heavy load in preformed roof

[Steve]

I was checking up at my grandma's house today (she's away for 3 weeks) and i had reason to check in the loft (had to drain water tanks). I noticed that the water tanks are about 18 inches above the loft floor, supported by a bodge-up flatform nailed into the roofing structure. The roof is a pre-formed job (early 1970's), made up entirely of what looks like 3x2 timber and metal plates at intersections. Is it safe to put this much load on this sort of roof? I thought they were manufactured with exacting sizes and strengths. And the way its been fixed means only the most agile can access the biggest part of the loft space (12 inch square gap beneath tank).

a wee diagram

 

[JohnCo]

You`ll probably find that there is a supporting wall underneath! Regards JohnCo.

 

[masona]

Is it safe to put this much load on this sort of roof? I thought they were manufactured with exacting sizes and strengths.

You're correct, it's shoddy work. Find out where the top of the walls are and hoping you can use that to support it by making framework off it to support the water tank at that height saving having to altered the pipe work.

If you can do another layout plan looking down on the ceiling area where the top of the walls are and where the water tank is position we can help you further. You're right you cannot leave it like that.

Can you do a photo of the roof structure, unless you know it is gang nailed trusses

 

[Steve]

I would do a photo, but in the diagram above, that is an accurate representation of the structure of each truss. The house was built circa 1967, using what was then, probably the latest building techniques (breeze blocks, plasterboard, preformed roof).

I suspect that none of the internal walls of the house are load bearing (if this is possible). The upstairs walls are not aligned at all with the downstairs walls anywhere (all timer framed walls internally with breeze block and brick externally). I have drawn an upstairs plan anyway with detail of where the water tank is and the direction of roof trusses. I cant see any way of properly supporting this weight given the structure of the roof and the floor below, short of using steel girders spanning the loft

The heating system is on its way out anyway, IMO. i might persuade them to get a combi boiler with mains fed hot water etc, save this hassle.

 

[JohnCo]

Like I said, the stud work is supporting the joist section of the trusses in the centre. Can`t see the link though. Regards JohnCo.

 

[Steve]

Like I said, the stud work is supporting the joist section of the trusses in the centre. Can`t see the link though. Regards JohnCo.

the water tank weight is being supported by the roof structure, which was never intended to take this weight. I think the best course of action would be to span a few of the truss ceiling joists using some chunky bits of 5x2 and stand the water tanks on these, either directly above the 2 closets or above the long stud wall (if this is, indeed, load bearing, which i cannot figure out because there is no corresponding wall on the ground floor anywhere).

 

[JohnCo]

Certainly Crafty, support the structure down on to the ceiling joists, but I would not advise lowering the tank as you will probably find you need the head of water. Regards JohnCo.

 

[SparkyMarky]

On the other hand, it's been there nearly fourty years, and (presumably) hasn't caused a problem yet....

I think this type of arrangement is actually quite common (my house is the same, as is my Grandparents one). When you think of the added weight most loft structures take (flooring, boxes of rubbish etc.) a loft of that age is probably more robust than you give it credit for. If the tank is suspended from the truss structure then the weight of the tank will actually be transferred directly to the exterior walls of the house. I'd probably be more concerned if the tank was sitting on the horizontal beams, as these are designed to be in tension (stopping the bottoms of the two sides of the roof from moving apart) and so are not really meant to withstand the bending forces imposed by having a water tank sat on them. If I were you I wouldn't be overly concerned about it.

 

[masona]

I think the best course of action would be to span a few of the truss ceiling joists using some chunky bits of 5x2

You're thinking on the right line there as you're having problem with supporting walls or not sure, however there is another way round it and your roof trusses are called Fink Trusses, click on the pdf link, on the bookmark page on the left hand side, scroll down to 3.2 Supporting Water Tanks, scroll down to page 51 (figure 69) use the + tab to make the diagram bigger, should be pretty straight forward, any problem get back to us Ideally the storage tank should be on a minimum 18mm WPB or exterior plywood. Hopefully your storage tank structure can be done while it's still in position. In theory no trusses should have any nails through the side frame, only on top for roofing battens. Your tank storage layout is quite dangerous

Fink Trusses for supporting storage tanks

 

[Steve]

I understand sparkymarky's comment "its been there 40 years", but i'd like to see this fixed, as the timber that the tank is sat on doesn't look very good quality, and a nail at each corner, supporting god knows how much weight . . . . well . .

Simply to reinforce it using an adaptation of a method in that PDF would be enough to put my mind at ease. My grandad used to do a lot of work with wood, so he can help me if he wants it done. I might have to buy him a new circular saw though - his 1970's relic doesn't quite come up to today's standards!! (its a green metal cased black and decker thing, his drill is the same)

I understand how roof trusses work - the stresses and forces involved, so supporting the tank as shown in that PDF makes perfect sense to me!

Cheers for your help masona, i will ask my grandad what he wants to do (money shouldnt be an issue, he's on a fireman's pension ).

I wish i could get into another house (all the same layout and structure) on this streeet and see the layout of their water tanks. I suspect that this tank used to sit on the ceiling joists, but has been moved up by someone to increase pressure, and a complete bodge done of it.

I wont be doing anything until the weather cools off - it was VERY hot in that loft yesterday.

 

[masona]

I might have to buy him a new circular saw though - his 1970's relic doesn't quite come up to today's standards!! (its a green metal cased black and decker thing, his drill is the same)

Stanley Jet-Cut saw under a tenner will do.

i will ask my grandad what he wants to do (money shouldnt be an issue, he's on a fireman's pension ).

As a guess £50-£70 materials, also use screws instead of nails

Hmmm a fireman, not a pull cord on the 2"x2" bearer somewhere ready for a sharp pull water tank sprinkler system

I wish i could get into another house (all the same layout and structure) on this streeet and see the layout of their water tanks. I suspect that this tank used to sit on the ceiling joists, but has been moved up by someone to increase pressure, and a complete bodge done of it.

I have done many roof trusses over the years and not once was I asked to fit a storage tank framework support I have seen many badly fitted water tank in roof as mostly are done by plumbers. Not their fault though but the roof trusses are cleverly design to use less timber.

 

[Steve]

bring back traditionally built roofs!

and i'd need the circ saw - i cant cut a straight/square line to save my life.

 

[Deluks]

bring back traditionally built roofs!

and i'd need the circ saw - i cant cut a straight/square line to save my life.

...and lets face it, a circular saw is more fun, we all like our toys.

My old man shuns technology in favour of a good sharp handsaw. He reckoned it would be quicker to saw through a 6x2 by hand than bother to set up the mitre saw, so we tested it.

He got sawing, I got the electric saw out of the box, plugged it in and cut through the timber. We were finished about the same time though.

"told ya" he said

"ah, but you're the one sweating" I replied.

 

[masona]

Ah but, now try cutting timber with a circ saw on the roof rafters getting the angle right instead of a handsaw I rarely use circ saw unless I have loads of cutting to do. You wanna see the size of my arm

 

[Nige F]

Thanx for link, Masona