loft panels - spreading load

[HarryPaget]

Hello,

I'm about to add some flooring to my loft space, but after reading as many posts here as I can find, I could do with some reassurance that what I'm planning to do won't weaken the structure of the building.

It's a smallish semi, with a total loft floor area of approx. 9m x 4.5m. The roof timbers are 'gang-nailed, with 600mm between centres.

Like many other posters, I'd like to maintain a fair amount of insulation (currently two layers of Knauf Contract Insulation) and as the joists are only 120mm x 37mm I'd like to counter batten with 100mm x 47mm to raise the insulation gap, and avoid having to notch any timbers for wiring.

My worry (as I've seen others have reservations about) is the weight of all the counter battens and boards.

As both long-edge walls are block-built, would it be sensible (or daft!) to use joist hangers (proposed positions shown in red on pics 2 & 3) for every other counter-batten (i.e. at 1200mm intervals) sleeve-anchored into the block wall, as a way of reducing the weight/stress on the trusses?

All counter battens would be screwed to joists at each point of contact; chipboard sheets then screwed onto counter battens.

I'm only planning to use the space for general storage, nothing heavy.

Any advice much appreciated.

Untitled

• HarryPaget
• 26 Jul 2011
• 1

Untitled

• HarryPaget
• 26 Jul 2011
• 1

Untitled

• HarryPaget
• 26 Jul 2011
• 1

 

[DAZB]

I would say your quite safe with your plans as you will no doubt also have upstairs internal walls that also support, to some degree, the ceiling joists so I'd consider it an ok method for light storage use.

 

[HarryPaget]

Thanks DAZB,

It's the first time I've lived in a house this new (2007) so I just wanted to check with the 'knowledge base' on this forum before going ahead!

Might start next week if the sun stops shining. The beach is calling…

HP

 

[Static]

If the house is that new i wouldnt worry.. but better off putting in lighter counter battens, so 100x37's.. and dont remove or cut through any of the diagonal bracing members on the ceiling ties..

 

[HarryPaget]

Hello, Static,

It's precisely because of the newness of the house that I'm cautious; I'd assumed the roof trusses were engineered down to the last ounce of efficiency to support just the roof tiles + first floor ceilings.

Are you suggesting that the structure may be stronger than I'm assuming?

Thanks,

HP

 

[Static]

All roof trusses have to be designed to take loft light storage load (unless no access to the loft is provided and it is unforseeable that storage will ever occur).. its something like 0.25kN/m2..

Due to more modern standards and building regulations newer buildings are more reliably designed.. take a building 200yrs old you would have no idea what the design was based on, if anything but what old timber they had lying around..