Poly Carb roof plans 3

Bob Hart · Post by **Bob Hart** » Fri Oct 26, 2007 6:08 pm

Based upon some of the previous comments, I've knocked up some more drawings for comment.

On the 4th drawing I've added thoughts as to the size of the timber being used. The roof will only be Poly Carb, so no real weight as such. The total length is 12-metres and it's 5-metres wide. Therefore the slope will allow for 3-metres lengths of poly carb to be fitted on each side of the slope. These will be 2.1 metres wide.

4" Posts along the back wall of pond, with 6" x 2" connecting beams between the posts. Is 6" needed, could they be 5" or even 4"?
[img]http://www.koipix.com/gallery/albums/userpi ... an%201.JPG[/img]

Similar alonmg the front wall. Some posts will need to be in the ground as the pond shape means they cant all be on top of the wall. I may need to brace between the front and back posts with some cross beams, what say you?
[img]http://www.koipix.com/gallery/albums/userpi ... an%202.JPG[/img]

The actual roof timber is shown here. See next pictures for proposed sizes of timber.
[img]http://www.koipix.com/gallery/albums/userpi ... an%203.JPG[/img]

Same as previous picture, but with sizes.
[img]http://www.koipix.com/gallery/albums/userpi ... an%204.JPG[/img]

tomy2ponds · Post by **tomy2ponds** » Fri Oct 26, 2007 6:30 pm

Hi Bob looks good but I think you may want a couple more posts along the front as the spans look quite long .

LEE

kayoss · Post by **kayoss** » Fri Oct 26, 2007 6:37 pm

I think you'll also need a few horizontal ties from front to back to prevent the roof from spreading under the weight - especially if we get any snow

Cheers

Bob

PS Daisy's disc should have arrived by now

Geoff9 · Post by **Geoff9** » Fri Oct 26, 2007 6:44 pm

Hi Bob
Not a lot of weight in pollycarb but I wonder about the wind blowing against it,my roof is flat and half the size of yours but I used 4"x2"6"x2" and the four posts were 6"x6",just something for you to think about,but it does look good and will keep you out of trouble for a few weeks

.
Geoff

dho · Post by **dho** » Fri Oct 26, 2007 6:46 pm

Hi Bob,

either more post as tommy said or thicker timber. No way are you going to get away with anything less than 6x2 with your span. Mine are 2 pieces of 8x2 with a 4x4 bolted in the middle. I hate saggy things.

David.

Gazza · Post by **Gazza** » Fri Oct 26, 2007 8:14 pm

Hi Bob,

More strength needed i think as mine are 6 x 4 and Ive only got a little one

tomy2ponds · Post by **tomy2ponds** » Fri Oct 26, 2007 8:42 pm

Very big of you to admit that Gazza

LEE

Jon W · Post by **Jon W** » Fri Oct 26, 2007 8:46 pm

And it's a funny shape!

Cheers

Jon

dave a · Post by **dave a** » Sat Oct 27, 2007 6:15 am

6x2 timbers between posts on front are not large enough they will sag as well as bow outwards with thrust and weight of roof timbers and sheeting

What are the distances between posts on front wall also 4x4 posts will not be large enough and will look thin to the eye with the structure over.

as a guide look at scaffolding the spans are no where near as great and tubular stell wont deflect like timber over a period of time

Bob Hart · Post by **Bob Hart** » Sat Oct 27, 2007 8:06 am

Back wall first - are the 4" square posts OK there, with 6" x 2" connectors? Distance between posts will be 3-metres or slightly less.

Front wall - So I can net fish, I want less posts. Likely distances are 3.5-mtres or maybe even a tad longer. Depends on whether I can go with the shape of the pond or not. Down towards the shed where the pond ends, the distances between posts will be shorter. So as there are fewer posts on the front, I'd need to make these 6" x 6" posts? The connecting beams would also need to be larger, say 8" x 2"?
I did wonder whether to put a metal 'I' beam right through the front, then I'd have nothing in the way when netting and it would keep the are 'open' rather than cluttered with posts. I do like having the fornt open though, If I did put a metal beam in there, what size - 4" enough?

The difficulty with this design over a flat roof, is te costs are escalating all of the time. The flat roof I thought I has sussed out and knew my costs, now I just dont know???? It could be that we get the pitched roof design correct, but then I cant afford to do it - LOL May then have to go back to flat roof

stuart t · Post by **stuart t** » Sat Oct 27, 2007 9:15 am

Bob,

Have you considered building a series of concete block pillars that will support decent roof plates, you could then polycarb between the pillars in winter and enclose the pond completely?

Stuart

tomy2ponds · Post by **tomy2ponds** » Sat Oct 27, 2007 9:49 am

Hi Bob a 4" I beam that long will not be strong enough and will bend/sag in the middle I would think you would need an 8" I beam, sorry mate but this is quite a construction you are building.Although there is not much weight in Polly carp you also need to consider the timber weight and as said before snow I am sure I don't need to tell you how much snow can weigh in at.I do think this design looks really good and will complement your pond much better than the first roof,and with a bit of tweaking will be just what you want.not sure about the cost though but when it is done with this design it will be worth it

LEE

kayoss · Post by **kayoss** » Sat Oct 27, 2007 9:51 am

Hi Bob

The more I look at your pond and drawings, the more complex the problem appears to be.

Unless I'm missing something (definite posibility

) it appears to me that the back wall of the pond is straight, the ridge timber will be parallel to the back wall, but the front timbers will be span posts positioned on a curved wall - i.e. at different distances from the back wall and ridge timber.

That means that the timbers from the ridge timber to the front timbers will not only be differnt lengths, but will also need to be cut at different angles - meaning the polycarb won't lie flat on any of them and will appear to have a hump towards the centre front post.

Just realised: The polycarb sheets will also have to be wider at the front than they are by the ridge timber!

Sorry if that's not explained very well, but I'm afraid it's the best I can do.

Also, have you thought of using more posts at the front and investing in a net to confine the koi to one end when you want to catch one (a la Cuttlebrook!)? I think it will certainly provide a stronger structure and possibly allow you to use smaller timbers - then you could offset that cost against the net!

Good Luck mate.

Bob

Bigbloke · Post by **Bigbloke** » Sat Oct 27, 2007 7:07 pm

Bob

Just looking at the structure you are considering, if it's all to scale, that's going to look fairly heavy and opressive over the top of your pond.

What would be wrong with a flat topped structure with a bit of slope for drainage. Most of these structural problems then seem to go away and you can have a lighter looking, simpler and cheaper structure.

Just my hapeth.

Paul

vippymini · Post by **vippymini** » Sat Oct 27, 2007 7:16 pm

bob, this may sound really stupid but why are you covering it with polycarb sheeting?
the reason for my question is that the green mesh type covering that many people use, including good old Gazza is in practice pretty water tight when it is mounted at an angle.
if you used the mesh plastic stuff your structure would be a lot lighter and your engineering problems would start to dissepate.
plus there would be lots more pennies in your wallet.