Wet patches bay window - help :)

[Aries491]

Hi Everyone!

Wondering if I could have some help and advice, we currently live in a 1920s mid terrace property and for a while have had some issues regarding wet patches on the wall under our bay window. They are very random and patchy and only seem to happen in cold and wet weather, when we air the room out they dissappear and they also aren't visible in the warmer months.

We have had a few people out to look at it but no one has come up with anything conclusive as to what it can be so wondering if any wise people on the Internet can help :)

I have attached some pics, please ignore the pumpkins lol but you can see the outside of the front and some images of the patches indoors.

Any advice is most welcome and thanks in advance.

Have a lovely evening x

Images didn't seem to attach:)

What is the height from the inside floor to the top of the window fill.
Those massive airbricks are very high, they are usually below the damp proof course.
Speaking of the dpc, those slabs are too high, they should be 5” lower at least. The rule is minimum of 150mm (2 corses of bricks) between ground level and the DPC.

@C4tastrophe it is around 2ft the height from floor to window sill.
Ah okay so would it be a case of us removing those slabs outside (the raised area I assume you are on about?) And getting the air bricks relocated to the correct place?
This is all as the house was when we bought it, nothing arose on surveys or anything regarding this and it didn't happen for the first year or so! Just find it odd how it clears if we air the room out and doesn't happen in warm months.

I’d start by lowering the ground level outside as much as you can , the more the better, and go from there.

2 ft is 8 courses of bricks. This means your internal floor height is about level with the slabs, whereas the slabs should be at least 2 courses of bricks lower.
It looks, by those drill holes, that there has been some sort of activity with regards to injecting something into the brickwork.
What are the neighbours airbricks like?
At a minimum, you should remove the slabs and lower the ground level around the bay. Doesn’t need to be wide, and you can back fill it with large ‘pebbles’ if it’s a trip hazard.
For the airbricks, you need to stop the rain getting in, but ideally leave them there as they will help dry the cavity. Do you have wooden or solid concrete floors?
If you have more airbricks then they should be wooden. What height are the other airbricks compared to the bay ones?

I think rainwater is splashing off the slabs and making the wall wet.

Yes, remove the slabs and reduce the ground level against the house by at least two bricks.

I don't believe the airbricks are at fault.

Look at the gutters and downpipe. If water is dripping, spilling or running at the front of the house it will make the wet worse. There is probably a broken and leaking gully as well so look for this while digging out.

I fear the bottom of the cavity will be full of builders rubble.

BTW the holes illustrate that silicone injections and magic do not cure damp.

Thanks @C4tastrophe in terms of neighbours air bricks I will need to take a look in daylight and see what they are like. No one else has this raised bit at the front like ours though I know that much. Flooring is floorboards (we have carpet on top).

@PigletJohn thanks for your response, will look at getting someone to remove the slabs out front and seeing what lies beneath haha! Forgot to mention in the original post our house is raised and set back from the street so steps up off the street then a front patio bit so we are a suspended floor I assume on the front? Not sure if this would be making an impact on these mysterious wet marks?

Agreed on the injection it doesn't cure damp, that was works done prior to us getting the property.