problem with damp

[brooklyn07]

Hello, looking for some advice about a damp problem I discovered yesterday.

I appreciate it would be easier to diagnose with some photos but camera is on the blink so will do my best to describe.

Its a 1930's semi and my garden slopes downwards towards the house, and there are houses behind which again are stepped up higher than my property.

The house has concrete floors downstairs except for the dining room and living room which are joined onto each other and have suspended timber floors.
The dining room had an extension built onto the back for a new kitchen and any air vents that were in the dining room were obviously blocked up by the extension.

The extension was not built the entire width of the boundary and it ends about 1 foot away from next doors boundary wall, So I have a 1ft alleyway between my kitchen extension and next door.

Where there is the gap, this is exactly where the damp is coming through into my dining room. This was obviously a problem for the previous owners too because they had half of the dining room floor replaced. The floor in that very corner has started to rot away, joists are wet and rotting and the first floorboard is rotten half way. The rest of the floor in the room is not affected, just that one corner but it has started to travel along the internal wall now too.

I'm wondering if because the garden slops down towards the house whether the rainwater is flowing downwards into the alleyway and congregating at the back wall and cant flow back out again and therefore seeping through the wall into the dining room?

Any ideas how I can remedy this? I don't really want to concrete the floor as I really cant afford it right now and was not planning to remain in the property long term.

There is a vent in the front living room but obviously not in the dining room, would the front vent be enough for ventilation?

 

[Nige F]

Front vent alone certainly WON'T be enough. Probably the best thing to do is get the rainwater away somehow . Then check under the floor for rotten wood

 

[brooklyn07]

any suggestion how to get the rainwater away? checked under the floor and the joists and boards are starting to rot....

 

[theprinceofdarkness]

Have you checked your rainwater goods around this area? What is the level of the DPCs with respect to the floor of this dead end. Has the extention's DPC been made of properly to the houses one. Can you put a reverse slope on this narrow bit of ground to get the water to run out.
Frank

 

[mcluma]

One of your options for your rainwater issue, which is rushing along side of your youse is a french drain. - although its going to be hard to do with only 1 foot of working space.

But you need to dig , get the earth out, get a special weeping pipe in there, and backfill with gravel. is there a manhole at the from of the building where you can connect the weeping pipe to?

secondly, you need to avoid that water is getting next to you property, or alongside of your dining room, but you are also fighting the water of our next door neighbours property. so although you can stop it from your own back garden, i do not know if you can stop it from your neighbour

Than you need to get airflow under your building

the builders were never ever allowed to block of air bricks, they should have bridged it through your extension with pipes, this is killing the airflow. and a major source of rot

 

[brooklyn07]

Thanks for all your replies. Ok so basically there is a DPC on the extension part of the house but as far as I can tell there isn't one anywhere else around the house and it looks to me that the part where the water is coming in is slightly lower than the extension which would therefore be a bit lower than the dpc by the looks.

There definitely hasn't been any vents made into the extension via any piping - I wonder why this doesn't get enforced when the planning permission gets approved and signed off!

The manhole is around the side of the building but im not sure how the floor can get dug out to put a drain in because the space all around the extension is extremely confined. I'm thinking the downward slope might be the only viable option to sort this although still not sure how I'm going to sort out the airflow problem....

 

[mcluma]

So, if you can get to the side of the property - although very confined, there you need to dig. lower the ground level. dig to at least a foot below the current indoor floor level (not the finished floor level - but the indoor ground level) then put in a french drain.

make sure run-off surface water is away from your building.

do you have air bricks in the front and side of the room?

On our side extension the inspector was very alert on making sure i extended the air vents by putting in a pipe. and as the pipe has less air movement he insisted to increase the number of pipes

 

[brooklyn07]

ok so I stuck my head under the floorboards to have a look at where the vents were yesterday - it seems there is one in the front room although I don't see how the air will get from the front room into the dining room because there is a wall between the two but we did create an opening between the living and dining room so I presume I could remove the bricks underneath the opening which go down to the floor to help with the increased air flow?
There are no other vents (well there are but they are blocked) as the rest of the house is concrete throughout except for the living room and dining room...

still don't understand why planning didn't insist on increased vents when the extension was built!

 

[mcluma]

ok so I stuck my head under the floorboards to have a look at where the vents were yesterday - it seems there is one in the front room although I don't see how the air will get from the front room into the dining room because there is a wall between the two but we did create an opening between the living and dining room so I presume I could remove the bricks underneath the opening which go down to the floor to help with the increased air flow?
There are no other vents (well there are but they are blocked) as the rest of the house is concrete throughout except for the living room and dining room...

still don't understand why planning didn't insist on increased vents when the extension was built!

I understand your frustration, but done is done. normally they honeycomb solid walls to create the airflow.

and what can you do on the side to stop the water getting in?

 

[brooklyn07]

so im guessing I cant have a vent put at the back of the dining room because the water will get in....

 

[mcluma]

so im guessing I cant have a vent put at the back of the dining room because the water will get in....

Oh,

my fault, i thought your new extension was at the back

 

[brooklyn07]

yeah it is at the back but they left a 1ft gap at the back between the extension and the neighbours wall where the water is getting in so that's the only place I could have a vent but im guessing the water will get through that as its lower than the rest of the ground....