Trench in slab- how waterproof for sheet
We have an about 5 year old Mannington Commercial insight
ponderosa pattern sheet ”vinyl tile” 12 ft wide installed on a cement slab ground floor.
This slab floor had a utility trench cut in it for plumbing, which was
then itself filled with concrete. then the tile put over it, (cemented
down). For the last 6 months or so we have been getting a slight
black/darker line on the surface of the tile, where the edge of the
trench in the slab floor is.
We assume this is from moisture coming up
from the ground at the edge of the trench and affecting either the
cement or the tile itself.. You can not rub the black mark off. Any solutions? If we have to take up the
tile floor, what should we do/use to seal the edge of the trench with? paint? fiberglass?
Replies
I am a bit surprised that a moisture line can be seen thru the flooring. First, try to clean the floor with plain soap and water, my thinking is there may just be a physical hump and so it just catches more dirt buildup.
If cleaning does not work, try bleaching in an area that won't show too much. Take a paper towel, fold into a 3" square, place on an obscure spot, pour bleach, then cover in saran wrap. If bleaching does not work, then it is mold from the underside. Live with it or rip up the flooring.
bump
I'm just sayin'
a tile forum said the black marks were from moisture that had come up on the joint line , and been stopped by the vinyl's "wear layer". They said it would be safe to put more vinyl over it but i doubt it - maybe pergo is a better choice as it breaths just a littla at the cracks. They said vinyl does this around toilets too.
Odd other people do not have the same problem
Moisture in the ground wants to come up through the floor. A cold joint in concrete, no matter how good, will have tiny gaps for the moisture to come up through. If it had been backfilled with hydrolic cement or if a gap had been left and filled with sealant then you might not have had a problem. That's why it's a good idea to put vapor barriers underneath slabs--water can come right up through the gaps between particles in the concrete.
Now what you have is the wear layer of the tile is acting as a vapor barrier. The black stuff is probably mold, hanging out at the water trough. Don't worry it won't hurt you. The easiest solution at this point is probably to go over the floor with another vapor barrier, 6 mil poly sheeting would work, and lay another floor on top of that. Or you could grind out the cold joint and fill it with a masonry caulk.
if you put poly on i how would you secure it to put down more vinyl (cant cement vinyl to poly sheeting- - or should you go with "laminate"
It would have to be sheet vinyl or a floating floor.