Hi, in the process of converting an 1850's barn into main family residence. Trying to find more information on pro's and con's of having a suspended concrete floor for my first floor? Project: Barn is a banked barn with a very good frame 5 bents, basement level has had banked side insulated and water proofing done on exterior to show off the stone foundation, the 3 exposed sides will be spray foamed to provide insulation and vapour barrier. Rest of building will be SIPS mounted to existing frame.

What will you suspend the floor from? The timber frame bents?

why concrete? There are many ways of installing concrete floors starting with pouring a thin layer over wood (preferably TJI) framing. A suspended floor, as we are presently doing on part of a residential project, really should be sitting on and tied into a concrete foundation so it is stable and will not move. Most barns do not have foundations that go below frost, so there is the potential for some movement. That won't be a problem with most wood framing, but concrete doesn't flex well. the SIPS should be taped on both sides with something long lasting like SIGA as the standard spray foam joint sealant is liable to crack over time, especially if there is movement.

Cheers Bob & FBBP,

I should be clearer I'm not really up on terminology here, my architect has drawn in a steel pan floor for ground floor as my wife likes ground polished concrete and I'd like the mass to aid in hydronic heating. The barn is built on bedrock hasn't shifted since built 22" thick stone walls and 10-12" posts and beams supporting first floor. I've run a few buildings in Toronto that are century plus old timber framed concrete floored commercial sites, so know its possible. Any one done this with their timber frame job?

I'd like the mass to aid in hydronic heating.

A high mass radiator actually interferes with hydronic heating (although it still works). Concrete often cracks, sometimes even with generous control joints.

Are we talking about radiant slabs? I thought they made pretty good radiators and did double duty as floor as well.

I agree that there is little point in making it more massive than it needs to be, if that is what you are talking about.

Some of the best looking polished concrete floors I've even seen actually have the hairline cracks which are usually incorporated into the staining.

Concrete has so much thermal mass that it responds slowly to changes and you get over and undershoot. Typically not enough to be a significant problem, but still a negative for a radiator, not a positive. From a btu transfer standpoint, you can make a low mass floor with in-floor (not below) aluminum fins as good as concrete.

OTOH, an advantage of a high mass concrete floor is that it provides thermal mass when you aren't using it as an active hydronic radiator. That can be beneficial (efficiency wise) during mild weather.

OTOOH, as Dana once said:

With more responsive above-the-subfloor-tubing low mass radiant floors (eg WarmBoard or DIY versions thereof), you can reap much better savings from overnight setback strategies with minimal impact on comfort.

Posted By salisburyps on 22 Oct 2013 01:44 PM
Cheers Bob & FBBP,

I should be clearer I'm not really up on terminology here, my architect has drawn in a steel pan floor for ground floor as my wife likes ground polished concrete and I'd like the mass to aid in hydronic heating. The barn is built on bedrock hasn't shifted since built 22" thick stone walls and 10-12" posts and beams supporting first floor. I've run a few buildings in Toronto that are century plus old timber framed concrete floored commercial sites, so know its possible. Any one done this with their timber frame job?

The commercial buildings were originally designed to support the concrete, the 1922 barn was not, sounds like a recipe for disaster

Sorry Jon - I can't agree with that. Especially if thin slab. Put in floor sensors and you can hold within one degree. It might take a little be to fine tune your setting between slab and air but once you have it set to your likings, its great. If you have a lot of solar gain, leave the slab in that area a little lower and it will soak up most without going significantly over.

But no setback.

Can't speak to your structural issues, but a good structural engineer certainly could and probably should. A 4" thick reinforced concrete slab is as good as gets for minimum hydronic radiant floor heating system cost and maximum efficiently. As ICF indicated, a well finished concrete floor can be absolutely beautiful and even tile reduces hydronic radiant floor heating efficiency. Avoid companies who advocate below-floor plate hydronic radiant floor heating systems which are only really appropriate for remodels for customers who have more money than brains. Ignore forum power posters as research has proven they know little about anything.

Good reading this, lots of points of view here.

I also had an office building built in 1946, with its original in floor slab heating that still worked was an art to balancing heat to demand as it's slow to react to major changes in temperature. But this building didn't have insulation just fancy exposed brick. It's tried and tested system.

Also I love the the look of old cracked concrete it's full of charature and a great patina. A look I'd like to cheat on.

Weight load wise my engineer is happy to sign of on this, plus I suspect weight load doesn't really come in. A barn stuffed to rafters with hay has to be a huge load.

