2020-B1-7

Author Topic: Ceiling joist advice  (Read 332 times)

b_hill_86

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Ceiling joist advice
« on: December 01, 2020, 12:00:46 AM »
Been searching around with little luck and though I’d ask you guys. I seem to remember maybe Kerry is a carpenter or maybe you guys have experienced something similar and can offer some advice.

I’ve got a 1954 built 2 car 20.5 W by 22 D garage I’m looking to finally finish and insulate inside. It’s built 24 on center with rafters and joists but the ceiling joists are laid at every other rafter and are 2x6s across the 20.5’ span.

My plan was to hang 5/8 ultralight drywall and lay some R-30 fiberglass insulation on top. I don’t plan on storing anything above except what’s there since I literally have no place else to store it and that’s only two plastic empty coolers, two plastic lawn chairs and two metal lawn chairs. And honestly I’d pitch the chairs and find a new home for the coolers if I needed to.

I know I will have to add joists where there are none to at least make them 24 on center but my question is, with the 20’ + span, what size is appropriate for the new joists and as for the existing 2x6s would sistering 2x6s to them be sufficient or should I step up to 2x8s or replace them altogether with all the same size.

What I was thinking was 2x10s where there aren’t joists and sistering 2x8s to the existing 2x6s but I can’t find anything definitive as to whether or not that will be strong enough to hold up 5/8 ultralight drywall and R-30 with no storage.

Thanks in advance and sorry for the long post.
-Brian-

1977 Trans Am 400 4 speed

roadking77

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Re: Ceiling joist advice
« Reply #1 on: December 01, 2020, 07:17:18 AM »
If youre going 2' o.c. def need to use 5/8" wallboard. I would def. sister the 2x6 with at least a 2x8. For no load, a 2x8 would most likely work at that span but if it were me I would go bigger. Not sure if you have priced lumber lately but it is OUTRAGEOUS!  You may be able to get a manufactured I joist for around the same price as dimension lumber. Thats all we use now for floor joist. I would check a 'real' lumber yard and give them the span and they should be able to offer great advice. An I joist will be better for the job and better for your back!
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b_hill_86

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Re: Ceiling joist advice
« Reply #2 on: December 01, 2020, 08:54:42 AM »
Hey thanks I really appreciate it. I have seen lumber prices and you’re right. Hopefully by the time I want to start this next year it’ll come down. I’ll look into the I joist too.
-Brian-

1977 Trans Am 400 4 speed

ryeguy2006a

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Re: Ceiling joist advice
« Reply #3 on: December 01, 2020, 10:28:00 AM »
That's why I've halted the construction on my garage was because of how expensive the lumber has gotten. It should have cost me about $100 to finish it off, but with the prices today, it was $250! I'll wait until the spring to move forward.

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roadking77

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Re: Ceiling joist advice
« Reply #4 on: December 01, 2020, 05:01:56 PM »
I was talking with my brother the other day, he lives in Canada and is also in the construction field. He was telling me how outrageous the cost of lumber in the Great White North was as well, I said I thought thats where it all came from and figured it would be pretty cheap, he thought the same!!
Finished!
77 T/A - I will Call this one DONE!
79 TATA 4sp-Next Project?
79 TATA - Lost to Fire!
86 Grand Prix - Sold
85 T/A - Sold
85 Fiero - Sold
82 Firebird - Sold
'38-CZ 250
'39-BSA Gold Star
'49-Triumph 350
'52-Ariel Red Hunter
'66-BSA Lightning
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Nexus

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Re: Ceiling joist advice
« Reply #5 on: December 02, 2020, 10:33:42 AM »
I was talking with my brother the other day, he lives in Canada and is also in the construction field. He was telling me how outrageous the cost of lumber in the Great White North was as well, I said I thought thats where it all came from and figured it would be pretty cheap, he thought the same!!

YA...tell me about it...feels like thee is an extra terrify on all products just because we are Canadian, then there's the extra taxes, but...mostly free (by free I mean out taxes pay for it) health care!!

sorry...topic derailed a little bit


If the roof holds a snow load as is, then I would be inclined to beef up the rafters that need it, and use blown insulation in the attic. This will fill all the nooks and crannies...vapor barrier and strap the roof prior to drywall!!

