Weight of water

[jonblair]

Thanks chris. Thats what i thought. ah well, another idea bites dust.
How about spreading the load over 6 joists?

 

[Bahco]

If it was my house I would use the belt and braces method and fit four 4 x 2 joists or larger across the span and re inforce with noggins. Then I would put 25 mm plywood across them to support the tank.

Ask a builder for advice though to be on the safe side.

 

[jonblair]

Thanks bahco....good idea...

 

[masona]

One other conundrum, the ceiling joists are not your usual 4 by 2!. The tank is to be positioned in the apex of a chalet bungalow, where the ceiling joists are 2 by 2 inches, spaced 18 inches apart. In the section where the tank is proposed, the length of joists is 4 feet.

Do you have any internal wall you can see? It's best to use the wall to take the stress load by bridging across wall to wall using bigger joists or tank position on the centre of the wall by packing it up.

Use exterior plywood (WPB) for resting the tank.

 

[jonblair]

Thanks masona. no interior wall, the space is in the apex of roof, above the ceiling of a room with dormer window. the most i could do is put in joists, above the ones already there, but connected to the roof rafters, making in effect a new floor above the existing ceiling. the joists would be connected to the rafters with timber connectors and coach bolts. that should do the trick.

 

[brumylad]

economics usually dictate that roof rafters are only strong enough to hold their own weight and that of the roof structure (tiles ect). The function of any joists should be to transmit any load to load bearing walls.

It sounds like your plans will need building regulations approval and I would submitt plans because I reckon your current proposal will result in your roof structure bowing inwards or even colapsing.

 

[jonblair]

Thanks for the advice brumylad...looks like back to the drawingboard....perhaps moving the tank to the floor below, where there are 4 by 2 joists, and since shower is being pumped, doesent matter where the cold tank is....

 

[masona]

Any photo?

 

[Panjandrum]

and since shower is being pumped, doesent matter where the cold tank is....

I'm not so sure about that. Is there not a minimum head for the pump?

 

[jonblair]

The minimum head for pump is 1 metre, and that ok.

 

[jonblair]

thanks masona....i will see if i can take a photo...