Issues with timber flooring & moisture

Need some thoughts from you guys on how to resolve this scenario and who is responsible:

Newly built property was sold and settled approx 18 months ago, ground floor has a floating engineered timber floor. Initially there was a leak from a window and when any moisture penetrates into the edges of this flooring it goes black, so builder returned and replaced the floor and repaired the leak. Now the floor by this window is slowly turning black again (only some boards), builder has checked that there is no further leaking, and surmised that the courtyard wall gets no sun and the slab remains damp after rain, causing moisture to enter the slab under the floorboards.

Potential resolution includes waterproofing the courtyard (and redoing decking over the top) and/or cutting a channel into the slab between the courtyard and the house to reduce moisture moving through. Neither of these can guarantee that the issue won't occur again.

What do you guys think on who should be responsible for the resolution?

 

Has the builder undertaken moisture testing of the slab?

Has the moisture barrier been breached?

 

The slab is not exposed, its under decking in the courtyard and the floating floor. He believes given its a single slab from the courtyard to the inside (although dropped in the courtyard) moisture is travelling in, does the moisture barrier make any difference in this instance?

 

Possibly - moisture under the slab getting the interior wet is a possibility. Water penetration via the external slab is also possible - what is the drainage off this slab like?

 

Its a narrow thin internal courtyard approx 1m x 6m, hence the lack of sunlight, has a single 90/100mm drainage point in the slab, draining to a pit, with decking over the top.

 

No damp course between external slab and internal ?? Wicking inside ?

When we had a courtyard external to house (immediately adjacent to wall) with stencil concreted they made it clear that external concrete section couldnt touch the house slab at any point and needed a thermal barrier (20mm dense grey foam) to prevent wicking into the house slab. It runs around our slab and has never posed a concern in 10+ years. I dont know if just cutting it will help. May need an injection filler as a waterproof membrane to seal the gap ?

Try calling Sika for tech assistance ? Sealing the floor may not address the issue.

 

Hmm it makes sense that you should have a separation between the house slab and external slab to prevent wicking. So was this the builder's responsibility to ensure got put in place? Is it a BCA requirement or just good practice?

I agree on a membrane of some sort in the new channel.

 

What about installing sub-floor vents?



Would that helps.