Korea Rooftop Waterproofing Lifecycle Cost & Renewal Calculator

Compare liquid membrane, synthetic sheet, modified asphalt sheet, and composite waterproofing quotes, renewals, leak exposure, lifecycle present value, and service-life sensitivity in KRW.

No market price or method-specific service life is prefilled. Use like-for-like quotes, warranties, and condition evidence.

1. Common analysis basis

Compare every method over the same area, horizon, and price date. Pair nominal cost escalation with a nominal discount rate.

year
㎡

Use one consistent rule for upstands and parapets.

years
%/year
%/year
%

Applied only to initial works and full renewals.

2. Method quotes and renewal timing

Normalize scope and tax treatment, then enter evidence-based values for each method. At least one method remains active.

Liquid-applied membrane (including polyurethane)

KCS 41 40 06Quote required

Confirm substrate, cracks, drain details, membrane thickness, and topcoat scope.

KRW/㎡
KRW

Removal, substrate, lifting, and other non-unit scope.

years
years
%
KRW/㎡·yr
KRW/year
KRW

Synthetic polymer sheet membrane

KCS 41 40 04Quote required

Align sheet material, thickness, seams, terminations, penetrations, and protection.

KRW/㎡
KRW

Removal, substrate, lifting, and other non-unit scope.

years
years
%
KRW/㎡·yr
KRW/year
KRW

Modified asphalt sheet membrane

KCS 41 40 03Quote required

Confirm laps, bonding, substrate preparation, protection, hot work, lifting, and removal.

KRW/㎡
KRW

Removal, substrate, lifting, and other non-unit scope.

years
years
%
KRW/㎡·yr
KRW/year
KRW

Sheet-and-liquid composite waterproofing

KCS 41 40 07Quote required

Confirm each layer role, seam reinforcement, details, sequencing, and warranty scope.

KRW/㎡
KRW

Removal, substrate, lifting, and other non-unit scope.

years
years
%
KRW/㎡·yr
KRW/year
KRW

Treat this result as provisional

  • At least one method has all-zero costs. The ranking is not meaningful until real quotes are entered.

Provisional result before real quotes

Enter evidence-based costs

Tied present values retain the displayed method order. Also assess performance, site suitability, and warranty scope.

Net lifecycle present value

KRW 0

Equivalent annual cost

KRW 0

Equivalent monthly cost

KRW 0

First renewal calendar year

2041

3. Lifecycle cost ranking

Common basis: 500㎡, 30 years, and a 0% discount rate.

Rooftop waterproofing lifecycle cost ranking
Rank and methodFirst renewalRenewalsInitial costNet present valueAnnual equivalentAbove lowest
★ 1. Liquid membrane20411KRW 0KRW 0KRW 0—
2. Synthetic sheet20411KRW 0KRW 0KRW 0KRW 0
3. Modified asphalt20411KRW 0KRW 0KRW 0KRW 0
4. Composite20411KRW 0KRW 0KRW 0KRW 0

4. Schedule, cost composition, and life sensitivity

Expand each result to inspect renewals, present-value composition, and service-life sensitivity.

★ Liquid-applied membrane (including polyurethane)KRW 0

Renewal schedule

2041

Next renewal

2056

Service remaining at horizon

0 years

Annual equivalent per area

KRW 0/㎡

  • All costs are zero. Enter a real quote before comparing alternatives.

