Engineering Firm for Garage Concrete Slab ??

[EZM]

Engineered Slab, if you are on a tight budget, is your best bet - but something that size will likely require some piles which adds cost.

Your best bet (also the most expensive) is pouring frost walls, inserting some piles and then infilling your slab. That's bullet proof but pricey.

We have never used hollow core on grade. Hollow cores are for second stories and up between short spans using a crane to crank out a building after you pour your cores.

I'm really not sure that hollow core sitting on grade wouldn't be a real moisture trap to create a path for moisture/frost/ice to crack your slab like a kit kat the first spring after your masterpiece is built.

I haven't seen it up here in Alberta and I'd say do your research on this .... maybe I'm wrong.

Hollow core is designed to save weight, go up quickly but is not cheap. On parkades, condos, etc... on a big project 99% of them still pour solid floors (Aluma Deck/Aluma Frames and/or Shoring).

https://www.formwork.aluma.ca/

If you need an engineers opinion you can talk to one of our guys at work who design these things for a living ..... I'm sure they won't mind answering a few questions. We don't do smaller work like this often but the guys are much smarter than I am anyways. PM if you like and I will set you up.

Hopefully they can at least give you some advice anyways.

[Arty]

Originally Posted by Trochu

Have you ever seen hollow core used on a single storey structure?

I never saw screw piling or grade beams being used for a single-storey structure - until I did. I never saw red-iron construction used in single detached housing - until I did. And I never saw sky-scraper on slab construction either until I did.

You have to think about what the intent of h/c is - and how it's so much better than non-prestressed anything or poured slab. In this case you suspend some serious weight across a couple of grade beams, transferring all the force down to pilings that can handle it. Nothing touches or is affected by surface conditions.

In a typical surface slab you'll have a portion or all of the load spread out over the ground underneath; with some of it transferred to pilings or pony-walls depending how it's structured. It will be affected by anything underneath it. Sometimes that won't matter. If you're pouring directly onto solid rock or well-packed gravel where nothing freezes it might never be going anywhere.

However, if you're going to try to build something that sort of works a little bit like h/c planking by using re-bar and varying thicknesses all over the place, partially suspended by walls or point supports to compensate for soft clays and/or frost heaves, why not just do h/c to begin with? It will be more predictable, never require heating, probably never crack, and have some insulating value too. Built-in conduit would be a bonus.

[Arty]

Originally Posted by EZM

I'm really not sure that hollow core sitting on grade wouldn't be a real moisture trap to create a path for moisture/frost/ice to crack your slab [...]

The h/c would not be sitting on grade. It would be suspended on grade beams like beams at any other height.

If you mean ingress of water to the voids, that can be sealed, drained or even ventilated. If you mean water under the planks, enough clearance and even drainage can be built to counter it. The top surface is sealed with with grout or stiffening c/c diaphragm.

This particular device also has the added advantage of being under a waterproof structure, which can skirt the planks and beams like an old-time covered bridge.

[Trochu]

Originally Posted by Arty

..why not just do h/c to begin with?

Multiple reasons:
-H/C planks are expensive;
-H/C is rough and you'd still require an overly, adding to the cost;
-H/C is typically 8" thick, with an overlay, maybe 10", with a void between the grade and bottom of H/C, you'd need 12". As most sites are at grade, you'd need to over excavate the entire footprint, adding to the cost;
-If you've over excavated 12", you've likely created a low spot where water is going to want to pond, meaning sealing, drainage, or ventilation, adding to the cost;
-If you're supporting the H/C planks via the grade beam supported by piles, for example, you've significantly added to the pile loading, requiring more substantial piles, adding to the cost; and,
-You'd likely require a custom grade beam with a lip to support the H/C and wall (unless you're going grade beam, H/C, then wall stacked on top, but that would likely lead to some exterior finishing issues...), possibly leading to moment issues, that rebar would solve, adding to the cost.

It would be a wicked system, no doubt, but given the cost, done properly, a slab on 6" of crush is really hard to beat.

[brendon444]

Called place in lloydminster they charge 480+ tax to develop and stamp a foundation drawing.