damp problems

[aaaoldhouse]

I have an old federation house with a damp problem. The house has strip footings and is built on clay soil.
I think we have some sort of natural watercourse flowing thru our block as we have never watered the lawn and it is lush and green even during extended dry spells.
I have installed Aletta wire mesh vents to increase ventilation however the damp problem remains.

the internal walls go thru the floors so there is little cross ventilation at present. Can anyone help out with the best way to increase cross ventilation ? is it safe to simply remove some of the bricks in the sub-floor walls ?

I was also thinking of digging a drainage trench along the front and sides of the house to keep the water which is coming down the hill from making it under the house. The house is built quite close to the fence on one side and I was wondering what is the closest you can dig a drainage trench without doing damage to the foundations.

Any halp/suggestions would be much appreciated as we are getting sick of living in a damp mouldy house.

[julianx]

Hi
This is how it's often done up here in qld. It may not be the correct way to do it in sydney as I think footings down there used to be much shallower on older houses.
To put the drain in you really need to dig right beside the brick wall down to where the footings start put the ag pipe in so that it sits below the top of the footings, seal the wall with a bitumen sealer, then put plastic in front this and back fill the trench with aggregate. the plastic should be that thick stuff that looks like corrogated cardboard, it's there to stop the aggregate from damaging the sealer. make sure the ag pipe is socked ie it has a thin stocking like material around it.

not sure about knocking out bricks

[wombat47]

Your lush green lawn sounds interesting (haven't seen one in quite a while). You or a neighbour don't have a plumbing problem perhaps. I think I would be looking into that.

There are a number of sub-floor ventilating fans available which create air flow under the house. Here's one -

http://www.edmonds.com.au/html/products/subfloor_ventilator_ecofan.htm

If you are going to knock out bricks, you may as install new wire mesh vents at the same time. Holes in the brickwork have no support (not good) and allow entry to various four-legged friends.