Hangar concrete specs

[RFguy]

What specs are people (or what is the legal specification)  using for aircraft hangar concrete for light and small aircraft up to 1500 kg ?

 

Much the same as a private motor vehicle garage loading ?

 

-glen 

Edited December 9, 2020 by RFguy

[Yenn]

What do you mean by specs. It reads as if you want to know the required concrete strength, but there is also reinforcing needs. The loads on a hangar from light aircraft are less than those for a carport. You would need to reinforce the slab to prevent cracking and also cut it up into several areas for the same reason. Another thing to understand is what is underneath the slab, is it reactive soil?

[RFguy]

Hi Yenn

Yes I expect the soil reactivity and a geotech would be driving the numbers

 

If is  a multi use facility,  imagine loading requirements will be dictated by pallet racking, forklifts.... As forklifts with solid wheels and racking feet have high pressure.

 

The aircraft , even on jacks is not very many Mpa.....

 

 

[NT5224]

Hi RF guy...I just built out of the dirt. No concrete slab.. but interested to follow this thread for when I hoist a proper hangar

[skippydiesel]

2 hours ago, RFguy said:

Hi Yenn

Yes I expect the soil reactivity and a geotech would be driving the numbers

 

If is  a multi use facility,  imagine loading requirements will be dictated by pallet racking, forklifts.... As forklifts with solid wheels and racking feet have high pressure.

 

The aircraft , even on jacks is not very many Mpa.....

 

 

 

Hope the following helps - I respond as an old "cocky" who has laid quit a few farm pads, for a range of applications - not an expert by any means.

 

Sounds like the maximum planned loads are for a forklift/industrial - you should be able to get the precise standards from your council, any half decent concrete contractor (in your area). I do not recommend a do it yourself project (unless you have a knowlegiable mate who will "oversee everythin) - too easy & costly to get it wrong  and you need quite a few tools to make a good job/finish.

 

In my experience the pad will be 100 mm or 150mm - if necessary thicker again, where additional loads are expected/planned eg heavy machinery tracks width, under heavy laths, etc

 

The concrete quality, aggregate size, etc  must be specified at the time of order (best left to your contractor unless you are laying it yourself) and includes "slump" which in my layman terms is the amount of water in the mix, which then impacts on the ease of laying, finishing and the strength of the pad.

 

I would very strongly recommend:

 

Having the area to be covered, leveled and compacted, if necessary. This will benefit the pad in consistent thickness, estimating quantities (your pocket) and support (less chance of voids) .

Consider drainage around & under the pad  may or may not be necessary - rubble drains and ag pipe are often employed in this capacity.

A plastic membrane under the "pad" this prevents moisture wicking up from the ground - in the future, what ever is sitting/placed on the pad will appreciate this. It will also reduce the likelihood of spaulding/concrete cancer where the rio start to rust/expand.

Discuss with your contractor, the type of "finish" you expect  - most hangers, factory, store type facilitates go for a hard smooth reasonably dust free finish, achieved, in large part, using a helicopter (mechanical troweling machine) and combined with finishing products..

Thinking about slope - do you want your pad level or with a slight gradient. If a gradient, to what side/direction do you want it to drain. - this impacts on wash down/spillage/setting up equipment etc

Consider the implications for a pad that is just the size of the shed or one that is slightly larger, a pad designed to have the shed built on it,  as apposed to having separate foundations/piers. On oversize pad should have a small "step" down all around (except entry ramp(s) to prevent rain entry.

When the concrete is ordered, it is normal allow an additional percentage - you dont want to be "short"  - this also means that you need to have a strategy for any left overs (I usually make up some large paver forms to accommodate surplus).

 

Enough?

 

 

[Jabiru7252]

From my experience the folks who build the hangar should know what's required. If they don't then they're shonkys.

Edited December 9, 2020 by Jabiru7252

[RFguy]

Hi Sean, Kevin

Kevin- yeah I agree  the contractor for a hangar should spec everything. 

 

Sean, that was very comprehensive ! An excellent primer for everyone.

 

I am doing some fishing around for a mate. a hangar I might share with. Someone i was talking to in the US is using a 5 ton forklift with huge tines to lift another sport aircraft above the other.

 

There are hangar turnkeys, and people that supply hangar  bodies for other people to manage. This will be a turnkey job.

 

[RFguy]

Maybe I need to better explain what I am trying to understand. It has been 25 years since I did a slab.

 

How does the specification for the concrete drive the size and slab cost  compared to the rest of the structure ?

 

Certainly site preparation  requirements drives it 

 

1) Mobilization of the work crew often drives cost for install- a small or a large hangar not too different in actual erection cost.

 

2) There will be fixed doors, access, plus incremental  on size for metal

 

3) and then the slab. Does slab size and the need to have the ground prepared over a larger area drive cost greater than the linear increase in area rate ???

 

-glen

[skippydiesel]

1 hour ago, Jabiru7252 said:

From my experience the folks who build the hangar should know what's required. If they don't then they're shonkys.

Problem is, you only find out they did a shonky job well down the track - if you can be involved in all aspects of the build, there is a better chance of catching some "short" work befor its implemented & covered up

[skippydiesel]

5 minutes ago, RFguy said:

Maybe I need to better explain what I am trying to understand. It has been 25 years since I did a slab.

