Hollow Core Slabs and Breather Membrane

IPFreely

Hi,

On my first floor I will have hollowcore concrete slabs resting on the 4 inch inner leaf.

I intend to wrap the ends of the hollowcore slabs so they are not exposed to the cavity and help prevent air movement within the cores leaking to the building interior.

I am curious about what products have other people used to achieve this? My concern is that the slab is resting on the inner leaf, concrete on concrete with the breather membrane/felt sandwiched in between. The potential for damage to the membrane here is large which I can see compromising the air tightness.

Any suggestions on detailing other folks have used to accommodate this? I see that the Pro Clima Solitex Plus has a hight resistance to tearing when compared with similar products from Isover, Siga, etc. Does it make sense to lay something above and below the membrane to protect it?

Any advice appreciated.

Thanks!

sydthebeat

IPFreely wrote: »

Hi,

On my first floor I will have hollowcore concrete slabs resting on the 4 inch inner leaf.

I intend to wrap the ends of the hollowcore slabs so they are not exposed to the cavity and help prevent air movement within the cores leaking to the building interior.

I am curious about what products have other people used to achieve this? My concern is that the slab is resting on the inner leaf, concrete on concrete with the breather membrane/felt sandwiched in between. The potential for damage to the membrane here is large which I can see compromising the air tightness.

Any suggestions on detailing other folks have used to accommodate this? I see that the Pro Clima Solitex Plus has a hight resistance to tearing when compared with similar products from Isover, Siga, etc. Does it make sense to lay something above and below the membrane to protect it?

Any advice appreciated.

Thanks!

I have detailed this for a client showing an engineered brick or concrete soap bar between the slab and the membrane to protect against tearing. The membrane can then be turned upwards and plastered over. I believe the risk of tearing is real and should be considered.

IPFreely

Great solution sydthebeat and would have been preferred but external block work is complet and internal block work is in progress. So I am stuck with this, a bit like 'putting the cart before the horse' I know but this is what I have to work with. Any one else encounter a situation like mine before?
Thanks!

sydthebeat

not willing to go up another 75mm??

just make sure the crane driving installer takes great care with the slabs.
Make sure the placement of same is vertically downward and not being pulled horizontally.

IPFreely

Thanks sydthebeat. I have a few 75mm's taken already above what was agreed on the planning so am reluctant to take further liberties! I think I will place a bed of mortar on the block and lay the membrane on this before the slab gets laid. This will hopefully prevent tearing and in the eventuality that small tears do appear they will hopefully be sealed when the mortar sets.

feelinfoul

correct me if i'm incorrect but does the hollowcore slab not have to sit 115mm on a block on the flat(215mm)and the inner leaf (100mm)continue on up as inner leaf,this is what i'm being advised on my house.
Are you going to build off the hollowcore?or continue up with timber stud?hope this makes sense

IPFreely

My inner leaf on the ground floor is 100mm. That what was recommended by slab vendor (Ducon) and my structural engineer. Slabs rest on this 100mm wall. Once slabs are in place then I grout the joints (structural screed not necessary in my case) and continue to build on top of the slabs. My internal first floor walls are block, not stud partition.

A numebr of 200mm steel beams with 100mm box-sections as support were specified for my build. You need to consult with both the hollow core vendor (they will have an engineering department) and your structural engineer for definitive advise. My structural engineer was required to sign-off the slab layout diagram from Ducon.

Maybe 215mm inner leaf is them 'playing it safe' or maybe the steel specified in my build allowed me to use 100mm inner leaf?

Poor Uncle Tom

I have posted up the following section from the forum charter

On construction related matters any specifying of structural components is prohibited. Any queries in this regard need to be dealt with by an architect/engineer privately.

Note carefully: We do not allow the specifying of structural components.

canine

A soft cushion of mortor under the precast before setting and fill the cores with expanding foam

Poor Uncle Tom

canine wrote: »

A soft cushion of mortor under the precast before setting and fill the cores with expanding foam

This should seal everything up quite nicely and fairly easily done too.

mark2003

IPFreely wrote: »

Hi,

On my first floor I will have hollowcore concrete slabs resting on the 4 inch inner leaf.

I intend to wrap the ends of the hollowcore slabs so they are not exposed to the cavity and help prevent air movement within the cores leaking to the building interior.

I am curious about what products have other people used to achieve this? My concern is that the slab is resting on the inner leaf, concrete on concrete with the breather membrane/felt sandwiched in between. The potential for damage to the membrane here is large which I can see compromising the air tightness.

Any suggestions on detailing other folks have used to accommodate this? I see that the Pro Clima Solitex Plus has a hight resistance to tearing when compared with similar products from Isover, Siga, etc. Does it make sense to lay something above and below the membrane to protect it?

Any advice appreciated.

Thanks!

Can you tell me is the membrane you have mention,the same membrane they use on roofs.and do they come in different sizes.thanks