water under house

[macklin]

Because we live at the bottom of a hill under the house gets very wet in bad weather (we have only just moved in). I have cut a channel to drain it. However it is still very damp and wet and I would assume not at all good for the stumps, what can i do. We are the only ones at the bottom so i cannot compare with somebody else, in fact there are only two other houses at the very top.


thank you

Jean Bloom

[echnidna]

Draining its the first step.
Have you got enough room to put 6" of packing sand under the house?

[johnc]

Jean,



Building up the soil level under the house so that it is slightly higher than the surrounding area does work in most cases but make sure you have sufficient air flow or you will provide a breeding ground for rot. In the end drainage to channel away water before it moves under the house is good and you have done the right thing ensuring water drains away. In some cases water can perculate up through the soil from pressure higher up, but this is rare just keep the ground under the house smoothish so water does not pool underneath and a little slope or drainage to ensure it gets away if it does move under the house. If its been damp for a long time you can get cracking of walls etc as the ground dries and the house shifts.

If in doubt get a builder in for a quick squiz, and maybe a few comments about recifying the problem,

JohnC

[Neo]

G'Day Jean,
I agree with JohnC, diverting the water before it gets under the house will go a long way to solving the problem. Even something as simple as some kind of small gutter, berm or swale to divert the majority of the surface water flowing down the hill will have a big effect - if that is the source of the moisture. Water seeping from underground is a little bit more troublesome but there should be a way around it. Then you need to allow routes for the moisture to escape (your channel) and evaporate (ie lots of ventilation) when it does get under there.
How old is the house and is there any sign of damage already caused by moisture?
Is there standing water which will have the added bonus of harbouring mozzies etc as the weather warms up?

Cheers and good luck
Pat

[BigPop]

Maybe this would help.
Putting some sort of guttering/buffer in would help divert the surface run off coming down the hill and also dig a trench and put Ag pipe in and run the pipe right across the back and then run some pipe from that down the sides and then cover with gravel/rubble and this should divert most of the subsoil water.

[jackiew]

another idea ....

my house is on a slope but is bone dry underneath.

It has fibre cement sheets (probably asbestos :eek: ) stuck in the ground to a height of 6 to 9 inches above the ground and the same below the ground all round the outside of the house. These strips of sheeting are painted to match the colour of the timber slats that enclose the underneath of the house and are not at all obvious until you inspect them.

while it won't stop water coming up underneath it should at least deflect surface water elsewhere.

[Wildman]

I would say that ground water is your biggest problem, surface water is easy to divert. If you are diverting the surface water but still have a water issue, I would follow Big Pete's suggestion and put in a "cut off" drain around the house, usually on the high side and the two adjacent sides to cut off ground water. This can then drain to the low side of the house. You may be in an area where there is shallow clay or stone below the surface so any ground water above it is getting pushed up under your house. This has to be collected, preferably all the way down to the clay or stone before it gets to your house.

A cut off drain is usually 400-1000mm deep depending on the soil conditions and wide enough to work in. Dig a trench, get your levels right in the bottom of the trench for best drainage. Line the trench in geotextile fabric (up and over the top as well, lay slotted 100mm PVC pipe in the bottom of the trench all the way around the house so that it can drain past the building then fill the trench with screened stone, at least 20mm or larger up to within 50mm of the surface level. Wrap the left over geotextile over the top and cover with topsoil. The geotextile will stop the screenings getting clogged while allowing ground water to flow into the stones which will then trickle down into the slotted pipe and away from your house.

If you have a groundwater issue, your cut off drain may flow continuously and you will be amazed by just how much water it collects. (I installed one on the edge of a mountain range that did flow continuously from mid winter until mid summer and was collected for use on the garden. It would go close to filling a 5000 gallon concrete tank in a wet year)

I have seen houses built in particularly bad areas with large cut off drains right around the house draining into a sump which was then constantly pumped out by an electric pump. Hopefully you are on enough of a slope that the drain can drain naturally through gravity.

