Crack in floor

[EssexBreeze]

hi everybody,
i am just about to lay some wooden floor on the ground floor concrete floor. i have a small bay window are protruding out from the front only on ground floor.trouble is once i have removed the carpet in the front room i have noticed a 2mm crack between the main house floor and the extension bit with a little damp on the floor. my questions are:
what can i do about the crack?
there is no visible damp on the wall, but, do i need to do anything to the wall?
to lay the wooden floor i was planning to glue it to the floor; can i do that or should i need a dpm membrane on the floor? in that case how do i fix the wood?
cheers
sorry about the long story

[Deleted-user-3]

is the damp patch and the crack across the original line of the outside wall? as though the bay window was extended after the house ws built?
how old is the house?
reason being you may get away with a resin based dpm... two part mix together compound that will seal your floor so you can apply the adhesive
this sort of thing... http://www.permagaurd.com/index.php?mai ... cts_id=116
the floor needs to be very flat before gluing down engineered timber floors.. about 2mm in 3m i think..

you could chop the crack out to the depth of the screed to investigate further and possibly just screed it back in if all seems reasonably ok...

worst case is if the bay is an extension and doesnt have a membrane, or the membrane in the extension doesnt lap the main house properly... you may still get away with the resin dpm though... if you screed the crack back in youll need to let it dry properly first.. could take a few weeks...

[EssexBreeze]

thanks for your reply chris.
the house was built in 1968 and the bay window part was built with the original building. it seems to my inexperienced eye the bay window part seems to have sank a bit which has brought about the crack.
is there any resin stuff that i can inject in the crack to prevent moisture coming up the crack?
cheers,
james

[Deleted-user-3]

easy way to check if its sunk is to run a straight edge across the main floor over the bay floor.. is the bay screed a different colour/finish to the rest of the main floor? has it been re-done in the past? 2 different screeds will cause a crack due to shrinkage of the screed
if its sunk youll need to bring the floor level up anyway so it may be worth having the screed off the bay for investigation purposes so you can screed it back level afterwards...
im not aware of a particular brand but i believe theres a product that can be injected into cracks, mainly used for concrete though...
this came up on a search, cant vouch though... http://www.radonseal.com/crack-injectio ... cracks.htm
the problem here is unlikely to be the crack in the screed, its whats underneath that will be causing the damp, the crack is in the screed, and the screed isnt the membrane. if its subsidence then the crack is likely though the concrete slab too...
personally, id want the bay area screed up and just have a look at the slab, see what the cracks like there, then screed it back up level... possibly even go for the epoxy resin dpm over the whole lot when the screeds dry..
ive seen a good few bays that have sunk over the years and its usually down to inadequate footings, they take the sub base and the slab with them and inevitably the screed... usually built on a busy road carrying heavy traffic..
depends how bad it is and whether its still moving...
you never know though, you might just get away with injecting the screed crack, hoping it penetrates the concrete too, latex it level and epoxy dpm the lot...
have you got a picture to clarify?