Supporting A Crawl Space
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ssdave
Banned
Personally, I'd put in R-19 or above. Different types are different R values for different thicknesses, I'd compare to see what is most cost effective. You can get up to R30 in that space (with high density insulation), but it may cost a lot more. Floors are your least return for your money in insulating a house, ceilings are most cost effective and walls next, followed by floors. R-19 is a good compromise between cost and effectiveness. If more insulation is cost effective, it might be good to do more.
Unfaced is where you want to be. It is the least costly, and the vapor barrier will do very little for you in this case. If you did use faced, it would need to have the paper on the floor side, not the bottom.
Unfaced is where you want to be. It is the least costly, and the vapor barrier will do very little for you in this case. If you did use faced, it would need to have the paper on the floor side, not the bottom.
Leaflessshadetree
Well-known member
I don't see any X bracing between the joists. Those would be easy and cheap to add between each of the joists and should stiffen the floor a lot.
benjamintmiller
Well-known member
Start with the x braces and see how much they stiffen the floor.
On an existing floor, it may be easier to to cut a block of 2x12 (or whatever your joists are) and nail it in from both sides. Stagger the blocks so you don't have to toenail.
On an existing floor, it may be easier to to cut a block of 2x12 (or whatever your joists are) and nail it in from both sides. Stagger the blocks so you don't have to toenail.
ssdave
Banned
Personally, I'd do the beam first. It's easy, and automatically gives you 4 times the strength that you had before, plus dampens the bouncing. X bracing just transfers a part of the load to adjacent joists, and there's diminishing returns fast as you get away from the first joist. I'd estimate that it will increase the strength at any one area by less than 30%. Once you have a beam supporting the joists, the x bracing is simply redundant, and would have very little effect. I doubt that x bracing would help a lot with the bouncing, as the bouncing is probably already occurring across more than one joist. Bridging between joists with cross bracing won't help that appreciably. X bracing is a technique that's best suited for stiffening floors that you can't or don't want to have to support throughout the span. So, would be great for over a basement. Over a crawl space, who cares if you have one or more beams supporting to the ground? They're not in the way.
If I did bracing, I'd just do solid blocking, cut out of 2x10's and staggered a couple of inches so I could face nail them through the joists. Solid blocking is a lot more effective than bridging with x braces, and would get up close to the possible 30% strength increase I guessed at before. Plus, solid blocking is easier to install on an existing floor. The only problem I see with blocking or x bracing is that it can make a floor squeak. A beam support shouldn't do that.
Highbeam
Well-known member
Add another beam. Match the one already there in terms of construction method. No guessing, easy. I use pier blocks with a hole on top, adjustable height saddles that support a 4x4 post up to the beam.
ludakris04
Well-known member
this would be my first step...
pmiranda
Well-known member
Yeah, unless the floor is deflecting, then IMO the bounciness is just due to a lack of stiffness. Some blocking would address that. Of course, adding another beam that puts pressure on all the joists would also add stiffness, damping the vibration at mid-span and is probably even easier, if a bit more expensive.
Ok.......someone help me guesstimate how much insulation I will need?
I have 16" OC joists, 2x10s
The joists are running roughly 229" length wise
The beam will be 23'6" long......so I should have 18 joists in the room
I have roughly 360 feet of insulation needed? Sound right?
I have 16" OC joists, 2x10s
The joists are running roughly 229" length wise
The beam will be 23'6" long......so I should have 18 joists in the room
I have roughly 360 feet of insulation needed? Sound right?
cowboy73
Well-known member
The joists are 229" so about 19 feet long. The length of the room is 23.5'. 19 X 23.5 = 446.58 sq ft. I would consider holding up the insulation with hardware cloth and some fender washers instead of the wire things. It would be guaranteed not to sag that way. A 3ft wide roll of hardware cloth wouldn't be to hard to maneuver in the crawlspace.
teal95
Well-known member
For your base I would dig a hole about 12" x12" X 6" deep and pour a couple of bags of concrete. Then you know you have a solid base that isn't going to break or move.
csp
Well-known member
Your ductwork isn't insulated, so the crawl space appears to be a conditioned space. If that's the case you don't really want insulation between the floor joists. It's not going to do much good.
When selecting insulation, the deciding factor with Rvalue with batts is either what's available, your wallet, or the board's thickness. Get as thick as the limiting factor will allow. That should go without saying.
As for how much, get out your tape measure and figure out how long each joist bay is and how many bays there are. Each package/bundle of insulation will be labeled as to how many running feet it will cover, so just do some simple math. It isn't based on square feet with batt.
Batt insulation comes in both rolls and pre-cut lengths. They are the same thing. You decide which is better to use in your situation. Paper face goes towards the living space above in a crawl space.
When selecting insulation, the deciding factor with Rvalue with batts is either what's available, your wallet, or the board's thickness. Get as thick as the limiting factor will allow. That should go without saying.
As for how much, get out your tape measure and figure out how long each joist bay is and how many bays there are. Each package/bundle of insulation will be labeled as to how many running feet it will cover, so just do some simple math. It isn't based on square feet with batt.
Batt insulation comes in both rolls and pre-cut lengths. They are the same thing. You decide which is better to use in your situation. Paper face goes towards the living space above in a crawl space.
