Help and adivce - building a roof

Help and adivce - building a roof

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Discussion

Ian Geary

Original Poster:

4,462 posts

191 months

Thursday 21st August 2014
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Evening all

There's an area of patio in my back garden I want to roof over. I'm thinking a simple car port style roof: a ledger down each side, 4x2 rafters with corrugated UPVC screwed on top (nice and cheap).

The first pic shows the area, and I'd expect the roof to fall away from the house where I'll fix a gutter into the existing down pipe

Fixing a ledger to the house wall is simple enough, but the other side of this space is taken up by my brick garage (part hidden in the pics by plants).

However, I need help with ideas how to fix this side in place. To get the roof level (left to right), the rafter needs to be about the same height as my garage's soffit.

I would rather not disturb the garage's flat roof, so am trying to think of a way to neatly fix a ledger in place at the same height as the soffit.

Can anyone suggest any ideas, or examples where this has been done? Also, any other comments on my plans are welcome too.





Pic 1 - the area I'm intending to cover (note, the timber is sloped uwards because it's resting on the garage roof)



Pic 2 - the section of garage wall where I need to fix the side of my roof - I'll obviously cut back the plants.




thanks

Ian

TA14

12,722 posts

257 months

Friday 22nd August 2014
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There's a lot we don't know about the existing structures however you appear to be proposing to rest a quarter of the roof on an existing lintol which will then potentially have to take any horizontal (wind) loading from the garage. Given the render, services pipes and lintol the fixings at both ends look to be proplematic. Better to do a more convential design and rest your new beam on a timber post at each end triangulated at high level (or portalised with a strong bracket) to give the necessary stiffness. (You might need to build a small 'frame' around the window.) I wouldn't connect the garage to the house via an existing lintol.

roofer

5,136 posts

210 months

Friday 22nd August 2014
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Make a timber gallows frame up and keep the roof coverings lightweight , Eternits for example.

ColinM50

2,630 posts

174 months

Friday 22nd August 2014
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Rather than fitting it to the garage wall, could you have it free standing on that side supported on a post or column of some description? Have the roofing a little higher than the garage roof and drain the rain water on to the garage?

My brother did something similar using an acrow prop which he then encased in brick.

Ian Geary

Original Poster:

4,462 posts

191 months

Friday 22nd August 2014
quotequote all
Thanks for the replies so far. I am looking up the meaning of "portalised"...

TA14 - whilst the 4x2 is resting against the lintel in the pic, I had planned on bolting a length of wood along that wall, which I thought would spread the load across to either side of the window (its a traditional cavity wall built 2002). Do you think this is risky?

The main force I'd been thinking about was weight downwards, from potential snow, the weight of the roof itself and maybe the odd cat from time to time. But when you say wind, are you implying the roof will be subject to sideways force? ie pushing against or pulling away from the house? How would I mitigate this?

I was planning on keeping the roof light-weight- made of clear corrugated uPVC. I guess I don't need 4x2 rafters to keep that in place. The length is around 2.4m and width 3.5m, so not particularly huge imo.

I planned on keeping the roof below the render (ie below the line of black painted bricks) and short of the service pipes too.

Having the roof slope across down onto the garage also occurred to me, but the front of the garage has a ridge which is about the same level as the render, which would screw up the fall.


An alternative could be to use the rear house wall to take a large supporting beam (above the patio door), and then use posts or strong brackets to fix a beam parallel to this from near the service pipes to the garage side.

Then, I could hang rafters from this, avoiding the need to connect directly to either the wall with the window in it or the garage.

The front pipe is a gutter, so I could easily drain the front of the roof into this pipe with the right connector.


My thoughts of some bank holiday DIY'ing are looking a bit further away...


Ian

Pheo

3,324 posts

201 months

Friday 22nd August 2014
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To no honest I'd just get a sail and put it up via eyelets. Not convinced that corrugated PVC won't look carp as soon as some leaves etc have got on it.

I would keep it mostly independent of the main house, by building a full frame. Partly because it's easier to take away again later eg for resale etc.