Strengthen loft joints with perpendicular battens

[tom23432]

I am boarding some of my loft for storage and am a bit confused on the best way to strengthen the existing joists. I have read conflicting advice, some say you can add additional joists on top and perpendicular to the exsting ones. Others say do them parallel and some say increase the height of the existing ones.

So I am not sure on the best way forward.

My house is a new build with what I think is are standard fink trusses.

I have pulled back the top layer of insulation to reveal the joists. I was planning on adding some additional 4x2 perpendicular support, then using loft legs to have my loft boards above the insulation with a small air gap. But now unsure whether perpendicular is the way to go, would I just be adding dead weight or would it actually stengthen it?

I don't plan on having anything too heavy up there since we already have solar batteries installed as seen in the picture. My main concern is the weight of those and if there is anything I can do to strengthen the roof to prevent issues in the future. The batteries weigh 76kg which is obviously quite a lot and then there is the inverter attached to the roof web (I think that's what it's called) on the left of the image which weighs around 20kg.

 

[OvertonPlumber]

I wouldn't worry we quite often add 350kg water tanks (Megaflo) into lofts.
Just try and spread your weights over multiple trusses

 

[tom23432]

I wouldn't worry we quite often add 350kg water tanks (Megaflo) into lofts.
Just try and spread your weights over multiple trusses

Thanks that's good to know. Would that be in new build homes? From what I can tell modern roofs are typically rated for max 25kg per sq long term.

 

[JohnD]

Additional timbers at right angles to the original are good at spreading the load and adding rigidity.

For the most rigid platform, skew-screw the timbers together, and a (preferably one-piece) 18mm ply deck to them, before loading it with weight.

Nails are avoided because the banging may crack the ceiling plaster, especially in an old house.

I like to treat timber in a loft with wood preservative before assembly. This may be compulsory in parts of Southern England prone to Longhorn Beetle, but woodworm might occur anywhere.,