Call us at 1-888-447-1946

Custom Plan Modification Services

The easy and affordable way to design your custom home

Redlining - fastest & easiest!

Very minor changes requiring only notes/drawings added to plan, great for communicating design intent with your builder, accepted by most building depts.


  • Changing exterior materials
  • Adding/Removing windows or doors
  • Moving interior non-bearing walls

Cost: $100 - $200 + cost of plan

Includes a phone consultation with a designer

Small Changes

Minor changes affecting components but not footprint or house size.


  • Flipping two rooms around keeping existing dimensions
  • Changing garage to side entry
  • Changing exterior walls from 2x4 to 2x6

Cost: $500 - $1000 + cost of plan

Includes a phone consultation with a designer

Medium-sized Changes

Changes affecting rooms and layouts but not footprint or actual house size.


  • Small garage expansion
  • Enlarging/shrinking existing rooms
  • Changing roof pitch

Cost: $1100 - $1900 + cost of plan

Includes a phone consultation with a designer

Major Changes

Significant plan changes affecting more than 350 square feet and/or house footprint.


  • Changing house footprint
  • Adding new rooms
  • Reconfiguring room locations

Cost: $2000 and up + cost of plan

Includes a phone consultation with a designer

Frequently Asked Questions:

What is a modification?

A modification is a change in the architectural plan of the house. Depending on the scope of the changes, edits can be made to the exisiting plan or the plan may need to be redrawn. Our in-house plan experts and designers can assist you with these edits. Commonly requested modifications include:

  • Changing windows & doors
  • Changing ceiling height
  • Stretching or reducing square footage
  • Swapping room positions
  • Adding/removing garage spaces
  • Reconfiguring outdoor spaces
  • Changing materials

Anything on a plan can be modified. We can answer any questions and provide you with quotes for all desired changes.

