Best way to level subfloor ?.


Old 02-29-08, 08:49 PM
Thread Starter
Join Date: Feb 2008
Posts: 1
Best way to level subfloor ?.

My house was built in 1980. After I removed the carpet to install laminate flooring in the hallway in the first floor. I noticed a drop by one 1’’ over an area of 8x10 ft’. Edges of the joists under that area were previously subjected to termite damage. Last summer I got a contractor who removed the damaged terminals of the joists, terminated the shortened joists to a new 2x10 beam and then connected the beam with the double top plate and the outside wall using a set of short new joists. No jacking of the old joists to compensate for the floor drop was done. The ceiling of the lower floor is finished with no easy accesses the joists from below. I have a ¾ inch plywood sub floor.

I am trying to find out the cleanest way to have that sub floor leveled for laminate flooring.

1) Is it better to remove the sub floor and then sister the sagging joists with some straight “levled” 2x4’s. Cut the subfloor around the walls and then relay the sub floor back on top of the leveled 2x4’.

2) build up the unleveled are with roof shingles and then cover the are with ½ underlayment.
3) use floor leveling compounds. And then put ½ inch underlayment.


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Old 04-05-13, 06:40 PM
Join Date: Apr 2013
Location: canada
Posts: 1
If your going level your sub floor take into account of the existing structure of the floor and why it has sagged, though as we all know time causes everything to sag, the main integrity of the structure should not be assumed 100%. Sistering your joists is a sure way to getting your floor level, but not if your are just adding Dead Load to your joists, what you need to do, is sister your joists with the same size/length joists, PL them and nail them together, if they are fastened with joist hangers then remove the old hangers and use double hangers to support the load, and first and foremost, check your local building code to see if your built up beams are capable of carrying the load, if not you may need to add to or replace ($$$).
Personally i feel that if it is done to code it will last. put your cross bracing every 7 ft minimum, and use PL, that $#@& could make chuck norris break a sweat.
Old 04-10-13, 04:22 PM
Join Date: May 2012
Posts: 83
You don't need to sister w/ the same size & length Sistering the middle third of the length is usually acceptable and there's nothing wrong with sistering a 2x6 to a 2x10.. And you don't need to end the sister in a hanger - the load will be tranferred to the existing hangers without problem. Glue and screw or Glue and nails.

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