Room Addition Cost Estimates
How to Estimate Room Addition Costs and not
Blow Your Construction Budget
By: Mark J. Donovan
Building a room addition is an
expensive endeavor and in general is not a do it yourself project. Typically a
series of contractors are required in building a room addition. Most homeowners,
however, hire a general contractor who provides the overall room addition cost
estimate and handles the hiring and managing all of the other contractors (a.k.a.
subcontractors). This said, sometimes homeowners elect to act as their own
general contractor to save anywhere from 15 to 30% on the overall cost of the
project. However, undertaking the role of a general contractor involves a lot of
First and foremost, the homeowner
needs to come up with the room addition cost estimate him or herself. And to do
this he or she has to generate/obtain the room addition build plans, calculate
the bill of material costs, and find, interview and hire all of the
subcontractors. Then they need to schedule and manage the daily workings of a
large team home construction project. So think twice before deciding to be your
own general contractor on your room addition project. Now with all this said,
I’ll focus the rest of this article on estimating room addition costs.
Building a room addition is an
expensive proposition. Home remodeling contractors typically specify room
addition costs in dollars per square foot to provide a rough order of magnitude
cost estimate. Room addition cost estimates are commonly 30-50% higher on a cost
per square foot basis then building a new home, due to the fact that a room
addition typically is more complicated to build. A room addition is more
complicated to build due to the fact that not only does it need to be
constructed, but it also has to tie into the existing home in a structurally and
aesthetically correct way.
This effort takes time and money,
both in the design and construction of the room addition. Consequently home
construction contractors charge a premium when providing a room addition
Room addition cost estimates can
vary dramatically due to a number of factors, chief amongst them being what
is specified in the room addition plans. For example, room addition costs
estimates of $80 to $130 per square foot for a basic family room addition is
If the room addition includes
bathrooms and/or a kitchen, the room addition costs can easily escalate to
$200-250 per square foot. So for example, if your room addition plans specify
the construction of 400 square feet of family room living space, without any
type of bathroom or kitchen area, you can expect to pay $32,000 - $52,000 for a
completed addition. If, on the other hand you are including a bathroom and/or
kitchen, you could see room addition cost estimates as high as $100,000.
|Room addition cost estimates can also vary with market
demand for building material and home construction labor. Price gouging is
not uncommon during hot housing markets, so it is important to study
contractor proposals carefully. Do not hesitate to visit your local home
improvement store and compare material costs if you think you may be getting
priced gouged on a contractor cost estimate. Keep in mind, however, that the
costs you see at the local home improvement store and from the contractor
will differ somewhat.
The contractor is in business to make money, and his time and
effort is money, so you need to expect some premium charge for the materials
that he orders and has delivered to your room addition project.
When obtaining room addition cost
estimates make sure your contractor provides you with a comprehensive
construction bid that includes a checklist of all the tasks to be performed, the
material to be used, and a detailed schedule of when the work will be performed.
To help in obtaining accurate and
consistent room addition contractor quotes, see my
Addition Bid Sheet. The Room Addition Bid Sheet provides a
request for quote section that you can provide to prospective building
contractors. It also includes a comprehensive room addition cost breakdown
table, in Microsoft Excel format, that allows the contractor to include his
projected room addition costs for every phase of the project.
Photo by Mark Donovan
The key to obtaining accurate room
addition cost estimates is to have a complete set of room addition plans and
specifications. The more thorough your plan, the less likely for unwanted cost
overrun surprises. By having a complete set of room addition plans, you can
price out every single building material item, even down to the curtain rod. By
including this level of specification you can avoid including TBDs and
contractor allowances in the room addition cost estimates. TBDs and contractor
allowances are the “third rails” of home addition projects as they inevitably
lead to higher than anticipated room addition costs.
For more help on building a home addition, see HomeAdditionPlus.com's
Addition Bid Sheets.
Addition Bid Sheets
provide you with the knowledge and information on how to plan a home addition project,
and what to look for when hiring contractors. They
also include detailed cost breakdown tables and spreadsheets for estimating
your own new home addition building costs.
Related Building Home Addition Articles
Additional Home and Room Addition Resources from Amazon.com
Free Room Addition
Price Quotes with No Obligation!
Fill out our 3-5 minute quick and easy form, and receive a free price quote
on a room addition from one of our prescreened and licensed home addition
contractors. This process is free and there is no obligation to continue once
you receive your room addition estimate.