Cost composition

Nominal and present-value cost composition
CategoryNominalPresent value
Initial worksKRW 0KRW 0
Routine maintenanceKRW 0KRW 0
Expected leak lossKRW 0KRW 0
Full renewalsKRW 0KRW 0
Residual service value creditKRW 0KRW 0

Service-life sensitivity

Service-life sensitivity at 80, 100, and 120 percent
ScenarioFirst/cycleCountNet PV
80% life12/122KRW 0
Base 100%15/151KRW 0
120% life18/181KRW 0

Annual cash flow

Annual rooftop waterproofing nominal and present-value cash flow
YearMaintenanceExpected leak lossInitial / renewalPresent value
2026 initialKRW 0KRW 0KRW 0KRW 0
2027 (year 1)KRW 0KRW 0KRW 0KRW 0
2028 (year 2)KRW 0KRW 0KRW 0KRW 0
2029 (year 3)KRW 0KRW 0KRW 0KRW 0
2030 (year 4)KRW 0KRW 0KRW 0KRW 0
2031 (year 5)KRW 0KRW 0KRW 0KRW 0
2032 (year 6)KRW 0KRW 0KRW 0KRW 0
2033 (year 7)KRW 0KRW 0KRW 0KRW 0
2034 (year 8)KRW 0KRW 0KRW 0KRW 0
2035 (year 9)KRW 0KRW 0KRW 0KRW 0
2036 (year 10)KRW 0KRW 0KRW 0KRW 0
2037 (year 11)KRW 0KRW 0KRW 0KRW 0
2038 (year 12)KRW 0KRW 0KRW 0KRW 0
2039 (year 13)KRW 0KRW 0KRW 0KRW 0
2040 (year 14)KRW 0KRW 0KRW 0KRW 0
2041 (year 15)KRW 0KRW 0KRW 0KRW 0
2042 (year 16)KRW 0KRW 0KRW 0KRW 0
2043 (year 17)KRW 0KRW 0KRW 0KRW 0
2044 (year 18)KRW 0KRW 0KRW 0KRW 0
2045 (year 19)KRW 0KRW 0KRW 0KRW 0
2046 (year 20)KRW 0KRW 0KRW 0KRW 0
2047 (year 21)KRW 0KRW 0KRW 0KRW 0
2048 (year 22)KRW 0KRW 0KRW 0KRW 0
2049 (year 23)KRW 0KRW 0KRW 0KRW 0
2050 (year 24)KRW 0KRW 0KRW 0KRW 0
2051 (year 25)KRW 0KRW 0KRW 0KRW 0
2052 (year 26)KRW 0KRW 0KRW 0KRW 0
2053 (year 27)KRW 0KRW 0KRW 0KRW 0
2054 (year 28)KRW 0KRW 0KRW 0KRW 0
2055 (year 29)KRW 0KRW 0KRW 0KRW 0
2056 (year 30)KRW 0KRW 0KRW 0KRW 0
Synthetic polymer sheet membraneKRW 0

Renewal schedule

2041

Next renewal

2056

Service remaining at horizon

0 years

Annual equivalent per area

KRW 0/㎡

  • All costs are zero. Enter a real quote before comparing alternatives.

Cost composition

Nominal and present-value cost composition
CategoryNominalPresent value
Initial worksKRW 0KRW 0
Routine maintenanceKRW 0KRW 0
Expected leak lossKRW 0KRW 0
Full renewalsKRW 0KRW 0
Residual service value creditKRW 0KRW 0

Service-life sensitivity

Service-life sensitivity at 80, 100, and 120 percent
ScenarioFirst/cycleCountNet PV
80% life12/122KRW 0
Base 100%15/151KRW 0
120% life18/181KRW 0

