Someone asked the below question, and I thought we all can benefit from it.
Pls can anyone help with a rough estimate for fencing a 6 plots of land close to Abeokuta Ogun state….I’m considering 10 coaches including foundation
It’s a flat and dry land. Estimation would include granite for any stone related job needed for the job if any.
Also, which is advisable between single and double gated fencing, considering the size of the land.
P.s I dont have any major plan for the land at the moment. But I want the fencing done asap after lockdown.
Thanks in advance
The first thing is to ensure the arrangement of the plots are known as this affects how much material is used. (see pics 1 for different arraignment)
The second note is the type of foundation needed, and in this case; its a strip foundation (Abeokuta is a rocky or ‘Laterite’ land)
The 3rd important information is the SIZE of the plot, although it wasn’t stated, he confirmed it is 18m by 36m
a. Lets find the LINEAR METERS of the proposed fence by simply adding the lengths and widths of the site
= (18 + 18 + 18 + 36 + 36 + 18 + 18 + 18 + 36 + 36) = 252m
b. Minus the space occupied by the gate from the above (since there wont be foundation or fence at that space); we assume the gate is 3.6m wide
= 252m - 3.6m = 248.4m
c. Lets Calculate the numbers of blocks needed (whether you’re buying or producing on site)
remember a (6′‘ and 9’' standard) block is 450mm (0.45m) long and he has also requested for 10 courses (meaning 10 blocks on each other)
the question we should ask is HOW MANY BLOCKS WOULD FILL ONE ROW OF FENCE
= Total Length of Fence / One length of Block
= 248.4m / 0.45m
= 552 numbers of Block.
since we know 552 blocks make 1 row and we need 10 rows, then we just multiply
= 522 blocks x 10 = 5220 blocks. (always remember that some blocks would break, so consider waste)
d. (a) Lets calculate quantity of cement needed for the foundation and block setting.
we start by calculating the volume of concrete needed for the foundation and apply a constant to give us number of cement needed, we would also apply a constant since we know the number of blocks we plan to set.
cement: the volume occupied by concrete is L x W x H
where L = Total perimeter to be fenced = 248.4m
where W = Is how wide we dig the foundation = 0.45 or 0.675 (Lets use 0.675 standard) = 0.675m
where H = How think your foundation concrete is = 150mm (standard; but some people use 100mm for cost savings) = 0.15m (note that I made sure all units are in meters, to minimise figures)
hence; volume of concrete in Foundation = 248.4m x 0.675m x 0.15m = 25.15m3 of concrete.
we would now apply the cement constants to know how many cements we need for Foundation
ratio: 1:2:4 = 6.5bags of cement per 1m3 of concrete *
ratio: 1:3:6 = 4.5bags of cement per 1m3 of concrete (we would use ratio 1:3:6 in this tutorial)
there we need 4.5 bags x 25.15 = 114 bags of cement.
d. (b) Number of cement needed to set 5220 numbers of 6′' blocks
here’s a constant you can always use: 0.16bag would lay 1m2 of blocks i.e. (10 blocks)
so; IF 0.16 bags = 10 blocks, how many bags would lay 5220 blocks
= 5220 × 0.16 (divided by) 10
= 835.2 / 10 = 84 bags of cement.
Total cement needed for task = 198 bags of cement.
SUMMARY: so far we know all the blocks and cement we need for the job ahead; now we go to sand and granite. (minus plastering)
e. (a) sand needed for 25.15m3 of concrete in foundation
constant = 1:3:6 has 0.46m3 of Sand in 1m3 of concrete, we just need to multiply the formula by 25.15m3 (its a different formula for 1:2:4)
= 0.46 × 25.15 = 11.57m3 of sand in foundation
e. (b) sand needed for laying blocks
constant = 0.02m3 in 1m2 i.e 10 blocks (multiple constant by 5220 and divide by 10)
= 0.02 × 5220 / 10 = 10.44m3 of sand for blocks
Total sand needed for the task is = 22.01m3 i.e (11.57m3 + 10.44m3) of sharp sand (lets convert to tonnes by multiplying by its conversion constant of 1.6m3 / tonnes)
= 22.01 × 1.6 = 35 tonnes of Sharp Sand.
f. (a) granite in 25.15m3 of foundation (NOW WE CAN FAST FORWARD, since we know the rules)
constant = 0.92m3
hence granite needed = 25.15 × 0.92 = 23.14m3 of granite (convert to tonnes by multiplying by 2.0)
= 46 tonnes of granite.
SUMMARY: so far we know all the blocks, cement, sharp sand and granite needed for the job ahead. (minus plastering)
g. water needed (Keep buying if there’s no borehole or well on site lol)
a. Digging of Foundation; this depends on how soft or hard the soil texture is; but its advisable to budget about N50,000 - N75,000 (there is a RATE but I do not want to apply it, since soil texture isn’t known)
b. Casting of footing (foundation): charged at about N3,500 to N4,500 per m3 of concrete; we have 25.15 × 3500 to N4500= N88,000 to N115,000
c. Setting of Blocks: at a rate of N50 - N60 naira per block; we have 5220 x N50 to N60= N260,000 to N313,000
d. Add miscellaneous cost like clearing of site, area boys, water and scaffold for workers = N100,000
- SAND = 35 tonnes (buy 40 tonnes for waste)
2.GRANITE = 46 tonnes (buy 50 tonnes for waste)
- CEMENT = 198 bags (buy 200 bags)
- BLOCKS = 5220 numbers (buy or produce 5500 of 6′')
- WORKMANSHIP = N503,000 (using the most expensive option)
- MISCELLANEOUS = N100,000
Find out the prices of Materials in your area (e.g cement is 2700 - 2750 in my area) and multiply for PROJECT ESTIMATE.
If you decide to use concrete columns at interval; then its a lot more to budget for. (more cement, reinforcement bars, 1×12 wood, 2×2 wood, nails etc)