950 pounds per square foot, too heavy for a roof garden?

G'Meister

Hi

Looks extremely unlikely that this will be viable, but I'd love an Outdoor Jacuzzi, like this one:

http://cgi.ebay.co.uk/BLUE-SEA-Portable-Spa-Hot-Tub-Jacuzzi-Hot-Tubs_W0QQitemZ350096298326QQcmdZViewItem?hash=item350096298326&_trkparms=39:1|66%3A2|65%3A15|240%3A1318&_trksid=p3286.c0.m14

Problem is, water is rather heavy; the jacuzzi itself weighs 32kg, plus 1000 litres of water (which weighs a kilo a litre, metric is simple like that, and it'll costs a little over a pound to fill up according to USwitch)... and then you add 2 people, perhaps at maximum another 200kg .
So, call it 1.2 tonnes.
With a diameter of 1.88m, I calculate that to be 2.77 square feet.
Supposedly, upper floors only have to handle 30 pounds per square feet under building regulations, yet this is a roof garden so I don't know whether these even apply. I calculate the psf to be around 950 pounds per square foot.

Basically, I don't have a chance in hell of the floor holding, but I'm hoping someone will say there's a slight possibility the floor is strong enough, or that there's something that can be done, like using a mammoth base that spreads the weight - going by the 30 psf standard, I'd have to spread it over 80 square feet, and to be honest it's a big roof garden, there'd be enough room to do that, and the wooden slats running across the roof would maybe dissipate the weight sufficiently without putting anything further over the top.

How difficult would it be for a Structural Engineer to calculate this sort of thing, and how much do they usually charge?
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meester

Gnomemeister wrote: »

Hi

Looks extremely unlikely that this will be viable, but I'd love an Outdoor Jacuzzi, like this one:

http://cgi.ebay.co.uk/BLUE-SEA-Portable-Spa-Hot-Tub-Jacuzzi-Hot-Tubs_W0QQitemZ350096298326QQcmdZViewItem?hash=item350096298326&_trkparms=39%3A1|66%3A2|65%3A15|240%3A1318&_trksid=p3286.c0.m14

If you're building a proper roof garden, put a proper hot tub in.

The air jets in that suck in COLD air from the atmosphere and chills your jacuzzi in a matter of minutes.

NOT recommended.

Also beware of the cost of heating, consider drainage and refilling (you will have to change the water, you don't want it to be a hassle)

What you need is a real hot tub with heated air jets or water jets. I'd do it properly, with decking.

Problem is, water is rather heavy; the jacuzzi itself weighs 32kg, plus 1000 litres of water (which weighs a kilo a litre, metric is simple like that, and it'll costs a little over a pound to fill up according to USwitch)... and then you add 2 people, perhaps at maximum another 200kg .
So, call it 1.2 tonnes.
With a diameter of 1.88m, I calculate that to be 2.77 square feet.
Supposedly, upper floors only have to handle 30 pounds per square feet under building regulations,

not sure what that means. If yer average 'larger gentleman' weighs 250 pounds, and has two feet (but only sole and toes touch the ground), there's probably only 1/4 of a square foot in contact with the ground, I make that about 1000 pounds per square foot.

Fred56

That's 2.77 sqm, about 30 sqft.

moonrakerz

Could I suggest you check your maths ? - very carefully !

You are either going to need a concrete roof 8 feet thick or will have a jacuzzi in your bedroom - very briefly- as it passes through on its way downwards !

gmgmgm

Your maths is wrong.

It is indeed 2.77 square metres.

So, for 1.2 tonnes, that's 433 kg per sqm. Or 2650 lbs over 30 sqft, giving 88lbs/sqft.

An easy way to look at it is 4 large people in each sqm.
Or: draw a circle 1.88m in diameter. Imagine 12 large people in that space (or get some friends over).

Sounds like you're going to need an engineer!

G'Meister

Thanks for all your replies! Unfortunately I'm not building the roof garden, it's a rented penthouse flat, and if I get a proper jacuzzi I'd probably need a crane to get it to the roof!
Looks like I'll have to carry on dreaming, least til I get a house of my own.

brownbake

Jacuzzi on a rented Penthouses that you are willing to get fitted by a crane - you must be scraping those pennies together lol