Adding 2nd storey to an extension

[Marty4000]

Hi,

 

I have started an extension, Length 4 M x Width 4M x Height ? , I was aiming for 3 M.

 

I have got to a point now where I need to decide, which I had not considered before, whether to continue going up another floor.

 

Making the extension in to 2 storeys, there is just one thing, as always cash flow, so I am pricing up, getting an idea of materials, before I resubmit for planning and building regs.

 

So any assistance would be appreciated!!

 

I am aware that 2 storey extensions can only be Max 3 M from the rear ion the property, I am proposing building a 3 M extension, on top of a 4 M extension.

 

My main area I am thinking is the bridging of the gap from wall to wall at the 3 M point, do I use a RSJ, 178 mm x 102 mm x 3.6 M, or can I use 175 mm x 47 mm x 3.6 M timber joists. More cost affective is the Timber joists, but I am thinking is this adequate support ( maybe doubling up the joists, side by side, making 175mm x 94 mm joists, or buying 175 mm x 100mm x 4 M and cutting to fit in to the walls, this/these Timber joists would be supported either side by aerated blocks, and an open span of 3.4 M. I would also be relying on this support structure to support the floor joists area 3.4 M width so floor joists joined to the support structure at 400mm centres.

 

Also the support joist would be expected to take the load of the outer wall of the extension, I am planning a Timber framed upper floor, so the outer facing wall would be Timber stud walling, with Brick Slip cladding. I am aiming for, not sure if I will get PP, but a flat roof, so no tile weight will be on the timber framed facing wall, but I guess with all of the elements, and other buildings regs regarding Timber framed buildings, the support has got to be adequate to support a big enough load, I do not want to get this wrong, as this is the foundation of the build, along with the outer walls of the existing extension.

 

I am currently researching Building Regs for this type of support structure, installation of floor joists, but any advice would be appreciated, is it even possible to use Timber/Steel for this type of installation.

 

Thanks in advance

 

Marty

[nod]

Bringing in a Structual engineer to do your calcs will only cost a few hundred 

BC will want a SE calcs