Vast amount of damp issues!

[Hatster]

Well, after the great response to my question about gutters, I'm back with a few more questions about... damp (surprise, suprise).

We have a 17th century timber framed farmhouse in Cambridgeshire. Most of it has had a
cement render on for the last 50-60 years.

I've got a number of damp problems in the house, and I'm looking for some extra opnions
on what might be causing them.

1. Damp problem number 1

This problem is in a 17th century brick 'extension' with three external walls, one
with a cement render outside, two with (masonry?) paint on the outside. It has a large inglenook fireplace
with a bread oven. We've removed the decrepit old wood-stove and replaced it with
a new wood-stove. It also has quarry tiles which I think are probably set in
concrete, and were probably done about 40 years ago.

We've improved the heating in the house so all the rooms can be kept at a permanent reasonable temperature.

At some point in the last 10 years, the previous limewash was covered in what appears to be some kind of standard paint. In patches around the bottom of the wall, the paint is bubbling up and flaking off. Where the paint has flaked off, there is a white 'fluff' which I believe is
salts leaching out of the brickwork.

There is a particularly dodgy bit of west-facing wall where a pipe leads through to an outside
tap (see picture) but there are several places where the paint is flaking off.



Outside, the west-facing wall was covered in climbers. I've taken all of those
out, have dug out a lot of the soil next to the house, and have fixed a massively leaking
waterbutt.

I've unearthed two drains which were concealed under planks for some reason,
and have removed soil which had fallen into the drains.

These drains turn out to have U-bends - so that a certain height of water is kept permanently in the bend
by the house. I presume that this is to stop smells from the drains, but I wondered
whether it might be causing damp problems. However, I can't work out any way
to check whether there's a leak in the drains. Even cleared and with a drain snake down them, the drains seem to be rather slow to drain away if I chuck a bucket of water down them.

To be honest, the place is damp enough that it's hard to work out whether there
are any extra damp bits which might signal a leak in a pipe or drain.

My plan is to remove the paint on the inside of the room, leave it to breathe for a while, and then limewash
the room.

If that goes okay, I'll also remove the paint from the outside walls, repoint with
lime where necessary, and replace it with a limewash. (Pending okay from CO)

So the questions are
- does removing the paint sound sensible to everyone else?
- does this kind of U-bend drain seem reasonable? is there a way that I can check if it might be leaking?
- is there any way to check if a pipe is leaking slightly in a generally wet wall?


2. Damp problem number 2

This is a mysterious damp patch in our dining room. By the chimney (now blocked up),
the paint and plaster is bubling up and coming away. There aren't damp problems
elsewhere in the room, and this room still has its original brick floor.

View attachment 2

View attachment 1

Any ideas what caused it? (Is the chimney leaking? If so, what on earth do we do to investigate a blocked up chimney in the middle of the house?) And what should I do to repair it? Should it be replastered using lime? I doubt
that much of the rest of the room is done in lime plaster. I'm pretty sure it's concrete underneath, anyway.

Again, the room can now be kept at a reasonable constant temperature.


These are just the first two of a list of different damp patches in different rooms... 8)

What do people think?

Thanks!
Hatster

 

[JoceAndChris]

This won't be particularly useful I'm afraid, but here's some soggy sympathy from one person with vast amounts of damp issues to another.

Where the paint has flaked off, there is a white 'fluff' which I believe is
salts leaching out of the brickwork.

I asked this question, Lime described it as "secondary efflorescence". It's amazing isn't it? For some reason I keep feeling really tempted to taste it. :shock:

The cement render sounds really bad to me and will be stopping the house breathing as I'm sure you're aware. What's the CO said about it? Can it come off?

I think taking off the paint from the inside walls can only be a good thing, I have asked the forum this question myself and not yet received a clear answer (probably because my question is buried in so much waffle!). But you want those walls to breathe, if they are made of lime plaster, and particularly if they are exterior walls.

If I understand you correctly, you're thinking of stripping the paint off the outside of the exterior walls? But underneath this non-breathing paint is cement? So what's the point? I went throught the same decision-making process myself and decided it's all got to come off, non breathing paint, cement render on the outside, cement plaster where we have it on the inside, then re-rendering and replastering and repainting with appropriate and beautiful products. What a job!

Hopefully someone else will be along to talk to you about the chimney and the drain.

 

[Hatster]

Hiya! Thanks for the reply and the sympathy!

The masonry paint is just on the walls with no cement render on - so it's not as daft as it sounds taking it off. Underneath the masonry paint we're down to pure bricks.

