Damp issues in my new flat - French drain or reduce ground level or both?

TranceNRG

david1951 wrote: »

There is an element of trial and error. The first place to start would normally be the cheapest option (dig a ditch and put some gravel in) and go from there.

I'm no expert but I think a French drain would be the ditch + gravel but also an underground pipe buried in the gravel that collects water flowing into the drain, and takes it away from the house.

There is no silver bullet but often the simplest solution can be the most effective.

Hi David thanks. Yes this is the simplest and cheapest option however if it doesn't' work then I'll have to end up forking another 4K or so remove the patio, lower the ground level and add a new patio. I'd rather get it right the first time so that's why I'm asking people hoping that some have been in this situation. My landscape gardener (who seems like a nice guy and he's been recommended by a mate) is not convinced the french drain will resolve the issue considering the ground level is quite high but then again he'll get a lot more money if I go for the new patio option.

david1951

TranceNRG wrote: »

Hi David thanks. Yes this is the simplest and cheapest option however if it doesn't' work then I'll have to end up forking another 4K or so remove the patio, lower the ground level and add a new patio. I'd rather get it right the first time so that's why I'm asking people hoping that some have been in this situation. My landscape gardener (who seems like a nice guy and he's been recommended by a mate) is not convinced the french drain will resolve the issue considering the ground level is quite high but then again he'll get a lot more money if I go for the new patio option.

I chipped in as I am kind of in the same boat, in that my outdoor levels are too high. The pavers in the back garden are at the level of the air brick which is not a good thing. However, I don't have any damp so I'm in no rush to fix it. Keep us updated with whatever you do, especially if it works or not (even if a few months down the line).

TranceNRG

david1951 wrote: »

I chipped in as I am kind of in the same boat, in that my outdoor levels are too high. The pavers in the back garden are at the level of the air brick which is not a good thing. However, I don't have any damp so I'm in no rush to fix it. Keep us updated with whatever you do, especially if it works or not (even if a few months down the line).

will do David. I'm going to take a few days to decide - going to have to ask around more as it's a lot of money. I want to get this right and not spend money on unnecessary things as I'm still recovering from financial pressure after doing a full refurbishment.

TranceNRG

Does anyone else want to add anything else?

In summary should I

1. Keep current patio but have a french drain around the house (remove a row of bricks to create the french drain)

2. Remove, current patio, lower ground level, have a french drain with a new patio - is a french drain needed if the ground level is lowered?

Thanks.

G_M

A French drain or weeping tile is a trench filled with gravel or rock or containing a perforated pipe that redirects surface water and groundwater away from an area. A French drain can have perforated hollow pipes along the bottom to quickly vent water that seeps down through the upper gravel or rock.

To me, a French drain is "a perforated pipe" that carries water away to...... somewhere else, whilst also letting it seep out through the holes and soak down .

However, if it's also "a trench filled with gravel" then, yes, I installed a French drain!

I don't think it matters whether you do 1) or 2) above, provided the ground/soil/slabs whatever are not touching the property walls above the recommended level - that is what causes water to seep through (penetrate) the walls and cause internal damp.

Of course if the general lie of the land means that there is a slope leading down towards the property (eg it's built on the side of a hill), then you get an adiional prospective problem: not just penetrating damp from adjascent soil, but possibly surface water running down against the property wall. If that's the case, yes, you need some way to re-direct that surface water or drain it away.

But this does not sound like your scenario.

Apodemus

A French drain can be just a gravel-filled trench or a gravel-filled trench containing a perforated pipe.

In option 2, if the new ground level is a bit below the level of your joists, you might not need the French drain - but the additional cost of digging it while the rest of the work is going on is likely to be relatively little, so I would still go for it.

In your position I think I would give option 1 a try first.

A question, though... Where does the water from your down pipes go? And are you sure that this water is not contributing to the problem? If you do either of your two options, what effect will this have on your down pipes and their soakaways/waste pipes?

TranceNRG

House is built on flat land and I think the current patio is sloped away from the house.

In regards to down pipes, the water all goes in to the main drain so I don't think this is causing damp and I can't see any guttering leaks.

Are there any adverse effects of lowering the ground level around the house (and having a french drain as well)? Could the foundation be too dry and could that cause problems?

Thanks.

TranceNRG

TranceNRG wrote: »

House is built on flat land and I think the current patio is sloped away from the house.

In regards to down pipes, the water all goes in to the main drain so I don't think this is causing damp and I can't see any guttering leaks.

Are there any adverse effects of lowering the ground level around the house (and having a french drain as well)? Could the foundation be too dry and could that cause problems?

Thanks.

Could someone please answer this?

G_M

Not that I know of.

Niv

TranceNRG wrote: »

House is built on flat land and I think the current patio is sloped away from the house.

In regards to down pipes, the water all goes in to the main drain so I don't think this is causing damp and I can't see any guttering leaks.

Are there any adverse effects of lowering the ground level around the house (and having a french drain as well)? Could the foundation be too dry and could that cause problems?

Thanks.

Pour a watering can of water over the patio and see what way the water goes, then you will know what way the patio is sloping.