FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Building a Bumpout For Gas Fireplace

cookieman | Posted in Construction Techniques on October 27, 2005 07:46am

Am installing a gas/direct vent fireplace in my LR (1st floor over full poured concrete basement) and need to build a 12″ bumpout so only half the fireplace projects into the room. How should this be framed, insulated and enclosed….exterior is vinyl siding? Really want to avoid dealing with concrete footing…….since bumpout will be 12-24″ above ground and about 12″ deep, think that should be OK. Checked this site and Fine HomeBuilding mags I have for How-To-Do articles but came up empty. Please help asap. Thanks.     

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. User avater
    CloudHidden | Oct 27, 2005 07:53pm | #1

    One that I saw was framed with a recessed tv nook above. Very convenient place to put it and a good use of "free" space. Not what you asked, but something to consider as you plan the whole thing.

  2. cookieman | Oct 30, 2005 03:09am | #2

    Can't someone out there please help me with this?

    1. User avater
      fengelman | Oct 30, 2005 03:33am | #3

      I've installed several this way and it always worked for me...first I determine the overall dimension of the unit across the front, then I add two wall thicknesses, and two sheet rock thicknesses, add a little wiggle room, and use this as the rough opening...

      I cut this opening thru the wall, and header it off, now the sneakey part...I sheath the bump out to the new trimmer studs, and build the floor inside of this opening...then build the walls on top of the floor, insulate, sheet rock, etc...

       

      the overall effect is that the entire unit is supported by the sheeting, that is supported entirely by the trim studs....if this interests you at all, let me know privately, and I'll be able to make a sketch for you, or offer any othe rhelp I can....

    2. piko | Oct 30, 2005 03:44am | #5

      So, you've access to the u/s of the floor? See which way the joists run, and if you can scab on about 4' or 5' of similar-sized joists to run thru the rim-joist to the o/s, thereby creating a cantilever for the req'd depth of stove . Glue and nail well .

      Ah, you've only access from the house. Since your stove is  only halfway into the wall it kind of balances, doesn't it? Make a rough opening 1-1/2" larger than req'd with doubled studs each side, then use 3/4" plywood to create the sides of the bump-out. This will cause everything to 'hang' off the studs. Frame out around the o/s, to code. Put a nice little roof on it. If you want to be sure - a pair of knee-braces under to help support the load. Don't forget that code stuff for base and roof as well as walls - don't need the heat going o/s, eh.All the best...

      To those who know - this may be obvious. To those who don't - I hope I've helped.

       

  3. Framer | Oct 30, 2005 03:33am | #4

    Are your floor joists exposed in the basement so that you can cut the box out and slip in joists and cantilever them outside?

    You'll also have to cut out your outside wall and put a header in. Is there a second floor above this outside wall?

    Also, is there a basement window underneath where this fireplace will be above?

    Joe Carola



    Edited 10/29/2005 9:34 pm ET by Framer

  4. Danno | Oct 30, 2005 03:09pm | #6

    If the bumpout is not even with the existing first floor (sounds like you are considering putting its floor maybe a foot higher?) you could remove a piece of the rim joist on the second floor and sister "extension" joists to the existing joists (if they run the correct way) and sort of hang the bumpout from them. Or do the other poster's idea of hanging it from the sheathing on the sides--or a combination of both. If the joists run parallel to the bumpout, you could build a "ladder" (like you would frame an overhang on a gable end of a roof) and nail that to the rim joist. It would be stronger though if you could tie it back into the last joist about 16" in from the rim joist.

    If you did this at the top and bottom, it would be a lot stronger than you need. And even if the bumpout floor is higher than the first floor, you could still extend it from the existing first floor joist and build a new floor up from those, or you could make the bottom a series of right triangles with the longest legs as the supports angling down to the rim joist and the members that act as the floor tied into the wall studs. Putting OSB or plywood on top, bottom and sides, glued and nailed would make it really strong (could even put in one or two traingular plywood gussets in the middle glued and nailed to the frame members. Make roof the same way.

    Probably way more than you wanted to know!

  5. Framer | Oct 30, 2005 03:53pm | #7

    I would be a good way to build it on top which has been mentioned. You can build it as if it was a 12" window projection. Which I also do with 3/4" plywood going in flush to the inside of the jack stud. I even cut the slope of the roof out.

    If you want a raised hearth it would be even easier. You can build a platform by setting 2x6's or 2x8's or whatever height you want sticking past the house 12" and then whatever your inside depth rough opening is plus the length of the hearth you want.

    If the inside depth is 25" and you want a 16" hearth your platform will be 41". The rough opening width you would add for the thickness of the walls for each side. On the inside of the house you can make the walls wider so that you can have space on each side of the fireplace for a mantle or tile. This way the outside box isn't to wide.

    If you didn't want it raised it can still be done but that would put you closer to the grade level which I don't think you want.

    I drew a raised hearth situation for you. I hope it's clear.

    Joe Carola
    1. cookieman | Oct 31, 2005 12:35am | #8

      Everyone.......Thanks for your advise.

      Joe.........thank you for the drawing.......sorry didn't respond to questions in your (Joe) earlier message but was out most of day. Fireplace will be flush with LR floor but outside ground under that portion of house slopes so bottom of bumpout will be 18"-24" above ground.

      Since fireplace will be 10-12" into LR (and its 22" deep overall) almost all its weight will be supported by the LR floor/joists and the basement foundation wall, so seems to me method of attaching 3/4" plywood sides to trim 2"x6" and attaching bumpout framing (2"x4" with 2" + 1" foam insulation board & sheetrock)  to that will work for my application.

      Again thanks to everyone for your responses. 

       

      1. Framer | Oct 31, 2005 02:47am | #9

        No problem, Cookieman.Just make sure that the pipe has enough clearance around the header being that it's sitting half in and half out> Do you have a cross section with all the dimensions of the fireplace yet?Here's the drawing with it flush to the floor.Joe Carola

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

FHB Podcast Segment: Finding the Right Fixer-Upper

Get expert guidance on finding a fixer-upper that's worth the effort.

Featured Video

How to Install Cable Rail Around Wood-Post Corners

Use these tips to keep cables tight and straight for a professional-looking deck-railing job.

Related Stories

  • Guest Suite With a Garden House
  • Podcast Episode 688: Obstructed Ridge Vent, Buying Fixer-Uppers, and Flashing Ledgers
  • FHB Podcast Segment: Finding the Right Fixer-Upper
  • Keeping It Cottage-Sized

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data