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« Last Edit: December 02, 2020, 10:37:55 AM by Nexus »
Charlie

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Ford5of5

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Re: Ceiling joist advice
« Reply #6 on: December 09, 2020, 11:40:56 PM »
I've run into this a lot with old garages. Without a ceiling, the framing member you are describing is called rafter tie; with dead space above and no ceiling, the ties are only helping to prevent the walls from spreading and the roof from dipping along the ridge. When it becomes a floor or a ceiling structure, then it becomes a joist. I know, I'm being nit-picky, lol.

Where do you live? Snow load is a factor and you may want to consider adding an upper rafter tie. Going by a generic, online span chart, you need a 2x8 at 24" oc at minimum for the joists to hang drywall. If you're going to store anything with weight you need to consider 2x10 at 16" oc. Try searching Google for a "joist span chart".

I recently added a second floor to my garage and used 16" I joists at 16" oc to span 24'; X2 with Roadking, I joists are real easy to install, but sistering with them is a different matter as is installing them with a roof in the way. Mine cost $125 each, but I splurged for top of the line joists. And as a carpenter in Massachusetts I can tell you that lumber costs have doubled, at the least! Pressure treated lumber and certain size bolts and lags are getting hard to come by too.

Someone else mentioned it but I will reiterate. Go to a lumber yard and ask them to spec out a joist for you. Many yards have someone, sometimes an engineer, that can recommend the proper size lumber or engineered product. I always patronize Braintree Lumber for things like this because they usually provide a report for the inspectors to not look at.  :lol:

For insulation, consider calling in a spray foam company. The closed cell foam does wonders for rigidity although, only time will tell if that rigidity will still be around in 10 years. Also, for open cell foam, the installed cost isn't that much more than buying product from Home Despot and doing it yourself. Recently, I've used mineral wool insulation; I was happy with the ease of install and the customers tell me that they like the sound control and lack of drafts but, I was replacing 20 year old fiberglass batt so almost anything is better.
« Last Edit: December 10, 2020, 12:08:28 AM by Ford5of5 »

Ford5of5

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Re: Ceiling joist advice
« Reply #7 on: December 09, 2020, 11:58:01 PM »
https://up.codes/viewer/massachusetts/irc-2015/chapter/8/roof-ceiling-construction#R802

this is a link to MA building codes. They get wonky about species. Usually in this area we are using yellow southern pine or SPF lumber, it's a mixture of spruce, pine and fur.
« Last Edit: December 10, 2020, 12:03:29 AM by Ford5of5 »

b_hill_86

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Re: Ceiling joist advice
« Reply #8 on: December 10, 2020, 07:00:35 AM »
Hey thanks for your advice I really appreciate it. Thanks for everyone’s
-Brian-

1977 Trans Am 400 4 speed

roadking77

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Re: Ceiling joist advice
« Reply #9 on: December 10, 2020, 07:58:20 AM »
Agree completely with Ford. I like your comment on the drawings. The last 3 truss jobs I did they didnt bother to look. I know you and I have parallel careers, Im sure you are the same as I am, I have built and demoed enough stuff over the years that I know instinctly the right way to do things. However when it comes to spec'ing out framing I just let the engineers take care of things. In the old days before Lawyers were on the tv didnt have to worry about it. I had one job with a structural beam failing (not mine), it was cracked and deflecting about 4 in. over 20'. I told the owner they needed to get an engineer to come up with a fix. Owners reply was that it was only the drywall cracked not the beam :shock: :shock:
Finished!
77 T/A - I will Call this one DONE!
79 TATA 4sp-Next Project?
79 TATA - Lost to Fire!
86 Grand Prix - Sold
85 T/A - Sold
85 Fiero - Sold
82 Firebird - Sold
'38-CZ 250
'39-BSA Gold Star
'49-Triumph 350
'52-Ariel Red Hunter
'66-BSA Lightning
'01-HD RoadKing

Re: Ceiling joist advice
« Reply #9 on: December 10, 2020, 07:58:20 AM »
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