Planning rehearsal space - floor slab sanity check?

Hokay, latest stack-up (found that I needed a thicker screed also): Latest pdf drawings: http://www.funkster.org/lab/a4.pdf http://www.funkster.org/lab/a3.pdf :o) -- Olly

Posted that without checking the pdfs yesterday, have just noticed that the rebar and UFH pipe isn't showing up on the second page of the A3 document. I hate computers :o( -- Olly

and you don't need the additional concrete on the edges for wall support. http://en.wikipedia.org/wiki/File:Raft-slab.gif

Hope not - have just worked out the wall loading (142Kg/m max) and will be sending the drawings to my tame structural engineer later on to get the sums done. Given the price of screeding, I might embed the UFH pipes directly in the concrete slab and make it a bit thicker - gets it all done in one pour then. Depends on results from structural sums of course. I take it you have no opinion whatsoever as to whether it needs another softer layer in there for isolation purposes? The structural stuff I can figure out, and have access to experienced civil engineers to check my work. The isolation stuff, less so! Cheers, -- Olly

i don't think you need anything soft as its earth damped.

gullfo wrote:

and you don't need the additional concrete on the edges for wall support. http://en.wikipedia.org/wiki/File:Raft-slab.gif

Even a sidewalk has a turn down...what does this wiki link mean in reference to what this project is :)? That link shows basically a beamed footer with an exterior block wall...where is the similarity and how does it relate to an interior wall with no seismic load? I know your presenting something here...but I don't get it :)

Brien - i'm not seeing the additional concrete under the slab where the walls will be support and wondering if all agree on the use of a simple flat slab. i think previously you suggested the additional concrete and rebar to ensure proper support.

Support, erosion control and some form of stability to reduce any shifting of the slab under extreme conditions should they ever be presented...just my opinions on what I would take into consideration and most likely do.

xSpace wrote:

Roguejackal wrote:

If the inclusion of mesh or rebar is heavy on the finances adding fibres in the concrete and thickening locally where the walls will be, would be fine.

You speak as though you have done this and been code compliant...is this correct?

I am a director of my own Groundworks and Construction company and have been in construction for 27 years so a working knowledge, I will be using a similar design for my own small studio,

Have just had word back from my civil engineer, 6" slab with one layer of steel reinforcement 40mm from the top will be just fine for my purposes. :o) Cheers, -- Olly

Roguejackal wrote:

xSpace wrote:

Roguejackal wrote:

If the inclusion of mesh or rebar is heavy on the finances adding fibres in the concrete and thickening locally where the walls will be, would be fine.

You speak as though you have done this and been code compliant...is this correct?

I am a director of my own Groundworks and Construction company and have been in construction for 27 years so a working knowledge, I will be using a similar design for my own small studio,

I appreciate your background and experience, a lot of us old timers run our own work and have been doing it for years but we still have a standard. Reason I persist on these things is that somewhere down the road someone else will read this thread and we really haven't given any conclusive information. The world is a big place and geography has as much to do with how a builder will construct something. So if I can ask the question again, for every-ones benefit and mine as well, have you done this and been code compliant in your country?

A Raft with reinforcement is a recognised design sometimes used in this country but I am not going to say any more than that and appreciate your comments that other people will see this, so I retract the comment suggesting the design, Carl

Reinforced 6" raft is very commonly used in the UK as a base for erecting garages made out of sectional concrete or single-thickness blockwork walls. However when used in this context the regs state that you need at least 150mm of slab extending beyond the outside of the walls, which I don't have. However the inside-out stud walls, even though they're carrying another ceiling, still turn out to be a sensible loading for this design - presumably concrete garages are somewhat heavier. I would expect that if I wanted two or more layers of plasterboard on both sides of the wall, a thicker slab with more reinforcement would be required. All the best, -- Olly

Agree with your post, in my case I am building an L shaped building comprising of a small tool store/shed, control room and recording room, the shell will be built with concrete blocks on conventional trench footings in the ground with the slab turning down on to the top of these footings thus creating a thickening of the slab where the stud work will be. As mine is an outbuilding as long as it is less than 50% of my total garden and and no higher than 2.4m high I do not require planning or building regs.