Annual cash flow

Annual rooftop waterproofing nominal and present-value cash flow
YearMaintenanceExpected leak lossInitial / renewalPresent value
2026 initialKRW 0KRW 0KRW 0KRW 0
2027 (year 1)KRW 0KRW 0KRW 0KRW 0
2028 (year 2)KRW 0KRW 0KRW 0KRW 0
2029 (year 3)KRW 0KRW 0KRW 0KRW 0
2030 (year 4)KRW 0KRW 0KRW 0KRW 0
2031 (year 5)KRW 0KRW 0KRW 0KRW 0
2032 (year 6)KRW 0KRW 0KRW 0KRW 0
2033 (year 7)KRW 0KRW 0KRW 0KRW 0
2034 (year 8)KRW 0KRW 0KRW 0KRW 0
2035 (year 9)KRW 0KRW 0KRW 0KRW 0
2036 (year 10)KRW 0KRW 0KRW 0KRW 0
2037 (year 11)KRW 0KRW 0KRW 0KRW 0
2038 (year 12)KRW 0KRW 0KRW 0KRW 0
2039 (year 13)KRW 0KRW 0KRW 0KRW 0
2040 (year 14)KRW 0KRW 0KRW 0KRW 0
2041 (year 15)KRW 0KRW 0KRW 0KRW 0
2042 (year 16)KRW 0KRW 0KRW 0KRW 0
2043 (year 17)KRW 0KRW 0KRW 0KRW 0
2044 (year 18)KRW 0KRW 0KRW 0KRW 0
2045 (year 19)KRW 0KRW 0KRW 0KRW 0
2046 (year 20)KRW 0KRW 0KRW 0KRW 0
2047 (year 21)KRW 0KRW 0KRW 0KRW 0
2048 (year 22)KRW 0KRW 0KRW 0KRW 0
2049 (year 23)KRW 0KRW 0KRW 0KRW 0
2050 (year 24)KRW 0KRW 0KRW 0KRW 0
2051 (year 25)KRW 0KRW 0KRW 0KRW 0
2052 (year 26)KRW 0KRW 0KRW 0KRW 0
2053 (year 27)KRW 0KRW 0KRW 0KRW 0
2054 (year 28)KRW 0KRW 0KRW 0KRW 0
2055 (year 29)KRW 0KRW 0KRW 0KRW 0
2056 (year 30)KRW 0KRW 0KRW 0KRW 0
Modified asphalt sheet membraneKRW 0

Renewal schedule

2041

Next renewal

2056

Service remaining at horizon

0 years

Annual equivalent per area

KRW 0/㎡

  • All costs are zero. Enter a real quote before comparing alternatives.

Cost composition

Nominal and present-value cost composition
CategoryNominalPresent value
Initial worksKRW 0KRW 0
Routine maintenanceKRW 0KRW 0
Expected leak lossKRW 0KRW 0
Full renewalsKRW 0KRW 0
Residual service value creditKRW 0KRW 0

Service-life sensitivity

Service-life sensitivity at 80, 100, and 120 percent
ScenarioFirst/cycleCountNet PV
80% life12/122KRW 0
Base 100%15/151KRW 0
120% life18/181KRW 0

Annual cash flow

Annual rooftop waterproofing nominal and present-value cash flow
YearMaintenanceExpected leak lossInitial / renewalPresent value
2026 initialKRW 0KRW 0KRW 0KRW 0
2027 (year 1)KRW 0KRW 0KRW 0KRW 0
2028 (year 2)KRW 0KRW 0KRW 0KRW 0
2029 (year 3)KRW 0KRW 0KRW 0KRW 0
2030 (year 4)KRW 0KRW 0KRW 0KRW 0
2031 (year 5)KRW 0KRW 0KRW 0KRW 0
2032 (year 6)KRW 0KRW 0KRW 0KRW 0
2033 (year 7)KRW 0KRW 0KRW 0KRW 0
2034 (year 8)KRW 0KRW 0KRW 0KRW 0
2035 (year 9)KRW 0KRW 0KRW 0KRW 0
2036 (year 10)KRW 0KRW 0KRW 0KRW 0
2037 (year 11)KRW 0KRW 0KRW 0KRW 0
2038 (year 12)KRW 0KRW 0KRW 0KRW 0
2039 (year 13)KRW 0KRW 0KRW 0KRW 0
2040 (year 14)KRW 0KRW 0KRW 0KRW 0
2041 (year 15)KRW 0KRW 0KRW 0KRW 0
2042 (year 16)KRW 0KRW 0KRW 0KRW 0
2043 (year 17)KRW 0KRW 0KRW 0KRW 0
2044 (year 18)KRW 0KRW 0KRW 0KRW 0
2045 (year 19)KRW 0KRW 0KRW 0KRW 0
2046 (year 20)KRW 0KRW 0KRW 0KRW 0
2047 (year 21)KRW 0KRW 0KRW 0KRW 0
2048 (year 22)KRW 0KRW 0KRW 0KRW 0
2049 (year 23)KRW 0KRW 0KRW 0KRW 0
2050 (year 24)KRW 0KRW 0KRW 0KRW 0
2051 (year 25)KRW 0KRW 0KRW 0KRW 0
2052 (year 26)KRW 0KRW 0KRW 0KRW 0
2053 (year 27)KRW 0KRW 0KRW 0KRW 0
2054 (year 28)KRW 0KRW 0KRW 0KRW 0
2055 (year 29)KRW 0KRW 0KRW 0KRW 0
2056 (year 30)KRW 0KRW 0KRW 0KRW 0
Sheet-and-liquid composite waterproofingKRW 0

