Concrete post foundation through frost insulation

[Liam Nesson]

Hi All,

I have approximately 25 heavy industry sites with frost depths varying from 450mm to 3m. For the sites with high frost depth we are using a raft foundation (to support pre-engineered single storey buildings) approximately a meter below grade and then have frost insulation that runs under the raft and beyond 2m either side. Another discipline wants us to put a concrete post foundation (say 450mm dia) through the insulation, has anybody done this and how have the addressed the cold bridge? I am thinking to make the post square and put insulation around the post down whatever depth i need, however i have not done this before. The post will take a small force (say 5kn of equipment) and should not have large lateral loads, it will be about 2m high.

 

[jayrod12]

I practice in an area of frost depth around the 1.8m mark. For equipment supports, we only put the foundations below frost if they can't tolerate movement. Otherwise, if the equipment generally has the capacity to tolerate some seasonal movement without affecting operations, then we just put it on grade-supported slabs.

 

[dik]

Same here jay... often use stiffened slab... and we have similar depths of frost penetration. Only with silt do we usually encounter movement. What's the soil? and does it suffer frost heave issues?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[Liam Nesson]

Thanks for the responses Jayrod and dik.

In the end I have got the other discipline to agree to a concrete pad that will be close to the main building and sit above the insulation. No insulation penetrations required. So I will just extend the insulation a little more at that side of the building.

For completeness:

@jayrod, agreed but i dont think my client would buy in, in this instance.

@ dik, there are a number of sites, the ones that have insulation are the sites that have been identified in a site specific geotechnical report to be frost heave sensitive and insulation was recommended.