I'd love to take the cement render off, but the advice seems to be that it's currently too firmly fixed on - taking it off would risk damaging what's underneath. Of course, it's not doing the timber structure any favours as it is, but it seems to be the lesser of two evils. We'll keep checking it at regular intervals to see whether it's coming loose. (And put some money in the pot ready for that).

I'd not really thought about the cement on the inside - there won't be much house left if all the cement goes - or that's how it feels.

And to top it off, we're now being invaded by a swarm of bees...

Hatster

 

[Flyfisher]

The C17 part of our house is built (mainly) of rubble walls. At some time the outside was cement-rendered and the inside gypsum-plastered. When we took it on a couple of years ago the guttering and a downpipe had been leaking into the wall for many years and there was visible damp inside, complete with flaking plaster and effloresence (and, yes Joce, it is tempting to taste it - it's not as salty as I thought it would be!). The wall was so wet that a timber window lintel had completely rotted to the point of being mostly missing and the window frame must now be supporting much of the wall.

Although I've yet to properly repair all this (because other part of the building were in a worse state) I did remove the broken downpipe and replaced it with a temporary flexible plastic service pipe (the sort of thing used as underground cable conduit) - not pretty, but very functional - and also stopped the leaking gutter discharging onto the wall by fixing some corrugated plastic sheeting to the affected area to deflect falling water away from the wall - again, not pretty but very functional. I then removed all the gypsum plaster from the inside of the wall.

Although this part of the house has been unheated for the past few years, the affected wall now seems to be bone dry and ready for more permanent repair when I've fixed the roof and guttering this summer (I'm working on the principle of top-down repairs).

I'm certainly no expert in all this, but from what I've read, discussed and experienced there are three main steps needed to tackle a damp problem. First, fix the root cause, second, ventilate to allow the damp to thoroughly dry out and third, repair the damage. Not exactly rocket-science, I realise, but I suspect that one of the biggest 'problems' with this approach is the second step, often because people want a quick fix and might not like the idea of living with a stripped down wall for a couple of years - which is probably why the 'honest-john-quick-fix-chemical-injecting-or tanking' merchants remain in business.

I'm fortunate in that we're not living in the affected part of the house at present so bare walls and draughty windows are not an issue and there has been plenty of other repair work to keep me busy. I can imagine such a problem being far more frustrating if you're living with it on a daily basis, but having seen how such a serious problem can almost solve itself given the right conditions I'm now very suspicious of any shortcuts. After all, the problem I've described was probably ticking away (and getting worse) for about 10 years, so expecting an 'overnight' fix is hardly reasonable.

 

[Hatster]

That's very encouraging - with the brick room at least, I'm pretty sure I'm well on the way to fixing the underlying causes.

I need to get a plumber to do some other jobs round the house, so might get him to replace the pipework there to make sure that it isn't leaking.

However, I'm still not sure what the underlying cause for the second damp patch might be (the one in the room with the green-painted walls shown in the pic below). Does anyone have ideas for practical first steps I could take to examine the problem?

Thanks!
Hatster

 

[Penners]

Just addressing some of your individual questions:-

1. The gulleys have traps in them, as you've guessed, to stop smells coming back up them. If they're draining slowly then the pipes may need rodding. Have the gulleys got "rodding eyes"? That is, a removable plate at the back of the gulley that enables you to get rods down into the pipe without passing them through the trap (which is impossible anyway)? If so, then give them a good rodding. It's impossible to say whether these gulleys are leaking - the only way to ascertain this is to empty them and give them a close inspection.

The above assumes that your surface water drains into the mains. If it drains into a soakaway, then there is a possibility that sluggish drainage might indicate a clogged up soakaway.

Do also ensure that the water coming down the downpipes is all emptying into the gulleys, and not overshooting.

2. The above comment about leaks also applies to your question about leaking pipes. I'm afraid careful inspection is the only was to find the answer.

3. As a general principle, if you have a damp wall and you've solved the cause of the damp, then the more that you can expose that wall to the air, the better your chance of drying it out. So removing paint, plaster, etc. is always a good plan. You then need to be patient, to allow as much drying out as possible to take place, before you think about replastering or repainting. And be sure to use lime materials to allow the wall to breather in the future.

There's a general rule-of-thumb that says that each inch of wall thickness will take a month to dry out. But that is only a very broad guideline, and depends very much on the weather and the time of year.

As regards your chimney, I'm not quite clear whether the damp is in the chimney itself, or in an adjacent wall. However, the fact that the chimney has been blocked up could be a clue to the damp. If I were you, I would open up the blocked in fireplace and have a good look around. If the top of the chimney hasn't been capped, it's quite possible that there could be a load of water-soaked rubbish inside the chimney, which is holding the moisture and allowing it to soak anto the chimney walls. Clear out any muck inside, and then block up the fireplace again, but ensure that you leave a breathing vent in the chimney wall - an air brick or similar.

