Rising damp?

[jaye900]

Well put. The front door threshold has now been lowered below the path level?
And the only two air bricks - one in the front bay, & one in the rear elevation, are way too high for venting the sub-area.

I have raised the ground outside such that it becomes a slope and the front door threshold is now level with FFL inside and outside. In the process, the air brick got partially blocked.


I am wondering if it will help if I dig a trench around the bay window such that the air brick can be unblocked. One of my neighbours did this. Another neighbour even exposed the bottom part back to bricks. They are the only ones who have done work to the bay window floor area on the street. Presumably if it is rising damp, it should affect my neighbours too?

 

[RandomGrinch]

May I ask about the joists?
Some seem to think that your original joists were rotten, hence more evidence for 'rising damp' - whereas I see joists in decent condition, that you have doubled up for rigidity and insulated. The ground beneath also looks pretty dry, in your original photos.
Was this the case?

 

[jaye900]

May I ask about the joists?
Some seem to think that your original joists were rotten, hence more evidence for 'rising damp' - whereas I see joists in decent condition, that you have doubled up for rigidity and insulated. The ground beneath also looks pretty dry, in your original photos.
Was this the case?

The darker joists were the original ones, and then I have some new ones added for levelling and insulation. The ground below was generally quite dry. I didn't find signs of damp before the renovation project. The damp is found after the renovation is complete, and only on one external side where I have raised the floor level outside.

 

[securespark]

Your ground level is very close to the bottom of the airbrick, which in a property with a DPC would be a problem.

Are you saying the current damp wasn't a problem before you raised the ground level?

 

[JohnD]

Presumably if it is rising damp

It's building defects, including bridged DPC and blocked airbricks.

 

[RandomGrinch]

Before @ree goes apoplectic (again) - I have to say that I agree with him and others that raising the ground level and blocking the air bricks was a bad idea; the underfloor void requires through ventilation to prolong the life of the suspended floor.
However (and again I could be wrong), I don't see that your current damp patches are down to 'rising damp'; this is my rationale:

Although, you have lifted the front yard, you have done nothing fundamentally different to what you had originally. Before any work was carried out, the render was already down to ground level and the DPC was already breached...

But, as you saw from the work inside, the ground was dry and the joists were sound.
I have a similar situation - my rendered solid walls come straight down to a concrete back yard. Without significant ingress from water elsewhere, the ground beneath my house is dry - the concrete acts as a sort of raincoat. Not nearly best practice, but I don't have rising damp.

As I said earlier, I believe the damp around the doorway is from water ingress around the doorframe and off of the bay, through the cracked render and other defects; being trapped inside by the render coating.
IMHO, your photos in post #15 tend to confirm this - the level of the water marks are high, and the change in damp pattern is very 'reactive' to the weather conditions.
It may also be a coincidence that the only other two damp patches are either side of the gutterless bay.
If there was also significant ingress from the air brick, I would suspect that the damp patches would appear closer to the front of the bay, rather than the far sides.

Yes, you need to address the subfloor ventilation and ideally fix the breached DPC, add french drains etc.
But fixing the render cracks and ensuring water from the bay is effectively removed from the walls, may also be a good idea.

 

[jaye900]

Thank you for all the advice.

An update after a few weeks where I have fixed the render cracks and filled the gaps between the doorframe. The damp is still there and is more visible after rain and will disappear after 1 or 2 days of dry weather. Given how high up the wet patch goes, and there is a line of water from the middle, I am starting to think this is less of a DPC issue but water ingress from outside. Any pointers or advice will be appreciated. Thank you.

Please see below a photo before the plastering was done. Some expansion foam used to fix the doorframe. Would that be the cause?


This photo was taken approx 1 week after plastering was done. You can see that the wall is mostly dry except for the same area where there is damp today.


How it looks today.