400mm2...???...I hope you mean 400M square.Anyway,instead of buying,this days you can easily hire timber and props....Saves you lots of money.

@Njunge
Thanks Njunge , I have taken note of that. Do you know anyone who hires out the formwork? What are the rates ?

@Rahatupu

Well, I will get in touch.

By the way, I will be doing 4 floors ,is it economical to make my own "Metal trappers" (as an investment) or leasing them will be alot cheaper?

@Rongla, @Njunge

The disadvantage with buying trappers is that 20% always wears off after slabbing, so the economies will not be realized. The ppl who lease use their own manpower to remove the trappers after you use them and are specialized in the trade so its not viable to buy with the intent of leasing after use

Metal trappers are better since they don't wear esp if they are oiled after use - lakini they are expensive to make atleast 750/= each (4*2 inch). So this is the way to go "in case tou went the G4S way:).

Props are cheaper to buy because they dont wear and need less care than trappers. The other timber 6*1 and 3*2 inch go for btwn 17 to 25 depending on your location, Kitengela seems cheaper to me.

Do the arithmetic given that hiring costs you 100/= per trapper for 40days. and buying 1 inch thick trapper will cost you 280/= to 320 (less 20%) 21 days after slabbing.

I once saw a contractor spread rolls of black polythene paper on top of his timber before he poured the concrete for slabbing. When I asked I was told that it helps in preserving the timber and that the underside of the slab appears smoother than if it had no polythene. maybe @rongla cud do the same and incur less wastage with his timber for formwork.

are yours steel formwork? If yes,what size is each and how does it cost

@pablo quick arithmetics, he needs 400msq since he will be doing 1 floor at a time.(unless he has 4 const.) the polythene paper not only gives a smooth finish, but creates a water tight surface.

and how much would it cost to hire form work (either Steel / wood) per SM?

Thats a myth. @jaggernaut

@dudej. What would you advice me on making steel trappers for multiple use.So that they last long.