Rotten joists and high ground without any drainage

[Suea159]

Hi everyone. Hope i can get some advice on what to do with external ground levels. We have rotten joists in our 1893 victorian mid terrace due to high external ground levels which we have now lowered. The problem we have is that our front yard area is only 3 foot wide until you reach the small front wall next to the public path that over the years has become higher than our floor level so there is no where to drain water off . We now have a one foot drop from the front gate then 2 feet of low ground then a step up into the house of one foot.
We have no drains and no way of making the ground level slope away from the house as it will just hit a foot under the pavement outside.
We were going to put in a gravel channel next to the house wall then raise the ground back to street level but I fear this will end up becoming a moat where water just sits against the wall again.
Any advice please?

 

[RonnyRaygun]

Dig out the soil for the whole front garden area to 450mm or so below ground level, coat the masonry with a couple of coats of Black Jack and replace soil with free draining gravel to within 150mm of DPC / FFL?? You could then put some pots out there to brighten things up if you wish. Just a thought…

You’ll need to see if your wall dries out above DPC, as there’s no guarantee your DPC hasn’t failed on a property that age, but your joist ends shouldn’t touch the wall anyway. You could protect your joist ends / floorboards / skirtings with a bit of DPM up the wall to the top of the skirtings?

 

[Suea159]

We don't have a DPC . We have dugout to 150mm below the joists which is the beginning of the very shallow footings, so we can't go any lower to enable us to put gravel on top. Any thoughts?

 

[nitro23456]

Raise floor level internally?

 

[John D v2.0]

Those joists have been replaced before. They should have been treated ones not standard.
If it was my house I would say replace joists with treated with 1 inch gap to all masonry walls,
injected damp proof course at the front (optional as it can be controversial),
dig out front yard as you have done
Build up level only as required for level access from pavement to door.
Leave remaining area as a permeable drainage area at least 3 inches below the bottom of the joists equivalent level.
Ensure air bricks are present and clear and above external ground level

 

[Suea159]

Thanks John, I think that's what we've decided to do.

 

[John D v2.0]

Oh and consider insulating the floor while you're in. Hang netting from the joists and put in loft insulation. But make sure there is a clear path for ventilation from air bricks to under the floor.

 

[Suea159]

Hi John, i agree insulation would be good, however, we only have a depth of 2 bricks in the subfloor so would be tricky to leave a gap deep enough for air flow. I have a question about the outside ground. We are going to go with your suggestion and build the path to footpath and doorstep level. You spoke about permiable drainage. Should we just leave the rest of the area soil and put some geotextile membrane (already purchased) on top and then 20mm gravel or should we dig out a little more away from the house wall and put in some hardcore then membrane and gravel?

 

[Suea159]

Thank you all for the advice so far

 

[John D v2.0]

I would say regarding the soil, as long as the level is low enough and it doesn't slope towards the house it should be ok with the membrane and gravel. However there is a small risk that the whole street somehow drains into that area and it might fill up, in which case you would need a sump as you suggest or really, something more drastic to be honest.
Regarding the path to the door, try to slope away from the house as far as possible, at least for the first section. And you can do some detailing with an aco drain grid, I'm not sure on the inns and outs regarding vertical dpcs, but whatever you can do to keep water away from the house end the better. Good luck!

 

[Suea159]

Thanks John

 

[JohnD]

We don't have a DPC . We have dugout to 150mm below the joists which is the beginning of the very shallow footings, so we can't go any lower to enable us to put gravel on top. Any thoughts?

cobbles or pebbles or clean broken stone are better to backfill the trench. The large irregular gaps mean they drain better and do not permit water to rise by capillarity.

dig down to the footings, hose the mud out of the eroded mortar joints in the wall and footings and pack with mortar, line the trench with fabric to keep mud out, and refill with large stones. you can put your prettiest pebbles on the top layer for appearance sake, and it will be safe to walk on.

p.s.
there is no point painting the outside wall with bitumen or synthaprufe or similar. It's natural to think this will prevent damp entry, I used to think it myself, but, in fact, water will rise into the wall from below into the unprotected strip foundation (if any) and brick footings. Leave the bricks bare. If the trench is filled with cobbles they can lose a bit of water by evaporation.

 

[Suea159]

Thanks John for all the excellent advice .