Box Gutter and roof trusses

[akist]

We are building the garage conversion and the back wall of the garage is actually the boundary wall so instead of a fence the neighbour sees a brick wall. It was decided then that there would be a box gutter running at the top of this wall so as not to hang out over the neighbour. However the builder has now found that we cannot have a normal cavity wall at the back and that the roof trusses will have to sit on the outside skin, and because of this we cannot have a box gutter anymore. I will ask the neighbour for permission to install a normal gutter but he will probably say no. Is there another way to solve this problem you can suggest?

 

[wessex101]

You do not need a cavity wall to construct a box gutter.

 

[^woody^]

another way to solve this problem you can suggest?

Get a different builder?

 

[Nige F]

Plenty of good ones in E. Sussex

 

[Leofric]

1 . What are you converting the garage to ?
2. Why can't you have a cavity wall ?
3. Have you had any drawings done for the conversion ?
4. If it isn't a cavity wall what is the outside skin ?

 

[akist]

Thanks for the comments.

I had a look at the plans and it clearly shows a GRP Box gutter and this is what we are going to do. Somehow the builder wanted to build a little parapet with bricks to hide it from view and this cannot be done if the trusses lean onto the outer skin.

 

[^woody^]

Unless the trusses have been already ordered (which they should never have been) then it's just a case of altering their design, irrespective of what skin they sit on.

 

[Leofric]

'However the builder has now found that we cannot have a normal cavity wall at the back and that the roof trusses will have to sit on the outside skin'- doesn't make sense, is it a cavity wall or not ? If it is a cavity wall why do the trusses need to sit on the outer skin ?

 

[akist]

Because the inner skin at the rear side is not to be trusted as it has no proper foundations. But this is not a problem if we use the "GRP Box Gutter".

 

[^woody^]

A few years ago, a bloke from Catnicshire invented a thing for putting across two walls which could then be built on. He called it a lintel. He made some out of timber too, IIRC.

 

[Ian H]

If you can’t trust the wall it needs to come down.

 

[Leofric]

Don't suppose you could post a section showing this box gutter to put everybody's minds at rest. I presume the inner skin of the wall has been built off the floor slab.

 

[akist]

Don't suppose you could post a section showing this box gutter to put everybody's minds at rest. I presume the inner skin of the wall has been built off the floor slab.

Precisely yes. It has not yet been built but will be next week. The slab is around 6 to 8 inches at that location. The planners however know about this and have designed the following:

 

[Leofric]

Confusing -what is existing and what is new , inner leaf will be wall will be built of slab but drawing shows all walls built off substantial concrete foundations,no trusses shown,one wall hatched as 2 skins of brick ,other as brick and block, no rafter trays at roof /wall intersection , sharp internal corner on 'box' gutter instead of flat channel ?!
Could go on.

 

[noseall]

What's the vertical bit retaining the box gutter supposed to be? A cricket bat? How is the water supposed to pass each rafter? A kind of RMS Titanic sectional sinking scenario?

Baffled.