Crawl space to basement conversions are complex structural projects, and understanding what drives the cost is the first step in making confident, informed, and rewarding decisions about your home and the contractors you hire.
The pricing estimates and considerations below are based on projects in Denver and Northern Colorado; however, you can use the considerations listed here to vet your contractors when getting bids—regardless of your location.
- Cost Chart
- What Affects the Cost?
- Cost of Crawl Space to Basement Conversions vs. Other Additions
- IMPORTANT: What to Guarantee Your Contractor Offers When You Get a Bid
How Much Does it Cost to Convert Your Crawl Space to a Basement?
A crawl space dig-out typically includes excavation, structural reinforcement, foundation work, and installation of stairs. Finishing is optional depending on your goals, but is highly recommended for maximizing your investment and getting the most usable value out of the space.
What Drives the Cost of a Crawl Space to Basement Conversion?
There are several structural and site-specific conditions that affect pricing.
Do you have a partial existing basement or are you adding a full basement?
Homes without basements require new stair openings and structural integration. Homes with partial basements and existing stairs may avoid these stair-related costs, depending on how the new space ties into the current layout.
What is your foundation type?
Whether your home is on footings or caissons plays into the cost of your conversion. Footing foundations, common in the city of Denver, are more complex and often require phased excavation and additional structural support. Caisson foundations, common in Westminster and Centennial where there are expansive soils, can simplify certain structural aspects. Learn more about the difference.
What is the material and condition of your foundation?
Brick, CMU block, poured concrete, or even older sandstone foundations all require different engineering approaches. The age and integrity of your foundation will play a major role in shoring requirements.
Do you need to account for asbestos risk?
We always recommend that older homes be tested for asbestos as part of the pre-construction process to mitigate this risk.
Are structural or mechanical system modifications needed?
Existing beams may need reinforcement or replacement with steel supports depending on load requirements. Ventilation, plumbing, gas lines, and electrical systems may need to be relocated or reconfigured for the new space. If you’re adding considerable square footage, you may need to install a bigger furnace or a new furnace to supply the new square footage.
What are your goals for ceiling height?
Some homeowners choose to excavate deeper to increase basement ceiling height during the same scope of work. As an example, if you plan to add a golf simulator or basement theater that requires more headroom, that added depth will come with additional excavation and structural costs.
What are the groundwater conditions?
High groundwater areas may require soil testing and specialized waterproofing or drainage systems. If groundwater is a concern based on your location, a soils test will need to be performed to find out the groundwater elevation.
Where will egress windows be located?
Egress windows are required for code compliance in finished basements. The number of egress windows will affect the cost, and the location of your egress windows are often coordinated with the excavation access points.
What are permitting costs?
In the City of Denver, the Affordable Housing Linkage Fee can add roughly $10 per square foot of new habitable space, which directly affects the total permit cost based on project size. As the square footage of the new basement increases, this fee becomes a meaningful part of the overall permitting budget. However, if you’re only digging your basement deeper, and not adding square footage, this fee does not apply.
How the Cost of a Crawl Space Dig-Out & Basement Finishing Compares to Other Types of Additions
Compared to other home addition methods, crawl space to basement conversions not only offer better cost control, but also more potential for space—and a much less invasive process.
Pop-Top Additions
- Typically $700,000–$800,000+
- Require major structural work and often an interior remodel of the main level in addition to the cost of the new story (due to increased structural load and exposure to the elements during construction)
- Home is not inhabitable during construction, often up to 1 year—leading to additional housing and rental costs on top of your project cost
- Complex and costly permitting due to height limits, bulk plane restrictions, and potential historic regulations or HOA rules
Ground-Floor Additions
- Typically can compare to the price of a crawl space to basement conversion, while offering less square footage in most cases
- Setbacks and limited lot space are common constraints in Denver, which can restrict design options
- Homes may become uninhabitable during construction depending on the scope of structural work and utility tie-ins
Crawl Space to Basement Conversions
- Typically $350,000–$400,000 for a fully finished space
- Home is livable during the construction process (~5–6 months)
- No zoning restrictions or historic aesthetic restrictions because the exterior of the home is unchanged—also leading to easier, more cost-effective permitting
- Quick construction timeline—typically 5–6 months
Getting Bids: Is a Lower Bid Actually an Accurate Estimate of the Full Project Cost?
