Concrete 1st floor and Dormer Bungalow

Sparky78

I had always assumed there would be no problem with a concrete slab 1st floor and a dormer bungalow but a carpenter told me today there would be no way of attaching the roof rafters.
Is this true?
How would you attach the rafters if it is possible?

Thanks

dingdong1234567

Not sure about that, i would asume that the truss' would be secured to the wallplate on the inner leaf of blockwork? Could expand on the detail at the truss/wall interface of the building?

sinnerboy

rawl bolt wall plate to slab edge ( just like you do at top of wall ) ...... carry on from there

you won't need trusses - i.e. no joists , just rafters

you do have a structural engineer ?

Sparky78

sinnerboy wrote: »

rawl bolt wall plate to slab edge ( just like you do at top of wall ) ...... carry on from there

you won't need trusses - i.e. no joists , just rafters

you do have a structural engineer ?

Thanks

Will have an engineer but just at the planning stage at moment.

Sorry meant to say rafters.will edit now.

sesswhat

Many designs use steel purlins or even a steel ridge beam to support the rafters. When you don't need to tie the rafters into joists, it can also allow you to add a bit of headroom by taking the walls above floor level upstairs, planning permitting, so it would be worth getting your engineer/architect involved at an early stage to explore the possibilities.

Sparky78

Thanks.

Can a 100mm block inner leaf hold the slabs or do you need to increase the block size?

hippychippy

Surely, your walls will continue up from the floor slab?? Then you fix a wall plate as normal and roof away. As for 100mm wall to support slabs, the usual procedure is to put them on blocks on the flat, i.e. the 9 inch way.

sinnerboy

Sparky78 wrote: »

Thanks.

Can a 100mm block inner leaf hold the slabs or do you need to increase the block size?

must be 215 . slab to bear on 100mm and screed over top to turn down side 115 thick

then bolt on wall plate

also

if you use 225 rafters you can
increase insulation depth
increase spacings of raters to 600
increase u value

muffler

sinnerboy wrote: »

must be 215 . slab to bear on 100mm and screed over top to turn down side 115 thick

then bolt on wall plate

This is a dormer bungalow. Why would you need to screed out to the edge of the slabs and why would you need a 215 inner leaf?

sinnerboy

to knit slabs together to form a homogenous floor plate . the effect of the downturn part of the screed will act like a ring beam

will also form a substantial base to anchor wall plates into

muffler

sinnerboy wrote: »

to knit slabs together to form a homogenous floor plate . the effect of the downturn part of the screed will act like a ring beam

will also form a substantial base to anchor wall plates into

I can see where you are coming from on this but in my experience Id rather see the wall plate secured to the slabs than to a screed. 100mm inner leaf is quite common and saves on cost of blocks and laying same and also saving on cost of a screed finish to an area that aint being used.

Different horses for different courses

sinnerboy

screed to edge is a bit of a misnomer - true it is poured continous with the screed but is reinforced to act as a ring beam - with continuity bars extending into slab to slab joints . depends on overall structral design ,of course , but sometimes the outward thrust at the rafter feet can justify this engineering

the op's own engineer may not deem "my" method necesary , I should clarify that ..........