Hi,
I'm proposing to lay a 21mm thick structural engineered oak floor in a 1st floor bedroom (~3mx4.5m). I have taken up the old floorboards that were in a bit of a state and am going to lay the new floor directly onto the joists. The joists are 2.5" x 6" and run across the short width of the room (3m) at about 350mm centres. They are individually pretty level without much in the way of sagging in the middle (maybe a mm or two at most).
However there is some significant variance in the levels between the joists - the ones in the middle of the room are about 12mm lower than those by the walls. There's a fairly smooth graduation - the floor basically has one single big dip in the middle lengthways. There's no evidence of any serious structural issues underlying this - I guess perhaps the whole house has settled slightly over 100 years , or maybe the joists were never properly level in the first place.
Obviously laying the floor is going to be easier if the joists are closer to level; it's also less likely to creak and be under less stress once it's down. I was therefore proposing to nail and glue some shims varying between 4 and 12mm to the tops of the existing joists. Is this an acceptable solution, and if so, what would be the preferred material to use?
I think the easiest solution for me would be take another piece of 2.5" x 6" kiln dried timber and rip slivers off it using my track saw, but I've seen various things online suggesting the ordinary softwood timber will be too compressible for this application. Do I need to buy a bunch of different thicknesses of ply instead? Or is this whole approach misguided?
Thanks for any help,
Lucian
I'm proposing to lay a 21mm thick structural engineered oak floor in a 1st floor bedroom (~3mx4.5m). I have taken up the old floorboards that were in a bit of a state and am going to lay the new floor directly onto the joists. The joists are 2.5" x 6" and run across the short width of the room (3m) at about 350mm centres. They are individually pretty level without much in the way of sagging in the middle (maybe a mm or two at most).
However there is some significant variance in the levels between the joists - the ones in the middle of the room are about 12mm lower than those by the walls. There's a fairly smooth graduation - the floor basically has one single big dip in the middle lengthways. There's no evidence of any serious structural issues underlying this - I guess perhaps the whole house has settled slightly over 100 years , or maybe the joists were never properly level in the first place.
Obviously laying the floor is going to be easier if the joists are closer to level; it's also less likely to creak and be under less stress once it's down. I was therefore proposing to nail and glue some shims varying between 4 and 12mm to the tops of the existing joists. Is this an acceptable solution, and if so, what would be the preferred material to use?
I think the easiest solution for me would be take another piece of 2.5" x 6" kiln dried timber and rip slivers off it using my track saw, but I've seen various things online suggesting the ordinary softwood timber will be too compressible for this application. Do I need to buy a bunch of different thicknesses of ply instead? Or is this whole approach misguided?
Thanks for any help,
Lucian
