Rising damp / hole in the ground

[Zebra]

Quite. Also a bit concerned about a large house nearby which has a sign announcing that it accommodates "Three Lions"... Haven't seen them yet but I do tend to run past quite quickly. Preferably with all my friends in a big group...

 

[Penners]

It might be safer if you change out of your pyjamas...

 

[Zebra]

:lol: A disguise you mean? Yes, good idea...

 

[LadyArowana]

Lions might not be so easy to fool, but it maybe worth a try....

 

[Zebra]

:lol:

It's the ears that give it away. What does one do with one's ears?!

 

[Penners]

Ears are difficult to hide, but it might help the disguise if you lose the Mohican.

 

[Zebra]

I have an update and another question, if you all don't mind:
Rising damp is still coming from problematic corner of house, even though I've removed all cement render, dug concrete slab up for 300mm inside affected area, lowered external ground level, and emptied nearby rainwater hole.
A few of you have been kind enough to advise that I must just wait for it to dry and it might take til next year.
However, it's wicking all the way up through the ground floor walls and making the timber ring beam wet, on which sit the joists for the upstairs.
I already had to repair this corner of the frame because the three pieces of timber which were supposed to form the corner weren't actually touching any more. And now the repair is getting wet along its bottom, soaking up from the brick. I'm a bit worried about it, and so perhaps foolishly I'm ignoring Flyfisher's comments about letting it dry out naturally, and I'm running an electric radiator underneath this corner, one hour on, one hour off constantly, to try to evaporate the moisture before it gets to the timber. (If the mortar cracks, I'll repoint again).
If the causes have been addressed, where is all this moisture coming from?!
A few metres away there is a raised garden - a retaining wall and then soil up to about knee height. Could this be affecting the water levels in the soil here?
And to what extent should I be worried about the timber? If the timber is open to the air, is there any harm in it getting wet?
Here's a pic of the repair I did, and the wetness on the timber:
Thanks for any more musings...

 

[Penners]

If the causes have been addressed, where is all this moisture coming from?!

That's one of the great questions of life, the universe and everything, I'm afraid. And to be frank, the fact that the moisture persists means that all of the causes haven't been addressed. Or perhaps they have and everything is still drying out. But nobody can be certain.

Personally I think it's more than likely that residual moisture in the ground and the wall is still finding its way into the sole plate. This may disappear in time - or it may not. But remember that it's only been a few weeks since you first posted here about the problem, and an even shorter time since you undertook your remedial measures. Think of all the water that poured into that soil-bottomed hole over the years, and it will become apparent that this is going to take a very long time to dry out. As Flyfisher said, you may have to wait a year or more.

By the way, have you definitely diverted all of the various run-offs that were emptying into the hole? If so, are they now draining a good long way away?

I'm not sure how effective your electric radiator treatment will be at resolving the problem. Are you ventilating the area effectively as the same time that you're heating it? If not, I fear that the air may quickly become saturated, preventing further evaporation. So your heater won't be of much benefit to anything except your electricity company's profit-and-loss account! To be honest I'd save yourself the expense. The joist isn't going to rot away over the space of a few months.

Is there a DPC between the joist and the brick pier? If not, then I think I would take a pragmatic approach and try to cut a piece in. I take it that's a flooring joist, supporting an upstairs floor, is it? If so, then although it's a slightly tricky job, if you use an Acrow prop carefully, you might be able to just ease the joist up by a couple of mm, sufficient to slide in a piece of DPC. It's worth a try.

 

[Flyfisher]

I agree with Penners about the electric heater. If you really wish to speed up the drying out process then I suspect that a dehumidifier would do a better job.

Think about things from the building's perspective. It wants to get into equilibrium with its immediate environment, which, thanks to that big underground pond, was rather damp to say the least. You've now taken that away and the immediate surroundings and your house will be in the process of finding a new - and hopefully drier - equilibrium. But I'd be very surprised if this could happen in the space of a few weeks.

 

[Zebra]

By the way, have you definitely diverted all of the various run-offs that were emptying into the hole? If so, are they now draining a good long way away?

Yes, hole is now dry, all water falls into a bin with a pump, which pumps it into the main drain. A temporary measure but definately takes the water away.

Are you ventilating the area effectively as the same time that you're heating it?

Well, my house does have one big ventilation challenge which I will not ever be able to overcome, which is that all the windows and doors are on the front, so there is no through draught, but at the moment there are holes in the wall and vents aplenty, and no ceiling upstairs so air can go straight through the roof membrane.

The joist isn't going to rot away over the space of a few months

Thank you for your reassurance, this is exactly what I'm most worried about.

I take it that's a flooring joist, supporting an upstairs floor, is it?

