Fungus or crystal under floor of my damp house? solution?

[drpepe]

We have a east facing terraced house (built 1901), in a clay soil area and with a lack of decent underfloor ventilation.
View media item 77344
There are:
3 airbricks in the lounge
0 airbricks in the hall
1 airbrick in the rear right of the dining room (no vents to conservatory)
Original solid floor in the kitchen

Although there is a decent space below the lounge floor (~20cm to the joists), there is no ventilation between rooms as the internal walls have no vents in them - see pic below of the lounge/diner wall (LHS) and a lounge pier wall.
View media item 77340
In other parts of the house there is very little or no room between the (very damp) ground soil and the joists - e.g. the hallway in the pic below, which was taken *after* digging out a lot of the soil - the hall is worst for damp/stale smell.
View media item 77342
Also there is widespread florid ,cauliflower-like growth of something under the floor (usually in the drier areas and on some of the wall plates (see pic below of lounge wallplate on lounge/hall interior wall)
View media item 77339 View media item 77343 View media item 77341
We get a lot of slugs in the house too (in all the ground floor rooms) - which is another major motivator to get this sorted.

I'm never going to be able to make the ground underneath drier, so I would like to increase ventilation. Could someone comment on whether my plan below is decent

1) Dig out the 'high spots' in the hall and diner.
2) Introduce conduits between rooms under the floor - can I/my builder just drill through?
3) introduce at least 1 airbrick in the front of the hall - tricky due to ground level, electricity meter etc
4) We plan to replace conserv with an extension in the near future - we will introduce airbricks from the dining room to the rear at that point.

Is the 'growth' something that maybe contributing to the smell? should i dig it out whilst doing the other work above?

Any other bright ideas to rid me of smell/slugs/damp?

 

[ree]

Essentially, to do a proper complete job of work on your suspended floors, the thing to do would be to lift all the suspended floors and wall plates.

If you Search back a little (FWIW follow my posts) and you will see how others had roughly similar situations and how they were advised in the Floors and Building forums.

The "fungus" stuff is harmless crystal.

The joists and plates were replaced say 20-30 years ago. The plates are wet rot decaying. DPC's are absent.

Eventually, Dry rot will enter the picture due to damp and lack of ventilation, unless you re-jig the whole set-up.

Venting tubes can be placed under the new extension. Search for extension pics/section drawings.

Smells and slugs will continue until remedial works are done including an oversite membrane.

Is the kitchen solid or suspended?

 

[drpepe]

Hi Ree - thanks for your comments (i'll have a search through your posts).

We have a builder involved to get this sorted.

By re-jig you mean :

1) Replace wall plates (add dpm), replace rotted timbers
2) introduce ventilation at front hall, between internal rooms and out the back
3) put plastic membrane down in all areas and screed over the top

The issue with #3 is that the hall contains all the utilities - water/gas/electric/soil pipe - how do we get a membrane in there?

Here's a pic of my kitchen floor - i assume it is original and solid. I am quite prepared to get rid of it totally and replace with suspended floor if it helps our issues here...

View media item 77374

 

[gregers]

ventilate ventilate ventilate.

if there is a lot of spoil on your oversites then scrape it up.

if you can remove your skirting boards then YOU might be able to lift the floors in situ??? with a few car jacks and carefully install dpc under the plates,if they are rotten then replacement has to be done?if any of the joists are touching walls then cut them back and maybe wrap the ends with dpc.
spray all timbers and walls with a biocide combined woodworm/rot fluid.

as allready said install dedicated pipes from airvents to the dead spots under your floors.

 

[ree]

No screed is necessary over a membrane.

The hall area - you can simply flop a membrane over any utilities that are running across the oversite. How come the soil pipe is down there - is your bathroom at the front of the house?

The hall joists in the pic appear to be sitting on the soil? Once the floor is up it will become clearer what you must do. Simply use reasonable precautions when working near the elec service.

Take precautions when working near the stairs - dont remove any support without propping first.

Neither can you dig out and totally expose your foundation/footings - for what they are.

Leave the kitchen floor alone - you have enough on. It probably wont have a membrane but if no damp is showing then leave it alone.

Your builder should know all the above.

 

[drpepe]

No screed is necessary over a membrane.

The hall area - you can simply flop a membrane over any utilities that are running across the oversite.

Thanks for your additional comments.

I am concerned that simply laying a membrane without something to hold it close to the soil will result in condensation and stagnant air issues underneath it - do you not think this may be an issue?

How come the soil pipe is down there - is your bathroom at the front of the house?

Actually the bathroom used to be at the front (with soil pipe running down the outside front left of the house), but the bathroom was moved some time ago to the rear to accommodate stairs to the loft conversion. Now the soil pipe descends in the front left corner of the kitchen and then along the left party wall to the front of the house (under the stairs and boards) - see pic
View media item 77389

The hall joists in the pic appear to be sitting on the soil? Once the floor is up it will become clearer what you must do. Simply use reasonable precautions when working near the elec service.

Take precautions when working near the stairs - dont remove any support without propping first.

Neither can you dig out and totally expose your foundation/footings - for what they are.

Leave the kitchen floor alone - you have enough on. It probably wont have a membrane but if no damp is showing then leave it alone.

Your builder should know all the above.

 

[drpepe]

Following on this thread, we have now had a serious go at lowering the soil levels under the house - in preparation for the builder to introduce new ventilation bricks to the exterior and spaces in the internal walls.

We have recently dug down in the rear dining room - which was very loose fine damp soil and rubble (tiles, cement, stones). About 15cm down we have revealed a hard layer which I am curious about as to whether it is some kind of surface created by the original builders (to prevent damp?) or it is a natural surface - it is light in colour with frequent black pieces embedded in it, it is quite a hard and 'crusty' surface. It is seemingly not damp as it dries out very nicely in a short time.

It has given me a fresh optimism that the dampness was simply caused by someone dumping a load of soil and then rubble underneath the floor and subsequently blocking the ventilation by poor building practice (conservatory at back and high block drive at front).

before soil & rubble removal:
View media item 82487after:
View media item 82488

 

[drpepe]

Hi. Back again.

After following the very useful advice on here, and lifting virtually every floorboard in the ground floor and digging out the subfloor, it appears our damp problems are nearly solved - slug count of zero during winter 2014/15 *touches wood* and hoping this first summer will help even more...

However, having removed all the soil, rubble and crap - we seem to be getting growth of new white furry 'mould spores' (?) up to 1cm in diameter all over the newly exposed soil:

View media item 95604View media item 95603They are confined to the soil (must be thousands of colonies all over the ground floor soil), and in slightly damp areas rather than the really dried out areas. They seem to form lines where I guess daylight penetrates between floorboards.


Any idea whether these are an issue? presumably/hoping not a rot as such, as they aren't on any woodwork (see a quite damp piece of timber in the pic which isn't affected).