Renewal schedule

2041

Next renewal

2056

Service remaining at horizon

0 years

Annual equivalent per area

KRW 0/㎡

  • All costs are zero. Enter a real quote before comparing alternatives.

Cost composition

Nominal and present-value cost composition
CategoryNominalPresent value
Initial worksKRW 0KRW 0
Routine maintenanceKRW 0KRW 0
Expected leak lossKRW 0KRW 0
Full renewalsKRW 0KRW 0
Residual service value creditKRW 0KRW 0

Service-life sensitivity

Service-life sensitivity at 80, 100, and 120 percent
ScenarioFirst/cycleCountNet PV
80% life12/122KRW 0
Base 100%15/151KRW 0
120% life18/181KRW 0

Annual cash flow

Annual rooftop waterproofing nominal and present-value cash flow
YearMaintenanceExpected leak lossInitial / renewalPresent value
2026 initialKRW 0KRW 0KRW 0KRW 0
2027 (year 1)KRW 0KRW 0KRW 0KRW 0
2028 (year 2)KRW 0KRW 0KRW 0KRW 0
2029 (year 3)KRW 0KRW 0KRW 0KRW 0
2030 (year 4)KRW 0KRW 0KRW 0KRW 0
2031 (year 5)KRW 0KRW 0KRW 0KRW 0
2032 (year 6)KRW 0KRW 0KRW 0KRW 0
2033 (year 7)KRW 0KRW 0KRW 0KRW 0
2034 (year 8)KRW 0KRW 0KRW 0KRW 0
2035 (year 9)KRW 0KRW 0KRW 0KRW 0
2036 (year 10)KRW 0KRW 0KRW 0KRW 0
2037 (year 11)KRW 0KRW 0KRW 0KRW 0
2038 (year 12)KRW 0KRW 0KRW 0KRW 0
2039 (year 13)KRW 0KRW 0KRW 0KRW 0
2040 (year 14)KRW 0KRW 0KRW 0KRW 0
2041 (year 15)KRW 0KRW 0KRW 0KRW 0
2042 (year 16)KRW 0KRW 0KRW 0KRW 0
2043 (year 17)KRW 0KRW 0KRW 0KRW 0
2044 (year 18)KRW 0KRW 0KRW 0KRW 0
2045 (year 19)KRW 0KRW 0KRW 0KRW 0
2046 (year 20)KRW 0KRW 0KRW 0KRW 0
2047 (year 21)KRW 0KRW 0KRW 0KRW 0
2048 (year 22)KRW 0KRW 0KRW 0KRW 0
2049 (year 23)KRW 0KRW 0KRW 0KRW 0
2050 (year 24)KRW 0KRW 0KRW 0KRW 0
2051 (year 25)KRW 0KRW 0KRW 0KRW 0
2052 (year 26)KRW 0KRW 0KRW 0KRW 0
2053 (year 27)KRW 0KRW 0KRW 0KRW 0
2054 (year 28)KRW 0KRW 0KRW 0KRW 0
2055 (year 29)KRW 0KRW 0KRW 0KRW 0
2056 (year 30)KRW 0KRW 0KRW 0KRW 0

