Hello,

My flat roof (over the car port) has started leaking so I thought it
might be better to replace the flat roof with sloping plastic sheeting
like this:

http://www.wickes.co.uk/content/ebiz...ges/gil/44.pdf

Wickes also sell a bitumised version, which they claim is better
because it is UV resistant. Has anyone used this? Is it worth buying
rather than the plastic?

I assumed that I would run some rafters parallel with the sheets but
the instructions say that actually I should use purlins perpendicular
to the sheets. I am puzzled by this. My way seems easier because I
have a wall at each end to attach the timber to. What am I supposed to
fix the purlins to?

The instructions are vague about the pitch. It seems you can use
anything from 5 degrees upwards. is there an optimum angle?

Do you have any other tips or advice?

Thanks,
Stephen.

Stephen wrote:

My flat roof (over the car port) has started leaking so I thought it
might be better to replace the flat roof with sloping plastic sheeting
like this:

http://www.wickes.co.uk/content/ebiz...ges/gil/44.pdf

I assumed that I would run some rafters parallel with the sheets but
the instructions say that actually I should use purlins perpendicular
to the sheets. I am puzzled by this.

Corrugated sheets are stiff only because of the corrugations.

With purlins as suggested, the sheets will comfortably support
themselves. If you run rafters parallel to the sheets, they will
tend to sag between them.

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

On 2 Jul, 12:10, Stephen
wrote:
Hello,

My flat roof (over the car port) has started leaking so I thought it
might be better to replace the flat roof with sloping plastic sheeting
like this:

http://www.wickes.co.uk/content/ebiz...ges/gil/44.pdf

Wickes also sell a bitumised version, which they claim is better
because it is UV resistant. Has anyone used this? Is it worth buying
rather than the plastic?

I assumed that I would run some rafters parallel with the sheets but
the instructions say that actually I should use purlins perpendicular
to the sheets. I am puzzled by this. My way seems easier because I
have a wall at each end to attach the timber to. What am I supposed to
fix the purlins to?

The instructions are vague about the pitch. It seems you can use
anything from 5 degrees upwards. is there an optimum angle?

Do you have any other tips or advice?

Thanks,
Stephen.

I just replaced the roof of my car port after 15 years - transparant
corrugated plastic sheeting. Pitch about 10 deg, I'd guess.
I put the beams parralel with the sheets because I think it looks
better, but along with what Chris wrote, I had to put 2" x 1" cross-
members in at 2' intervals to stop the boards sagging. So an easier
sensible job would be to put them perpendicular in the first place.
The plastic lasts 10-15 years before it becomes brittle and prone to
crack on impact. It has the advantage of being cheap, easy to install
and nice and bright, though.
Tony

Wickes also sell a bitumised version, which they claim is better
because it is UV resistant. Has anyone used this? Is it worth buying
rather than the plastic?

The bitumenised version sold at Wickes is called Onduline. I would use it
instead of plastic if only for aesthetic reasons. Also I suspect much
longer lasting and "quieter" in the rain (if that's important).

Download the "fixing guide" from here for more info:
http://www.onduline.net/

It gets "soft" in the sun so purlins at 30-45cm really are a necessity.

Beware B&Q sell a similar product called Coroline (AFAIK made by the same
people) which is inferior but no cheaper.

Wickes also sell a bitumised version, which they claim is better
because it is UV resistant. Has anyone used this? Is it worth buying
rather than the plastic?


the plastic I used to do my conservatory ( about 6 years ago ) seems
to have some sort of UV filter/ resistance.
I used shorter 90 degree bits of plastic to join these B&Q sheets to
the wall and the shorter bits have all gone brown and brittle.

Simon