Joists too small in loft?

[Georgie73]

Hi

We have taken down the bedroom ceilings and exposed the loft timbers. We want to board out the loft and create storage space but we was surprised to see the loft timbers are only 3 by 2.

What do we need to do to make the area strong enough so that we can board over?

Should we replace all the wood with a larger size?

Many thanks
George

 

[rob_j20]

Same as our loft, i'm adding more 3x2 on top of the existing and glueing and screwing them together, giving 6x2. Means i can get 140mm celotex in then as well and 18mm chipboard on top.

 

[Georgie73]

Would that method add strength? I want to feel safe if I have to walk up in the loft.

 

[Gerrydelasel]

Indeed, adding joists on top doesn't really add strength, only weight. If you just want to store light stuff then it will be strong enough to board over as is. Otherwise you need some thicker joists actually running wall to wall.

 

[Georgie73]

Indeed, adding joists on top doesn't really add strength, only weight. If you just want to store light stuff then it will be strong enough to board over as is. Otherwise you need some thicker joists actually running wall to wall.

Thank you. Does that mean we have to add 'extra' joists in between the current ones, or should we replace the existing joists?

 

[tony1851]

Screwing additional 3x2 joists on top of the existing will work fine. Just use 100 x 4-5mm (old 4"x12s) and countersink the screw holes by using a borer to go down about 25mm. Screw approx every 300-400mm. It won't quite be the strength of a 6x2, but not far off in practice.

 

[rob_j20]

Screwing additional 3x2 joists on top of the existing will work fine. Just use 100 x 4-5mm (old 4"x12s) and countersink the screw holes by using a borer to go down about 25mm. Screw approx every 300-400mm. It won't quite be the strength of a 6x2, but not far off in practice.

Great to know, would there be any benefit in also fixing the ends of the new 3x2 to the large support that runs along the length of the roof either side, cant think what its called but looks very substantial. Could use metal ties i suppose, to help hold the weight?

 

[tony1851]

'Every little helps', as they say.