'd stay away from it and see if you can solve in other ways.

Thanks Damped out and team. My original post was in June. This is an update 3 months or so later! Here's what I've done so far! I paid a builder to dig a French Drain, and having new gutters and downpipes installed. Some pics below. Exciting stuff. I (slap my wrist) installed a slurry in a couple of subterranean walls which were wet (french drain and new gulley with new soakaway pipe into nearby stream should address). Like I said in original post, I was advised to DPC and slurry membrane the whole place.. and its a big old place so at least I've only been naughty on a few walls in the kitchen.

My one remaining challenge is that some walls get soaking wet. like, drops of water on the walls and the paint on those walls becomes wet to touch. If I chip back to the outermost level of gypsom, it also looks wet. My assumption is that this is condensation? If so, I;'ve never seen anything of the like before (I've always lived in shiney new modern houses!), so I'm intreagued as to why its happening only on certain walls (one wall was internal, and the other external), and in certain rooms only. We've had the doors mostly open during the summer, and live near a river so perhaps its just moist... and no heating (since we had it all ripped out)...

fun and games.



I guess its a case of wait and see now!

 

[brianos]

That's a long question to try to answer. It's good that you aren't thinking about DPCs and tanking as that will make things worse. Breathability is much spoken about and that's based on the very simple idea that if more water gets into a wall than can get out again the wall will become wet. There isn't normally a lot of water getting into walls so just making sure the wall is breathable should prevent it from getting damp.

Occasionally you can get too much water coming in. Leaky or overflowing drainage and high exterior ground levels would need sorting first.

Pink plaster is gypsom. It's not all that breathable and very often it is on top of cement or something even less breathable. Lime would be much better and with breathable paints would go a long way towards fixing the problem. It's a lot better to send excess water outside rather than have it inside so concrete render and plastic paints outside are a bad plan, and people are less likely to paint a nice looking exterior in magnolia emulsion so the breathability will last longer.

Probably worth searching some of those topics on the forum - there's a lot of good information on here.

What is your advice for filling big holes in walls (from inside). how best to fill the hole and then render and paint? is all breathable materials the must do? Do you have product names I should use?