Constructing a vehicle Inspection Pit

[redpis]

I considering installing a inspection pit on the drive..

Has anyone practical expriance of shuttering and casting sequence to make a concrete pit that would be willing to share.

The following has been discounted:
Liner
Ramps
Lift

The following has been considered;
Planning/Building control
Gassing/Ventilation
Covering when not in use
Lighting
Drainage


Many thanks,

I will be posting up pictures, quantities, learning points etc as the project progresses to assist others.

Ian

 

[^woody^]

Lay a 150 concrete slab at the required depth and build the walls in 215mm engineers bricks

It will be a lot of faffing about trying to cast this in concrete

 

[freddiemercurystwin]

//search.diynot.com/forum_search.php?q="garage+inspection+pit"&stype=0&action=Search&sort=score

 

[redpis]

//search.diynot.com/forum_search.php?q=%22garage+inspection+pit%22&stype=0&action=Search&sort=score

Freddy,

Searched prior to posting, but nothing answered my questions, done a fair amount of research on google but nothing specific just yet.

Thanks for the reply though

 

[redpis]

Lay a 150 concrete slab at the required depth and build the walls in 215mm engineers bricks

It will be a lot of faffing about trying to cast this in concrete

Woody,
Brick is an option, however a cast in situ pit is my preferance at the mo.

Cheers

 

[^woody^]

What about control of cracking in the mass concrete? It can't be just a cuboid concrete box

 

[redpis]

What about control of cracking in the mass concrete? It can't be just a cuboid concrete box

Fair point Woody, I'm looking for other experiance in these matters and how they overcame them.

 

[marshman]

Depth, length & width ?.

 

[^woody^]

To shutter this in one you are looking at a lot of timber inside the centre bit, and then a really wide excavation to allow you to get to the external shuttering, unless you do a lot of messing about all from the inside

If you do it in stages, either horizontal rings or vertical panels, then you have problems with sealing the joints

And all the time you have to think about natural movement causing cracking, and so would probably need some reinforcement designing in

It's all do-able but it will be a lot of messing about and a lot of time, and you either get some steelwork designed or you drop some mesh in ad-hoc and hope for the best

Brick, or block is the much better option

 

[Norcon]

Brick, or block is the much better option

Brick or block is OK but not the best option.
We've done a few lorry ones about 10m long in concrete. Single pour.
We can do about 30m X 2.4 with shoring gates up to 2.8m wide in a single pour completed in one day. (excluding excavation , flooring and striking)

 

[^woody^]

Thats fine, but how does the OP access the equipment and design of these commercial pits like the ones you built?

Tha't why brick or block is the best option for the OP, doing some DIY building on his small drive

 

[Norcon]

Thats fine, but how does the OP access the equipment and design of these commercial pits like the ones you built?

The same way we do. Buy it or hire it.

You're right though, it's not something an inexperienced person should involve himself with or experiment with on his front drive. A lot can go wrong.
Bricks and blocks it is.

 

[redpis]

Thanks for your comments all.

Currently this is an idea and is in the scopeing phase, got to check buried services and maximum pit width based on car wheel distance, length will be fixed by how much drive space I have and the practicalities of construction, finished floor level to top of pit will be typically 1.6m

I have expansive clay so I'm looking at managed drainage to reduce wall pressure (sump and pump external to the cast box)

Obviously water ingress is an issue, I will post up my inital drawings next week for comment.

Outline is for a hole lined with multiple layers of DPM, sealed and taped,layer of sand with reinforced mesh on plastic shoes, cast a 150mm base with 100mm kicker also including sealed sump fully within the cast.

Prior to casting, sing a lower borehole with sump to keep the excavation dry, this will remain in place topped with a small manhole cover, pumping away from the pit.

Once the floor is set, shutter a box using the kicker plate and cross brace, concrete pour to fill between excavation and shuttering only, reinforceing mesh again used and tied into kicker rebar mesh.

Problem is as already illuded to is the danger of leakage through join, have looked at sealing materials, ensuring angular mating surfaces etc, interested in thoughts on doing it in a single pour, and what are the problems.

I have no problems in hiring the shuttering to do this, as the purchase of 18mm ply and timer is dead money anyway.

Please keep the advice and comments comming

Cheers

Ian

 

[freddiemercurystwin]

Regards to waterproofing have a look at RIW, they're products are designed for these kind of structures, taping up dpms is a sure way to failure.

 

[redpis]

Regards to waterproofing have a look at RIW, they're products are designed for these kind of structures, taping up dpms is a sure way to failure.

Freddy,

Thanks for the pointer, I'll contact RIW for advice on Tuesday.