Yes, in the foreground of that picture are the joists supporting the upstairs floor. The one nearest to the problem area isn't fixed and will be no problem to lift out along with the floorboards. But the timber above the brick is an external wall. Nevertheless, we jacked it up when we repaired it, so it would be possible to do again.

your house will be in the process of finding a new - and hopefully drier - equilibrium. But I'd be very surprised if this could happen in the space of a few weeks.

Yes, you're no doubt right, and I wish I could see in my crystal ball whether it's dried out on its own in a year's time before deciding whether to take more action. I find it's hard to be patient when you've got damp timber!!

 

[Flyfisher]

Yes, you're no doubt right, and I wish I could see in my crystal ball whether it's dried out on its own in a year's time before deciding whether to take more action. I find it's hard to be patient when you've got damp timber!!

I know the feeling only too well. All the experts I spoke to before taking on our house were far more relaxed than I was about all the faults, even though the roof had been leaking in many places for many years. The general view seemed to be that the house had already survived 450 years so it was unlikely to collapse in the next few years even given its generally poor condition.

This view was borne out when I repaired the roof, which included fully stripping it down to the timbers. Yes, there were some repairs required but only a few timbers required complete replacement. In fact, I think more water damage was done to the upstairs ceilings than to the timbers themselves. 3-4 years on, the house has shaken off that clammy damp feeling, even in the parts of it that still have no heating.

So, while I endeavour to always stress my limited experience, it has certainly been the case that sorting out the basics and then applying a generous measure of time has worked for our house. I don't mean to sound grandiose about it, but it sometimes seems like being a doctor (not that I have any experience of thet either!) - the body (house) is remarkably resilient and good at looking after itself but every now and again it needs a healping hand to cure a particular problem, after which it will recuperate quite well in its own good time.

 

[Zebra]

I'll try to bear that in mind, and remember not to chop off the patient's arm because it's cut it's finger.

 

[Lime]

If the causes have been addressed, where is all this moisture coming from?!

And to be frank, the fact that the moisture persists means that all of the causes haven't been addressed. Or perhaps they have and everything is still drying out. But nobody can be certain.
.........

A leak from an internal pipe may be very small indeed but that is all it takes to saturate a wall.
I suspect that there is still a leak into the wall somewhere.

 

[Zebra]

There is no plumbing anywhere near there.....

 

[LadyArowana]

There is no plumbing anywhere near there.....

Well then that's obviously the problem, the water isn't in a pipe the way it should be, even I know that and I'm a girl :roll: !

 

[Penners]

Isn't it wonderful the way that a female mind can bring an entirely new perspective to a problem?

 

[Lime]

When rebuilding the tile floor in my parlour I discovered an old lead water supply pipe under the tiles.
It once fed a sink but had been stopped off and buried under the tiles.
It was and is still connected directly to the mains from outside the house.
I did not know of nor was there any sign of its existence.

 

[Penners]

A surveyor once told me that the great majority of this country's underground infrastructure - water, drainage, electricity - is completely unmapped. Nobody knows where all the legacy pipes and wires are and whether they're still in use or not.

 

[Feltwell]

Quite correct Penners, and if it is mapped at all then it's vague at best - from someone who has had to trace services before roads are dug up in the past!

Power cables are quite easy to find, you use something called a "Cat" - Cable Avoidance Tool I think it stands for, you scan the ground and it detects the current in the cable, it's a bit like using a metal detector in operation. Doesn't tell you how deep the cable is though (or at least they didn't 20 years ago when I last used one), see my other post!

BT copper cables are usually OK, they are fairly well mapped and you have service boxes that you can open and attach a "Genny" to the cable - a signal generator, which sends a pulse down the cable that you can then scan for with your "Cat". Likewise, this method works for metal water pipes, so long as you have a bit open somewhere to attach the Genny to. So if you need to trace your lead water main to your house, hire a "Cat & Genny" from a tool hire shop and attach the Genny where the main comes into your house.

http://www.brandontoolhire.co.uk/directory/prodview.asp?idproduct=289

Sewers aren't too bad as you can usually find the manhole covers and know that generally they run straight between them.

The hard ones are plastic water pipes, gas mains or BT fibre optic cables. BT used to have special kit to detect their fibre optics, and they would come out free of charge on their "Dial Before You Dig" service and mark them up for you. It's very expensive if you go through those!

Plastic pipes are a real pain though, as whilst they may be mapped all that tells you is that they are in the road and what size they are, exactly where they are is very rarely known.

As a result you can now get kit like this - beats a Dyson any day, but harder to get round the back of the sofa with it.

http://www.vactruck.co.uk/vac_ex.html

 

[Penners]

harder to get round the back of the sofa with it.

...and pretty tricky to find the cat, afterwards.