Cellar stairs construction

I’ve had a cellar built under my new extension and need to get some stairs set up. The access is via a trapdoor (approx 1200 long and 800 wide) in kitchen floor and currently I’ve just got a ladder down to the floor of the cellar. The overall height from cellar floor to the underside of the floorboards is approx 2800.

I don’t think I’ve got the room to set up a flight of stairs which fully complies with the BCA rules for tread and riser dimensions as this wouldn’t give enough head height. Therefore I’d be looking at something more like a loft ladder which I’d hopefully be able to get past the building surveyor.

Given that it has to be simple (and cheap), I’m looking at a getting a couple of pine stringers and using the same material for the treads (it would be open treads). So the questions:

• Any suggestions on what thickness timber for the stringers and the treads?
• Can I just use steel brackets to hold the treads to the stringers? For the brackets I was thinking of getting some angle iron and cutting to lengths
• I’ve seen a lot of similar stairs with steel rods running under the treads holding the stringers together – this could be as well as or instead of the brackets- are these necessary?
• Would I need to make a rebate in the stringers to slide the treads into or would the bracket be sufficient?

thanks
hJ

Anyone got any thoughts on this? I'm keen to get this project started.

Thanks
hJ

Any suggestions on what thickness timber for the stringers and the treads? stringer = 150x50 F7 OB hardwood, treads = same - make handrails running down the stringer using 1/2 gal pipe
Can I just use steel brackets to hold the treads to the stringers? For the brackets I was thinking of getting some angle iron and cutting to lengths
Yes - angle is fine - 50x50x3 gal
I’ve seen a lot of similar stairs with steel rods running under the treads holding the stringers together – this could be as well as or instead of the brackets- are these necessary? Yes - it stiffens the structure. You can use the angle - run it in a triangular cross behind the treads
Would I need to make a rebate in the stringers to slide the treads into or would the bracket be sufficient?
the latter is fine

Thanks very much.

hJ