Lean-to patio roof/veranda plans

[Gareth79]

Hi all, I am planning a "catio" for my cats (and me) when it warms up a bit and am interested in comments on the rough plans I have drawn up. I don't have any experience of building something like this, but I'm a relatively confident DIYer and will likely have my father for a few days, who isn't much of a DIYer but would stop me making silly mistakes!

Overall width: 6.6m
Overall depth: 3m (ish)
Roof pitch ~15 degrees

Rough sketch:


All timber C16/24 and treated:
- Posts: 4x4. Sitting on a standoff fixed to concrete approx 30x30x30cm (Deeper perhaps? The soil here is sandy and well-draining)
- Header: 8x2 (As 2x lengths). Planning to notch the front top of the posts and fix using 2x M10 bolts per post.
- Wall plate (not pictured): 8x2 fixed by M10x100 Thunderbolts (top and bottom spaced every 50cm approx, so about 20 required?)
- Rafters: 6x2, 600mm centres, sitting on speedy hangers at the top (birdsmouth to fit), birdsmouth at the bottom. It will overhang, and not join as pictured. Do I need ties at the bottom of the rafters, nail/screw them to the header, or both?

Not pictured:
- Bracing between the header and posts, using 6x2
- A set of noggins halfway down the rafters to stiffen it a bit (I think this might not be required?)
- Horizontal 8x2 end joists to continue the header around, fixed to the wall using concealed-flange face fix hangers. (Other option is to cut into the house wall, but I'd rather not do that)
- There will be additional framing inside with 25mm steel mesh panels and a door. I'll probably make them easily removable so I can entertain people sans-cats.
- After lots of thinking about the roof, I lean towards red bitumen shingles because they will work well at that pitch, look relatively nice and seem easy to install. (11mm OSB and torch-on felt base, then nail on top). A transparent roof would seem better for most people, but I think it will end up too hot for the cats in the summer.

When it's all done I'll put a patio underneath, but I'll likely level, dig out and put the sub-base in first so I can be sure of the correct height for the post bases.

Any other ideas/tips are most welcome!

[elanfan]

A retractable awning would probably be cheaper, more useful, less hassle and not cause access problems for the rear roof and gutters

[MG Mark]

elanfan said:

A retractable awning would probably be cheaper, more useful, less hassle and not cause access problems for the rear roof and gutters

This for the reasons stated - moreover, you would significantly reduce the natural light in the ground floor rooms on that face of the house unless the roofing was transparent.

[Gareth79]

An awning is worth thinking about, thanks. It'd still need to have a mesh framework underneath though, but that should be easy to do without looking strange.

The point about natural light into the downstairs rooms is very good, I think I have been imagining it in the summer whereas any other time of the year it will make them very dark the whole time. The polycarbonate corrogated sheet roofs look ok and I guess I could fit blinds and hideaways inside for the summer...

[xstian]

So you are building a giant cat cage? Its true what they say about cat people, how may cats do you own.

I don't have a cat, so I don't understand these things, but would it not be easier to cat proof the garden. I'm sure you must be able to get something to put on top of fences to stop cats getting out.

[Gareth79]

xstian said:

So you are building a giant cat cage? Its true what they say about cat people, how may cats do you own.

Only two at present! I adopted them and originally planned to let them outside, but they are basically too friendly/dumb and I think would get stolen or into trouble quickly. They are definitely not timid or shy cats!

xstian said:

I don't have a cat, so I don't understand these things, but would it not be easier to cat proof the garden. I'm sure you must be able to get something to put on top of fences to stop cats getting out.

Possibly, the fences are high enough and you can get sloping upper sections to screw on, but I think it would be constant battle/worry to keep it maintained and secure. They are pretty large Siberians which are known for jumping/climbing.

[samdale]

Gareth79 said:

Possibly, the fences are high enough and you can get sloping upper sections to screw on

Have you seen the roller type sections? They attach to the top of your fence and rotate freely so if a cat does jump up it just rolls off and can't grip. Seems a much more elegant solution to me and means you can enjoy the garden without sitting in a cage...

[Eddieslofart]

That is well over the top if it only has to carry a polycarb sheet. You can actually fix the correct glazing bars to the header and wall plate, with just end rafters to keep it square.

[meehaja]

Slight hijack, but I’m building a similar structure to roof the gap between my house and my garage. If I built a wall at each end and turned a window into a door would that be a planning permission job?

[geeks]

samdale said:

Have you seen the roller type sections? They attach to the top of your fence and rotate freely so if a cat does jump up it just rolls off and can't grip. Seems a much more elegant solution to me and means you can enjoy the garden without sitting in a cage...

Friend of mine had these, his cat defeated them in about an hour!

[Gareth79]

samdale said:

Gareth79 said:

Possibly, the fences are high enough and you can get sloping upper sections to screw on

Have you seen the roller type sections? They attach to the top of your fence and rotate freely so if a cat does jump up it just rolls off and can't grip. Seems a much more elegant solution to me and means you can enjoy the garden without sitting in a cage...

I had seen those and priced them up roughly, it would be £750ish so not hugely expensive (but still a lot more than the roof/cage). My issues would be other cats getting trapped, mine escaping (there doesn't seem to be any guarantee they won't find a way around it!), and also I would like a covered area outdoors anyway.

[Gareth79]

Eddieslofart said:

That is well over the top if it only has to carry a polycarb sheet. You can actually fix the correct glazing bars to the header and wall plate, with just end rafters to keep it square.

How do you mean, there'd still need to be beams across to hold the sheet edges somehow? I did think that for polycarbonate I could halve the rafters to the 1200mm sheet size, but I'd then probably want 3-4 rows of purlins across to mount the sheets on to keep everything snug, otherwise it will presumably go like a wobble board in the wind!