Lean-to roof: solid polycarbonate

rje66

DIY KING wrote: »

Nice job with the glazing. Are they painted timber joists with glazing gaskets and cappings ? What glass spec did you go with ?
On the overlapping of the multiwall, you hardly have any photos ?

Yes painted and used the glazing bars, they ain't cheap.
Think glass is 10mm toughened. They are very heavy so was conscious of weight.

Calahonda52

Lumen wrote: »

I think the ends are supposed to be sealed to prevent this.

yep there is a breathable tape

Fine Cheers

Here's some of photos. The area to the front where you can see the timber rafters is the area to be glazed with solid polycarbonate hopefully.

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rje66

DIY KING wrote: »

Here's some of photos. The area to the front where you can see the timber rafters is the area to be glazed with solid polycarbonate hopefully.

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20201024_135542.jpg

20201024_161049.jpg

Nothing spared on the the joisting!!!

Fine Cheers

:rolleyes: Indeed but that was really to match the depth of other roof and and to allow poly or glass run over the little parapet. 225 x 50 x @ 600mm ctrs well over sized without doubt but main roof rafters are 175 x 50. Span = 3.7m .
Also wanted it fairly sturdy to brace the front wall of cladding / gate.

NIMAN

How is the rain draining off the existing roof?

Fine Cheers

I have a continuous concealed gutter just below the concrete wall capping with the epdm dressed into it. For the poly element though, as the wall steps down I plan just to run the sheets out over capping and water will run off into adjoining grassed open space (we are end house). This will also allow some ventilation to bins etc.

listermint

Would have to come out significantly far so as not to come back and drench the wall and the gap. Probably as much as 300mm

Calahonda52

or he could fix a drop down in a bit from the edge

Fine Cheers

6mm toughened glass is working out a hell of a lot more expensive than 6mm solid poly. That's just for the material and then need to add in gaskets, cappings etc (which are not cheap) whereas with the poly I will be just drilling through and fix. Also need to notch around a flue and column. I know that can be done with the glass too but when I think of the glass weight and getting it up into place etc, I think I will stick with the 5mm or 6mm clear solid poly for this project, whichever I can source.
Also going to go with straight forward overlap joint across the roof of about 150mm and see how it goes. I will shim up the upper sheet the 6mm. I'll keep ye posted.

Lumen

DIY KING wrote: »

6mm toughened glass is working out a hell of a lot more expensive than 6mm solid poly.

That's interesting.

The triple glazing I bought was €132/sqm + VAT for 3x6mm layers, which works out at €44/sqm and includes argon filling, low e coatings and sealing into a unit.

6mm poly is about €46.50/sqm + VAT on the 365plastics.ie website, and that's before cutting.

listermint

Lumen wrote: »

That's interesting.

The triple glazing I bought was €132/sqm + VAT for 3x6mm layers, which works out at €44/sqm and includes argon filling, low e coatings and sealing into a unit.

6mm poly is about €46.50/sqm + VAT on the 365plastics.ie website, and that's before cutting.

ya glass is quite cheap, i get quite surprised how cheap tbh.

Fine Cheers

Is that price for toughened glass ? I have more prices coming for 6mm toughened which is what has been recommended. I've been told that you can't get toughened longer than 3.1m ? Ideally I'd use 6 panes 3.8m long x .6m wide to match rafters.

Lumen

DIY KING wrote: »

Is that price for toughened glass ? I have more prices coming for 6mm toughened which is what has been recommended. I've been told that you can't get toughened longer than 3.1m ? Ideally I'd use 6 panes 3.8m long x .6m wide to match rafters.

Yes, toughened. Now in fairness I'm taking the cost of the individual panes making up the unit, it's possible that individual panes are more expensive for some reason, but maybe shop around.

Whereabouts in the country are you? I got quotes from First Glass and Diamond Glass in Dublin for delivery to Wicklow.

Honestly, I think polycarbonate is fine, it's incredibly strong and light but I couldn't justify spending more or even the same for it given how easily scratched it is.

Mango Joe

I'm not an expert in these builds in any sense, believe me....But this thread seems to be arriving at a point where a good polycarbonate V glass debate makes a lot of sense and could be very helpful when people are decision making in the future.

I'm open to correction - But to my mind a build using glass is going to top a polycarbonate build any day.

There's just so much that can go wrong with polycarbonate cracking, scratching, going cloudy from UV light, sagging, splitting, mildew growth within....

With glass you've safety considerations overhead, extra weight, and extra cost/labour with more specialised fittings.

I think it would have to be glass for me, interested to hear people's thoughts.

Lumen

Mango Joe wrote: »

There's just so much that can go wrong with Polycarbonate cracking, scratching, going cloudy from UV light, sagging, splitting, mildew growth within.....

Solid polycarbonate doesn't have problems with mildew within, that's only an issue with the multiwall and only then if the edges aren't properly sealed.

UV also shouldn't be an issue provided that you buy the polycarbonate with the UV protection on it.

The ultimate solution is scratch-resistant polycarbonate, which is used where you need safety, light weight and similar optical/scratch resistance to glass. Unfortunately

(a) it's horrifically expensive
(b) all the coatings are different, and trying to figure out which ones gives what level of scratch resistance is a total head melter.

