Foundation extension
Footings, stem walls or piers matched to existing depth, with dowels into the old footing and waterproofing at the joint
LF / CYFoundation plan and existing-condition notes
Residential additions
Home addition estimates that price the tie-in, not just the new square footage
An addition is never a small new house. The money disappears where new framing meets old: a foundation that has to match an uneven existing footing, a roof valley that forces a tear-off of three courses of shingles, siding that no longer exists in the original profile. LEEDS estimates additions by pricing the connection points first, then the new volume, so your number holds once the first wall is opened.
Tie-in scope itemizedSecond stories and bump-outsPermit and weather protection included
4.9/5 from 180+ contractors
- 5.0 Google
- 4.9 Trustpilot
- 4.9 Clutch
“The conduit and wire takeoff matched what my foreman pulled from the drawings almost to the foot. Labor hours were realistic for our crews. It is the first outsourced estimate I did not have to redo.”
Reviews
What contractors say after their first bid with us
What general contractors, subcontractors and developers say after bidding with our numbers.
Trustpilot
“The conduit and wire takeoff matched what my foreman pulled from the drawings almost to the foot. Labor hours were realistic for our crews. It is the first outsourced estimate I did not have to redo.”
Dana Okafor
Owner, Okafor Electric · Houston, TX
Trustpilot
“Squares, underlayment, flashing lengths, fastener counts, even the ridge vent. The waste factors were right for the roof pitch. Bid-ready out of the box.”
Greg Lindqvist
Estimator, Summit Roofing Co. · Kansas City, MO
Direct
“We feed every lender package through LEEDS. The documentation standard is high enough that underwriting has never asked for a second opinion.”
Sarah McAllister
Director of Preconstruction, Harborline Developments · Tampa, FL
Scope of takeoff
Addition scope we quantify
New construction and tie-in work measured separately so allowances are visible and change orders are rare.
Scroll through all 12 line items
Overview
How an addition estimate differs from new construction
A home addition estimate quantifies two projects at once: the new structure and the alterations that make it part of the existing house.
The new work is conventional, with footings, stem walls, floor system, framing, roofing, windows, mechanical rough-in and finishes. The alteration work is where estimates go wrong, because it depends on conditions that drawings rarely show, such as the true depth of the old footing, the actual size of the ceiling joists or whether a bearing wall hides a duct run. Each of those unknowns is carried as a named allowance, so the owner sees the risk in the budget instead of discovering it with a sledgehammer.
We separate the two in the workbook. Selective demolition of exterior walls, header installation in bearing openings, shoring, sistering of existing joists, extension of HVAC trunk lines and subpanel capacity checks are each priced as their own lines. Temporary weather protection, dust barriers and daily cleanup are carried as time-based costs, because an open wall in November costs more than the same wall in June, and a second-story lift can leave a roof open for weeks. Winter-open walls also add heater rental, tarps, and extra drying time before insulation and drywall can close the envelope.
Finish matching gets the same treatment. Hardwood that has to be blended across a doorway, siding that has to be replaced on a full elevation to hide a seam, and paint that must continue through adjoining rooms are quantified so the homeowner sees them in the base price instead of as change orders. Permit, engineering and utility upgrade costs close the estimate, so the number the owner approves is the number they pay. Allowances for cabinets, plumbing fixtures and lighting carry unit budgets, which makes upgrade conversations quick and the contract easy to adjust.
Estimate types
What type of home addition estimating can you get?
Match the estimate to where your project is. Every option is priced as a flat fee before work begins.
01
Feasibility budget
A per-square-foot range with the tie-in and structural unknowns flagged, built from a sketch or a first design pass.
- Accuracy
- ±15-20%
- Turnaround
- 24 hours
02
Design-development estimate
Assembly-based pricing from DD drawings with named allowances for cabinets, tile, fixtures and windows.
- Accuracy
- ±8-10%
- Turnaround
- 48 hours
03
Fixed-price bid estimate
Full takeoff of every trade from permit drawings, with documented exclusions and an alternates list.
- Accuracy
- ±4-6%
- Turnaround
- 48-72 hours
04
Second-story structural estimate
Focused pricing of shoring, new floor system, stair, roof lift and temporary roofing for vertical additions.
- Accuracy
- ±6-8%
- Turnaround
- 48 hours
05
Change-order pricing
Quick pricing of owner-requested changes and unforeseen conditions found after demolition, with labor and material split.
- Accuracy
- ±3-5%
- Turnaround
- Same day
Process
How our estimating process works
Four steps from upload to a bid-ready estimate, with a senior estimator signing off before anything leaves our desk.
Upload plans and scope
- 1
Step 1
Upload plans and scope
Send your drawings, specifications and bid invitation through the secure upload form. We confirm scope, deadline and a fixed price within two business hours.
