Temporary floor giving way to mould

[tcm]

If it's that wet you need to lift as much of the floor as possible to air it out, it looks like a lot of it will need replacing anyway.

Increased access will also mean that you can get in there with old towels to mop up the worst of it and give you a better chance of seeing / feeling where the water is coming from.

[Sinead888]

I think you need to provide pictures of the back and front walls at ground level. In a suspended floor, as you have, the DPC should be below floor level and the recommended gap between ground and DPC outside is 150mm (2xbricks).
If, as you state, the rear concrete ground level is above joist level then likely it is above any DPC, therefore there is no barrier to damp soaking through; water will be forced by hydraulics from hi to low. As to the wetting your room experiences I think there is more to it than that and you have not confirmed anything about the blocked chimney.
You can pay for an expert to tell you all this. On the right of the bay picture there are two black pipe ends, what are they?
To reduce high ground near to a wall this method is often successful, solid wall shown, but cavity would be a separate DPC layer on each wall; some extend the channel run off to the surface water drains; common term is French Drain. My Uncle had this done to his Bungalow on sand in Dymchurch, it was partly successful mostly because the pebbles stones were to land level!.
The drilled holes in your picture should go through the brick and then the injected compound can fill the cavity, the idea being there is a barrier between outer brick and inner brick; I think this can be a bit hit and miss as there could be insulation or cement snot in that area of cavity and moisture would still travel across to the inner brick.
Notes: brickwork can take a month per inch height in dry air, to dry out after a good soaking. The channel width about 300mm.

Thank you.
This is starting to sound like it will address two problems I have:
1) - new to me - you say the raised ground level to the rear is a source a water entering/breaching above DPC to cause damp. *Yes, I have "rising" damp across ALL ground floor walls.
2) I need airbricks OR telescopic / periscopic air vents installed to establish air flow...
It sounds like you are saying I need to have a trench trench dug either way to remedy 1 + 2 above, correct?
I've spoken to one builder who's plan is to dig a french trench in the raised concrete at the rear wall in order to place AIRBRICKS (*NOT telescopic air vents). Is there any reason why the telescopic air vents are what I should be going with here?
Is it possible to dig a french trench deep and wide enough, with proper directing of rainwater away from the house, to address 1+2 above, without and problems resulting? Is there any reason to view this air brick placement (with deep enough trench) approach as a less effective / more risky approach than opting for telescopic air vents?
I'm having trouble finding information on or people to do installation of these telescopic air vents. Dies anyone here have guidance on if this the way to go? And how they can be retrofitted into an Edwardian house like mine? (It sounds like I need a trench dug out either way, I'm assuming the difference is the depth)

[aeromech3]

See pictures, Duct 3 might be the minimum you can try; for #1 option still needs a small trench to fit. As repeated the source of so much damp needs investigating be it gutters, chimney, internal pipes and just how high is he ground at the rear of the house?

[Sinead888]

The big question from me here is HOW to place these telescopic / periscopic vents?
One brick guy says it is NECESSARY to go UNDER the house (crawl through the subfloor) to retro-fit there types of vents.
My current brick guy does not want to do that.
Is it possible to retro-fit these telescopic/periscopic vents from the external wall only?

[aeromech3]

Not impossible if you know the location of the old vents and don't mind a lot of excavation (need space to get tools in) Did you look at the Duct 1 diagram??????
You have not answered our questions ?????

[Razor]

I haven't read all the posts in extreme detail but...

If you measure down from a window to the floor internally and externally how much higher is the outside than the floor? Telescopic air vents can be installed from above in the room if you take a section of floor up.