Checks before contract or diagnosis

  • Normalize tax, removal, substrate repair, drains, parapets, penetrations, protection, lifting, temporary protection, and waste.
  • The 15-year/100% value is a Korean apartment long-term repair reference, not a method warranty or a universal mandatory date.
  • Discount, escalation, residual service value, and expected leak loss are planning assumptions, not contract prices or statutory damages.
  • Law and standards were checked on 2026-08-10. Verify the current plan, specification, and product data before procurement.

Related calculators

Korea-specific scope

This calculator compares rooftop waterproofing quotes in KRW and square metres under a common lifecycle-cost basis.
Its optional 15-year reference comes from Schedule 1 of Korea’s Enforcement Rule of the Multi-Family Housing Management Act, checked on August 10, 2026.
That schedule describes full repair of external-roof waterproofing at a 15-year cycle and 100% repair rate for the applicable long-term repair planning context.

The reference is not a guaranteed life for any method, a universal replacement mandate, a project diagnosis, or a decision that reserve funds may lawfully be used.

Why the opening waterproofing quote is not the lifecycle cost

A unit-price comparison captures only part of the economic decision.
Removal, substrate repair, drains, parapets, penetrations, protection, access, lifting, routine inspection, local repair, leak exposure, business interruption, and future full renewal can materially change ownership cost.
A cheaper opening system may therefore become more expensive if it renews earlier or carries higher maintenance and leak exposure.

The calculator places liquid-applied membrane, synthetic polymer sheet, modified asphalt sheet, and sheet-and-liquid composite alternatives on the same roof area, base year, and analysis horizon.
It turns user-entered quotes and timing assumptions into annual nominal cash flow, present value, residual service value, equivalent annual cost, and equivalent monthly cost.
Market prices and method-specific service lives start at zero or an explicitly editable planning reference so the tool does not create false precision.

Normalize price scope

Align VAT treatment, removal, substrate preparation, details, protection, lifting, temporary works, safety, and waste before comparing unit prices.

Evidence the service period

Replace the editable 15-year start with evidence from the specification, product data, warranty, condition survey, actual long-term repair plan, and comparable site history.

The four method families and KCS classification

Korea’s Construction Standards listing separates waterproofing work into method families.
The calculator uses those families only to label comparable quote slots; a KCS code does not certify a product, set its price or life, or establish suitability for a particular roof.

Rooftop waterproofing comparison families and Korean construction-standard work sections
Method slotKCS sectionScope to align
Liquid-applied membraneKCS 41 40 06Moisture, cracks, reinforcement, dry-film thickness, topcoat, and details
Synthetic polymer sheetKCS 41 40 04Material, thickness, seams, termination, penetrations, and protection
Modified asphalt sheetKCS 41 40 03Laps, bonding, preparation, protection, hot work, access, and removal
Sheet-and-liquid compositeKCS 41 40 07Layer roles, seam reinforcement, details, sequencing, and warranty interfaces

Method names do not replace a roof survey

Existing membrane adhesion, moisture, cracks, falls, drainage, roof use, thermal and ultraviolet exposure, wind, structural loading, insulation, and condensation remain outside the numeric model.
A designer, surveyor, or specialist contractor must determine whether overlay, full removal, structural work, or another build-up is appropriate.

How to read Korea’s 15-year apartment reference

The National Law Information Center OPEN API returned the current Multi-Family Housing Management Act as law ID 012345, MST 284009, effective July 1, 2026.
Articles 29 and 30 provide the long-term repair plan and reserve framework, while the current Enforcement Rule was returned as law ID 012648, MST 288369, effective July 30, 2026.
Enforcement Rule Article 7 links to Schedule 1, where external-roof waterproofing appears as full repair at 15 years and a 100% repair rate.