Cheers
Wildman

[macklin]

echnidna

there is enough room for sand.

neo

the house is 12 years old, and there is no visible means of damage, have not looked underneath as I am waiting for it to dry after draining the water. The road outside is a made road with a gutter and a channel right outside where the water goes down into wherever ?????? a horrible suspicion being it goes under our house, I notice there is a lot of green moss on the tar road outside
both before and then for about 50ft after the house I am beginning to get more than a bit curious.

to all the other replies I have put on floppy and will read and study later.

thank you for all the very informative replies

Jean Bloom

[seriph1]

surprised no brissy-ites have chipped in ..... I allegedly grew up in Brisbane and this is an issue lots of folks faced due to the steep gradients of many properties (if the dead mountain goats at the bottom of most, were any indication!) :)

What I recall dad doing was first of all working out where the water was coming from - in our case, runoff from the places above us. so he dug a channel right along the back of the house about 2 feet deep and filled it with this weird multi coloured stone, each piece about 2/3rds the size of a PC mouse.

Then he fed those into a dug trench on either side, running down to the street's gutters from memory. This fixed most of the water issues under the house - which was inordinately important to me as I had a tgrain set running its entire length. (Man, I really miss having an under-the-house)

:D

After doing this, only on BIG storm days did we get wet feet under there. Dad eventually concreted much of it, over a 1 foot, compacted bed of this same stone. I think that pretty much ended the water issues.

Thinking about everyone's replies, it may be best to get a builder/plumber or even Archi-centre in to offer some advice, the latter being the best I feel

http://www.archicentre.com.au/media/archinews3102002.htm

post some pics if you can - might help

[bitingmidge]

One of the biggest issues you will face if you decide to dry the place out, is movement in the foundations/footings.

If the house has been there and standing in a wet pit for ever, it is highly likely that by removing the water source entirely you will dry out the subsoil and suffer consequential movement, even if the soil is relatively stable.

If you have room to get under it, that's probably not too drastic, once all the movement has finished (in a year or so) you'll need to pack the bearers to bring it all back to level...there are a couple of other threads on this board discussing that subject.

You could do worse than taking up seriph's suggestion, but I'd probably just do a concrete channel round the house rather than an ag. drain.

If you decide to build an agricultural drain, line the trench with filter fabric before filling it with gravel, and use a poly ag drain that has a fabric cover, that will give you the best chance of preventing blockages due to siltation.

Cheers,

P

[IanA]

maclin,

Is the water problem chronic or did it just pop up after heavy rain? (If you've only just moved in this information may not be well established.)

Which general area of Vic are you from? Rainfall intensity, as well as annual totals vary considerably across Vic.

The ultimate solution needs to suit your specific climatic conditions and also your soil type. Bitingmidge makes an important point about soil movement, this will depend on the particular clay type. (Assuming it is a clay soil.)

It would be worthwhile contacting the building department of your council. They will have the original soil test report on file, and this will give you valuable insight into potential movement. (There may be a small fee for the info, often $30, but this will be money well spent IMO.)

[IanA]

Oh yeah!

One extra piece of advice.

If you do go to your council for info, get all the info you can.

Usually there is only the one archive search fee plus a small fee for photocopying. Copies of most of the documents in the building permit file may come in handy at some time in the future.
In particular get hold of a copy of the warranty insurance certificate, and details about the builder.

This problem with water under the house should not happen. (Given that is noly a few years old.) Clearly the works do not comply with the requirements of the Building Code of Australia!!!!!

Rectification may be simple, but be prepared!!!

[Toymaker Len]

I'll supply the beer if you will come around and fix it for free Wildman. We have the same problem at my house. We made a cutting to place a slab on the downhill side of the house. The water just started to flow out when we hit rock and now digging a proper drain involves hand cutting through rock. I have bought the pump. Installation comes next.

[macklin]

IanA I live in east gippsland and the rain does seem more than elsewhere.

thank you once again to all replies will add latest replies to my list and then sort it out from there


Thanks

jean Bloom