Ceiling joists are TRUE 2x4s.
AWCs calculator is for regular dimensional shit… not the old true boards.
Do you think true 2x4s will be able to hold up a ceiling over a 10ft span, with no load other than insulation/drywall?
and ceiling fans…
The span is actually 20ft, but there’s a wall diving it in half. The wall is technically non load bearing as it was built within the last ~25 years, but was not there when the house was built 100 years ago… But in this case it will now be load bearing.
So, does NYSpeed think I should switch them out in favor of 2x6s?
I really would like to get 16-18" of insulation up there, then have plywood down so I can actually store things up there. But then I’m probably better off going with a truss design obviously.
It’s a rule of thumb that wherever I can use 2x6’s I use them. Not much of a price difference and allows for better insulation and sound proofing if you have an upstairs.
understood, but I’m just wondering if it’s worth tearing down all the existing ones to replace them… if it will offer much of a difference adding 1"… (4" vs 5.25")
For 16" o.c. sister in 2 x 6 SPF, especially if you plan storage above. Not worried so much about breakage, but sag. Sistering and nailing them togethet will give more strength but just a little more difficult to insulate, but not much.
What room is this for? Depending on OC and room we can better help you. I don’t recommend sistering joists unless I need to, non-load bearing joists are easy enough to remove if you have the know how.
and it’s my entire house, minus kitchen/laundry room, both of which were additions that I gutted/finished last year.
So living, bath, dining, bedrooms…
It’s only a 34’x20’ area… So it’s not big by any means (my house is only 792sqft).
2x6 theory aside for a minute…
How could you be able to insulate 16" or so, and then lay down plywood to make the space useable?
Going with a truss design is the best option I can think of.
I’m trying to get some storage space as I don’t have a basement, and live in a smaller sized house.
Unless I run 2x12s, then put some 2x4-6s running perpendicular to them then insulate and put plywood on top of that.
But that doesn’t seem very realistic.
I think I may just throw up some 2x6s, and forget about storage up there.
edit;
GF has my phone by accident, when she gets back I’ll throw up some pictures so you guys know what I’m looking at. :]
I’m really wanting to get a decent R value this year… last year I went through winter (my first year with the house), and paid about $1600 in propane.
Considering this house is 800sqft… That’s pretty awful. There was about 4" of insulation in the attic then.
However I’ve switched to wood heat for this year and maybe the next… Until I get around to putting in a propane forced air furnace. https://www.blazeking.com/EN/wood-chinook.html
I probably should tackle my rafters at some point too…
I somehow doubt 2x4 @ 24" OC is code for my size house.
granted the roof pitch is 1:1, but still.
Going to suck it up, and make a truss design up in the attic.
Anyone have any suggestions? Looking for a 12-14" rise.
I’m honestly thinking about just doing a simple warren truss w/ lap joints to the existing 2x4s.
But then I might sister a 2x6 on the 2x4 joists, then run the truss design off the 2x4…
Hum.
Oh boys.
CLIFFS:
Basically, a 20Wx34L room, with true 2x4 ceiling joists.
Trying to insulate to 16-18", which being able to lay down ply above it for storage.
18" OC
The 2x4s in the picture perpendicular to the joists have 2x4s running up to every other rafter.
[ATTACH=CONFIG]18952[/ATTACH]
Solution #1:
Sister a 2x6 on to the existing 2x4s.
Build a warren truss, Using the 2x4 as the bottom chord, being nailed in to the 2x6 as a lap joint.
2x4s as lateral braces, with a 2x6 as the top chord.
All lap joints, to save $$ on the metal whatchamacallits.
Obviously it will need to be with inclined end posts… The roof pitch is 1:1, so 45 degrees, and a warren truss is at 60 degrees, so that might prove to be a slight problem, but one easily dealt with.
Cost is approx $36/joist (with a shitload of labor to boot)
Blown in fiberglass R value = ~3.25 (actually 2.2-4.3 depending on how retarded you are)
R value = ~58
Solution #2:
Sister on plain 2x12x20s, blow in insulation and call it a day.
Cost = $22/joist
R value = ~39
Solution #3:
Scrap the idea of storage in a tiny fucking house (who needs storage anyway?), and sister on 2x6s.
