Construction FinancingTreasure Valley, Idaho
The financing structure that funds a custom build — draws, conversion, and what lenders require at each stage.
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Dennis Fomin
Fomin & Company · Associate Broker, GRI, RSPS · 2026
Quick Answer
How does construction financing work for a custom home build in Idaho?
A construction-to-permanent loan — also called a one-time-close or construction perm loan — funds your custom home build in two phases. During construction, the loan functions as a revolving credit line: funds are disbursed in draws tied to construction milestones, and you pay interest only on the amount drawn. At construction completion, the loan automatically converts to a standard permanent mortgage. You qualify for the full amount once, at the start, and go through one closing — which reduces closing costs and rate lock risk compared to two separate loans.
Dennis Fomin — Founder, Fomin & Company. Construction financing is where many custom home buyers encounter their first major surprise. The draw process, the interest-only period, and the appraisal-on-plans requirement all behave differently from a standard mortgage. Here is how it works.
The Construction-to-Permanent Loan Structure
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Application and Approval — Before Ground BreaksYou apply for the full loan amount — land plus construction cost. The lender orders an appraisal based on your plans and specifications — an ‘as-completed’ value. Your loan amount cannot exceed a percentage of that appraised completed value (typically 80-90%).
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Closing — One TimeYou close on the full loan amount before construction begins. If you already own the land, the land equity counts toward your down payment. If you are purchasing land as part of the transaction, the land purchase and construction loan close simultaneously.
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Construction Phase — Interest-Only DrawsAs construction progresses, your builder submits draw requests tied to the agreed draw schedule. The lender sends an inspector to verify work completion before releasing each draw. You pay interest only on the outstanding draw balance — not on the full loan amount.
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Construction Complete — ConversionAt construction completion (certificate of occupancy issued), the loan converts to your permanent mortgage. Your first full P&I payment begins one month after conversion. No second closing, no second set of closing costs.
What Lenders Require for Construction Financing
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Complete and approved building plansPlans must be approved (or approvable) by the county or city before the lender will order the appraisal. Incomplete plans cannot be appraised.
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Signed construction contract with the builderThe contract must include a defined scope, price (or cost-plus structure with a defined maximum), and draw schedule. Lenders will not fund a vague builder agreement.
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Builder’s license and insurance verificationThe lender verifies the builder’s Idaho contractor license and insurance independently. An unlicensed or uninsured builder disqualifies the loan.
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Down payment — typically 20% of completed valueConstruction loans typically require 20% equity — either in cash, land equity, or a combination. Some lenders allow land equity as the full down payment if land value is sufficient.
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Income and credit — same standards as conventional mortgageQualifying for a construction loan uses the same DTI and credit score standards as a conventional mortgage. The construction period payments (interest-only) must fit within qualifying ratios.
The Draw Inspection Process
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Lender sends an inspector before each drawBefore releasing each draw payment to your builder, the lender’s draw inspector visits the site and confirms the milestone is complete. This protects you — the lender is verifying work before releasing your money.
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Lien waivers required with each drawYour builder and major subcontractors must provide lien waivers with each draw — confirming they have received payment and waive their right to lien the property for that draw amount. This prevents mechanic’s liens from unpaid subs.
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Draw timing — typically 10-14 business days from request to fundingPlan your builder’s cash flow needs around the draw timing. A builder who needs payment immediately upon milestone completion will be frustrated by a 10-day draw cycle. Discuss this with your builder at contract.
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Contingency reserve — built into the loan or held separatelyMost construction loans include a contingency reserve of 5-10% of construction cost. This covers cost overruns and change orders without requiring a separate loan modification.
Land-Plus-Construction Loans vs. Two Separate Loans
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One-time-close construction perm — one closing, one set of costsThe most efficient structure for buyers who have not yet purchased land. Land and construction financed together, one closing, one permanent loan at the end.
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Two separate loans — land loan first, then constructionSome buyers purchase land with a separate land loan, then refinance into a construction loan when they are ready to build. This works for buyers who want to hold land before building but involves two closings and two sets of costs.
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Check current lender availabilityNot all Idaho lenders offer construction-to-permanent loans. The universe of lenders with custom build experience in the Treasure Valley is smaller than the universe of standard mortgage lenders. Your agent and builder should have current referrals.
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Rate lock on construction loans is different from standard mortgagesConstruction loans may offer a rate lock for the permanent phase at application (one-time-close) or set the rate at conversion (float-to-perm). Understand the rate risk structure before you commit.
Frequently Asked Questions
What is a construction-to-permanent loan?+
A construction-to-permanent loan funds both the construction of your home and the permanent mortgage in one loan structure. During construction, you pay interest-only on drawn funds. At completion, the loan converts to a standard amortizing mortgage.
How much down payment do I need for a construction loan in Idaho?+
Most construction-to-permanent lenders require 20% of the as-completed appraised value. Land equity counts toward the down payment — if you own land outright, that equity may satisfy the down payment requirement entirely.
What happens if construction costs exceed the loan amount?+
You must fund the overage from savings or a separate loan. This is why contingency reserves and accurate pre-construction budgets are critical. Never build to the absolute maximum of your loan approval — leave room for overruns.
How long can a construction loan stay open?+
Most construction loans have a 12-18 month construction period. If your build takes longer — weather delays, permitting delays, or scope changes — you will need to request an extension. Extensions typically require lender approval and may incur fees.
Can I use a construction loan to buy land and build in the same transaction?+
Yes. A one-time-close construction-to-permanent loan can finance land acquisition and construction in a single closing. The land purchase and construction loan close simultaneously, with draws funding construction as it progresses.
Starting the Financing Conversation for Your Custom Build?
Dennis Fomin — Founder, Fomin & Company. Associate Broker, GRI, RSPS. Free 2026 This Is Boise Area Guide.
- —Land equity analysis — whether your land purchase satisfies the down payment requirement
Serving Boise, Meridian, Eagle, Nampa, Caldwell & the Treasure Valley.
Summary
Construction financing is the mechanism that makes a custom build possible for buyers who do not have the full construction cost in cash. The one-time-close structure — one approval, one closing, interest-only during construction, conversion to permanent at completion — is designed for exactly this purpose. The key: understand the draw process, the lien waiver requirements, and the contingency structure before your first dollar goes in the ground.
Construction financing is not complicated once you understand the sequence. The mistake is treating it like a standard mortgage — it has its own mechanics and its own risks. Know them before you sign.
