Primarily for general aviation discussion, but other aviation topics are also welcome.
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By mmcp42
#1451688
looking to put a concrete base inside my nice hangar
hangar is 12.4m x 8.5m; planning on a small apron ( 3m x 2m) outside as well to make manoeuvering easier
aircraft is an AA5 AUW 1 tonne

I was thinking 6" would be enough (stop it!!)

any views, experience, ideas, suggestions?

thanks
#1451692
The most expensive part of a building is the floor. A 6" base sounds too much - between 3 and 4" would do. The yard at the back of my house is laid 4" thick and I've have fuel tankers weighing several tons on it. You could reduce the thickness even further by putting reinforcing screen in it.
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By rikur_
FLYER Club Member  FLYER Club Member
#1451694
as others have said, getting the base right is key ..... a 'normal' domestic driveway would be about 4" of hardcore topped with 4" concrete .... but does vary depending on the ground conditions, and the type of concrete to be used.
For outbuildings its fairly common to have deeper concrete for the outer ft, perhaps 9 - 10" or more deep as the edges are most vulnerable to cracking/subsiding
#1451695
An SEP isn't very heavy in respect of live loads and you'll not have much in the way of dead loads so it's essentially a garage floor, in which case minimum 100mm (4") over a suitable base.

Somebody doing it on the cheap without a professional look at ground conditions might steal from the NHBC specifications and proceed with caution. < Not professional advice.

http://nhbccampaigns.co.uk/landingpages ... ult.htm#D4
#1451696
I used at least 150mm (depending on sub- base) hardcore, which was crushed concrete or type 1 stone, vibro-rolled and then 150mm concrete laid on top.

Presumably you will power float? - you will never regret doing so especially when it comes to pushing aircraft around single handed, or sweeping up.....
If so, think about it before floating the outside apron as floated concrete can become very slippery when wet. We just tamped the outside areas to semi rough finish to give some grip.

It is always worth trying to avoid fresh concrete going off too fast by covering with poly sheet for at least first 48hours.

All the above might seem overkill for a hangar base but if you do once and do it right, you won't have to worry when an errant HGV heads your way.
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By mmcp42
#1451716
wow
some excellent advice there chaps
little light reading before I start wielding the digger then!
#1451733
Whack your hardcore down well and cover with a damp proof membrane such as Visqueen. Duct tape any overlaps. If you're using steel mesh, keep it off the membrane by supporting it on bits of broken paving or similar. If using fibre reinforced concrete there's no need for mesh. Don't let the surface dry out too quickly. It will crack.
You can cut control joints in with a Stihl saw when it's workable. No more than 8ft apart. An alternative is to sink thin timber strips to form the control joints. Pull them out while the concrete is still green.

Don't forget to sink a silver coin in the slab. For the fairies.
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By cockney steve
FLYER Club Member  FLYER Club Member
#1451763
Maybe stating the obvious, but the topsoil must be removed first. have laid a few bases and a couple of barn-floors.
4-6 inches of rough hardcore as this will take broken concrete and half-bricks. locally, we use "mot-base" or "Crusher-run" (basically dust/aggregate ) compacted to a level-topping over the main area, which should then get a DPC membrane......dig the base edges a bit deeper and just leave as a hardcore-border you should now be back to ground-level...add shuttering to lift your finished base above ground-level.....slope your apron down to ground at the edges.....when you pour the concrete, the edges, being rough hardcore, will infill with concrete and form a strong periphery to the slab . The slab, over the DPC will be adequate at 3" ( A 3-ton , 4-post car-lift, is specified for 2" concrete base...the post-bases are about 8" square.)

The couple of inches above ground-level, should ensure the slab remains dry, whilst the slope is not too hard to push the aircraft up. We make the sweeping assumption tou are not siting in a dip or low-point!

People tend to either skimp unduly, or go for a ridiculous overkill. As others have said, you are not carrying any greater point-loading than a domestic garage. Hardcore is cheap or free,so don't skimp there.....you may wish to consider sinking sockets or small piles, where stanchions or posts are to be bolted.. hth.
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#1451767
What you could also do is 'de-lethalise' the edge of the apron where it meets the grass. Rather than having a vertical edge of 4-6 in of concrete, slope the edge under the grass so that if it's a bit soggy and your wheels are sinking in a bit as you approach the apron, your undercarriage won't be presented with a vertical face of 4" of concrete but with a gentle slope upwards.
It's a requirement on licensed airfields and a 'good idea' anywhere else.
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#1451780
As remarked above, make sure the concrete surface is flat and above the level of the surrounding terrain.
Make sure that rain draining off the roof is trapped in a gutter below the level of the floor for draining away (soakaway to ditch?).
If your hanger is out in the boonies, do you need to store fuel? An old friend of mine in France built his hanger as described above, but with a pit for a fuel tank with a hand-pump to raise the fuel into his Jodel. The pit was covered by a padlocked steel hatch. (He owned a small country petrol station, and had no problem getting deliveries of Mogas). Legal? Dunno. But it worked fine for 40 years.