heated garage floor build

[hifly2000]

I am in the early stages of planning my garage/workshop,

I have allocated an 4mx9m area for it, the workshop will have a lathe and milling machine and the garage section will be for working on my land rover and transit.

the garage will be timber.

I will be installing wet underfloor heating in each section,

I would be grateful if someone could advise on the construction of the base as most data i can find relates to houses and i am not sure if the normal 50mm screed will be tough enough.

I will probably get a contractor in to lay the concrete but i can do the rest myself when i know whats required.

my sub soil is green sand.

Cheers

Vince

 

[SimonH2]

Can't really comment (not my area), but I'd say you'd need more than 50mm for a garage floor - though it might be OK for a workshop.

But, as the owner of two 25 year old Land Rovers (90 and 110) that I have to maintain outside, and having had to pass up on a number of machines/equipment due to lack of space, words just do not do justice to how envious I am.

 

[fmck]

I would imagine you have solid concrete where you have heavy equipment or the vehicle running. You would have a recess area for your insulation/ heating/ screed. Basically the walking areas. Need a perimeter expansion joint mind.

If you wanted to have it really strong conbextra GP is a structural grout its about £7 quid a bag. Once slab is poured shutter areas with lengths of timber and fill with grout before stripping and filling the recessed areas with your underfloor heating make up.

 

[noseall]

Is it your intention to fix these heavy machines to the floor?

My feeling is that UFH and heavy machinery do not mix.

the garage section will be for working on my land rover and transit.

....and somewhere to hang the banjo and a li'l ole place for the grain still.

 

[hifly2000]

Is it your intention to fix these heavy machines to the floor?

My feeling is that UFH and heavy machinery do not mix.

the garage section will be for working on my land rover and transit.

....and somewhere to hang the banjo and a li'l ole place for the grain still.

no not fixing to the floor,

the banjo will be in the cider shed. this is already built as you have to get your priorities right

 

[SimonH2]

I don't see why unless you have concrete that is not thick enough. AFter all, we lay large slabs of concrete on what is effectively flexible ground, and then rely on the strength of the concrete pad to spread the load such than nothing moves enough for it to break.

Either lay the slab on the ground (with the usual compacted hardcore etc) and no insulation, or allow for the flexibility of the insulation and lay a concrete slab thick enough to spread the load until the insulation compressing isn't a factor. I'd go for the former and just accept that some of the heat will go into the ground to start with - but the floor will have a massive thermal mass and won't cool down fast either ! I'm assuming that the plan isn't to heat things up as warm as a house would be, but just to take the chill off.

My biggest concern would be fixing things. If you need to bolt things down (such as a 2 poster lift that may need "substantial" anchors, then there's always a risk of hitting your UFH pipes.

 

[noseall]

My biggest concern would be fixing things.

Hence my questions.

I kinda see where you are coming from regards a thicker slab over the insulation to counter any 'give' but surely a thicker slab in itself would counter the need for insulation in the first place.

 

[fmck]

Now that I think about it recently we did a school refurb where a huge court yard was glass curtain walled over with a massive inflatable roof. It was going to be a dinner hall and had wet underfloor heating plus screed. We were left with no option but to run large scissor lifts on it but chucked loose sheets of ply down for the wheels to run on them. We had no bother seems a simple solution to just lay some plywood down when you bring the vehicle in.

 

[SimonH2]

I know when I used to work ona farm, we used to lay concrete to 4" where it had light traffic (including tractors), and something like 6" where we expected heavy traffic (such as tractors with loaded trailers). We never properly compacted hardcore - if we put any down then we just drove back and forth with the tractor.
I don't recall any of it cracking.

So If I had to put any figures on it, I'd just put some sand down (so as to have no sharp stones to damage the pipes) and compact it, fit the pipes (how to fix them ?*), and stick some concrete down on top (at least 4" over the tops of the pipes.
* Perhaps put a layer of concrete down first, fix the pipes to that, and then the pour main thickness on top.

But that's a very "suck a finger and stick it in the air" type of guesstimate.

And perhaps take some very detailed and careful measurements of where the pipes are for when you need to drill more than 4" down.

 

[hifly2000]

i'm not keen on pumping heat in to the ground as its just a waste,

what about putting a steel mesh in the screed how much will that improve its strength?

I will not be fitting any lifts as i don't want to make it to high, hence the warm floor as most of it will be done laying down

thanks for the input.

 

[Deluks]

Well you won't be laying on all of the floor, so why not just put a heat mat under tiles, where you would be working on the landy, and get a space heater fixed to the wall or ceiling in the workshop part where the machines will go?

It just requires you to park in the exact place each time, maybe have an uninsulated solid concrete strip for each of the wheels to roll over, clearly marked as such.

 

[hifly2000]

all heating will be underfloor as it will be running of an oil boiler running on home made biodiesel, can't afford to pay for fuel for a garage.

i think that if some area's are not heated then i could get cracking between the hot and cold sections.

i also may park more on one side or the other depending on what job i'm doing on the truck so am realy looking for full floor heating

keep the idea's comming

 

[themiddleagedun]

It's straightforward, to my way of thinking. What I'd do: a solid hardcore base, sand blinding, rigid insulation boards, lay heating pipes then 100mm of concrete... Job's a dream

 

[hifly2000]

It's straightforward, to my way of thinking. What I'd do: a solid hardcore base, sand blinding, rigid insulation boards, lay heating pipes then 100mm of concrete... Job's a dream

would you build some sort of retaining structure around the perimeter for the timber garage to be supported on, a sort of strip foundation and then insulate between that and the floating fllor.

100mm seems a bit thick to heat up, would it not be better to lay 50mm or 75mm with a reinforcing steel mesh in it?

 

[mointainwalker]

You need something to attach the pipes to as they are pretty strong when bent into circuit-shape: the mesh can therefore fulfill both purposes i.e. fixing and strengthening.

From things I have read on here in the past, 100 mm is minimum needed in garage, especially for something like a Landy.

If you are happy with the surface finish you would get with concrete, no reason IMO not to lay that, but that might be a bit rough on the back.

As someone said, either mark very precisely where pipe runs are ( not easy in my experience ) or don't heat those areas so you can fix machinery worry-free. I don't see why there should be any cracking because there will of course be diminishing heat-transmission across the whole slab and because of its nature, you can't get a sharp hot/cold divide.