Simplistic Damp Remedy

[ephraim_pule]

Before anyone shouts, "Yes I know it will infringe building regs, water co regs, sewage co regs etc. etc." So I don't want to know if it's illegal. I'm sure it is. Don't waste effort in telling me so.

What I want to know is:

Can you relieve rising damp in walls or falls by drilling out bricks in adjacent inspection holes.

Specifically, there's a 4' x 3' inspection hole only a few feet from the house. I have been told that I can lower the water table under my house by drilling horizontally through the side walls of the chamber into the surrounding earth.

The effect is far from instant but over time water will leach very slowly into the sewer and so reduce the water table with the effect that some/all of the problems may go away.

SO: Answers not accusations about breaking the laws & regs, I know it's wrong but .... will it work?

PS: My advice has come from a "C Eng., MICE" working in Gl;Glasgow for Scottish Ware

EP

[ephraim_pule]

Couple of typos

falls = walls

It's Scottish Water and Glasgow.

(There used to be a preview facility on this site that sorted this kind of stuff out)

Anyway, it's about whether it will work NOT whether it should be done.

My informant says it's very common.... and he's looking into the sewers every day! EP

[Phil L]

I'm afraid he's pulling your p!$$er mate - there's not a snowball's chance in hell of something like this working..it may take a few drops of water away, but it won't make the slightest bit of difference to the water table...you need to aquaint yourself with land drainage systems, IE soakaways, their sizes and how they cope with huge volumes of water, also land drains and how they work, then ask yourself, will a few holes in a brick manhole really make any difference? - it's akin to poking a needle into a pork pie and expecting the filling to drain away.

[ephraim_pule]

Thanks "Phil L",

I'll pass on your opinion.

However, my informant is sure that given time and we're talking months, you can drain the water table below a house in this way. Moreover, his experience in fixing Glasgow's sewers suggests that draining ground water to the sewer is very common even when new separated systems have been built.

But I'm not slagging-off what you've said, what you've said looks like a reasonable point. I look forward to more answers.

EP

[Phil L]

The water table isn't 'below a house', it's below everything, IE all the houses, shops, offices, roads and everything else, it can't be drained away via a few small holes

[Owain]

No.

There might be a *very* localised draining of ground water into the sewer, but then again there might also be draining of sewage out into the ground. I suggest this might be a bit malodorous, and encourage rats.

Civil engineers, eh. Tarmaccers in suits.

Owain

[Owain]

Yes, but that's draining surface water drains into the sewer, not making holes in the sewer.

Owain

[meow2222]

and the problem is unlikely to be rising damp anyway. The majority of rising damp diagnoses are false positives.

NT

[The Natural Philosopher]

Probably up to a point yes.

I had terrible damp in the old house..the new one is fantastic, because having found a small lake under he floor of the old one, when I demolished it (I kid you not) I go very paranoid about it, and we ended up with a gravel filled trench with a perforated pipe running all round the house, to a meter deep and a meter or more wide, and teh outflow of that lot feeds the pond. I can leave a hose permanently running anywhere around the house, and it fills the pond..

However juts taping a hole in the side of the sewer won't really do a great deal unless you are on fairly sandy or permeable soil, in which case you probably don;t have a local water table problem anyway.

What you need to do in analogy, is to create a moat around the property, and drain it to somewhere lower. My friends house actually has a sump and a pump underneath its floor..and a float switch..when it rains, the pump pumps the water out from under. I suspect this might be a better way to proceed.

If you have a proper soakaway that could be the target..otherwise just chuck it into a sewer and pretend it comes from a washing machine.

[The Natural Philosopher]

A lot depends on the soil layout.

And where the water is actually coming from.

i.e. if you have for example soil thats is relativly free draining overlaying something impermeable that slopes..then rain up the hill will come down as an underground flow and feed the water table from below as it were, in which case a hole into a sewer will work reasonably well..

The key is how permeable the soil is..

Roundn here on heavy clay, we do drain land with perforated or porous clay pipes, and boy it really makes a difference..the farmer has perf pipes a meter down. and once every three years he moles diagonally across those..at 500mm depth..

His fields stay relatively un waterlogged, whereas the compacted paths beside them are awash. I have seen the water coming out of those pipes too..a bloody torrent sometimes.

If the soil is a clay, one perf pipe is no good..you need to feed it..and that means a while network of pipes.

If its fairly shingly or sandy, or chalk, you stand a better chance as the lateral flow will be pretty good. But even so the hole in the sewer needs to be connected to a long perforated or porous pipe really.

[The Natural Philosopher]

Oh, thats a very simplistic statement..the LOCAL water table can be - very much so, or we wouldn't use land drains.

And of course on the Fens, we pump the water upwards into the rivers..thereby lowering the water table of the whole of east anglia to somewhat below sea level..

>

[Brian Reay]

I suspect he is confusing "ground water" with rain water run-off. The later normally goes into "soak aways" these days but, in older houses, it was often piped to the sewers.

As regards the original idea, I really think it is a none starter. The quantity of water you'd need to shift to drop the local water table is huge, we aren't taking gallons but 1000s of gallons. If some did "leech" away, next time it rained the local ground would become sodden again and the process would repeat.

Also, the primary protection against rising damp is the damp proof course. That is above ground and above the water table anyway. If that is bridged, water from the damp ground will "rise" but if the water table was so high that the "surface" was touching the bridged damp proof couse, the house would be in a puddle (or lake!).

Check the damp proof course isn't bridged but also explore if the REAL problem is condensation

Brian

[Andrew Mawson]

In my experiance most 'rising damp' is in fact penetrating damp from rain splash. Look at your outside walls when it is raining and you will see a very significant amount of splash up the bottom of the walls, particularly where there is a hard suface like a path adjacent to the wall. The other 'non rising damp' factor is condensation. Water vapour is heavier than air when cold, and will settle in a low layer. If your wall is colder then water will condense out and this will tend to be at a low level as that is where the cool water vapour has settled. The Building Research Council did a lot of experiments trying to get water to rise in various types of bricks that were sat in a bath of water, and iirc they concluded that water rising by capillary action was fairly insignificant.

AWEM