Questions on my tenders..

JacEim

Hi All
Have just gotten my tenders back and I'm not overly happy with them. I have a reasonably high spec but I'm seeing quotes of around €155 sq ft for finished house (I thought it would be around €125 sq ft)

Anyway, I have a few questions that you experts might be able to help with (PLEASE )

1.Does anyone know what the cost per sq mt of a concrete first floor (to include all elements) should be. I have been quoted €164 per sq M for 140 sqm of floor surface. I think my architect has spec'd the Rolls Royce - 200MM slabs, 75mm screed, A142 Mesh, 100MM Kingspan floor insulation, 50mm easy screed, Powerfloat finish, Casoline MF Suspended ceiling system on underside of floor, gypsum plasterboard and skimmed finish. Do I need all of these pieces ?
2. We have a balcony and are looking to put in toughened glass fixed to the blockwork - ie a seamless look with no metal or timber frames etc. Any idea of cost per metre for this installed ?
3. Is there a cheaper alternative to Villar del Rey slate - anyone got comparisons of prices ?

I have loads more questions and promise to share my experiences as we get into our build process - thanks for any help you can provide..

mickdw

In relation to the first floor slabs. What you have detailed there is the slab itself with a structural screed directly on top, then insulation, then finshed floor screed. Unless you have very large spans for the slabs, it should be very possible to design this with no stuctural screed resulting in a makeup of 200mm slab, insulation, then finished screed. The whole idea there is that if structural screed is required, it must be in contact with the concrete slab for the whole unit to gain strength. Your architect might just have taken a cover all approach here but when it comes down to the actual design of your building, your Engineer together with hollowcore slab supplier will specify the required floor design.
The ceiling components listed are typical enough as you will need some form of ceiling void anyway below the concrete slab.

JacEim

Thanks Mickdw
I am planning on having underfloor heating on the slab - would this be a driver of having the extra layer of screed?
At €164 per sqm the cost is much higher than a regular timber floor with soundproofing etc - many posters have been saying that a concrete floor is not much more expense than timber but my experience tells me otherwise..

JacEim

MickDW
Sorry - meant to say that the depth of the house is 10M (not deep as I would understand)

FesterBeatty

mickdw wrote: »

In relation to the first floor slabs. What you have detailed there is the slab itself with a structural screed directly on top, then insulation, then finshed floor screed. Unless you have very large spans for the slabs, it should be very possible to design this with no stuctural screed resulting in a makeup of 200mm slab, insulation, then finished screed. The whole idea there is that if structural screed is required, it must be in contact with the concrete slab for the whole unit to gain strength. Your architect might just have taken a cover all approach here but when it comes down to the actual design of your building, your Engineer together with hollowcore slab supplier will specify the required floor design.
The ceiling components listed are typical enough as you will need some form of ceiling void anyway below the concrete slab.

Without the structural screed your floor has ZERO diaphragm action and ZERO peripheral ties. As such it does not meet the requirements of the masonry code or the building regs.

I thought it was against the charter to advise on structure - certainly when the advice is wrong? !

I assume the OP doesnt have a structural engineer involved?

muffler

FesterBeatty wrote: »

I thought it was against the charter to advise on structure - certainly when the advice is wrong? !

Can you point this out please?

FesterBeatty

Section 1.5:

1.5 Structural items . Issues relating to the specification of structural components is prohibited. Any queries in this regard need to be dealt with by an architect/engineer privately.

...

muffler

Im aware of that part of the charter as I wrote it myself

Where was the structural advice given on thread?

sydthebeat

FesterBeatty wrote: »

Without the structural screed your floor has ZERO diaphragm action and ZERO peripheral ties. As such it does not meet the requirements of the masonry code or the building regs.

I thought it was against the charter to advise on structure - certainly when the advice is wrong? !

I assume the OP doesnt have a structural engineer involved?

fester, perhaps you can comment then on how some wideslab manufacturers can specify, and stand over, a constrution of wideslab, insulation and screed??

the latest job i specified for has this arrangement.

is the strcutural screed a requirement of hollowcore slabs alone??

mickdw

FesterBeatty wrote: »

mickdw wrote: »

In relation to the first floor slabs. What you have detailed there is the slab itself with a structural screed directly on top, then insulation, then finshed floor screed. Unless you have very large spans for the slabs, it should be very possible to design this with no stuctural screed resulting in a makeup of 200mm slab, insulation, then finished screed. The whole idea there is that if structural screed is required, it must be in contact with the concrete slab for the whole unit to gain strength. Your architect might just have taken a cover all approach here but when it comes down to the actual design of your building, your Engineer together with hollowcore slab supplier will specify the required floor design.
The ceiling components listed are typical enough as you will need some form of ceiling void anyway below the concrete slab.

Without the structural screed your floor has ZERO diaphragm action and ZERO peripheral ties. As such it does not meet the requirements of the masonry code or the building regs.

I thought it was against the charter to advise on structure - certainly when the advice is wrong? !

I assume the OP doesnt have a structural engineer involved?

Can you expand on this please.

brdboard

I don't see where diaphragm action comes into designing a precast concrete floor, unless you're suggesting that a precast slab doesn't provide sufficient horizontal tieing capacity and a screed is required for this? I think IS 325 states that a pc slab does if all walls are tied to the floor.


Regarding peripheral ties, i have seen a detail in IS 325 where cores are broken out and steel bars concreted in to provide the peripheral tie, so no screed needed.

BB

sinnerboy

Lets try to avoid detailed a engineering debate and revert to the reasoning behind the OP .

That floor spec is good quality. Very good. But appropriate. In my opinion if you deviate from it you are reducing quality.

The combined 275 concrete (slab and screed) gives you excellent airborne sound acoustic separation.

The 100 insulation combined with 50 thin screed will get you a terrific response from the UFH installation.

The suspended ceiling spec is the most cost effective and practical method to create a void below a concrete floor to run drain pipes cable and ventilation ductworks. Do you want downstands / bulkheads ?

So if you want to pear back on costs - what are are you prepared to tolerate in reduced quality ?

You have a good architect on board .

Budget €300 per lineal meter for the frameless glass guarding . Better yet obtain quotes.

Can't help you with the roof spec other than to say - meet some reps to see real life samples and send PDF files out for pricing.

bruschi

is 100mm thick insulation absolute overkill on a suspended slab tho? minimum requirements are for 25mm (please correct me if I am wrong), now granted, you should always do more than the minimum requirements, but its effectively there to stop UFH pipes from heating downwards.

sinnerboy

I'd say cutting back to 50mm would not be so bad a compromise.

I would not say 100mm was overkill.

JacEim

Thanks Folks
I spoke with my Architect (I think he is pretty comprehensive in his approach) and my Engineer (he is structural).
It was the Arch who wanted the second screed - we have a balcony on this floor and he wants to have a seamless passage from inside to outside (including integration of the sliding doors which he wants flush with the floor). We are looking at how we can possibly remove one of the screeds and achieve the same thing. Also on the insulation on the slab - we are going to reduce but not eliminate, we have UFH on this floor so we dont want heat going down into the slab...
Thanks for the feedback!!
More questions coming...