Temporary floor giving way to mould

Sinead888 · Post by **Sinead888** » Wed Mar 01, 2023 1:35 pm

Hi, I'm new to the site. I moved into my house 2 years ago. Pulled up the carpet to find the floorboards from the front half of the living room (downstairs front bay window room of 1890 terraced house, previously removed fireplace) had been replaced with a temporary floor, presumably as part of a damp issue rotting the floorboards. A guy who was going some work for me placed a laminate floor on top, but with no vapour barrier. 2 years later the musty smell that was gradually increasing in the room became too strong to ignore. My brother and I lifted the Laminate floor today to find black mould has infiltrated the temporary floors surface. See pictures. You can also see the make-shift bits of card/wood placed around the fireplace area is wet.
I also, before lifting the floor, made enquiries about my airbricks and, sure enough, there is only one air brick at the back of the house and is in blocked position! A previous owner had raised the ground level out the back of the house by laying concrete. They moved blocked all airbricks and placed just one in too high a position so that it is not actually allowing air access to the subfloor. So I know I need to get that issue addressed and that a chronic lack of airflow under the house is an underlying cause. Any suggestions on a solution for this is also welcome!
But the main question i have is, what do I do with this temporary floor? I was hoping to just put a vapour barrier down and refit the laminate floor. But looking at the state of the temporary floor, perhaps I need to do a better fix?? The fireplace area obviously needs to be sorted too, but how? Any suggestions would be hugely appreciated. I'm in Liverpool L15.

aeromech3 · Post by **aeromech3** » Thu Mar 02, 2023 4:37 am

I think it is a bit more than damp, water seepage perhaps, the square with a finger hole in the temporary flooring looks like an inspection access, worth a look, its about the size of a standard pit access.
As the fireplace has been blocked off, is their a possibility for rain to enter the chimney and seep into the underfloor?

Razor · Post by **Razor** » Thu Mar 02, 2023 8:03 am

I would be checking for an old lead water main that's pinholed. If it is you can usually hear it hissing using a long screwdriver on the tap with your ear on it

I hope the bed doesn't mean someones sleeping in there?

As for the ventilation I would fit some of these to go under the floor and rise above ground level externally

https://www.bcprofiles.co.uk/products/m ... UkQAvD_BwE

dewaltdisney · Post by **dewaltdisney** » Thu Mar 02, 2023 8:43 am

You can see the damp treatment on the bay wall. There is a row of holes for the chemical DPC so I do not think that damp from there is an issue. Firstly check gutters for leaks as you would be surprised how rainwater finds its way into the walls from leaking gutters. As has been said it would be sensible to pull up that inspection panel and check it out underneath if it proves to be an access point.

DWD

Sinead888 · Post by **Sinead888** » Thu Mar 02, 2023 11:00 pm

Thank you. I am going to follow your lead on investigating for a pinhole. I had two tradesmen by for an opinion today and both identified that the joists are all SOAKED. While there is no proper airflow, they both still thought it surprising the joists would be dripping wet

Sinead888 · Post by **Sinead888** » Thu Mar 02, 2023 11:09 pm

Thanks also for the suggestion of the telescopic airvent, I've passed this on to the guy who's going to try and put airbricks in.
No it's a guest bedroom. But I need to fix this as it's affecting the whole house, smell wise, possibly health wise, with the whole downstairs feeling cold / damp.

aeromech3 · Post by **aeromech3** » Fri Mar 03, 2023 8:44 am

Sinead888 wrote: ↑Thu Mar 02, 2023 11:00 pm they both still thought it surprising the joists would be dripping wet

As per my thoughts above thanks.
Usually injected DPC would be into the mortar line not the brick face!
What is the level of the land out side, if it above your joist level then not good.