The calculator initially places 15 years and 100% into each editable method slot, but those values are not empirical lives for the four systems.
Where the user confirms the Korean apartment reference is relevant, the output reports only the difference between the entered first-renewal period and 15 years.
It does not decide building applicability, whether a plan has been lawfully reviewed or adjusted, whether reserve expenditure is permitted, or whether a delayed or early project is compliant.

Act

Articles 29 and 30, law ID 012345, MST 284009.

Enforcement Rule

Articles 7 and 9, law ID 012648, MST 288369.

Schedule 1

Schedule serial 18339091, full roof-waterproofing repair at 15 years and 100%.

What each quote and timing input means

Area, unit cost, and fixed cost

Use one rule for horizontal roof area, upstands, parapets, plinths, and other vertical surfaces.
Put area-proportional material and labour in the unit rate, while removal, lifting, temporary works, safety, and waste can sit in fixed cost when that better matches the quote.

First renewal and recurring cycle

Years to first full renewal start at the current installation, while the recurring cycle separates later full-renewal intervals.
Do not assume they are equal; replace both with warranty, survey, plan, exposure, specification, and comparable-site evidence.

Maintenance and expected leak loss

Convert inspection, drain care, local repair, and topcoat budgets into an annual rate without duplicating items already included elsewhere.
Expected leak loss should be an annual probability multiplied by net loss after insurance or recovery, not a claim amount or legal measure of damages.

Renewal ratio and extra cost

The renewal ratio prices full rework relative to today’s initial works on the same price date.
Put renewal-only disruption, relocation, temporary protection, extra access, or lifting in the per-event extra field and avoid counting it in both places.

  • Use the same VAT-inclusive or VAT-exclusive cash basis for every quote
  • Align removal, disposal, substrate, falls, drain, parapet, penetration, and movement-joint scope
  • Align protection, insulation, topcoat, access, temporary protection, and warranty exclusions
  • Separate local maintenance from full renewal so one repair is not counted twice
  • Document any insurance recovery, tenant allocation, salvage, or business-interruption assumption

How the lifecycle calculation works

Initial work equals roof area times unit cost plus fixed cost, with the common works contingency applied at year zero.
Annual maintenance and expected leak loss occur at each year-end; the year-one amount equals the input, with escalation beginning in year two.
Full renewal begins at the entered first-renewal year and repeats at the recurring cycle, but an event exactly equal to the analysis horizon is excluded.

Nominal renewal cost

Base renewal = base initial works × renewal ratio + per-event extra cost
Renewal in year t = base renewal × contingency factor × escalation factort

Present value

Present value in year t = nominal cost in year t ÷ (1 + nominal discount rate)t
Net lifecycle PV = initial cost + future-cost PV − residual-service-value PV

Residual service value and EAC

Residual service value = last full-work cost × remaining years ÷ that service period
At 0% discount, EAC = net lifecycle PV ÷ analysis years
Equivalent monthly cost = EAC ÷ 12

Residual service value is a straight-line comparison credit for unused service at the horizon, not cash resale value.
Equivalent annual cost smooths uneven renewals into a comparable annual burden, but the annual cash-flow table remains necessary for liquidity and reserve planning.
The method follows the common-period and present-value comparison principles described in NIST Handbook 135e2022 without importing a US federal discount rate into a Korean project.

