Pergola - assurances sought!

[Si Fillo]

Hello everyone, I'm new to the forum!

After a few summers of not getting around to it, I am determined to get a lean-to-pergola erected this year. My procrastination has mainly been down to a few issues I need to be sure of before commencing. Please refer to attached images.

I want the pergola to cover the entire area of the raised patio which is 5m x 5m with a height of 2.3m to the centre of the decorative brick course.

 

My idea is for the ledger board to be attached to the garage. I will then have 4 supporting posts (6"x6"?) sat behind the low wall. My 1st doubt is how to secure the posts and would like advice please.

Posts 1 & 2 have a drain pipe underneath the patio so digging isn't an option. Post 1 can be secured to the bungalow wall IMO.

 

Posts 3 & 4 could be dug and secured with concrete(?). Post 4 I have concerns as it is right in the corner of the raised patio area and I would suspect that digging will result in the collapse of the immediate earth? (image)

Could Post 2 & 3 be secured with a kind of 'above deck' post bracket? I would suggest a bracket for Post 4 too, but as you can see the paving bricks already seem to be falling away so I have concerns about solid foundations for Post 4 if I went for a bracket.

These 4 posts would support the main beam (2"x8"?) which has a total length of 5m! The gap between posts 1 & 2 and 3 & 4 would be 1m leaving a span of 3m between 2 & 3. There would also be a number of cross rafters from the ledger board to the main beam, which raises more doubts...

 

1) The main beam: a 5m length of 2x8 will be quite weighty I imagine. Will I need 1 beam or 2 (1 at either side of posts)

2) the 5m rafters will have no support along their span, is this unadvised? i guess the rafters aren't as thick/heavy as the main beam(s) but still, 5m might be a bit of an ask.

-The light post would obv be removed - the existing electric supply would be kept to supply lighting to the pergola.
- the low wall would be rebuilt to extend to hide posts.

I would appreciate any advice to help with the build. 🙏

 

 

Edited February 9, 2023 by Si Fillo