replacing lean-to roof

[PaulTheTiler]

Hi all.

I have an existing lean-to with the old corrugated plastic roof that I want to replace.

After some research I think a 10mm polycarbonate roof supported by timber joists is the best solution for me.

I am reasonably confident of installing it myself and the flashing to weather the joint between house and roof (I'm thinking Alu-flash?)

However there are 2 problems:

1; how do I weather around the soil stack that comes down through the roof (at the moment the old one has been masticked around but still leaks when it rains)

2; This one is difficult to explain so I'll add a couple of pictures at the bottom to help.

As you can see, at one end the new roof will end abutting a tiled roof of an extension. The main question is, how on earth do I make the roof weather-proof against this ?

My first thought is to slide some extra wide flashing under the roof tiles to lap over the new polycarbonate roof at that end - not sure if that's even possible but I would love any input or ideas from the experts

Btw - I will probably fix the joists to the beam already bolted to the house wall and replace the timber on the exterior lean-to wall with something that slightly larger. Including the new joists (I assume 3x2 would be large enough?) the new roof will probably be 3-5 inches higher than the existing.

Thanks in advance for any help

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• PaulTheTiler
• 3 May 2010
• 1

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• PaulTheTiler
• 3 May 2010
• 1

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• PaulTheTiler
• 3 May 2010
• 1

 

[noseall]

What you have at the moment is what is described as a Fred Flinstone cobbled up affair that should not be mimicked in any way.

The way that the lean-to roof joins the hip roof is a joke and will never be successful.

The hip roof either needs extending across or leave the hip well alone and construct the new lean to either below or abutting the fascia detail of the hip roof.

You can not make a silk purse out of a sows ear.

 

[Alastairreid]

What you have at the moment is what is described as a Fred Flinstone cobbled up affair that should not be mimicked in any way.

well put.

 

[freddiemercurystwin]

If its not leaking I'd be inclined to see if it'll clean up and leave well alone.

Can't see how you can join a flashing to a flat poly roof.

Either that or replace the existing corrugated sheets with like for like at least then a lead flashing could possibly be dressed to take any rain over the top and be dressed into the bottom of the corrugations.

The only proper solution (which will still look cr*p BTW) I can see is a split level flat roof beneath the pitched roof and then it would need to step up to retain the opening evident in the second pic on the left.

 

[theoldun]

Paul, Jist noticed your post, also know that you have only just moved in.
Reminded me of the very first house that I bought, Saved up for a long time to buy it. I knew there was so much work to do, but it was mine, mine, and I knew that given time I could make it the way I wanted it. You can do the same fellow. I feel tired to-night, but will come back to you tomorrow and see if I can help you out.
old un.

 

[freddiemercurystwin]

The ultimate solution would be to extend the existing tiled pitched roof.

 

[noseall]

The ultimate solution would be to extend the existing tiled pitched roof.

The hip roof either needs extending across

 

[theoldun]

Paul. Deal with the two problems you have asked advice on.
1. Leak to roof at soil pipe. Assume it is soil and vent and not stink pipe at head of run and that discharge pipes are entering soil pipe in roof space of plain tiled roof. If this is the case even though you may be head of run their is a possibility that you could cut the soil pipe our altogether and squeeze a air admittance valve on to soil pipe in roof space. Their are certain rules with regard to air admittance valves that the drain run should have a clear vent to air at top of run, however if your neighbour has not fitted a air admittance valve to his soil pipe and he is on the same run as you with a clear vent to air you will be okay.
If this is not feasible, Then you want a lead slate or sometimes called flexible soil pipe flashing. Feel sure that you know what they are, but if not google lead slate.. Easy enough to fit, but may have to extend the portion of soil pipe above the roof to give you about a 200mm up stand to accommodate the height of lead slate. Easy enough to do, but you may have to buy a few tiles including tile and half’s. If you are not sure, come back.
2. Gap between roofs. If you are an end house with no neighbour then your gutter overhanging the wall is not correct but no big issue, however if you have a neighbour then you are out of order overhanging the gutter into his garden. Have a think about it, come back and say what you would like to do and I will tell you the best way of doing the polycarbonate roof and altering the gutter. so that it will look presentable, seal the gap, and not look out of place.
Also consider repairing leak, living with roof as it is for a while and then, when you have enough in your budget, either extend tiled roof round, or flat roof with domed light and GRP finish.
Hope this may help. old un.

 

[PaulTheTiler]

thanks for the reply Oldun.

soil pipe:

I have added a photo of the soil pipe so you can see the problem - it's an old asbestos one and I really don't want to get involved with disturbing or replacing it if I can avoid it! so the lead slate isn't really an option.

If I add the joists the new poly would raise just over the lower collar and old air-brick.

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• PaulTheTiler
• 4 May 2010
• 1

roof:

there are no neighbours on this side of the house - just a driveway down to some garages. I know the gutter over-hanging the boudary is not "right" but I figured if this one has been here 20 years....no harm in putting a new one in

I did consider a flat roof but for various reasons I ruled it out - mainly for height and wight restrictions.

any ideas how to deal with the weathering of the joint between the 2 rooves would be most appreciated

Paul

 

[theoldun]

Paul, Not forgot you. will be back.
oldun