R value = Whatever the fuck I want
Thoughts?
If I ran 2x12x20s, I could just run 2x4s or something the opposite way to give more height for extra insulation.
i’m pretty sure you want at least R49 up here, but Somewhere around 65-70 is the preferred.
OK, without actually seeing the whole splace, here’s what I can tell you. Your determination on the use of the “attic” space will determine what you want to do for a ceiling.
Storage:
Depending on what you’re storing up there will determine the size of the ceiling joist needed. You mentioned earlier the span was 20’ with a center bearing wall. Assuming this is the case, I would go no less than 2 x 6 and you can go Spruce, or Doug Fir if you want stiffer. This limits your insulation value if you go with a plywood or OSB floor. You would only ba able to run up to an R-21 with that cavity (based on fiberglass) Other products may offer greater value. Unless you’re storing engine blocks for Choda up there, general storage should be fine. Especially if you’re going to sister and nail to the original 2 x 4’s, you will be plenty strong. If you want storage and more insulation, you’ll need to bump up the joists or get insulation with higher R values.
Non storage:
You can still run 2 x 6 ceiling joists, but without the flooring above your insulation options are wide open. You can layer R-38 batts, or go blown in and insulate to the extent your budget allows. Minimum good insulation R-38 to R-49.
In either scenario, I would consider the joist spacing. If it were me, I would run the new joists to 16" o.c. to allow for installation of Kraft faced fiberglass as well as ease of installation of drywall. If you just want to sister to the 2 x 4’s for additional strength and simplicity, suffer through a few more drywall cuts and waste and do blown in above after the fact. I don’t know what your access to this attic space is like. Based on a 12/12 roof pitch and the age of the house, I would guess the roof rafters are pretty stout and don’t really need the benefit of a truss construction, although you could run strongbacks, from the mid-span of the rafters or the ridge board, to the center wall if it makes you feel better. You also need to consider lengths for installation. I don’t think your gonna be able to run 20’ers of anything and get them in. Go 12’ers and lap the joists as I assume they did with the original 2 x 4’s.
Again, you have some options but you need to determine what your goals are for the space above. I don’t know how you’re going to access this space and how much it will be used so it’s up to you how badly to want to make it storage. No matter what you do, read up on attic ventillation and make sure your insulation does not choke off your bottom edges of the roof to allow for better ait flow up there.
thanks qikz,
there is an attic stairway, I actually replaced it in the winter as the old one opened, but didn’t have any stairs and was framed AWFULLY.
So attic access is no problem.
I think I can squeeze 20s up there, barely.
I have some unused 2x8x20 PTs that I can use to try to squeeze in there as a demo, if I decide I feel like trying to muscle it up there.
I’m more than likely going to suffer through the extra cuts of drywall, just going to use the longest I can grab from gypsum supply after I do some math when the time comes.
Roof rafters are 2x4 24" OC, with 1x6s perpendicular to them and ~2" gap in between each.
No ply or anything as such, just many, many previous roofs. I had quite a ways to drill when I was popping a hole for a bathroom vent.
Here’s a picture of them.
[ATTACH=CONFIG]18954[/ATTACH]
Is R39 good enough for these our area? Or is it going to be 10+ years or so to see a return on the expense?
I’m not too knowledgeable on the diminishing returns of fiberglass.
Be cautious using PT lumber indoors. As far as insulation, never done the math but i guess it would also depend on furnace efficiency and how well the rest is insulated. Guess you could add more down the road. If you’re not seeing deflection in the roof rafters by now, you’re ok. Lot of old houses are constructed better than people think. If you re-re-roof anytime soon, please do it right and strip it.
No harm in using PT lumber indoors, it does not off-gas or leach at all. Why not use regular lumber though? Unless you plan on having a moist and damp attic? It’s not cost effective in my mind to use PT lumber inside unless it’s for a bathroom or garage.
Some of you guys have alot of knowledge I’d like to learn. Ever let anyone do grunt work with you and essentially apprentice once in awhile?
I need to gut my bathroom and want some other stuff done to the house but lack the knowledge at the moment. This is stuff I’ve always wanted learn…I only learn hands on though. 8/