How does a room addition cost to build?

So people ask all the time, “How much does a room addition cost?” Our average detached guest house cost’s about $100,000 to build.  That includes all permits, materials, designs, labor, etc.  There are many variables to construction costs. It depends on the scope of work, and the actual building materials that are going to be used. We build a lot of our room additions in Alamo Heights and Terrell Hills, the 78209 area. There’s a lot of two-bedroom, one-bath homes that families come in and purchase and immediately don’t have enough square footage. That’s where we come in and have to add an extra bathroom, bedroom, living areas to those smaller homes.

It’s really tough to say exactly a cost per square foot, because again, there’s just so many factors. Are we talking stone exterior? Hardy plank? Brick? Rock? Are we talking eight-foot ceilings? 10 foot ceilings? 20 foot ceilings? A lot of it, too, depends on if we’re adding plumbing or an additional restroom or moving a kitchen around. We’ve got to figure out how we’re going to tie in that plumbing to drains. A big thing is the sewer. How are we going to tie into the existing sewer line and whether it runs to the front or the back? The existing electrical needs to be looked at to see if the panel has been updated at all, where the service is located, and if the service will need to be relocated based on location.

For example, if you’re looking to add a room addition on the back of your house and the … You know, all the electrical lines run there, that panel … The meter is going to have moved. If there’s gas at the house, a lot of times the gas meter is located directly where the room addition has to go, and that, of course, needs to be moved as well. Again, there’s just so many variables. If you’re looking at kind of a bottom-of-the-basement starting price, I would use about $160 per square foot, and it quickly increases from there. We’ve done homes at $560 per square foot, and it just depends on the construction; on what type of materials you’re using, and a lot of things that just affect cost, you know. Formica countertops, marble, granite, quartz, quartzite.

Our average detached guest house cost’s about $100,000 to build.  That includes all permits, materials, designs, labor, etc.

Anyway, if you have any questions, we’d love to talk to you about your upcoming room addition. Give us a call.