Calahonda52

L,
The OP may have mildew in the overlap if driving rain gets up under it.

The key with the UV is to know what side should be up.

I had a job done years ago where the sheets came, pre-cut, covered in a green film on one side and orange on the other.

The lads doing the job duly stripped both films off while the sheets were on the ground, so nobody knew which side was up, the orange film was the uv resistant side.

It all got replaced, they kept the old sheets for their next job

Fine Cheers

Good discussion and thanks for the input, much appreciated. I'll keep ye posted.
I need to balance budget with ease of installation and the end use which is bin / bike storage etc as opposed to a patio, decking etc.
Calahonda, have you any photos of your project, how did it weather over time ?
The overlap detail I need to have a close look at to avoid mildew etc.
I either fix one sheet tight over the other or have say a 10mm gap between the sheets to allow for cleaning.
Overlap length will be circa 150mm at 8 degrees pitch. I can use a packer or spacer and seal to prevent blowback.

Calahonda52

No pics. don't live there anymore, it weathered pretty good over the 25 odd years I was there after it went up.
Should have said it was not clear, it was twin wall polycarbonate.
I did gently power wash it once or twice for moss only

Fine Cheers

So think I have flue sorted so need to get going on finishing roof. Managed to source 2 large sheets of 6mm clear polycarbonate so going with that. I have single sided glazing tape to use at perimeter to give a good seal. Do I need to place anything between the poly and top of Intermediate timber rafters ?

TimHorton

rje66 wrote: »

This is something I did recently. Works for me. BTW its glass.

What brand/colour is the paint , Looks really well.

rje66

TimHorton wrote: »

What brand/colour is the paint , Looks really well.

Johnstones, think colour is ghostwriter. I can check .

shazaaaaam

DIY KING wrote: »

So think I have flue sorted so need to get going on finishing roof. Managed to source 2 large sheets of 6mm clear polycarbonate so going with that. I have single sided glazing tape to use at perimeter to give a good seal. Do I need to place anything between the poly and top of Intermediate timber rafters ?

Hey DIYKING! First off - fantastic work on the Lean-to.

I'm planning something similar myself at the moment and would love to see how you got sorted with the flue so that I can see if it would make it feasible for me to continue with my existing plans and also to explain it to an RGI engineer when the time comes.

Fine Cheers

Project nearly finished. Will post a few pics when complete. See attached diverted flue which goes up through roof. Check the boiler manual. It should specify max flue length and number of bends. Check TGD Part J diagram 16 for seperation distances to windows, doors, vents etc.
I have fitted CO sensors also.

shazaaaaam

Thanks for the quick reply and the photo - that looks perfect for what I need too.

Cheers!

patrickowens1

https://www.boards.ie/discussion/comment/115808013#Comment_115808013

Hello,

Reading with interest.... Did you get this project finished and could you post some pics please? Did you go with the solid poly in the end? Cost? Supplier? Anyone else with pics to post or advice?

I also thought the corrugated or twinwall doesn't look as nice and would prefer solid (although I'm reconsidering due to cost!). Similar to your response above I'm also finding equivalent toughened glass a lot more expensive (even in 4mm, which is structurally enough for my 666mm rafter spacings). Would be approx 1200 ex vat from online quotes! Although could probably save a bit by ringing around.

I'm currently building a 4mx4m lean-to pergola at the back patio door, out of PAO larch. Was intending to cover with 6mm clear polycarbonate and was quoted as follows - 6mm sheets 4000mm x 2050mm @ €367.45 per sheet ex vat (Access Plastics). So only one joint running longitudinally down a 10% fall. I couldn't get 4m lengths anywhere else in Ireland.

I've just sent off some requests from UK suppliers mentioned above for 6mm clear poly and also to "Rockwell meridian" who were mentioned on another thread.

Anyway, would appreciate any pics and feedback. Thanks a mill.

Pat

Rover365

I got 6mm solid polyguard from roofingmegastore in the uk (prebrexit) although only went with them as they do 6m lengths. Product was clear amber. Got the glazing bars etc all in the one order. Id say it will be cheaper to buy in ireland

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ratracer

That looks lovely, and I hope to do something similar in the spring. Did you lose much/ any noticeable light coming into the room in the house?

Rover365

https://www.boards.ie/discussion/comment/117822953#Comment_117822953

Thanks, no i was worried that it would make the room it is outside darker but it hasnt. Its a dining room on the north side of the house so darker than other rooms anyway but the pergola hasnt made any difference.

I did use steel beams (with cladding) for the main structure to allow longer spans and greater spacing reducing the amount of columns and rafters which im sure has helped

Fine Cheers

Hope these photos help. 6mm solid clear uv coated both sides (4050 x 2050) from Plastic Solutions Dublin - nice lads and very helpful. Bit of a makey-uppy overhang detail at joint of 2 sheets but worked out fine. Basically one sheet 19mm above the other - gap created by 2 x 1 treated battens on top of rafters.

Might have said already but do not underestimate the challenge in getting the big size sheets up into place.