Determining Floor Joists Direction

forgottendreams77

I've been told that floor joists nearly always run perpendicular to floorboards - is it possible to tell from the below if that is the case here (I can add more pics if needed)? So the joists are running from top to bottom? Or can you only truly know by lifting the boards? Thank you.

Edit: the top wall is 2.67m long if that helps at all

born_again

Look at the nail/screw spacings.

forgottendreams77

born_again said:

Look at the nail/screw spacings.

Sorry, can you elaborate? Thank you.

Section62

forgottendreams77 said:

I've been told that floor joists nearly always run perpendicular to floorboards - is it possible to tell from the below if that is the case here (I can add more pics if needed)? So the joists are running from top to bottom? Or can you only truly know by lifting the boards? Thank you

This only ever really applied where traditional solid wood floorboards were used (approx 4 to 6" wide).  What you have are chipboard sheets which could be laid in either orientation depending on the whim of the person who laid them.

You've actually answered your own question with the words "nearly always" - at best this would only be a guide to the joist direction.  You can only be sure by lifting a board (or with T&G chipboard it is easier making a hole, but beware of pipes and cables).

Also, if you are doing this to work out if a wall is loadbearing, bear in mind loadbearing walls aren't exclusively perpendicular to the joists.

Gavin83

As mentioned by born_again you need to take a look at the nail positioning. Assume the joists run top to bottom in that photo. The nails are in the same position on each board spaced evenly apart. If you measure the distance between those nails I'd imagine you'll find they're roughly 400mm apart, which is the standard distance between joists.

If they were to run left to right where would the joists actually sit? The spacing isn't even and the gaps between those nails look too wide for a joist anyway.

Essentially they almost definitely run top to bottom. 

stuhse

You can see from the screws your joists are running perpendicular to those floor boards.  

Draw lines through the screw heads , thats the line of the joists, all evenly spaced.  Clear as day in your photo.

CSI_Yorkshire

forgottendreams77 said:

born_again said:

Look at the nail/screw spacings.

Sorry, can you elaborate? Thank you.

You can't have a useful screw or nail if there's nothing underneath to screw or nail to.

FreeBear

Section62 said: Also, if you are doing this to work out if a wall is loadbearing, bear in mind loadbearing walls aren't exclusively perpendicular to the joists.

And a stud wall can be be load bearing, even if there isn't a wall below. Never knock down walls or punch big holes in them without consulting a structural engineer first (and never rely on the opinion of a builder).

woody7777

FreeBear said:

Section62 said: Also, if you are doing this to work out if a wall is loadbearing, bear in mind loadbearing walls aren't exclusively perpendicular to the joists.

And a stud wall can be be load bearing, even if there isn't a wall below. Never knock down walls or punch big holes in them without consulting a structural engineer first (and never rely on the opinion of a builder).

How does a wall be a load bearing one with nothing below? Is the floor load bearing?

Section62

woody7777 said:

FreeBear said:

Section62 said: Also, if you are doing this to work out if a wall is loadbearing, bear in mind loadbearing walls aren't exclusively perpendicular to the joists.

And a stud wall can be be load bearing, even if there isn't a wall below. Never knock down walls or punch big holes in them without consulting a structural engineer first (and never rely on the opinion of a builder).

How does a wall be a load bearing one with nothing below? Is the floor load bearing?

There are various ways, but as an example a 'stud wall' can act as a beam.  E.g. see "trussed partition".

Or the first-floor loadbearing wall can have a beam at the bottom of it to take the loads into the perpendicular walls.