In brief
- A low paving block rate often means sand bedding, edge restraint or drainage has been left out of the price, not that the work is cheaper.
- Ask for the bedding specification, the edge restraint detail and the surface water route in writing before comparing bids.
- Sample the subgrade and check levels yourself, because a weak or uneven base shows up as rocking blocks after rain.
Contents
A paving block bid in Borama comes in low when the price leaves out work that still has to be done. The rate may cover only laying blocks, not the bedding sand, edge restraint, subbase or drainage that make the surface stay flat. Underbidding risks on paving blocks in Borama sit in those omitted layers, and they show up after rain.
What gets left out of a low paving block bid?
The omissions sit in the layers under and beside the blocks. A bid can look complete while silently dropping the subbase, the bedding sand, the joint sand, the edge restraint, the drainage channel and the levels survey.
Paving is a system: subgrade, subbase, bedding, blocks, joints and edge restraint. Remove one layer and the rest move. Sand bedding is generally laid loose, then compacted, and joints are filled and compacted. Confirm the bedding thickness and the jointing passes against the project specification or engineer.
Each item costs money. If the bid omits them, the contractor has two choices later: ask for more money or cut the layer. Both are worse than a higher original price. Ask every bidder for a written build-up by layer, and ask where the surface water goes at the low corner of the plot.
Why does a weak base make the surface uneven?
Blocks rock when the base moves under them. Expansive clay soils can swell and shrink with moisture, and a thin subbase spreads wheel loads over too little depth. The blocks then settle at different rates and the surface goes uneven. Have the site's soil identified by a laboratory so the design matches the ground.
General practice for a driveway is a compacted granular subbase laid on a proof-rolled subgrade. Treat that as a starting point, and get the required subbase depth from the project specification or engineer, because it depends on the soil and the loads.
Detect the weak base before it is buried. Ask to see the subgrade proof roll, watch the compaction passes and water content, and take levels at a grid of points. A laboratory can run a sieve and Atterberg test on a sample. Walk a recent paving job after rain and look for ponding and rocking blocks, then ask the municipal engineer's office what records exist for the site.
How do you close the gap before signing?
Make the bid comparable line by line, and tie stage payments to signed inspection of each layer as the contract allows. Give every bidder the same schedule: subbase, bedding, blocks, joint sand, edge restraint, drainage, levels, compaction and testing. Ask for the source of the blocks, the cement content and whether test records exist.
Check what the contract allows on variations and payment terms, and follow those terms rather than any arrangement outside them. Tie releases to signed inspection of each layer, not to the calendar.
Drainage is the item most often dropped. A surface that cannot shed water will fail regardless of how well the blocks are laid. Ask where runoff collects, whether a channel or soakaway is priced, and who clears it after the rains. If the answer is vague, the bid is not complete.
What to do next
Ask each bidder for a layer-by-layer written build-up of the paving system, including subbase depth, bedding thickness, edge restraint, joint filling and drainage. Then take one bid to the inspecting engineer named in the project's contract and ask which layers can be inspected on site before payment. Compare the answers, not the totals.
Frequently asked questions
Why is a paving block bid in Borama so much lower than the others?
The lower bid has often priced only the blocks and laying, leaving out subbase, bedding, edge restraint, joint filling and drainage. Ask for a written build-up by layer so you can compare like for like.
How do I check the base under paving blocks before it is covered?
Watch the subgrade proof roll, check levels at a grid of points, and ask for compaction and soil test records from a laboratory. Confirm the required subbase depth against the project specification or engineer.
Can I refuse to pay until the omissions are fixed?
Check what your contract allows on variations, defective work and payment. Take advice on the specific clauses before withholding anything, and tie stage payments to signed inspection of each layer.
Local reporting: this article is written for building work in Borama and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.