Almost every house plan site offers to change their stock drawings to suit your specific requirements. That's a valuable service - but be careful, some seemingly small changes can be expensive to make, and even more expensive to build.
One Change - Lots Of Drawings
There was a time when changes to house plans were done in the field with no documentation at all. If you wanted to make the house a little bigger, you only needed tell your contractor - and you didn't have a plans examiner and a building inspector looking over your shoulder.
But as we'll learn in Chapter #4 "A Set Of House Plans Isn't Enough", building codes across the country are getting tougher and plans examiners are looking at house plans more closely. When a change is made to a set of drawings, that change must be as well documented as the original plans, regardless of the size or complexity of the change. Sometimes that's not a big deal but sometimes it requires quite a few changes to the set of drawings and expensive changes to the house itself.
Consider for example, a theoretical two-foot extension of a family room at the back of a two-story house with a basement. If you're working with a typically complete set of plans, your two-foot extension will require a change to all of the following drawings in order to be accepted by your local building department:
Foundation plan
First floor plan
Second floor plan
Roof plan
Left side elevation
Right side elevation
Rear elevation
Main building section
Those are just the "architectural" drawings - you'll also need to have structural changes made, which may require review by a Registered Architect or Professional Engineer. And in areas that require compliance with energy codes, those calculations will have to be redone.
Don't let this scare you away from considering altering your design - just be sure you get a firm quote on all of the work needed to get your drawings completely ready to submit for permits. Or better yet, find a plan that doesn't need these changes.
Some plan services have popular "pre-designed" additions and alterations with all of the necessary drawings already completed. If one of those designs meets your needs, that's a much more efficient and cost effective way to go.
Consider The Impact On The Rest Of The House
If you find that the change you want to make isn't offered as a pre-design, you may want to have a custom alteration made. But don't get caught up in major changes - the trick is to avoid doing so much modification that you'd have been better off choosing another plan, or designing a custom home from scratch.
Every day, my staff counsels homeowners who have gotten their home design almost done - and then added just one more room. Too often we find that final room (frequently a screened porch) is difficult or impossible to blend seamlessly into the design.
If they don't consider the entire design from day one, they risk "cobbing up" a perfectly good home plan.
The same concept applies to pre-designed house plans. Don't buy one that has almost everything you want and assume that your other rooms can be easily added. That one more room could mess up everything you fell in love with about the house plan in the first place.
Adding rooms to a completed plan can sometimes start a chain reaction of changes - the new room blocks a bedroom window; the window can't be moved without moving a wall; the moved wall makes the bath too small...etc.
Instead, take advantage of the "study plans" that most services offer. Buy a study set of the plan that's closest to what you want, and have the plan service or your design professional evaluate it for the feasibility of the change you want. Study sets aren't cheap, but they're a lot cheaper than having to rework an entire plan.
Architects Can't Stamp Plans
It's written somewhere on every plan service website: "You may need to have your house plans reviewed and stamped by a local engineer or architect."
Unfortunately, that's against the law in many jurisdictions - for Architects. By statute, Architects must prepare or supervise the preparation of architectural drawings before they can affix their seal or stamp to them. To do otherwise is called "plan stamping" and is a practice than can cost an Architect his license.
It's a bit of a catch-22; you have permission from the plan's author to alter the plans, but not from your state's Architect licensing board.
An Architect can - in some instances - stamp a set of plans he didn't prepare if he's made significant alterations to them. What's considered "significant"? That's for your Architect and his State Board to decide. If you're making lot of changes to the plans, you're probably in the clear, although there's no accepted legal threshold for what are "significant" changes. But what if the design you've found is OK as is, and you simply need to get it ready to submit for permits?
Ironically, a "non-architect" - a residential designer, drafter, or structural engineer - might be a better choice in this situation. As an Architect myself that's tough to say, but the law is the law!
For structural review the answer is easy - find and hire a local structural engineer to review the plans, size the structural members, and place his stamp on the set. An experienced structural engineer might catch a few "non-structural" code issues along the way, too.
For non-structural issues you may be able to have an Architect provide a sheet of standard notes that you can attach to the drawings - without the need to stamp the drawings. You may also be able to get this information from your builder, or from a residential designer or drafter.
But then again all this might be moot - since very few jurisdictions in the country require an Architect's stamp on single-family home construction drawings!
So check with your building department first - but don't assume an Architect can always "stamp" your pre-designed plans.
Minimum Code Compliance
Plan services sell plans that conform to the code that was in effect in the location the house was built, and at the time the house was built.
In the United States, local building codes are based on one of four current "model" codes. Each of those codes share similarities, but each has its differences, too. Each code goes through periodic revision, so they're constantly changing.
It's very likely that the house plan you buy will need some changes to bring it "up to code".
More importantly, however is the idea that the plan you buy will at best be only minimally compliant with the building code. That will get your plan past most building departments but will leave quite a bit of the specifications and details of the house undecided.
That's the case with most single-family construction drawings, even the ones you get from an Architect. It's your job to work with your builder and maybe your interior designer to address all the details you need to build out the interior and exterior finishes.
Check your plan service's list of drawings - some services include more detail than others. The plans are a good start, but you might still have a lot of work yet to do!