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Spot on man, thanks.......this was something I did not even think about
Yes, there is one large piece of duct work running down the entire crawl and also one side piece of duct work running to the other side of the crawl
So what you're saying makes sense to me, that the duct work itself will radiate heat/cold air (A/C) also behind what is being distributed through the two vents
For now, I will save time/money and not insulate the open area in the joists
I will focus on making the beam, running parallel with the other beam.......and support it by four adjustable columns and a solid concrete base
THANKS!
cowboy73
Well-known member
Most rolls of insulation I've seen also list a square footage coverage.
Just wanted to update this thread.........for $150, I went with the beam route
All bought during Menards 11% rebate sale, plus I had an old $15 rebate amount to use..........so $150 I was VERY HAPPY with the results
As some said, the floor did have a slight bow in the center of the room, near both walls and about 6 feet out it was very level, just sagged in the center
The original beam was 6 feet off the one wall, so I positioned this new beam 6 feet off the other wall............leaving a 7 foot span in between each beam
4 adjustable columns
4 square concrete pads
80 GRK screws
6 - 2x10x8 boards
I just had to cut about 5 inches off two boards, to fit the size of the crawl
Took about 3-1/2 hours, all by myself
The difference above the crawl, walking and jumping in the family room, is night and day different
How often, if any should the columns be re-tightened or checked? I was thinking every 6 months?
All bought during Menards 11% rebate sale, plus I had an old $15 rebate amount to use..........so $150 I was VERY HAPPY with the results
As some said, the floor did have a slight bow in the center of the room, near both walls and about 6 feet out it was very level, just sagged in the center
The original beam was 6 feet off the one wall, so I positioned this new beam 6 feet off the other wall............leaving a 7 foot span in between each beam
4 adjustable columns
4 square concrete pads
80 GRK screws
6 - 2x10x8 boards
I just had to cut about 5 inches off two boards, to fit the size of the crawl
Took about 3-1/2 hours, all by myself
The difference above the crawl, walking and jumping in the family room, is night and day different
How often, if any should the columns be re-tightened or checked? I was thinking every 6 months?
toolmiser
Well-known member
Looks like a good job and successful. Since you were talking about insulation, and it is conditioned space, you might think about insulating the walls and sill boxes at some point.
There are two vents in the crawl, which lead out into the attached added shop
Obviously, when the house was built, these vents were on an outside exterior wall
Any issues or problems with dealing these two off? Sometimes paint fumes from the shop permeate inside the crawl and into the family room (above the crawl)
Obviously, when the house was built, these vents were on an outside exterior wall
Any issues or problems with dealing these two off? Sometimes paint fumes from the shop permeate inside the crawl and into the family room (above the crawl)
Definitely! When I bought my house, it was 1 year old and didn't have any insulation in the crawl space. Before I got it all insulated and sealed off, there was one area that had rotted and had to be replaced.
ssdave
Banned
Good Job! Nice work in wading through the BS and doing exactly what needed done.
The vents are to let air circulate and keep the moisture in the crawl space down. Not necessary if it doesn't get too damp in there. It looks like you have uninsualted ductwork down there, which will heat it somewhat, and I bet it's not sealed and leaks some air also.
The plastic on the dirt helps a lot. The block looks like it might leak a bit of moisture into the space, but hard to tell. If you can, tape the seams in the plastic you have on the ground, and around the posts you installed to keep moisture out.
You could try sealing the vents off and check periodically to see how humid it fees in the crawl space. You could also install some forced ventilation into the space; it would best be done through a heat recovery ventilator. If you do, look into doing a homemade one, the design that works well for a crawl space is a computer size fan blowing through an aluminum dryer duct suspended in a plastic pipe. The aluminum transfers heat between the incoming and outgoing air, to avoid bring in moist hot air in the summer, or cold air in the winter. Do a google search and you'll find a design. Until you start doing more to insulate the space and close off the leaks in your ductwork, I doubt that you'll see a problem.
The vents are to let air circulate and keep the moisture in the crawl space down. Not necessary if it doesn't get too damp in there. It looks like you have uninsualted ductwork down there, which will heat it somewhat, and I bet it's not sealed and leaks some air also.
The plastic on the dirt helps a lot. The block looks like it might leak a bit of moisture into the space, but hard to tell. If you can, tape the seams in the plastic you have on the ground, and around the posts you installed to keep moisture out.
You could try sealing the vents off and check periodically to see how humid it fees in the crawl space. You could also install some forced ventilation into the space; it would best be done through a heat recovery ventilator. If you do, look into doing a homemade one, the design that works well for a crawl space is a computer size fan blowing through an aluminum dryer duct suspended in a plastic pipe. The aluminum transfers heat between the incoming and outgoing air, to avoid bring in moist hot air in the summer, or cold air in the winter. Do a google search and you'll find a design. Until you start doing more to insulate the space and close off the leaks in your ductwork, I doubt that you'll see a problem.
Nice job. I had the same problem in my basement, but I added more cross bracing between the joists (about tripled the number of braces). It helped a lot.
But I was seriously considering doing what you did. The posts getting in the way was the only thing that stopped me from doing it that way.
I would consider sealing your crawlspace and insulating it. I did that at my cottage along with adding a dehumidifier and it's been a great improvement.
But I was seriously considering doing what you did. The posts getting in the way was the only thing that stopped me from doing it that way.
I would consider sealing your crawlspace and insulating it. I did that at my cottage along with adding a dehumidifier and it's been a great improvement.