Damp under Edwardian house bay

[Tangus]

I wanted to ask advice please regarding the wet patches we have under our front gf bay windows on our Edwardian house. (It's the same house I asked about the pointing ie lime or cement on another post)

It has had cavity wall insulation put in at some point but it's not on the ciga register sadly so we can't afford to remove it.

The outside has been painted over so I'm thinking its either.

1) condensation internally as both sides don't have the radiator on and it wasn't there in summer when we had the survey done!

Or

2) that the insulation has got damp and failed and due to the painted bricks outside (Accrington bricks), it's bridging and coming out internally.

I doubt the second option only because it wasn't wet in summer and as the damp isn't rising - how would it have got inside if the bricks are sealed. (We have quite high sun floors and ventilation).


Ps internally there are two rads (one on the middle of the bay) and a gas fire which of course creates moisture, but the room is 3m high ceilings and is around 17' x 15' so not tiny. We only have the gch heating on maybe an hour a day.


Thank you

 

[aockenden]

So you're saying the cavity has been filled with some kind of blown-in insulation crap which is packed tight filling the entire gap between the outer and inner skin of bricks and pressing against the inside surface of both skins? If that's the case, then couldn't you take a few samples (drilling through the mortar joints between the bricks) either from the inside or the outside into the cavity to see if the blown-in insulation is sopping wet?

Then if all your samples of the blown-in insulation are all bone-dry, it would narrow it down to being more likely a condensation issue. Also you could rent a thermal imaging camera and see if that part of your internal wall is colder than the rest of your internal walls, which would also support the conclusion that it's due to condensation. What are the typical relative humidity levels in that room?

 

[Tangus]

Hi there,

Thank you for replying.

Yes we believe it's got those grey ball insulation as it's everywhere else in the house.

The only issue with drilling into it is that it would create a pocket then and cause issues - but a thermal camera would be less invasive. Will check on where I can get one.

Not sure on the humidity levels but we are going to get a dehumidifier in soon to check it.
It's generally a colder room because it's north east facing and large

 

[housewinnie]

Our old house had bay windows and they too always suffered from condensation. They just always get so cold.