 

...........................................................................................................................................

 

3) and then the slab. Does slab size and the need to have the ground prepared over a larger area drive cost greater than the linear increase in area rate ???

 

-glen

Shed size, will have an impact on site preparation, which in tern will be influenced by things like drainage (surface & sub surface water movement) soil, slop and access (sort of thinking on the go here). A small slab will likely "float" have less & be lees of an environmental impact. On the other hand a large shed will require considerably more planning if it is to be a durable structure eg if its a hanger, it will have wide doors - a small shed will inherently be more likely to have a "stiff" frame, the doors (whatever their design) might be expected to work effectively for a long time. The larger/wider the structure, the more thought/planning will be involved in ensuring the tolerances required for the doors to continue operating without constant adjustment/modification.

[facthunter]

The concrete floor is a substantial part of the overall cost. A lot of hangar floors are just gravel or blue metal if it's rolled and drained well  a light spray of sump oil will keep the dust down but it has to soak in before you run good tyres over it. Your plane can sit on some plywood pads and that tells you exactly where it should be as well. it's very nice to have a lovely painted concrete floor but it's COSTLY. You need concrete where the door runners are. Another option once the surface has consolidated is Bitumen. (Tar) .It's easily repaired  too.  You don't want DUST. it gets into everything and must cause a lot of wear. Nev

[Kyle Communications]

Most concrete floors are costed as a sq metre cost. There is a rough rule of thumb for it and that includes the reo and footings

 

[facthunter]

Well then you get into HOW best to do it. You can pour the pads first and the floor later in sections after the shed is built .That will minimise cracking and you should use black plastic sheet underneath to stop moisture forming salt affected areas..  Making it vermin proof is a consideration but more cost. Tricky form work and flashing. Nev

[NT5224]

Hi Glen

 

I said earlier that my new hangar has been built without a concrete floor, exactly along the lines of what Nev has suggested. I would echo  this as a genuine alternative to a slab, depending on what and where you are building.

 

I have built plenty of slabs. My wife and I built our whole home including outbuildings, workshops, sheds and now hangar entirely with our own hands. We have only had outside assistance with electrical wiring and our off grid solar system. All our slabs have been hand mixed and poured on site, because we are too far for a concrete delivery (even with retardant) and at any rate our home site is inaccessible to trucks. 

 

In our experience the key issues are the mixture, quality of cement and materials but most of all the  base and screeding.

 

My wife is an excellent screeder. I personally wouldn't worry to much about polishing unless you're aiming to get onto Grand Designs.

 

But even then we are now opting for a gravel /metal dust compacted floor. Can't face doing another  144 square metre slab! 

 

But seriously, throwing up a shelter structure  isn't a big deal and can be done quite cheaply if you do it yourself.  No arcane knowledge required. My wife and myself have hoisted  our fabric roofed arched structure  

unassisted, with total budget of under $10,000.  Would accomodate two C172s comfortably..

 

Alan

 

 

[Jabiru7252]

When the shed at mums was concreted the idiots didn't put down any plastic sheet so we had this problem of salty stuff coming up through the floor. Ended up coating the floor with some goo using a broom and it did the job.

[RFguy]

Thank you everyone for their replies!

 

Seems that for an 8" slab in NSW, including earth works, labour, concrete, budget about $150/sqM seems about the right number.

 

 

[Kyle Communications]

why a 8 inch slab..your not putting 20 tonnes on it...most big slabs are 4 to 6 inch max

 

[RFguy]

agreed.  6" would do it.  5 ton forklift is probably the highest load.  a couple of mega pascals max.

[APenNameAndThatA]

I know far less about this than others. If you love measuring things, you can buy harness testing kits to measure the hardness of concrete. They are a variation of the Mohs scale of hardness. Some concreters are literally criminals. For some reason, there are far more criminals in concreting than other trades. Buyer beware.

[Jabiru7252]

100mm would seem thick enough to me, but I'm not a concreter's ass...

[RFguy]

I'll do some asking of what people have used.. minimum sample size N=16   I think.

6" is common for vehicle garages.

Mine is 8" at home (1976 ...)

[Kyle Communications]

Mine is 6 inch at the farm hangar and it is 18m x 15m  I have a huge 140hp SAME tractor it weighs about 8tonne in there and my Massey is about 5 tonne...no dramas at all plus heaps of other stuff its been up about5 years now and not one sign of cracking

 

[RFguy]

of course tractor has big tyres, unlike a forklift.

But 6" would do it. 8" is about an extra 9$ sqM , very very approx.  

 

[skippydiesel]

RF - you are absolutely correct - tractors & their ilk have comparatively low point loading - a sold tyre forklift could have a much higher loading depending on size/capacity and wheel set (have seen them with double front wheels to minimise point loading).

 

I dont much wok in imperial however 6 is near enough 150mm (I think) and is usually considered to be a HD floor. As I said earlier, if projected loads are particularly high and can be restricted to certain areas, you can have thicket/more reinforced pad where required and thin for thinner for the lower load areas.

[RossK]

Std Garage floor is 100mm or 4 inches for metrically challenged.

Our factory floor is 150mm - ie takes pallet racking and forklifts etc.

Not sure on the mPa ratings on either though.