Storing in attic - weight concerns

[icarusbop]

Hello:

I have an attic space constructed from rafters, as opposed to pre-built frames (roofing trusses).
It is a pitched hipped roof on a semi. There is a big beam (12") forming the peak, and big beams also about 1/3rd then again about 2/3rds down the roof, these have rafters on them going vertically, then the smaller wood strips with the tiles hanging on them.
The ceiling of the upstairs (the floor of the attic) is 2x3" beams, there is a brick supporting wall in the centre (except for over the landing because the wall stops) there are another two walls upstairs, but the top half in made of wood studding up to the ceiling as opposed to brick all the way up)
There is a decent sized space up there which is half floored with chipboard and already used for storage.

I have need to store books up there, but am concerned about weight issues. The best place for the shelves is above the landing - meaning there is a span of about 20ft where the ceiling/floor beams have no extra support from underneath.

I am wondering if I can use the heavy duty (5mm) galvanised steel straps that builders use, between the floor beams and the large beams in the roof construction to help transfer some of the weight to the roof structure, is this allowed?
As an extra question - the builders straps only seem to be 1m long - can I bolt two together to get the length I need, or should I use 3x4 wood instead?

Thanks very much
Ian

 

[mrcrow]

the highest floor dead loading in the design manuals is paper..and so books...
we had a similar roof in our bungalow with large members running gable to gable taking the load midspan off the roof vertical/sloping support beams...with horizontal battens for the tiles
i do believe the ceiling joists were similar to yours
transferring point loads to incur local bending and raise shears in the wrong places...

really for point loading as you mentioned using ties from the ceiling up to the existing roof members which are already probably quite heavily loaded, may not sag but will be transferring that load to the supports raising shears and bearing on the wall plates which... and as i mentioned in the opening...paper is heavy might overload the connectors and wall mortars.

we stored my daughters books from university for about a year in another similar roofed house close to the point where the ceiling timbers connected to the roof support beams..we got sag in the ceiling and cracking in the plaster...when the books went the results stayed meaning some resultant plaster work..

you mention shelves...what wall do they go on?

cheers
geof

 

[icarusbop]

you mention shelves...what wall do they go on?
geof

Geoff:
Thanks for your response - There is currently a set of metal shelves you find in sheds up there, they are sat on the floor, but also fixed to the wall.
The wall is the divider between our attic and the neighbours attic, it is brick all the way to the foundation as it is the dividing wall between the houses.
I was thinking of putting another set of the shelves up there and storing the books on it - there are not many approx. 20-kg of them, but more are likely to get added over time if the shelves go in.

 

[mrcrow]

Geoff:
Thanks for your response - There is currently a set of metal shelves you find in sheds up there, they are sat on the floor, but also fixed to the wall.
The wall is the divider between our attic and the neighbours attic, it is brick all the way to the foundation as it is the dividing wall between the houses.
I was thinking of putting another set of the shelves up there and storing the books on it - there are not many approx. 20-kg of them, but more are likely to get added over time if the shelves go in.

what my daughter did with all her books when she got a house was to put them in the garage with metal stacking frames...safer and less likely to spread cracking or require dubious strengthening...

what is strange is that none of the real experts here, whom i would trust, haven't put their toe in the water
??

Which means you would not be advised to do what you suggested unless under the advice of a structural engineer...sorry

cheers
geof

 

[cdbe]

I have strengthened my loft floor considerably, but I still store the (hundreds of) books directly above the spine wall (the solid wall below). I keep them in big plastic storage boxes and stack them up. I wouldn't risk hanging anything heavy from your roof purlins.