'Floor' loft for storage

[Technaut]

Hi

Our loft has 35x 100mm joists at 500mm gaps.

Will this size and spacing of joists handle either 9mm ply or 18mm loft boards? Should i get the loft legs or put down some battons.

Any advice appreciated

 

[tony1851]

If it's just for storage, 9mm ply would be OK, or 11mm OSB might be cheaper, though not as nice in finish.

 

[JohnD]

I wouldn't be happy walking on 9mm ply. Perhaps you are very thin.

18mm ply would be much better all round.

 

[Technaut]

i was more worried about adding weight of cross battons and then loft boards and then storage items. Thats why i was thinking of thiner wood for the flooring.

Tried (and failed) to make sense of span charts etc to work out if the ceiling joists would take the extra weight

 

[tony1851]

Agree that 9mm ply seems thin at first glance, but when you consider that it would be fixed across several joists, the continuity will reduce the bending stress considerably. It's only supposed to be for storage so would be ok IMO.
18mm ply is heavy stuff.

 

[Technaut]

Guys,

Here are some pics of the loft http://imgur.com/a/qQTPr

Still think with this type of truss it could handle the weight of battons, ply and storage? There is a main truatss every 4th rafter if that makes sense.

Just a bit para as new baby on the way

 

[tony1851]

Are you in Scotland, by chance?

 

[Technaut]

Yep?

 

[tony1851]

You will probably have a dividing wall somewhere below the centre of the roof (in line with the chimney, perhaps?).

If so, 100 deep joists should be fine bridged with 9mm ply, as long as you don't go overboard with the stuff you store, and try and keep the bulk of it near to any l/bearing wall below.

(BTW, Scottish roofs have sarking boards nailed across the rafters - not usual practice south of the border, regrettably).