How much do modifications cost for your house plans?
This is a great question. We will be happy to provide you a Free Modification Quote for most of our house plans. Since each plan is different and each modification request is unique, it is hard to give a price without knowing which plan you like and the changes you want to make to it. We can tell you the average cost of modifications, in addition to the cost of the Reproducible set or CAD set, is between $900 - $1500.
Why do modifications cost more than the original plan?
A finished home design is the result of many hours of work by one or more highly trained architects or home designers. To create a design and working drawings for a new home lower-end designers charge $3-$10 per foot and well-known architects are paid $25,000 and up. Our ready-made plans are priced much lower because they are sold and built multiple times and they are available imediately. When a plan is modified, an architect or designer charges their standard hourly rate. Often modifications that seem simple will require changes to multiple floors, windows and the roof and foundation.In the end, starting with a $1,000 plan (that would have cost $25,000 if you engaged the architect in a traditional relationship) plus $2,000 to significantly modify the plan to make it perfect for you and your site still represents a huge savings in both money and time.
How long do modifications take?
Your modification project starts the minute you place your order. The timeline for receiving your modified plans depends on how quickly you respond to your designer and the scope of the changes involved. Quick changes that don’t affect other parts of the plan may simply require a brief conversation with a designer and a few hours of design work. Significant modifications involving multiple floors or redesigning major features may require more back-and-forth with your designer and the new drawings may need a few weeks to be finalized. Timeline estimates will be included with your quote. Regardless of your changes, we will customize your plans as efficiently as we can.
Can I make minor changes to the design and not have to change the house plan drawings?
Many of the changes you may want due to lifestyle preferences are probably modest, and often these can be done by your builder without modifying your plan at all. Changing the garage space or door location, changing interior walls, eliminating or changing windows, reconfiguring a kitchen--these are things, depending on where you live, that this kind of information.
If my local building codes require some major structural changes, will a stock plan still cost less than an original customized house plan?
Yes. If you're "lucky" enough to live in a place that has earthquakes, hurricanes, or floods, think of the structural modifications this way: Whatever modifications your local building codes require, the additional drawing time to account for these prerequisites will be the same, whether you commission an original house plan or modify a stock plan. The modifications are likely to be straightforward, and with a stock plan, you have the advantage of a drawing that's already been tested in the real world. But even with modifications $1,000 or more, purchasing a stock house plan is still more economical than a custom plan.
If I buy a set of plans from Houseplans, can I have them modified?
Yes. With the purchase of a Reproducible set or a CAD set, Houseplans Services Inc. can make the changes for you. You are also able to take either of these sets to a local professional to have changes made. To have Houseplans provide you with a quote to make changes, please click on "Modify This Plan" button on the plan detail page.
If I've already purchased my plan and then find out I have to modify it, can I avoid buying a new set of plans?
Yes. If your building department mandates changes to your house plan for your permit or if you discover something on your site that makes modifications unavoidable or for whatever reason you need to modify your drawings--after you've purchased your house plan--don't worry. You don't have to start over and buy a new set of complete house plans. We will give you a credit from your original stock plan purchase towards a reproducible set of the same house, if it's available, which you can have modified. With reproducible plan sets, you also receive a license that permits you to make up to 10 copies of your plan set to complete your house. So you don't have to start over, you can move forward. To determine the amount of the credit, please contact us at 1-888-447-1946.
What if the foundation option I'm looking for is not available with the house plan I want to buy?
You should call us so that we can verify whether it's available. Often, changing a foundation type is a very simple matter and can be done during construction without modifying the drawing. If your building department requires drawings that describe the exact foundation you are planning to use, Houseplans Services Inc can design your foundation. You also have the option of purchasing either the reproducible plan set or the CAD-file version (if available), and hire a local designer to make the changes for you.
Do you offer custom designed house plans?
Yes. You can build your own uniquely designed home with the expert help of Houseplans. Our custom home design service provides extraordinary possibilities, affordably. Save thousands of dollars on architect and design fees when you work with us to create a custom home design with a low, fixed price. Use our team of designers to create a custom home plan in only a few short weeks. We work with you through several design iterations to create your dream home and ensure that it has everything you're looking for. Once you finalize and approve the custom home plan then we provide the construction documents, blueprints, and plans you need to build your own home. Click here to learn more about our Custom Home Design Service.
Do you offer Additional Services?

Yes. In addition to ordering a Stock House Plan, Houseplans Services Inc., can provide the following services. To receive more information or a quote for these services, please give us a call at 1-888-447-1946.

  • County / City Research
  • Design Review Drawings
  • Site Plan
  • Energy Analysis
  • Title-24 Energy Calculations
  • *Structural Engineering
  • Systems Integration
  • Materials List
  • Plumbing Drawings (Isometric)
  • HVAC drawing
  • Plan Check Revisions
  • CAD file upgrade
  • California Service Package - * County / City research * Site Plan * Title 24 * Venting calculations & Details * Structural Review & Coordination
  • 3D Renderings
  • 3D Design Services
  • BIM (Building Information Modeling)

* Structural Engineering is provided and coordinated through our engineering partners. Houseplans LLC is not an engineering firm.

If a Material List is not available, can you create one?

Yes. If a material list is not available, please give us a call to receive a quote for a new material list. If you decide to have Houseplans create a material list, we have two lists available (Basic or Premium)

  • Basic Materials List
  • Framing Material
  • Hardware
  • Roofing
  • Siding
  • Decking
  • Insulation
  • Sheetrock
  • Premium Materials List
  • Foundation
  • Framing Material
  • Hardware
  • Roofing
  • Siding
  • Decking
  • Windows
  • Exterior/Interior Doors & Trim
  • Insulation
  • Sheetrock
  • Paint
  • Flooring
  • Cabinets
  • Appliances
  • Plumbing Fixtures
  • Bath Accessories

* Materials lists are estimates and not a guarantee of all the material needed for each project.

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