Crown In Floor Due To RSJ

[thomp1983]

Hi all,

I'm fitting a new floor to an upstairs room as the original floor is excessively noisy, I thought it was originally due to a plumber trapping pipes across an rsj and nailing the floorboards around it causing them to crown and not fit together correctly.

Now I've the floorboards up around the rsj I can see the crowning issue is due to how the floor joists have been cut and fitted to the rsj.

I plan to cut off the small 'tongues' off the joists that are sat on top of the rsj so they are no longer forcing the floor upwards.

When I lay the new floor I'll pack the gap over the rsj, the new floor is plywood so I can screw it nicely either side of the rsj.

I can't see why removing the bits of wood causing the crowning would cause an issue but thought I'd check here first?

Thanks,
Chris

 

[Notch7]

Hi all,

I'm fitting a new floor to an upstairs room as the original floor is excessively noisy, I thought it was originally due to a plumber trapping pipes across an rsj and nailing the floorboards around it causing them to crown and not fit together correctly.

View attachment 398205

Now I've the floorboards up around the rsj I can see the crowning issue is due to how the floor joists have been cut and fitted to the rsj.

I plan to cut off the small 'tongues' off the joists that are sat on top of the rsj so they are no longer forcing the floor upwards.

When I lay the new floor I'll pack the gap over the rsj, the new floor is plywood so I can screw it nicely either side of the rsj.

I can't see why removing the bits of wood causing the crowning would cause an issue but thought I'd check here first?

Thanks,
Chris

I trust the joists are cut into the web as well -not using that little bit to support!

otherwise just cut them off, they were cut because the original floor was timber floorboards

 

[thomp1983]

Yes they are nicely cut into the web, someone just appears to have done a poor job of the top

 

[tony1851]

If the joists are firmly supported off the bottom flange of the beam, or securely fixed to the web some way, the reason they have sheared is because the joists have shrunk.
When they were installed, they will have had a relatively high moisture content, perhaps being stored uinder cover but outside in a timber yard. After a time in a heated building, they dry out and shrink - some timbers can shrink 5% or so across the grain.
If those projecting bits were originally cut tight to the top of the beam, its no wonder they have sheared as the bulk of the depth of the joist shrinks and pulls down. You sometimes see this in loft conversions if the joiners finish the tops of the joists level with the top of a steel beam.
Assuming the joists are well-supported, there will be no problem cutting the thin bits off.

 

[^woody^]

Fit a thinner strip of ply across the beam. Gripfill or pack to ensure it sits flush with the floorboards either side.

 

[Ivor Windybottom]

Keep it as a safety feature, to slow people down if they're running too fast across the room.

 

[thomp1983]

All sorted including breaking a finger with a table saw.

 

[Ivor Windybottom]

Was it worth it?

Broken is better than removed.

 

[thomp1983]

Yes as the floor is now flat, with 36mm of plywood screwed into the joists and fully supported in the web there not going to go anywhere

 

[noseall]

, with 36mm of plywood

 

[thomp1983]

Yeah there was a bit of a mistake with the level of the extension but laying 36mm in the existing bedrooms makes them meet nicely.