Sinead888 · Post by **Sinead888** » Fri Mar 03, 2023 10:49 pm

Further to my recent post about mould breaching a chipboard floor...
viewtopic.php?p=865631#p865631

...The joists under the floor, while fairly new it turns out (so, thankfully not rotted) are soaking wet, with the only apparent cause being that there are no airbricks at the back of the house, so a chronic state of no air flow. This has clearly led to a rotted floorboard issue for previous owners, hence half the floor is chipboard (now itself rotting), and the other half is original mixed with newer floorboards.
My question is how do I dry out the joists as quickly as possible? I'm heating the room, with the chipboard manhole open, and a dehumidifer working away. But will that work? Is there anything else I can do? (I won't get airbricks in for another week and the tradesmen are saying it could take months for the joists to dry, which is a problem).
Really appreciating the advice so far. More welcome!

big-all · Post by **big-all** » Fri Mar 03, 2023 11:14 pm

its sounds like far more than just blocked air brick as its soaken wet in many areas now you should alway have good to very good airfow when possible
with zero circulation and zero moisture input it will be dry as all fabric including bricks will let water pass
with a small input it will still evaporate eventually its when the rate off water added exceeds evaporation you get a problem
saturation means the leak or source off water needs sorting first now iff you have covered this already sorry

moderator2 · Post by **moderator2** » Sat Mar 04, 2023 6:33 am

Threads merged. better to keep this all in one thread.

dewaltdisney · Post by **dewaltdisney** » Sat Mar 04, 2023 9:59 am

Drying it all out is important as finding the cause of moisture. A dehumidifier under the boards will extract a lot and speed up the drying out. There are lots to choose from and they need not cost the earth. I am still focusing on that bay wall as the haphazard drilling for what I am assuming is a chemical damp course is actually above the floor level? The damp could still be present?

DWD

Sinead888 · Post by **Sinead888** » Sat Mar 04, 2023 7:50 pm

big-all wrote: ↑Fri Mar 03, 2023 11:14 pm its sounds like far more than just blocked air brick as its soaken wet in many areas now you should alway have good to very good airfow when possible
with zero circulation and zero moisture input it will be dry as all fabric including bricks will let water pass
with a small input it will still evaporate eventually its when the rate off water added exceeds evaporation you get a problem
saturation means the leak or source off water needs sorting first now iff you have covered this already sorry

In response to both replues above; thanks.
Yes, ALL of the downstairs walls are confirmed to be damp half up their height. Presumably rising damp.
There is no visible source of leakage? If no leak can be seen or heard from pipes under the floor, then where else can a leak be coming from? No, the floor has not been closed up, not even nearly.

Sinead888 · Post by **Sinead888** » Sat Mar 04, 2023 7:57 pm

aeromech3 wrote: ↑Fri Mar 03, 2023 8:44 am
Sinead888 wrote: ↑Thu Mar 02, 2023 11:00 pm they both still thought it surprising the joists would be dripping wet
As per my thoughts above thanks.
Usually injected DPC would be into the mortar line not the brick face!
What is the level of the land out side, if it above your joist level then not good.

No the land level outside is below the level of the joists - at least at the front of the house where these wet joists are. **As for the back of the house** where the airbricks have been blocked by concrete of a raised ground level, its quite likely the external ground level is at or above the joist level!... Can you tell me why is that a problem please?
Good to know the positioning of the DPC holes behind the skirting are redundant!

dewaltdisney · Post by **dewaltdisney** » Sat Mar 04, 2023 8:08 pm

It might be an idea to get a quote from a damp prevention company. At least that way they should test the walls with a meter and that will show if the chemical DPC is working, it might be necessary to run a new line lower down perhaps but you don't have to go with it just get the quote so you understand the situation better. Be careful as there are a lot of charlatans in that business. The issue with airbricks front and back is to allow airflow if they are blocked on one side there is no airflow and any moisture laden air will condense on the coldest surface. So my view is to check the damp course, get the air bricks sorted, and use a dehumidifier to dry out the timbers.

DWD

aeromech3 · Post by **aeromech3** » Sun Mar 05, 2023 4:37 am

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.