Shed Roof - Stupid Questions??

[Belboz]

Hello all

I am looking at building a new shed. I am quite happy with the construction of the shed itself save for the roof.

The shed will not have a full roof but a 'half roof' (apologies but I don't know the correct term for it) which will basically be a single sided roof at an angle.

I have considered the normal method of Ply/OSB sheet with roofing felt but I have also been considering using polycarbonate sheeting - the twin-wall stuff and not the corrugated single stuff.

Before I actually make any decisions, I would like to ask the following 'stupid' questions please:

(1) Is using polycarbonate sheeting a good idea?

(2) Do the sheet ends (the open sections) run lengthways? Reason I ask is that I see the sheets have 2 sealed curved ends and 2 open ends. Clearly the only method would be to ensure that the sealed ends are at the top and bottom of the roof because the open ends - even if clipped with capping - would leak water.

(3) I have researched the sheeting and I know that I will need end capping/edge flashing [as well as glazing bars if I need to join sheets] Am I right in thinking that I can lay the sheeting then just place end capping on the open ends?

(4) The glazing bar will fix directly to the shed but in other places what is the preferred method of fixing? Is it screwing from above right through the sheet or is there a method of securing from beneath?

Sorry to ask all these stupid questions but I know you guys will be able to give me the right answers.

Thanks in advanace.

B

 

[tony1851]

You are describing a 'mono-pitch' roof.

The sheets run with the lines down the slope.

They are supported off aluminium t-sections which are screwed to timber rafters. rubber stripes are provided as seals, and plastic cover strips are pressed down into grooves in the aluminium.

You do it from above, not below.

The components will all be available as a system where you buy the sheeting.

 

[Belboz]

Thanks Tony.

I get the idea but......

If I have two sections held in the centre with the glazing bar (screwed to the rafter underneath etc.) what happens with fixing the ends where there is no join? (i.e. the overhanging ends)

Also, if the sheets run with the lines down the slope, what is used to seal the top and bottom ends to prevent water getting in and running down the insides?

Sorry to be an idiot but I am new to this polycarbonate mularkey...

B

 

[nickjb]

You are describing a 'mono-pitch' roof..

Or a pent roof. Can't help with the other bits

 

[tony1851]

Best not to have overhanging ends with that material - wind uplift can cause a problem. Finish it with the metal bar and trim and cut the sheet to the required width,
They supply end strip for covering the holes.

 

[Belboz]

Best not to have overhanging ends with that material - wind uplift can cause a problem. Finish it with the metal bar and trim and cut the sheet to the required width,
They supply end strip for covering the holes.

Ahh..thanks Tony - I didn't think about that.

Maybe it's time to revert to ply/osb and felt. Fecking more expensive though.....

 

[noseall]

Only thing I would comment on regards Tones' excellent post is that polycarb roof systems are self-raftering i.e. no need for additional timber rafters and they are usually erected from one end off steps etc.

I personally would not bother unless you require a lot of daylight within the shed below. If you have trees nearby then go for a mineral felted shed roof.

 

[Belboz]

Thanks noseall.

No trees anywhere near where I am siting the shed.

I was looking at the bronzed stuff - not the absolutely clear.

Main reasons for thinking about poly were cost and maintenance. The price of OSB/ply and felt these days is shocking. Plus the 'cheaper' felt only guarantees a life of 5 years. I assumed poly was much more hardwearing and easier to maintain.

I costed the poly and it worked out cheaper than the traditional method.

Anyhoo.....another idea down the pan.

Back to the drawing board.



B