Patio slab same as house?

Anonamoose · Aug 02, 2018 8:12 am

G'day everyone,
The plans for our slab show that the back patio and path are the same slab as our house. After reading much about slab insulation including edge insulation i am concerned it might make our house uncomfortable. I've included our plans and if anyone is able to give some advice we'd really appreciate the help.
The back patio and path is above the 'S2' dropdown at the top of the image.

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StructuralBIMGuy · Aug 03, 2018 7:00 am

anonamoose
Welcome to the forum, that looks like a nice deign and is a standard waffle slab, Cheap and potentially nasty, void former's are used to improve slab stiffness, thermal beaks will need to be engineered, Talk to an engineer about alternate details, but I suspect your builder won't be interested.
BTW I would recommend you increase slab thickness, for tiled areas. hth

Anonamoose · Aug 03, 2018 8:35 am

Thanks so much for replying StructuralBIMGuy, I've spoken to the local engineer who created the design and they have no experience with thermal breaks etc. for residential work. The builder is actually a relative although you are spot on with the interest level

I've searched online for an alternate engineer although it's not clear to me what I'm looking for, is this a standard skillset?

StructuralBIMGuy · Aug 04, 2018 7:19 am

It's not something that structural engineers would look at as architects generally champion insulation, thermal breaks, the built environment,etc
here's the problem in a nut shell

The Math & Science in Environmental Studies that couples Structures hasn't extended to Art/design school

Architects/Designers Building Information Models (3D,BIM) is disjointed from the Engineering BIM required

The engineering software is extremely expensive, complex, and finding new applications is left to researchers & Students Cladding & Insulation

Even tho I have the software and knowledge there are other more pressing problems to focus on.
hth

Anonamoose · Aug 05, 2018 10:26 pm

Thank you for your help StructuralBIMGuy, I guess we will go with whats been engineered. Maybe in 15 years or so when we build again things might be better.
Will reply to this with our experience once we have lived in our new house a while. Might be of interest/help for someone.

Thanks again StructuralBIMGuy!

StructuralBIMGuy · Aug 06, 2018 8:13 am

You can trust your engineers to give you the best,most cost efficient solution, and if things ever change.."they will be all over it...."
You might want to read this VBA is nothing more than a giant failure and there are many on this forum that would agree with this article
Goodluck

alexp79 · Aug 06, 2018 1:15 pm

For thermal break in your scenario you would need to introduce thicker "double" edge beams around the edge of the internal slab (one edge beam will be holding the internal slab and another one - external) and place XPS/EPS insulation boards between them. Those beams will be located exactly where your currently have your articulation break.

StructuralBIMGuy · Aug 06, 2018 2:44 pm

alexp79

For thermal break in your scenario you would need to introduce thicker "double" edge beams around the edge of the internal slab (one edge beam will be holding the internal slab and another one - external) and place XPS/EPS insulation boards between them. Those beams will be located exactly where your currently have your articulation break.

And you have created a hinge joint , which is subject to movement/Rotation ?

alexp79 · Aug 06, 2018 2:50 pm

StructuralBIMGuy

alexp79

For thermal break in your scenario you would need to introduce thicker "double" edge beams around the edge of the internal slab (one edge beam will be holding the internal slab and another one - external) and place XPS/EPS insulation boards between them. Those beams will be located exactly where your currently have your articulation break.

And you have created a hinge joint , which is subject to movement/Rotation ?

... and I have created two independent/isolated slabs. How come movement/rotation properties will be different from the current implementation?

StructuralBIMGuy · Aug 06, 2018 2:58 pm

That is a continuous Pod/Slab the 1c step downs are clearly hatched.hth

alexp79 · Aug 06, 2018 3:01 pm

This is why if he wants to properly thermal break it, he would need to design and build two independent slabs instead of a continuous one, with the layer of edge insulation in between them.

StructuralBIMGuy · Aug 06, 2018 3:15 pm

Care to share the details ,Calculations/Simulations?

alexp79 · Aug 06, 2018 3:24 pm

I have similar set up for rafted slab with piers, so it is a little bit different story.
But from what I see, the extra cost will be cost for two extra edge beams along the patio perimeter (concrete and reo mostly).

StructuralBIMGuy · Aug 06, 2018 3:36 pm

You have the 2 drop beams separated by insulation & Tied Together? How do you propose to transfers Bending Moments & Stresses?

alexp79 · Aug 06, 2018 3:56 pm

StructuralBIMGuy

You have the 2 drop beams separated by insulation & Tied Together? How do you propose to transfers Bending Moments & Stresses?

I have a piered slab and piers are not tied together but are on the same footing and reinforced.

alexp79 · Aug 06, 2018 4:07 pm

To be specific:

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StructuralBIMGuy · Aug 06, 2018 6:16 pm

Thanks for the details, You have a reinforced concrete Wall Tied into the footings
Anonamoose unreinforced Brick walls on those footings will be subject to movement, rotation, tensile stresses and cracking
and require Bond beams and reinforcement.your cracking will be hidden under the insulating material,,ingress of moisture will be an issue since you don't have a cavity

alexp79 · Aug 06, 2018 6:31 pm

Is he having any bricks at all (other than veneer)? I believe he is talking about timber framed house here.

StructuralBIMGuy · Aug 06, 2018 6:33 pm

i suggest you get a copy of AS3700 masonry codes hth

Anonamoose · Aug 12, 2018 8:14 am

Hi Everyone, welcome to the conversation alexp79,
Interesting conversations! Yes we have plain brick veneer with timber frame. I've discussed the dual slab idea with our builder and he estimates $10k plus engineering for the dual slab idea, does this sound accurate? I am concerned about movement of two relatively independent slabs although other alternatives such as paving may move as well. I never though it would be this hard :-/

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Thanks for your help StructuralBIMGuy and alexp79, we really appreciate you guys taking the time to reply.