UKC

I want to cover an unused vehicle inspection pit - the original wooden sleepers have rotted in the damp conditions. I'm pricing various material options and wondered about steel. The pit is 1.4m by 1m and the steel would be supported along the long edges. Can anyone suggest what type of steel would be appropriate and what thickness please? The heaviest thing it would ever need to support is probably me, or maybe a motorbike.

I'd probably find some checker plate and stiffen it with 50mm unistrut (the solid walled stuff, not the one with slots in)

If there's the possibility you'll move out of the space assume it'll have to support whatever you can get into that space and over the pit, whoever is there after you will assume it was made safe. If you don't use the pit any more I'd fill it and cap with concrete, that way it can't fill with fuel vapour or gas and kill you unexpectedly. If you want steel plate then something in the 10-12mm range is likely to be safe assuming a couple of wheels of a 2T car is the biggest load that can be placed mid span on it. If you screw the edges down with closely placed screws into solid concrete and you could tolerate some sag you'd get away with much thinner, maybe 3-4mm. A thinner 2-3mm skin still over closely spaced treated timber joists is another option as is just replacing the old timber. I'd fill it.

jk

I'd just get some scaffold boards - really cheap 2nd hand, still quite cheap new from B&Q etc. Treated / painted ones will last a long long time.

In reply to:

Thanks for all the replies.

I don't want my dying thoughts to be that I haven't told my wife not to walk on the inspection pit, just in case the cover rusts or rots, so I do need something which will last! Doing a proper job with steel looks to be prohibitively expensive.

I'll also get a quote to have it filled.

I have a quote for some recycled plastic beams 50mm thick, which might work.

The pit is in a single garage so it's not possible to get a car wheel on it.

Just replace the timber like for like, cheap easy to fit (only need a hand saw) . The originals have probably been there 20+ years. Trouble with steel is a suitable thickness and getting it cut to size.

Dangerous things, fill it in.

Oh the irony, a garage not big enough to get a car into it.

Why not fill the pit with rubble then cap it, safer in the longer term - assuming yo never see a use for the pit. 

I think the op means the garage is big enough for a car, but given the inspection pit is central, the car wheels will run either side of the pit, therefore not bearing any weight.

It is big enough for a car. If I were buying a house a pit in the garage would be an asset.

I'd replace with wood again although Checker plate would be an option but probably heavier.

I agree, filling it in is a waste.

Filling it with concrete or covering it with steel would be a waste, and quite expensive, you need to start thinking 'outside the box' and go for the fun option.

https://www.especialneeds.com/media/catalog/product/cache/1/image/1800x/b39...

The original cover was several thick timbers (the long edges of the pit are rebated by 85mm), covered over with what looks like marine ply. When I lifted the ply I found that most of the timbers had disintegrated completely or turned to Weetabix. It looks like the ply had trapped condensation, so maybe any future timber solution which allows the pit to breath would do better. It is probably 20 years since I had last looked in the pit though.

Throw a couple more pieces of marine ply on it.

It won't rot for ages and 50mm thickness will easily stand your motorcycles (and presumably your wife's) weight.

I could make you a steel or aluminuim checkerplate cover thats plenty strong enough, where are you located?

Just noticed Derbyshire on your profile , i'm over in Staffordshire.

If you happy to supply all dimensions I could sort it if your interested.

It's 980mm by 1380mm. The long edge is rebated by 85mm depth. I haven't measured but it's probably about five feet deep. It doesn't fill with water but it is pretty damp. I'd imagine steel or aluminium could get expensive?

This is looking like my preferred solution at the moment.

Okay , well the cheapest possible solution would be ....

I could fold a  980x1350x85 "tray" from 3mm Aluminium and reinforce with welded stiffeners. This then ideally i would clad the top face with checkerplate. 

drop me a text on 07935 016912 or email pkrynicki1984@icloud.com if your interested and i'll give you a price and lead time, could probaly turn it round within a week.

Alternatively if you just want a great big heavy lump of steel with a cutout or two so you could maybe lift it out... I could sort that too.

You could fill it with water and have an indoor swimmimg pool/jacuzzi or stretch a tarpaulin over it on bungees and use it as a kiddies trampoline.

Actually, I'd use wooden floor joists on their sides/scaffold boards, treat the ends to reduce rot and keep it as a pit 'just in case'. Personally I'd love to have an inspection pit and if buying a house would regard it as an asset.

Would not fill it in. Its an asset decent timber or 3 mm steel plate would be fine. You may not want it but if you sell the next person may well.

Do you think 3mm would be rigid enough?

Have a look at trench covers. They come in various sizes and are plastic, but take the weight. I used to know someone who designed them. Road tested lorries going over them.

Yes , Folded into a four sided tray with return bends and welded stiffeners... and checker-plate plate top it would be very strong indeed.

If you find a way of removing the pit, I'd happily take it off your hands. Have wanted one for ages!

If it were me I'd replace the timbers. If you're concerned about their longevity then perhaps some railway sleepers would work well. They last a long time without rotting! Otherwise normal timber soaked in creosote or some alternative would be rather good. Keep it ventilated, don't seal it. If you're concerned about it filling with vapours you could fill it with broken polystyrene, plastic bottles etc to reduce the volume in it (or a ball pit...). This would also be good if the cover collapsed somehow and you fell in...

I'd follow up whatsit-1984 on his offer, it sounds like it's his job to do this kind of thing, from his knowledge and keenness. 

I've just picked up some treated timbers of the right depth which will fit with sufficient gaps for ventilation.

Thanks for the offer Pkryniki1984 but the timbers were a bargain instead.

He's right by the way about 3mm being rigid enough if it's used in the method he describes. Having played around with metal sheeting before, it'd be too flexible if left flat, but not if he does what he's described to it.  

No problem , glad to offer a solution where I can.

You might want to treat the cut ends with cuprinol 5 star or similar - the factory treatment doesn't penetrate very far into the timber, so any fresh cuts need ot be treated. If they're going to sit there for ages undisturbed sit them on damp proof course to stop them absorbing moisture from the walls of the pit.