Slope Conflict on the Plans and a Demand for a No-Allowance Lump Sum
You are bidding a gable reroof on a rectangular building 100 ft by 40 ft with 2 ft overhangs on all sides. The roof plan is noted "4:12," but the elevations and the structural sheets are dimensioned at 5:12, and the framed roof measures 5:12 in the field. The specifications name a discontinued 30-year laminated shingle, require 15-lb felt underlayment, and show no valley or penetration details. You carry 10 percent waste on shingles and price starter and hip/ridge cap by measured length. The owner wants a firm lump sum with no allowances, and the general contractor wants a number today.
1. Resolve the slope conflict and quantify the difference in roof area and squares at each slope.
Read the worked answer
- Which governs: the field and the structural sheets. The roof physically is 5:12. Bid 5:12 and still submit an RFI so the answer is in writing and the general contractor cannot later argue you should have known.
- Plan area with overhangs: (100 + 4) x (40 + 4) = 104 x 44 = 4,576 sq ft.
- Slope factors: 4:12 = sqrt(1 + 16/144) = 1.054; 5:12 = sqrt(1 + 25/144) = 1.083.
- 4:12: 4,576 x 1.054 = 4,823 sq ft = 48.2 squares; with 10 percent waste, 53.0 squares.
- 5:12: 4,576 x 1.083 = 4,956 sq ft = 49.6 squares; with 10 percent waste, 54.6 squares.
- That is about 1.4 squares of field shingle plus the accessory difference - small in dollars but exactly the kind of gap that gets argued at closeout. Carry the 5:12 quantity.
- Linear items at 5:12: ridge = 100 ft; eaves = 2 x 104 = 208 ft; each rake = 22 ft horizontal x 1.083 = 23.8 ft, four rakes = 95 ft. Starter at the eaves and rakes, cap at the ridge.
2. The owner demands a firm lump sum with no allowances. How do you price the unknown deck condition and the discontinued shingle?
Read the worked answer
- A no-allowance lump sum is a request that you absorb every unknown. You can do it, but only with written unit prices and exclusions in the bid form.
- Unit prices are not allowances: quote a price per 4x8 sheet of sheathing replaced, a price per sheet for a structural overlay, a per-linear-foot price for fascia or sub-fascia repair, and a per-square price for any slope change. Unit prices let the work proceed without renegotiating and without you eating the cost.
- Discontinued shingle: do not install an unlisted or substituted product on your own judgment. Request a written substitution for an approved equal with the same warranty tier and a color approval, and price the currently produced product in the base bid. State the manufacturer and warranty term explicitly.
- Exclusions to list: decking beyond the stated quantity, dry rot, structural repair, code-required ventilation or underlayment upgrades ordered by the authority having jurisdiction, permits and title-24 documentation if not in your scope, and PV detach/reset.
- Thin spec items: the 15-lb felt and the missing valley and penetration details are RFI items. Price what the manufacturer requires, note the deviation, and do not silently upgrade something the contract didn't buy.
3. The general contractor pushes back on your unit prices and wants them waived. How do you respond, and what does that mean for the bid?
Read the worked answer
- Unit prices are the mechanism that lets a fixed price survive field reality; waiving them moves all the risk of an unknown deck onto you at a price you cannot verify in one site visit.
- Response: keep the unit prices but cap your exposure by stating a quantity of sheathing replacement already included in the base bid (for example, ten sheets), with unit prices applying beyond it. That gives the GC a firm number and gives you a defined risk band.
- Make the qualification part of the bid form, not a cover letter - qualifications buried in a transmittal get lost when the contract is issued.
- If the GC refuses any qualification, the practical choices are to decline the bid or to add a contingency large enough to cover a full overlay, and then say so in writing. Bidding low and hoping is how contractors end up in a dispute.
- Confirm in writing that your price assumes the 5:12 field condition and the RFI answer; if the RFI later confirms 4:12, you want a documented basis for the reduction.