How to raise and seal pergola roof attached to house?

[Amar]

Hello Everyone, 
I am in need of some advice regarding my existing pergola, which is attached to my house. Pergola roof is a 2-degree slope towards the main house roof, and rainwater drains through the main house gutter.  

I am facing huge rainwater overflow and leakage during rain, which makes the pergola completely unusable. Now I want to increase pergola roof height to a 10-degree slope towards the boundary and install a gutter towards the boundary. Can you please suggest a possible solution to " make good " of this pergola.

[JacobZ]

Hi @Amar,

This is a fairly complex project that could potentially significantly alter the structure. As a first step, it is worth contacting your local council to confirm if they have any requirements relating to the alteration of a roof structure. It's always better to be safe than sorry.

Assuming they are happy for you to proceed, we will need to work out how much height needs to be added to achieve a 10-degree slope away from the house. If the height required to create the angle is fairly low, it is likely possible to remove the roofing sheets and battens, then add angled timbers over the rafters to create the fall. You could use timber such as this 140 x 45mm Outdoor Framing H3 Treated Pine cut into triangles and then attached to the top of the rafters.

 
 

Once the rafters have been altered to increase the slope, you can reinstate the battens and roof sheets and add your guttering on the low side of the structure.

Allow me to tag our knowledgeable members @Dave-1, @TedBear and @Nailbag for their thoughts.

Let me know what you think.

Jacob

[Dave-1]

Good Afternoon @Amar 

Doable with new posts installed is how I would be thinking of this idea

Finding out if a higher roof is ok from your local council would be a first step (generally they will have a webpage that tells you the rules for your area)

The roof will have to be removed to raise the height I suspect.

The look of the walls in the sunroom area (from your outside pic) makes me think that they may have been added later to enclose the area (council will  have a few thoughts on that)

Due to the size and the extension plus the new roof it may be an idea to have it professionally drawn up. You have several things coming together at once and I agree it would be a good idea to get it all sorted but it will be a large project with the extra supports needed. 

One way around it would be potentially change the sizing of the gutter to be able to carry the added water from the square area of the pergolla. The stormwater pipes may also need to be checked that they are clear. 

Dave

[Nailbag]

Hi @Amar 

I am along the same lines as both @JacobZ and @Dave-1 

1. This sized project will need a council permit even if primarily you're rebuilding a similar structure. And then that permit will require proper plans.

2. Get a few quotes from a Draftsperson (not a builder) as this will be your most effective and cheapest option. They will factor in how the structure will attach to the existing roofline to all the additional requirements for water run-off etc and overall angle that will most likely be a lot less than 10deg if designed correctly.

3. Once the permit is in place you can then decide based on your level of skillset to either build it yourself or engage or part engage a builder or carpenter and plumber.

Nailbag

[Amar]

@JacobZ  Thank you very much for your insight. I am awaiting feedback from the council; however, I am thinking of considering non-structural alteration. I may raise the roof using some roof-raising posts attached to the existing fascia and make 8-10 degree slope towards the boundary and install a gutter towards the boundary. I can see a stormwater pit under the existing veranda, which I can use to connect downpipes. I want to insulate the colourbond and change the existing transparent poly sheet to a more weather and heat-proof roof sheet. Do you have any product recommendations?
Thank you 

[MitchellMc]

I'm sorry, @Amar. Were you looking for suggestions on new roof sheeting to replace the polycarbonate? If so, Colorbond sheeting would be the way to go.

On a side note, I see that we haven't really talked about why this issue is occurring. I would have thought that when the roof was installed, some thought would have gone into drainage. Have you enlisted the services of a professional to check why the house gutter is overflowing and if the correct flashings are installed? This is a significant project you are embarking on, which potentially could be resolved by installing a higher capacity gutter on the house and additional downpipes to cope with the water load.

Mitchell