Thoughts about suspended floor

[JustAnotherDave]

Hoping for some advice...

 

I'm renovating a terraced house and having some issues with damp in and around what was probably the pantry (sits between kitchen and back room).

 

When I bought the house, the floor of this room was covered with about 16 layers of lino with a concrete slab underneath. The concrete was poured onto rubble and moisture was coming up at the sides, which was starting to creep up the walls and had rotted out the post for the staircase. I removed the slab to find quarry tiles and what I think is the old settle.

 

I'd like to make the room usable but the quarry tiles are laid on soil, so there's no chance of keeping anything dry that's placed on the floor. I'm thinking about putting in a suspended floor, attached via ledger boards at the sides to hang joists across the width. Does this sound like a viable solution? My plan is to put DPC behind each ledger before attaching to wall but not sure about whether I need to add insulation? Also, the walls are quite uneven - there's a layer of what seems to be slurry/tanking that's a couple of bricks high - can I just pack any voids with wood to make sure ledger is flat? Hopefully the pics help shed some light.

 

A couple of builders have suggested taking the quarry tiles up and laying a new DPM and concrete floor but that seems like a lot more work.

 

Any thoughts much appreciated.

[Redbeard]

Assuming you are planning to insulate as well I would consider a floating floor - level out over the tiles with a sloppy screed, then DPM, insulation, T&G OSB and final floor. Suspended timber floors, when they already exist, can be a real pain to insulate in terms of moisture issues arising, so if you haven't got one, why build one?!

[JustAnotherDave]

1 hour ago, Redbeard said:

Assuming you are planning to insulate as well I would consider a floating floor - level out over the tiles with a sloppy screed, then DPM, insulation, T&G OSB and final floor. Suspended timber floors, when they already exist, can be a real pain to insulate in terms of moisture issues arising, so if you haven't got one, why build one?!

Thanks for the feedback.

 

I'm not so concerned about insulation if it's tricky to get right. After all, this is just a cupboard area and will only be used for storage.

 

It's awkward because there's almost no space between the DPC on the left wall and the tiles, so it would be difficult to avoid bridging the damp course; the quarry tiles don't extend all the way back, and the outside wall of this space is at the back of the house which has foundations that appear to be considerably higher than the rest of the building. I also can't find any evidence of a DPC along this entire wall, which is presumably why it's been tanked. I thought a suspended floor would help to ventilate the room and the room next door - it's currently at around 78% humidity.

 

I've added another pic to show the wall on the left that adjoins the dining room. The ends of the joists in that room (see pic) have already gone rotten. I imagine I'd have to take the tiles up, excavate and then lay the screed and DPM? That's why I thought a suspended floor would be easier.