deflection confusion ??

[doug boardley]

thanks for your replies wot is actually moving in deflection ? .. is it the joists its self or the floorboards not having a good contact with the joists ?? i keep thinking iam learning loads but then get knocked back down to earth !

usually the joists move Terry, it's just the spring in the wood

 

[DHTiling]

The boards could be the problem.. to thin or to wide a span between joists... the joists could bounce/deflect... this all needs assessing before giving a price or even starting the job.

 

[2020Tiling]

deflection bounce can be removed by adding extra noggings between the joists, this will make the joists braced togeather and will stiffen the floor..
However it depends on how much deflection/bounce there is? It may need propping as you say if there is a solid base underneath either by timber supports or by bricking underneath them to give extra support!
over plying will remove vibration, and possibly some deflection!
Ditra will NOT stop deflection this is for laterall movement!

It all depends how bad the deflection is as to what work needs to be carried out before tiling, but this comes with experience as to how much deflection/vibration will be cured with different methods!

hope this helps

helps a lot ! thanks

 

[Spud]

remember to use decent wood screws when overboarding or securing floor boards to joists ,I have been to countless jobs where the builders have screwed down floor boards and ply wood with black plasterboard screws these simply dont have the strength or thread grip to secure the boards well enough ,we always remove these and refix using appropriate wood screws

 

[mikethetile]

wood suspended floors are designed to deflect slightly, this absorbs shocks and cuts down on noise transference, these floors are not really intended for tiling which needs a deflection free floor, so you need to alter the floor in order to tile

so the main deflection is in the joists and the rest is in the floorboards

 

[Rob Z]

Hi there Terry, check out this thread http://www.tilersforums.com/tiling-forum/33808-floor-spane.html

The "4 S's" are an important concept to learn about when assessing whether a floor is ready for tile. Adding blocking or noggins will help in a local way to transfer a load from one joist to another, but they won't fix a floor that is under-framed and under-sized.