New 70 gallon tank in a dormer roof

[therhinouk]

I've got the tank in the loft and I have an idea of where I would like to put it BUT the concern I have is will it be strong enough to hold where I want to position it.

Its a semi detached house. The roof is a dormer roof and our loft has two sides bricked up to the top (one is the gable end the other is the join to the house next door) and the other sides are where the dormers are which are timber frames with stud walls below. The middle part of the loft has been boarded up.

I would like to position my new 70 gallon polytank (dimensions 1650 x 610 x 500mm) as close the the edge where the rear dormer is (so centrally but away from the boarded middle of the loft and pushed as close to the edge of the loft / roof).

I can see the joists going parallel to the gable and, where I want to put the tank, there is one length of timber (going cross joist if that's the correct term) which is 5 inches deep by 2 inches wide. I was thinking I would get some more 5x2's (perhaps 4 or 5) and screw them inline then put a 18mm bit of ply on top of this then sit the new tank on top of that?

Does that sound ok and the the loft being able to take the weight of the new tank in this position? Are there any engineers on here that can give me a thumbs up on this?

If so how many 5x2's should I be looking to screw in and at what gaps? What kind of lenght should I try to be installing and how large should the plywood board be?

If any one can help / advise that would be terrific!

 

[catlad]

The plan sounds ok at the moment, but you do not state the size of your joists or if there is a supporting wall underneath, is that load going to equate to 350kgs.

 

[therhinouk]

I will measure the joists and report back. I don't think there are any supporting walls underneath as the are mainly stud walls. I don't know for sure if the dormers have brick / block work on them. Even if they did would they be considered supporting walls?