It's a while[1] since I've played with twinwall and I want to make an
awning-style roof over the patio, to keep the rain off. It'll be about 3m
deep (from the house wall to the outer edge) and about 3m5 wide. I'm
planning to make a frame of treated CLS-ish timber with spars at suitable
centres to take the sheeting. Last time did anything like this I used 6mm
twinwall but it was a bit floppy and wimpy-feeling[2]. What's a sensible
thickness to go for, for reasonable width of sheets? Any recommendations
on fixing systems (glazing bars etc)? And heads-ups (or downs!) on
suppliers? Any other gotchas?

tia


[1] measured in decades

[2] though it did just about survive a brick falling onto it from about
10' above - the brick made a big dent in the sheet but didn't go through
(and I don't recall if it broke either skin)

--
John Stumbles

I used to be indecisive but now I'm not so sure

On 14/04/2013 18:07, John Stumbles wrote:

It's a while[1] since I've played with twinwall and I want to make an
awning-style roof over the patio, to keep the rain off. It'll be about 3m
deep (from the house wall to the outer edge) and about 3m5 wide. I'm
planning to make a frame of treated CLS-ish timber with spars at suitable
centres to take the sheeting. Last time did anything like this I used 6mm
twinwall but it was a bit floppy and wimpy-feeling[2]. What's a sensible
thickness to go for, for reasonable width of sheets? Any recommendations
on fixing systems (glazing bars etc)? And heads-ups (or downs!) on
suppliers? Any other gotchas?


10mm is probably a better minimum... Last time I used some (on a mate's
conservatory roof - 7m wide, about 2.5m depth) I went for Corotherm and
ordered from:

http://www.roofingsuperstore.co.uk

Fitted glazing bars the length of each rafter, and then selected a width
appropriate for the rafter spacing. IIRC there is a requirement to add
mid span support when over a certain length.

Fitted ali tape over the top cut edge (which went under the flashing),
and then fly screen mesh tape over the bottom edge to let it breathe.

Installation guide he

http://www.roofingsuperstore.co.uk/u...xing-guide.pdf

The end result was nice and solid and looked pretty good.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sun, 14 Apr 2013 17:07:18 +0000, John Stumbles wrote:

It's a while[1] since I've played with twinwall and I want to make an
awning-style roof over the patio, to keep the rain off. It'll be about
3m deep (from the house wall to the outer edge) and about 3m5 wide. I'm
planning to make a frame of treated CLS-ish timber with spars at
suitable centres to take the sheeting. Last time did anything like this
I used 6mm twinwall but it was a bit floppy and wimpy-feeling[2]. What's
a sensible thickness to go for, for reasonable width of sheets? Any
recommendations on fixing systems (glazing bars etc)? And heads-ups (or
downs!) on suppliers? Any other gotchas?

tia


[1] measured in decades

[2] though it did just about survive a brick falling onto it from about
10' above - the brick made a big dent in the sheet but didn't go through
(and I don't recall if it broke either skin)

Give me a while and I'll post photos and details of our veranda roof.

Recently done, but has been tested by snow.

Cheers

Dave R

Could you please tell me what distance the rafter should be? If I use a 700mm polycarbonate sheet (and have to allow 2mm each side against the supporting bar that sits on the rafter) should I also take into account the thickness of the inner part of the supporting bar, where the screws fox it into place?

So my question is, given that the gas hiss are 50mm with an inner part (where the screws go) of 15mm should the spacing of the rafter be calculated as follow:

Sheet width 700 mm
Space to allow expansion 2. mm
Inner part of support bar 7.5mm (15mm/2)

Spacing of rafter 709.5mm?

Thanks

On 22/08/2016 09:15, wrote:
Could you please tell me what distance the rafter should be? If I use a 700mm polycarbonate sheet (and have to allow 2mm each side against the supporting bar that sits on the rafter) should I also take into account the thickness of the inner part of the supporting bar, where the screws fox it into place?

So my question is, given that the gas hiss are 50mm with an inner part (where the screws go) of 15mm should the spacing of the rafter be calculated as follow:

Sheet width 700 mm
Space to allow expansion 2. mm
Inner part of support bar 7.5mm (15mm/2)

Spacing of rafter 709.5mm?

Sounds about right...

I most cases the rafter positions are already set, so you just cut the
sheet to fit once the glazing bars are fitted.

You probably ought to refer to the installation instructions for your
particular roofing system regarding the amount of expansion space to
leave. e.g.:

https://www.roofingsuperstore.co.uk/...xing-guide.pdf




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/