Before designing the addition, decide whether the project makes sense.

The decision before the design

Feasibility is for current owners and prospective buyers

Some homeowners know that their current house needs more space, but they do not yet know whether the right answer is a rear addition, second story, interior reconfiguration or a combination. Other clients are still considering a purchase. They may like the street and lot but need to know whether the house can support the bedrooms, common space, accessibility or long-term flexibility their household requires.

In both cases, the first useful question is not “What should the addition look like?” It is “Can this property support a project that meets the owner’s needs at an investment and level of risk they can accept?” A feasibility study answers that question with progressively better information.

For a prospective purchase, the scope is organized around the access and time available. A short contingency period may support a focused screening of zoning, visible structure, site conditions and likely project range. If the purchase moves forward, boundary and topographic survey work, concept development and deeper engineering can follow without discarding the first analysis.

Step 1

Spend time understanding what the owner actually needs

A list of rooms is not enough. We discuss how the household uses the house now, what is not working, which relationships matter, how long the property should serve the family and what future changes should be anticipated. A first-floor bedroom for a parent, two quiet offices, a larger kitchen and a better connection to the yard each lead to different structural, zoning and budget priorities.

We also separate needs from preferred solutions. An owner may arrive asking for a two-story addition, but the underlying program may fit through a smaller addition and a more effective interior plan. The opposite can also be true: trying to force a large program into the existing footprint can create expensive structural work and compromised rooms without solving the long-term need.

The discovery conversation establishes the investment range, decision deadline, expected years of ownership, appetite for construction disruption and any information already available—surveys, inspection reports, prior plans, permits, utility records and listing documents.

Step 2

Build an accurate record of the house and property

Feasibility depends on existing conditions. We review the house in the field, measure the areas affected by the concept and identify visible clues about framing, foundation type, roof geometry, drainage, utilities and previous work. We look for the conditions most likely to control the next decision—not just the finishes that are easy to photograph.

For additions and major site changes, Dena House can coordinate both boundary and topographic surveys. The boundary survey establishes property lines, recorded easements and the relationship between the house and legal parcel. The topographic survey records grades, walls, significant features and elevations that influence drainage, foundation exposure, walkout conditions and how a new floor can connect to the existing building.

Permit history, tax records and old drawings can help, but they are not automatically accurate records of present construction. Where a concealed condition could materially change the decision, we identify the next investigation rather than pretending certainty.

Step 3

Test technical feasibility from the lot to the mechanical room

Technical feasibility begins with the legal and physical envelope. We screen zoning, setbacks, lot coverage, height, infill rules, easements, municipality or historic review, tree constraints, well or septic conditions and the likely permit path. Our separate Montgomery County zoning guide explains how R-60, R-90 and R-200 standards can shape an addition, but every real property still requires address-specific verification.

Next comes buildability. We study where new foundations can go, how they connect to the existing house, which walls and floors carry loads, how the roof will drain, whether new openings need concentrated support and how construction equipment and materials can reach the work. A concept that looks simple in plan may be difficult if it requires underpinning, retaining work, long material carries or extensive temporary weather protection.

Building systems are part of the same test. Added bathrooms and kitchens affect plumbing and service capacity. New conditioned area affects heating, cooling, ventilation and electrical load. The study identifies which existing equipment might remain, which systems require further calculation and where new routes or equipment could be located without sacrificing the plan.

The goal is not to finish every engineering calculation during feasibility. It is to determine whether there is a credible technical path, identify the risks that matter and define what architecture, structural engineering, civil work or specialty investigation must happen next.

Step 4

Evaluate economic feasibility without pretending ROI is a single percentage

Economic feasibility compares the likely project investment with the owner’s budget, alternatives and expected value from the completed work. That value has two parts. Owner-use value includes years of better daily function, the cost and disruption of moving, access to schools or family and the ability to remain in a preferred property. Market value asks what informed buyers may pay for the improved home compared with relevant local alternatives.

We build the cost side from the likely construction path: site work, demolition, structure, enclosure, mechanical systems, interiors, design, engineering, permits, long-lead materials and contingency. Early numbers remain ranges, but the assumptions are visible. A smaller addition with a kitchen and complex roof connection can cost more per square foot than a larger, simpler room because expensive systems and tie-ins are concentrated into less area.

ROI scenarios use current property and market information carefully. They are not appraisals and do not guarantee resale value. Their purpose is to compare concepts, show which assumptions control the result and help an owner decide whether the project remains sensible when cost, financing, time and uncertainty are considered together.

Step 5

Turn a promising direction into plans, specifications, budget and timeline

If the technical and economic analysis supports moving forward, the next package becomes more specific. Dena House can develop coordinated architectural plans that define layout, dimensions, exterior form and relationships to the existing house. Structural and other engineering work then establishes the load path and the systems required to make the design buildable.

Material specifications are developed with the plans. They identify the performance and finish assumptions behind the budget—from windows, roofing and exterior cladding to cabinetry, tile, fixtures and equipment. This reduces the gap between an attractive drawing and the work actually being priced.

The budget is organized in detail by trade and decision package rather than hidden behind one blended square-foot number. Allowances, exclusions, owner selections, investigation needs and contingency are stated. The timeline connects remaining design, engineering, permit review, procurement and construction so the owner can see which decisions must happen before each milestone.

See the residential addition feasibility example for a concise view of how these workstreams fit together.

Typical schedule

What happens during the two-month feasibility process

We work closely with the owner throughout the process. Feasibility is not a report prepared in isolation and delivered at the end. Each round should improve the decision while there is still time to change direction economically.