Did They Use R 13 For Ceiling Joists In The 70's - Insulation - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread
Display Modes
Old 06-25-2016, 08:26 PM   #1
Member
 
Join Date: Aug 2007
Posts: 289
Rewards Points: 534
Default

Did they use R 13 for ceiling joists in the 70's


Florida

I need to replace insulation in a small bathroom. I think the insulation is only R 13, but it is fluffed up in some areas, so it could be R 19. The joists are only 2x8's (not attic flat roof). Should I just put R 19 up? I don't want to block any airflow through the joists, as I'm replacing the insulation due to mold concerns already.
weatheredwood is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-25-2016, 10:16 PM   #2
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,661
Rewards Points: 124
Default

Re: Did they use R 13 for ceiling joists in the 70's


Hi weathered,
Do you know the original cause for the mold?
R-13 is possible in the 70's, but I'm not familiar with Florida or really warm climates, hiding in Maine. When I built in NJ about 72 they were at r-13 and within a couple of years went to r-19.

In any case, I suspect FL would be about r-30 now, but always confirm with local code authorities. Another concern is air leakage as all homes experience a lot of undetected air exchange. A typical number would be a complete air change in 3 hours. If your house is extremely tight then you can have air quality issues and even mold.

You are in Florida, but near the coast, up north, or down by the Keys. Looking for your daily humidity levels.

Bud
Bud9051 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-26-2016, 06:51 AM   #3
Member
 
Join Date: Aug 2007
Posts: 289
Rewards Points: 534
Default


I'm located in Central FL near Orlando. I think the mold was from inadequate ventilation. It was just on the surface of the ceiling drywall. I added a bath fan and added a drop from the Ac.
weatheredwood is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-26-2016, 07:01 AM   #4
Member
 
Join Date: Jan 2014
Location: Central Kentucky
Posts: 4,581
Rewards Points: 10
Default

Re: Did they use R 13 for ceiling joists in the 70's


R-19 was the standard zone 6 and colder in the 70's. Florida could be a different set of rules.

I personally would go back with R-19.

As you stated, your mold problem was most likely cause by lack of a fan. I experienced a similar problem in a rental unit here (mid 70's construction). A new ceiling, fan and oil based primer solved the problem some 10 years ago.
__________________
Colbyt
Retired drapery and home furnishings installer.
Fact: World-wide 96.5% of Covid-19 victims fully recover
Colbyt is offline   Reply With Quote
Old 06-26-2016, 07:11 AM   #5
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,661
Rewards Points: 124
Default

Re: Did they use R 13 for ceiling joists in the 70's


They make high density batts r-21 in fg and r-22 in mineral wool and you are correct, don't block the air flow.

As you know, mold was an inside issue. You can also add a delayed off switch to the fan so when you leave you turn it off and the fan will continue for some selected time. Also, make sure the undercut for the door is sufficient to provide a source of air fro the fan.

Note, if you have room for more insulation, there is nothing wrong with more, but best laid across the tops of full ceiling joists.

Bud
Bud9051 is offline   Reply With Quote
Old 06-26-2016, 08:57 PM   #6
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default

Re: Did they use R 13 for ceiling joists in the 70's


R-13 always has been for 2x4 walls/ceiling... R-19 (for 2x6 ceiling) compresses a couple of inches even without a vapor barrier helping as in a crawl .. as my "70's R-19 is now 1-1/2" thick.... good stuff. R-13 replaced the R-11 here around 2011, I doubt it was R-11 also for a 2x4 space.

You speak of not blocking the air-flow above the insulation; so it is a cathedral ceiling? Or are they horizontal ceiling joists with a pitch roof above on other framing where there would be air flow over the insulation... ?

You certainly don't want oil paint for a vapor barrier on the drywall in FL.

Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sister joists or to add joists in between... dftc Building & Construction 32 02-26-2014 09:54 PM
Replacing too-short joists after mud bed removal dgfit Building & Construction 5 01-02-2014 10:15 PM
Updating Timber & Balloon Framed Home (LONG POST) Pittsville Building & Construction 13 05-29-2013 12:15 PM
OSB Stronger than Plywood? Weathermaker01 Flooring 15 12-22-2012 09:06 AM
Strengthening Joists Before Basement Finish braverichard Building & Construction 16 06-20-2010 07:28 PM




Top of Page | View New Posts