adding ceiling joists and insulating a vaulted ceiling
I am a DIY homeowner looking for a solution to a rather unique problem. My home was built in 1972.
My living room has a vaulted ceiling with exposed 4×8 beams on 48″ centers. The beams rest on a center 4×8 support beam below them. The wall framing is standard 2×4 on 16″ centers with double 2×4 top plate. The ceiling is a hot roof with no insulation. It is 1×4 tongue in groove covered by sheathing, tar paper, and shingles. The temperature in the room is about 4 degrees different than the other rooms because it loses heat/cool.
I would like to add additional ceiling joists between the beams to cut down to 24″ center, insulate, and finish with tongue in groove leaving only the center support beam exposed.
My problem is:
How should I tie in the new joists to the wall?
How should I insulated to prevent moisture/rot and achieve better temperature control?
Will the 24″ span be adequate for the tongue in groove to prevent sagging?
Thanks in advance for your help and input
Replies
Not clear what is behind the wall on the left in your photo.
You might be better off to insulate above the roof deck.
What does the rest of the house look like, related to the roofline and ceiling?
Are sure of the current T+G being only 3/4” thick?
I’d guess at the time these would have been 2”.
24 OC is probably plenty to support 3/4 t&g material. You would want to cut your drywall back to land your intermediate rafters on top of the walls. Don’t get too crazy removing drywall and you won’t have anything to fix. Snap a line and use an oscillator… and a vacuum. You may have to tinker with the rafter cuts to get something that can slide in and still have some meat to fasten to the top of the wall. If the existing supports are 8” nominal using 2x6 would be easier, no reason to go full depth.
If you want to see that center beam make sure you measure ahead of time for your material and any trim and pull some string lines to check for bows or out of plane conditions.
As far as insulating climate zone matters but here’s an article
https://www.finehomebuilding.com/project-guides/insulation/five-cathedral-ceilings-that-work
Option 4 seems promising considering your fixed depth. Might be expensive but it’s probably not something to skimp on.
joining Calvin on the T&G thickness
if you have sheathing (usually 3/4", sometimes less) and 1x4 t&g, gives you maybe 1 1/2 inch
if the shingles are or were standard 3 tab, held by 1 1/4 nails, hand nailed in 1972, sounds like you might have some nails popping through
maybe not the case if it's been reroofed at some point.
I'd go with Uncle Mike and check out re-roofing with rigid foam on the roof sheathing for insulation
good luck, Merry Christmas
Sorry for the delayed reply to all of your help and direction. Lots of holiday distraction!
Unclemike: The wall to the left is the entryway hall. The home is a traditional ranch with a gable end roof and 8' drywall ceilings. This room is the living room with vaulted ceiling and gable end at the right of the front entry.
Calvin: Yes, the current tongue and groove is only 3/4. It really is under built by today's standards.
Firedudec56 : Funny you mentioned the nails coming through. When it was re-shingled 7 years ago, initial nails came through. Luckly, the worker realized what was happening and adjusted.
zoocat: I think this is how I will proceed. Thanks for the help.
Thank you all for sharing your expertise. I run an auto repair shop in Georgia and really appreciate skilled craftsman and their willingness to share experience!
Cool!
Repair shop in Georgia!
We travel and camp a lot. Will give you a call if we have “sensor problems” in our Sprinter…….
To tie in the new joists, you could use hurricane clips or metal brackets to securely fasten them to the wall. For insulation, consider using foam board or spray foam to prevent moisture buildup and ensure a proper vapor barrier. As for the 24" span, it should be fine for tongue and groove, but you might want to double-check with the wood thickness you're using to prevent sag