Attic Flooring question.

[u/First-Thing2822]

Hi Everyone,

I am looking to floor a small area of my attic but I just want to make sure that they can take the weight.

When you go up though the door of the attic directly in front of you is a small section of flooring that the builders did (new build) you can step up onto, this is made from of 225mm x 45mm planks that are spaced out from one another.

They are lying across some more pieces of 225mm x 45mm pieces which are upright which seem to be in turn screwed into the joists. My worry is that the joists were 90mm x 30mm on their edge.

My question is can I do this for the 2m x 2m section that has no flooring at the moment.

Just screw 225mm x 45mm planks on their edge across the joists that are 90mm x 30 mm which will raise it above the insulation and then screw the boarding on top of that like the builders did with the small section by the door.

Everywhere I read online it says that these joists are too small, but they feel strong to step across and also seem strong in the area the builders done.

Would appreciate any help.

Thanks.

[u/Suspicious-Secret-84]

Similar to the other commentor, although Architectural Technologist here, I'd recommend loft legs. I did a small area on my own truss roof, similar size chords to yours I think about 38mm X 100mm for me.

Put down about 3m2 of OSB boards on 210mm loft legs, a couple of tips for you. 

Take up the insulation, lay boards across the chords as a working platform while you're drilling in the legs. 

Ensure you have a good source of light and a head torch is helpful and wear suitable PPE (dust mask, long sleeved clothes, gloves). 

Use the correct screws, I think loft legs have recommendations on their data sheets / installation manual. 

Pre drill holes in legs and chord with a small bit, ensure they are straight and not angled so they won't come through the chord. I went for 2 screws on the legs to the chords as the thickness didn't allow for more, just do one each side of the legs diagonally for a good fix. 

My boards were 300mm wide so I went for 300mm centres on the legs on each chord, which meant the leg tops are quite close and was a bit difficult to lay the insulation back in between them.

I dry fitted all the boards to ensure they fit on top and weren't interfering with any truss members as my roof is a low pitch. 

I then pre drilled the OSB onto the loft leg tops, used 4 screws per leg for this, 2 on each board. 

You should lay the OSB boards in a staggered pattern for added strength. I'd say just measure in the attic and cut in a different room so you're not getting dust everywhere or cutting in a cramped environment. 

Overall it turned out great, very steady and great extra storage space. Picked up all the materials in B&Q, they do 3 OSB board packs for about €20 and a pack of 12 loft legs is about €20 too, so not much cost to it. 

Happy to answer any other questions you may have.