preparing underlayment for laminate installation

boxy_brown

I've just finished laying a plywood underlayment to install laminate flooring. Overall everything looks great and ready to go, except for one area. There is a fairly good size dip in the floor right next to the front door to the house. I laid an 8 ft straight edge across the area, and the dip looks to cover roughly 9 square feet (about a 3x3 area, but more rectangular than square), and is somewhere between .25 and .5 inches deep in the middle.

I've read a few different suggestions on how to deal with this. I've got some DAP leveling compound that I was thinking about using. Other suggestions include a self leveling cement and using roofing felt to level it out.

self leveling cement sounds like the best/easiest way, but there are small gaps around the perimeter of the room and since this area is at the edge of the room, I don't know how well it would stay in place as it dries. I've never used it before so I don't know how thick it is as you pour it. And as for the roofing felt, it would take several layers cut just right and I'm just not sure that would be the best way to do the job.

What would you do in this situation?

thanks in advance,
boxy_brown

Just Bill

If that is a slab, use leveling cement, if not, I would be trying to find out why it is sagging. Has water leaked around the door causing framing to rot, or what?????

boxy_brown

it is over a full unfinished basement. And yes, after taking a look it does appear that water has been leaking near the front door. I suspect that the leak is actually under the front door because there is a small concrete porch, and the soil has washed away from underneath the porch.

This probably warrants a different thread in a different section, but what can be done to repair that? Can you pack fill dirt underneath the slab or would it be best to have the porch removed to seal up the leaky areas?

regardless, would it be ok to finish the flooring job and address the leak later (but soon) ?