Lean to roof questions

[oddjob]

Hi all

 

I've been put to work a fair bit now that I work from home  all the time and the newest project is a lean to roof that goes over a paved area at the back.
I have a good general idea of what I want to do but am a bit unsure on loads and span calculation so hope to pick the brain of the community here.

The back garden is 5 steps down from the back of the house so the ledger board I need to fix to the house is 3300mm off ground level, the roof will run 6400mm along side the house and 2700mm out form the house.

I'm thinking a 6x2 ledger board, 8 5x2  joist going out to a 7x2 beam that sits on 3 4x4 posts spaced 3000mm apart. and about 3100mm off the ground
The posts will be anchored with brackets to concrete footers that is going to be 2sqf. 

What I'm unsure about is if the timber is of big enough dimension to take the span and also on how to afix it to the existing wall that is cavity blocks.
I know epoxy slieve achors are prob preferred for cavity blocks but not sure of suitability as the cavity blocks have been filled at some point post build.
I was thinking masonry bolts ccd at 600mm like this type https://www.screwfix.com/p/rawlplug-lx-masonry-bolts-x-120mm-10-pack/6892f#product_additional_details_container
the roof will only be a PVC one so no weight other than the frame it self and me as i intend to paint the wall standing on it before fitting the pvc roofing.

attaching a pic for reference, you can see where the roof is going to attach to the house because I've knocked off the pebble dashing there.

I appreciate any and all input

 

[Temp]

4 hours ago, oddjob said:

The back garden is 5 steps down from the back of the house so the ledger board I need to fix to the house is 3300mm off ground level, the roof will run 6400mm along side the house and 2700mm out form the house.

 

Check it doesn't need planning permission  first. Eg within 2m of the boundary the eaves  need to be <3m high to come within permitted development rules. However I think that's measured at the point furthest from your rear wall. Details in here..

 

https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance

 

4 hours ago, oddjob said:

I'm thinking a 6x2 ledger board, 8 5x2  joist going out to a 7x2 beam that sits on 3 4x4 posts spaced 3000mm apart. and about 3100mm off the ground
The posts will be anchored with brackets to concrete footers that is going to be 2sqf. 

 

Those dimensions sound ok to me. For the brackets I would use something like this that raises the bottom of the posts off the ground a bit.

 

https://go.twenga.co.uk/to?s=9720237&gap=&gat=pla&aagid=48884992022&acid=1017976262&atid=pla-405564714126&aadid=247473114207&mcoid=114135292651&appid=405564714126&gd=t&mcid=166725238&url=https%3A%2F%2Frover.ebay.com%2Frover%2F1%2F710-53481-19255-0%2F1%3Fff3%3D4%26pub%3D5574631662%26toolid%3D10001%26campid%3D5338624526%26customid%3D%26mpre%3Dhttps%3A%2F%2Fwww.ebay.co.uk%2Fitm%2FHeavy-Duty-Galvanised-Concealed-Fence-Gazebo-Post-Support-Base-Bracket-Shoe-%2F114135292651%3Fvar%3D&gclid=CjwKCAjw34n5BRA9EiwA2u9k37T3KqGX8p8ITrqewKeFRaJagIVu38y1rLaNeymfLDUqZ3arwX3BexoCJbQQAvD_B

 

If using pressure treated timber I'd cut the post to height and put the cut end at the top where its sheltered under the roof leaving the deeply pressure treated end at the bottom. Obviously treat the cut end but I reckon it will last longer if you do it that way up.

Edited July 30, 2020 by Temp

[oddjob]

thanks for your input lad, I' think dropping the roof 100mm is a go so, don't want to have to rip it out again.

those post brackets looks very solid, i like em