A significantly lower price can be a warning sign on projects of this complexity. Crawl space conversions are structural, high-risk builds where experience and process matter.
As a crawl space to basement contractor, we typically have 6 or 7 active crawl space to basement conversion projects running at a time. This kind of work requires steady management and real experience with both the project type and the local conditions you’re building in.
To ensure the success of your build, these are the kinds of questions that separate a low number on paper from a complete, accountable scope of work. When getting your bids, ask your contractors:
1. Experience With This Type of Work
- Have you completed crawl space to basement conversion projects before?
- How many have you successfully completed in the last few years?
- Can you provide examples of recent projects and references from those jobs?
- Do you manage design, engineering, permitting, and architecture in-house, or do I need to hire my own architects and engineers?
2. Insurance Coverage & Risk Protection
- What insurance coverage do you carry for a structural project like this?
- If there is structural damage during excavation, how is it handled and whose insurance applies?
- What are the policy limits, and what specifically is covered during construction?
- Do you carry builders’ risk insurance that covers the entire structure while work is in progress?
- Will I be listed as an additional insured on the policy?
3. Foundation Method & Structural Approach
- What type of foundation system are you proposing for my home?
- If my home uses caisson foundations, are you planning an underpinning method? If not, why?
- Are you proposing any benching of foundation walls, and if so, what is the structural justification for that approach?
- How do you plan to properly connect new foundation work to the existing structure?
- How do you decide between underpinning, benching, or other foundation reinforcement methods?
4. Excavation, Shoring, & Safety Plan
- What is your excavation and shoring plan for this project?
- Are your plans designed and approved by a structural engineer?
- How are you handling OSHA requirements for soil safety and excavation support?
- What soil type assumptions are you making for the site (Type B, Type C, etc.)?
- How many excavation phases will the project be completed in?
- How many feet are you excavating at a time in each phase?
5. Waterproofing and Drainage
- What waterproofing system are you installing on the foundation walls?
- Are you installing a full foundation drainage system and sump pump?
- Are you using vapor barriers, and if so, where are they being placed?
- How do you prevent moisture from being trapped inside the foundation walls over time?
6. Project Management & Oversight
- Will you have a dedicated project manager assigned to my job?
- How often will the site be supervised and inspected?
- How often can I expect communication during construction?
- Will I receive regular updates, photos, and progress reports? How will I receive them?
7. Dirt Removal & Site Impact
- How will excavated soil be handled and removed from the property?
- Is soil hauled away daily, or stored at my home during construction?
- How do you protect existing landscaping and surrounding areas during excavation and hauling?
8. Licensing & Compliance
- Do you hold your own general contractor license in the City of Denver (or other local jurisdiction)?
- Are you operating under your own license, or another contractor’s license?
9. Pricing Structure, Schedule, & Guaranteed Limits
- What type of pricing structure do you use (fixed price, cost-plus, etc.)?
- Can you provide a guaranteed maximum price for my project?
- Can you offer a guaranteed construction timeframe?
- If delays occur, is there any accountability tied to schedule overruns?
- What risks exist for cost overruns under your pricing model, and how are those controlled?
- Are you willing to put timeline guarantees and penalties for overruns in writing?
Get an Estimate on Your Crawl Space to Basement Conversion
Serving Denver Metro & Northern Colorado
PR Builders is a crawl space to basement conversion contractor serving Denver, Wheat Ridge, Centennial, Broomfield, and the surrounding areas along the Northern Colorado Front Range. Over our years of experience with these projects, we have developed a process centered on complete transparency and total peace of mind. We carry full builders risk insurance on every project, operate under proper licensing, and offer both a guaranteed maximum price and a guaranteed project duration so you know your cost and timeline upfront with no surprises.
For an estimate or more information on a crawl space to basement conversion project, send us a message or give us a call today at 970-692-4589.