- 2
Step 2
Digital quantity takeoff
Estimators measure every item from calibrated plans in Bluebeam and PlanSwift, color-coding each layer so quantities can be traced back to the drawing.
- 3
Step 3
Pricing and labor
Quantities are priced with location-adjusted material costs, crew productivity rates and equipment, then marked up to your overhead and profit targets.
- 4
Step 4
Senior review and delivery
A second estimator audits quantities and pricing, documents assumptions and exclusions, and delivers your Excel workbook, PDF summary and marked-up plans.
Why LEEDS
Why contractors switch to LEEDS
An estimating desk that behaves like an extension of your team, not a software subscription.
- Tie-in work is priced as its own section so owners can see exactly what the connection to the old house costs.
- Foundation extensions are quantified with dowels, matching depths and waterproofing at the new-to-old joint, not as a plain footing.
- Second-story estimates include shoring, temporary roofing and the weather days that an open roof will realistically cost.
- Siding, flooring and paint matching is quantified by elevation or room so the base price already reflects a seamless finish.
- Allowances for cabinets, plumbing fixtures, tile and lighting are written with unit budgets you and the owner can adjust.
- Permit, structural engineering, survey and utility upgrade fees are estimated for the specific jurisdiction.
Deliverables
What's included in your estimate package
Every deliverable is formatted so it can go straight into a proposal, a purchase order or an owner report.
.xlsx
Estimate workbook
Quantities, unit costs, labor hours and totals organized by CSI division, with subtotals, markups and a bid summary tab.
.pdf
Marked-up plans
Color-coded takeoff drawings showing exactly where every measured quantity came from.
.xlsx
Material procurement list
Consolidated material quantities with waste factors applied, ready to send to suppliers for quotes.
.xlsx
Labor hours by task
Crew-based labor hours and productivity rates so you can check the schedule against the estimate.
.pdf
Assumptions and exclusions log
Every clarification, allowance and exclusion documented so your proposal scope is defensible.
.pdf
Bid summary sheet
A proposal-ready one-page summary with overhead, profit, bonds and contingency applied.
Free quote
Get a fixed quote for this scope
Upload drawings or a plan link and tell us the bid date. A senior estimator confirms scope, price and delivery before any work starts.
- Scope confirmation and a fixed price within two business hours
- Most estimates delivered in 24–48 hours
- Unlimited revisions until bid day
- Plans stay confidential and are deleted on request
Prefer to talk? Call +1 (800) 555-0199 or email info@leedsestimating.com.
Nationwide
Priced for your zip code in all 50 states
Labor rates, material costs and code requirements are adjusted to the project location, not a national average.
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FAQ
Home Addition Estimating FAQs
Straight answers on scope, turnaround, pricing and deliverables.
Why do home additions cost more per square foot than new homes?
Additions carry fixed costs a new house spreads over more area: mobilization, tie-in carpentry, demolition, temporary protection and matching finishes. The new volume is often cheaper per foot than the connection work. We separate both so you can see which part of the number is square footage and which is the transition.
Can you estimate a second-story addition without opening the walls?
Yes, with documented assumptions. We price the likely condition of the existing foundation, bearing walls and ceiling joists from photos, original plans or field notes, then carry an explicit contingency for what only demolition will reveal. The estimate lists each assumption so a surprise becomes a priced alternate, not a dispute.
Do you include permits and engineering in an addition estimate?
We include plan review fees, structural engineer letters, surveys and utility connection charges as line items, using the fee schedule of the jurisdiction. If you prefer to carry them as an owner cost we show them as a separate subtotal so the contract price stays clean.
How do you handle matching existing siding or flooring?
We quantify the match by actual need: full-elevation siding replacement when profiles are discontinued, sand and refinish across thresholds for hardwood, and paint continuation to the nearest natural break. Each is a visible line, so the owner can choose between blending and a visible change.
Will the existing HVAC and electrical panel handle the addition?
We run a load check from the existing nameplate data and the new square footage. When the panel or furnace is undersized, the estimate carries a subpanel, service upgrade or separate mini-split system, so the cost appears at bid time and not after rough-in inspections.
What does a garage conversion estimate include?
Slab or raised floor insulation, infill framing of the overhead door opening, egress window, wall and ceiling insulation to code, drywall, flooring, added HVAC capacity and electrical circuits. We also flag setback and parking-count rules that some jurisdictions apply to conversions. It also confirms whether the old room's heating and cooling can be extended or must be replaced.
Related
Related estimating services
Most projects need more than one trade. Bundle them into a single upload and we price the whole scope together.
Ready for a home addition estimating quote?
Upload your plans and get a fixed quote within 2 business hours. Most estimates are delivered in 24–48 hours.