Step-by-step use

  1. Set one common basis
    Use the same measured area, base year, ownership or repair-plan horizon, nominal discount rate, escalation, and contingency for every alternative
  2. Normalize written quote scope
    Reconcile VAT, demolition, substrate, details, protection, access, safety, lifting, and waste in a side-by-side schedule
  3. Enter unit and fixed costs
    Separate area-driven work from site fixed cost so a small roof does not hide mobilisation and access effects
  4. Replace the timing reference
    Use the actual warranty, condition survey, specification, long-term repair plan, and comparable performance record
  5. Add maintenance, leak exposure, and renewal extras
    Keep insurance, tax, accounting basis, and duplicated scope consistent across every method
  6. Read ranking and cash flow together
    A lower PV does not override site suitability, installation quality, warranty, safety, or a large renewal-year funding requirement
  7. Stress the service life
    Check whether the ranking or number of renewals changes when first and recurring life fall to 80% or rise to 120%

Worked boundary example

This example verifies the model and is not a market quote.
Assume 100㎡, a 10-year horizon, 0% discount, escalation, and contingency, and no residual credit.
One method costs KRW 10,000/㎡ initially, renews first at year five and every five years at 100%, and carries KRW 1,000/㎡ of annual maintenance with no other cost.

Simple rooftop waterproofing lifecycle cost verification example
ItemAmount or eventCheck
Initial worksKRW 1,000,000100㎡ × KRW 10,000
Ten-year maintenanceKRW 1,000,000KRW 100,000/year × 10
Full renewalYear 5 · KRW 1,000,000The year-10 event equals the horizon and is excluded
Net lifecycle PVKRW 3,000,000Same as nominal cost at a 0% discount rate
Annual and monthly equivalentKRW 300,000 · KRW 25,000Divide by 10 years and 12 months

Residual-value boundary

In a 15-year study with full renewals at years four and ten on a six-year recurring cycle, the next event is year 16 and one service year remains.
If the last full-work portion is KRW 1,000,000, the straight-line residual service value is one-sixth, or KRW 166,666.67.
Renewal disruption and routine maintenance receive no residual credit.

Property use cases

Korean apartment planning

Compare normalized alternatives for a management report after reviewing the actual long-term repair plan and project scope.
A period different from 15 years requires plan, condition, technical, approval, and legal-process review rather than an automatic compliance conclusion.

Retail and offices

Reflect net interior damage in expected leak loss and renewal-period closure, tenant access, temporary routing, and protection in per-event extra cost.

Factory and logistics roofs

Consider equipment, inventory, net production interruption, permits, hot-work restrictions, cranes, access, and safety controls.
Keep phased-zone work distinct from one full-roof renewal.

Pre-acquisition due diligence

Use vendor records and a condition survey to scenario-test capital expenditure over the intended holding period.
The resulting residual service value is not a purchase-price adjustment, and structural, insulation, hazardous-material, and liability review remains separate.

Frequently asked questions

Why is there no default polyurethane life or average price?

The name does not establish material grade, thickness, reinforcement, substrate, topcoat, exposure, installation quality, or warranty. Use the actual specified build-up and comparable written quote.

Must every Korean apartment renew waterproofing at year 15?

Schedule 1 provides a planning reference for the applicable multi-family housing context. Confirm the current plan, statutory review or adjustment, condition, approvals, and current law before execution.

How should expected leak loss be entered?

Multiply an evidence-based annual probability by net loss after insurance and recovery. If evidence is unavailable, leave zero and disclose that leak exposure is excluded.

May both discount and escalation stay at zero?

Yes for a transparent undiscounted comparison. For capital budgeting, use approved nominal assumptions consistently and do not mix real discount rates with nominal cash flow.

Should the lowest present-value method be selected automatically?

No. The ranking reflects entered economics only and cannot replace substrate suitability, detailing, programme, safety, quality control, warranty, contractor capability, or legal procedure.

Turn the result back into procurement questions

Identify methods with missing cost, a ranking reversal under 80% life, or a large single renewal-year requirement.
Convert those differences into written questions about substrate preparation, thickness, seams, details, protection, maintenance conditions, warranty, and full-renewal scope.
Recheck the current National Law Information Center material, the CODIL KCS listing, NIST Handbook 135 guidance, the project specification, and product documentation before procurement.

Check Korean lawCheck KCS work sections