Then install a ventilated cap of some sort on the top of the chimney. This will allow air to circulate within the chimney, but prevent rain from entering it.

You should also ensure that all external flashing around the chimney stack is in good order.

 

[Hatster]

Many thanks, Penners for your wise words (as always). I shall investigate further and report back on any findings!

 

[Lime]

does removing the paint sound sensible?
It is the cement you need to remove.

I don't know of any clay drainage system of an age that does not have leaks.
It is one area of building that properly-laid plastic is effective long term.... and I hate plastic.
Your clay piping will leak.


Fireplace damp?
Chimney stacks catching water in exposed brickwork (top part usually) and water migrating down through bricks is a common cause.
Blocked cavity prevents any internal drying.

 

[Penners]

It is one area of building that properly-laid plastic is effective long term

I do agree with Lime. Plastic drains are an enormous leap forward from previous designs/materials.

 

[JoceAndChris]

The masonry paint is just on the walls with no cement render on - so it's not as daft as it sounds taking it off. Underneath the masonry paint we're down to pure bricks.

I'm a bit confused about whether your damp is worse on the wall with the cement render or not. To clarify, you have a brick extension some of which has cement render and some of which has no render but inappropriate paint inside and out. Is that right? You want to remove the paint from the inside and outside but leave the render intact?

You're right- it can be hugely damaging to remove cement render - look at what's happened to mine:

But, damage occurs anyway if moisture is trapped beneath 2 unforgiving unbreathing layers. Over time it just crumbles and disintegrates with rot. That stone was saturated when I took the render off. Now it's drying nicely. (Admittedly, it's going to be a b****r to repair) But, if it was my house, I'd be thinking about where and how I could remove cement in the damp sections, and then how I could repair and make good using lime mortars, renders, and paints, as it used to be.

 

[Hatster]

* Hatster adds 'replace clay drains' to the list of jobs to do *
* Mr Hatster looks at costs and tears his hair out. *
* Hatster reminds Mr Hatster it was his idea to buy a 17th century house, and all she had asked for was a larger garden. *

That's right - in the brick built room (the first photo), there are two external walls with masonry paint and no concrete, and one external wall with concrete render and no masonry paint. Inside, there's inappropriate paint on all walls. The damp is really bad on one of the masonry-painted walls (the one which also has the drain and used to have the vegetation), and there's slight damp on the other walls. That's why I'm thinking in the short term, I should take the paint off inside and out, but not the cement render. The logic is that the paint is going to come off nicely without damaging the bricks, and the paint is where the problem's worst, while the cement render obviously isn't doing the house any favours, but tentative banging at the render seemed to do more harm than good. Does this make more sense?

More re. chimney later when I'm not at work...

 

[Hatster]

p.s. thanks for the pics, Joce - looks like it's going to look wonderful in the end!

 

[JoceAndChris]

Does this make more sense?

A lot more sense. In your case it sounds like the vegetation and the drain are priority evils. And taking the paint off the non cement walls has got to be the way to go. (though I wouldn't bother touching it on the exterior of the cement render- however, might be wrong about this, if you are planning to use limewash can limewash sit on top of non breathing paint and cement render? And the 2 paint finishes are very different, so I suppose if you left it you'd end up with an un-homogenous mess on the exterior)

A very good idea to blame husband for all serious purchases, by the way, but you do love your 17th century house nonetheless don't you?

while the cement render obviously isn't doing the house any favours, but tentative banging at the render seemed to do more harm than good.

I have to confess to full on banging at the render with tools I'm too embarassed to name publicly, but suffice to say that banging the render was very much frowned on by several much respected members of this forum, if you read the thread "Stripping Exterior Render" I seem to remember DaveBrigg gave some excellent advice on how it should be done.

Don't hold your breath for pics of my house looking nice or finished anytime soon- but thanks! Hopefully will be all sorted by 2035.

Good luck with it all anyway!

 

[Penners]

Hopefully will be all sorted by 2035.

By which time a substantial number of today's bijou executive dwellings, standing by their overcrowded thousands in places called "Duckpond Meadow" or "Daffodil Fields", will be crumbling to dust.

 

[Hatster]

Oh yes, Penners! You'd think that calling a new development 'Wellbrook Way' would set alarm bells ringing in a few minds, wouldn't you? But I'm told it's only the affordable houses that are in the bit that floods.