How to build walls with a pitch

[^woody^]

How come i can't have slopped supporting walls ? I spoke to my mate last night and he is a builder and it is possible to do this

You can have what you like, but you will have problems in detailing and constructing the wall/roof junction for uplift, fixing and damp ingress. That's why a flat roof has the kind of edge detail it has, and not a sloping wall.

You obviously can't have a ventilated roof with that idea, so it will be a warm deck. And you don't seem to have allowed for the depth including the insulation - which will also affect your planning submission for the eaves height and total height.

And are you sure that the joist and beam section sizes are adequate for those spans? They seem not to be deep enough.

And you are also working to a minimum slope. With large spans like that, the roof deck tends to sag, so if you don't increase the slope and beef up the timber sections to compensate, you end up with a nice pond on the roof.

 

[trevorbayliss]

Is my architect responsible for giving me all this detail ? He doesn't seem to know a huge amount about building. e.g., he can't spec what insulation for the whole extension i need. Apparently i need to get another quote from his other contractor for this. He is not experienced in oak, that is my idea. He is a sort of friend, and not expensive. For the drawings and measuring of the house it has cost £475 so far. I have pretty much told him what i want in terms of the layout etc. He has really only done the drawings,

As to the insulation. The architect has spec'ed a warm roof with joists at 125mm, filled with insulation, or do you need some insulation over the top of the joists as well ? Then OSB board, then fibreglass kit. Is his spec wrong then ?

So my finished height of 3.35m at the back of the house is a good starting point and i have to then slope the design down to a 3m eaves height at the front of the extension. This is a good fall for a flat roof i think, but it means i can't do the furrings idea i think. I have to go with the sloping walls idea.

 

[tomfe]

Is my architect responsible for giving me all this detail ? He doesn't seem to know a huge amount about building.

a warm roof with joists at 125mm, filled with insulation

I would be a little concerned if my architect knew nothing about building. They need to think about how it's going to be build after all especially the detailing.

This is not a warm roof.

 

[trevorbayliss]

Will it be warm if i lay some insulation over the joists then ? Then OSB and fibreglass.

 

[^woody^]

I thought you were doing the drawings yourself.

It is concerning if the bloke drawing this does not actually know how it will be built. The details are the important bits. As that drawing stands, it does not appear that he has considered section sizes or the actual roof design.

All this needs to be worked out now at the design stage, else the builder may not know what to do and bodge it, or it may need to be altered to what would otherwise be the approved planning design.

 

[trevorbayliss]

No i am not doing the plans BUT i am the one going to do the work. The plans are done and have gone to planning consult. Everything will be managed by me, i will dig the drains, foundations etc. I am thinking about doing the block work and bricks but undecided at mo on that one. The roof i can do in fibre glass and i can fit the windows etc. Plastering i will be doing and helping out with the electrics. So i am really trying to get my head round the main details on this and this forum helps to iron stuff out.

Generally the build is fairly simple and if i wasn't aiming to use oak would be much easier.

It seems weird that the architect knows so little, but his cost for these plans has been £175 and £300 for the measuring of the house which was done by his contractor. He is also a friend so not sure how to challenge him and ask for more guidance. It seemed strange when he said he didn't know about the insulation requirements and could get me a quote. Could he be just a draughtsman and not an architect ?

 

[^woody^]

For a warm roof, you are going to need something like 125mm of insulation above those roof joists. That will need to cover the whole roof to the face of the outside wall, or to the back of the outside skin, so as to meet with the cavity insulation.

Thats why you would not have sloping brickwork, and your plan monkey has not thought of that at all