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DIY'er Polycarbonate Roofing over deck

I would like to build a roof (2m x 10m) over the deck on the 1st floor.

I envisage having 90x90 posts (4 off) in a line parallel to the house.

The roofing would slope upwards from the 4 posts towards the house.

There is a mezzanine type deck (1m x 10m) on the 2nd level. The joists for these are covered by a fascia board. This what the rafters and roof will rest on, and not the actual house wall.

The roofing material is 10mm x 2m x 1m polycarbonate. They only weight 2.4kgs each sheet, and I need 12 of these.

I would like advice please on the following;

a. What size wood is ideal for the beam running across the 4 posts?

b. What size wood is ideal for the rafters? I have been told to have 13 rafters (1m apart).

c. The fascia board is probably not strong enough to hold the rafters, so should I reinforce it (from behind the fascia) so that a ledger board can be screwed onto the fascia and onto the extra wood for stronger support.

The extra wood would be placed behind the fascia and be screwed onto the joists.

Any words of advice would be highly appreciative, thank you!

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Comments

Jason

How would you tackle this one @Brad?

Jason

Brad

https://www.workshop.bunnings.com.au/discussion/comment/6788#Comment_6788

I will take it that you are using Sunlite10 which has joiners and end caps at 50mm widths with the front cap 38mm. There is your minimum thickness for appearance. They show pergola style rafters which are much deeper than the standard 2x used for framing. Appearance wise you may want to match the facia board for the ends and front or have the bottom flush with the facia. Will have to chech the width that the back channel ends up at as it is the same as the end caps and it would need a purlin to fix to in the same way as the front will be set up.

Not it sure if you tried to use a metric 2 x 4 if the width of 45mm would make it look like a dogs breakfast or not? 65mmas the next size up would hide the joiner looking up but looking down depending on the colour of the sheets your using you could see the rafters.

65mm will also give you a margin of safety in getting your centres right.

Kokonut

https://www.workshop.bunnings.com.au/discussion/comment/65569#Comment_65569

Thank you for that, I hadn't considered the width of the joiners (65mm), so that's food for thought.
If I may pose another question.

I have 4 posts in one straight line. They are 90mmx90mm.
The distance between each of them is 4m, center to center.

OPTION ONE
I'm thinking of placing 3 x Beams measuring 45mm x 140mm x 4m on top of the posts (doubled up, so there's 6 beams in total).
Can you confirm that a T-Bracket, bolted onto the post and through the 2 Beams be OK?

OPTION TWO
I could place the 3 Beams and not double up, so that I would just cut and chisel 45mm into the post (and 140mm deep) for the beam to sit on.
Is this option just as stable, as Option1?

I need 13 rafters and these will be placed 1m apart. These are 45mm x 140mm x 2m

Each beam would carry the weight of 3 rafters and 4 roof panels. I have excluded the rafters that sit directly above the posts.
Each rafter is about 7.5kgs and the roofing panels each weight 1.5kg.
In total, each beam is carrying about 28.5kgs between 2 posts.

Is the beam 45mm x 140mm x 4m OK?

Mathy

https://www.workshop.bunnings.com.au/discussion/comment/95567#Comment_95567

Hi @Kokonut - do you need to have Cuoncil approval for this? Generally, when putting a roof on a structure, Council’s like to make sure that the structure is capable of surviving whatever windspeed you have in your area and, what do you propose to do with the stormwater that comes off that roof? Cheers Deb 🙂

Brad

https://www.workshop.bunnings.com.au/discussion/comment/114375#Comment_114375

4m span and roof attached to existing building, I would say that requires approval if the simplified planning laws are consistent between states?

There is a drip line built into the front cap but that doesn't deal with runoff. Info from the makers on guttering is non-existent I think.

I would think a t-bracket would be the easy option, points given for style by using traditional joinery. Mortice joints if the posts are in place will be a challenge. How are you planning to fix the rafters? Size sounds about right for beams but see if you can find a span table somewhere to check.

Walter

https://www.workshop.bunnings.com.au/discussion/comment/124945#Comment_124945

Here's what we did.

We wanted to remove a really old, classic aluminium awning, which didn't cover all the way to the door anyway, and replace it with polycarbonate.

We decided to make this a project, and yes, we watched a lot of YouTube, and the advice videos on Bunnings before we started

So we removed the old aluminium:

We fitted some new wood to the existing eaves under the existing guttering to give us the distance, seal, and give us something to secure the awning:

We wanted to re-use the 3 original aluminium verticals, but add 2 more, so more trips to Bunnings, and we wanted to have everything a light grey colour to match the chosen polycarbonate, so sealing, painting everything as we went.

Now we needed to get the "frame" perfect, with the verticals bolted to the cement base, and perfectly vertical and secured.

There's only 2 old guys working on it, but starting from the door, we got each post perfectly vertical. So we needed 10 clamps to get everything square. As we progressed, we found we only had 9 clamps between us. It so happened that I had 3D printed a clamp about a year before, and it was sitting on my bench

That clamp stood up to heavy winds, and everything was great (bear in mind we were not working on this project every day)

When we were satisfied, we bolted the poles to the rest of the frame, and added wood to the structure:

More wood, and aluminium as we went, and "Suntuf" polycarbonate for the roofing. With matching foam (which you can buy along with the polycarbonate) along the strip for sealing and dampening of any possible vibrations:

My friend and I can see where we made a slight mistake by not pulling the far side of the polycarbonate as much as we should have, but you really have to look closely.

Obviously

So now for the drainage. We had a lot of luck with a neighbour who just happens to do this for a living, and he got us matching colour pipe, which runs across the front of the awning. He also got us a matching "barge cap" made to size for the far side where we finished off at the edge

That connects to an existing drain pipe, unfortunately, not the same colour, but I can live with that.

Not bad for 2 old guys who had not done this before.

Now another trip to Bunnings to buy a leaf blower with attachments to remove debris from gutters.😆😆 I think that's my Christmas present.

Oh, and BTW, we have had some seriously high winds since this was built earlier this year, and I'm convinced that if a tornado hit and blew away the house, the awning would still be there,🤣

Jason

https://www.workshop.bunnings.com.au/discussion/comment/132027#Comment_132027

Awesome work @Walter. Many thanks for sharing!

I'm sure @Kokonut really appreciates it.

Jason

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