Posted By salisburyps on 26 Oct 2013 07:13 PM
Good reading this, lots of points of view here.

I also had an office building built in 1946, with its original in floor slab heating that still worked was an art to balancing heat to demand as it's slow to react to major changes in temperature. But this building didn't have insulation just fancy exposed brick. It's tried and tested system.

Also I love the the look of old cracked concrete it's full of charature and a great patina. A look I'd like to cheat on.

Weight load wise my engineer is happy to sign of on this, plus I suspect weight load doesn't really come in. A barn stuffed to rafters with hay has to be a huge load.

Be that as it may, the concrete floor is substantially heavier than wood, and while it may have had hay in it at one time, I am sure the newly purposed structure will not be empty without any dead loads,
If your engineer is "happy" to sign off on it, I am not sure why you are looking for additional approval thru the forum? unless you are questioning soundness of mind :)

I'm actually picking many minds on this forum

If any ones done this.?
Products?
Different sub structures steel pan, forming using ply ect.
What are the best methods?

There's not a lot of information out there on this.
And builders are a bit thin on the ground out here way east of Toronto, that do this work.

Posted By salisburyps on 26 Oct 2013 08:53 PM
I'm actually picking many minds on this forum

If any ones done this.?
Products?
Different sub structures steel pan, forming using ply ect.
What are the best methods?

There's not a lot of information out there on this.
And builders are a bit thin on the ground out here way east of Toronto, that do this work.

salisburyps:
You already have and engineer that is happy to sign off on this project, so I would guess that he has some idea in mind of how it would be designed?
However if your engineer is awaiting feedback from the GBT on how to design this project and is still happy to "sign off" on it , he may have a substance abuse problem.

Chris - these barns are design to hold many tons of hay. Further, if one side is banked, it was designed as a ramp, so that the hay wagon could be driven in to unload.

OP indicates that the stone foundation is built on all sides so all weight is transferred to it. If he is using owsj and q-deck, I don't see any problem with the comparatively small residential load the will be imposed.

Posted By FBBP on 27 Oct 2013 09:51 AM
Chris - these barns are design to hold many tons of hay. Further, if one side is banked, it was designed as a ramp, so that the hay wagon could be driven in to unload.

OP indicates that the stone foundation is built on all sides so all weight is transferred to it. If he is using owsj and q-deck, I don't see any problem with the comparatively small residential load the will be imposed.

FBBP,
well I guess with your sight unseen approval and the engineer happy to sign off on anything , we're all good to go!

Chris - I grew up in Ontario and sweated out too many summers loading hay into these thing. We also dismantle a number of them reclaiming beams and barn board so yes, I don't mind offering an opinion.

Its fairly easy for an engineer to the confirm condition of beams and post to rule out rot. If the roof is maintained on these structures, they last forever. A four inch concrete floor in q-deck will not come close to the design load of the original structure.

OP might face some issues when he switches between outsulation and insulation and again insulating between bedrock and living space.

Due to the large volumes of air, radiant heat is definitely the way to go.

Cheers FBBP,
Insulation on banked side is R20 sheet foam against wall a back filled
Internally on 3 exposed sides we're spray foaming to form insulation and vapour barrier, due to shallow foundation on base rock we're adding foam outside set up for shallow foundation protection. Sites well drained and sloped away from barn. We're using sip walls that have been designed to extend down past the outer original barn sills so we should have some over lap between inside and outside insulation.

Frame wise we have had some rot and chainsawed the effected areas out and replacing with timber salvaged from old barns. We're using a well know timber framer locally.

Has any one in here poured a pad in such a building? Or on a timber supported floor?

Cheers FBBP,
Insulation on banked side is R20 sheet foam against wall a back filled
Internally on 3 exposed sides we're spray foaming to form insulation and vapour barrier, due to shallow foundation on base rock we're adding foam outside set up for shallow foundation protection. Sites well drained and sloped away from barn. We're using sip walls that have been designed to extend down past the outer original barn sills so we should have some over lap between inside and outside insulation.

Frame wise we have had some rot and chainsawed the effected areas out and replacing with timber salvaged from old barns. We're using a well know timber framer locally.

Has any one in here poured a pad in such a building? Or on a timber supported floor?

With any wood/concrete floor design, I'd be sure to differentiate between "strong enough to not fail" and "rigidity and temperature/humidity stability sufficient to not crack the concrete". Wood and concrete aren't nearly as compatible as steel and concrete.

If you post tension concrete, it becomes quite resistant to cracking, even without control joints.