Doing an addition for a customer. It is on concrete piers about 2.5 ft off the ground.
The platfrom will be 2×10 framed with 3/4 advantech floor sheathing.
on the bottom I will putting 1/2 plywood over 3/4 foam. to seal out the
vermin etc.. And r-30 fiberglass insulation.
I really don’t want to put the insulation in from below. Minimize crawlling around in the dirt. I plan on putting the underplywood on as I frame the floor.
Given that, any have a opinion on;
1) put the fiberglass and let the construction adhesive and T&G keep it dry for a couple of weeks.
vs.
2) Frame the walls directly on the 2×10 framing and put the advantech down temporarily and then pull it up once the addition is weather tight and insulate then.
or any other good suggestions!
Replies
Toolin,
1) put the fiberglass and let the construction adhesive and T&G keep it dry for a couple of weeks.
This will not keep it dry.
You could build a large tent over the project or:
Sheath bottom / insulate / deck the top / cover the deck wrapping the edges down with one piece of 6 mil poly with no joints or laps if possible / protect the poly with a product such as 1/8" Thermoply (inexpensive 1/8" laminated cardboard sheathing / thin and strong) / frame on top of the Thermoply / when "dried-in" cut out the Thermoply and plastic
If you must lap the plastic use a window wrap on the joint and do it well.
We have done this before for the same reasons and it worked.
tx
"This will not keep it dry."Maybe 95%
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95% if it does not rain. : - )
Aside from that, if it performs to 95%, I would not want 5% dampness in the insualtion that is sealed on both sides, unless I am starting a mold farm.
I don't know that either #1 or #2 will work very well. #1 sounds like the insulation will get wet anyway, and #2 sounds like more trouble than just installing the insulation and plywood underneath after you are completely dried in.... which is what I would do.
this sound like a job for sip panels as floor underlayment
Frame the walls in your shop, bring them on your landscape trailer - precut the rafters, or have the trusses ready. Have everything ready and a crew on hand.
Hit it hard and dry it in.
Toolin,
how big is the addition and will you need to run plumbing/electrical/HVAC ?
Geoff
Addition is 13' x 32'. one of the 32' sides is attached to the house. Have one outside faucet that needs to be extended and the oil tank fill and vent.
Electric can be done in the wall without to much trouble.
Force hot water heat also.
Could pre run this without any problem. But it is starting to add up. And with the conclusion that the insulation won't stay dry. I think I am going for a version on
pulling the floor up later.Current thought.
Along the long 32' wall put a 1' strip of sheathing down. Build that wall on it normal construction. Add a series of blocking in the two outside joists bays to support the floor and the wall, Build these walls directly on the joists. Put the floor sheathing down temporarily with screws until the building is weather tight.Another idea I had was in the two outside joist bays. Add two more 2x10 joists. Spaced off of the rim joist by 2" foam board. This give me a bearing surface for the Floor sheathing on the edges. If I used 1.5" insulation it would be perfect, picking up half of the wall and the floor.Thanks for taking the time to opine.PS; This is a solo job. The only time I have a crew is when I forget to take my meds and Sybil shows up!!
with a 13' wide frame, you can run a sheeet of decking a foot wide or so on the whole outsdie frame for under that wall, leaving a layout of three four foot sheets to get back to the rest of the house, and frame or floor under the short walls just like you said, to leave a nailing edge for sheathing to attach to later.
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Last summer, we had to put a second story over an existing house. To facillitate an open floor joist inspection, and still get the second story "dried in", we pre built all the walls and set them on a 1x6 that we installed around the perimeter. We just spread the plywood around loose.
blue
In that scenario what is your plywood nailed to around the edges? Doesn't sound like it goes under the walls to the rim joist.
see if this detail explains it.
Sure, that detail makes sense parallel to the joists, but you will also need blocking perpendicular to the joists at each exterior wall line. It seems like a LOT of work to me to avoid some time getting dirty. Don't you have to put the foam and plywood on from underneath too? How much longer can it take to install the insulation. If this is just about avoiding a little crawling then I don't understand it. It certainly would not make sense to me as a contractor framing a job for a price.
If the clearance under the joists is painfully low, then maybe I'd change my tune. Maybe you addressed that previously and I missed it.
Blocking.
blue"...if you just do what you think is best testing those limits... it's pretty easy to find exactly where the line is...."
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I forgot what we were talking about.
Well thanks to all that chimed in on this one.
As someone earlier said, it just all sort of fell into place when I started framing.
Had 3/4" foam board on site two layers made the perfect spacer between
the two rim joists allowing me to frame the walls and still be able to
pull the floor up later for insulation.here are some pics of the progress to date,
What about using spray foam insulation instead of the fiberglass batt insulation?? Just throwing that out there, havent really thougt out the pro's and con's of it.
Thought about the foam, it solves the wetness problem but doesn't help with the utility rough in. For the extra expense I think I would rather solve both.
once you understand the "natural order of things" the tasks fall into place...
in most cases there really is only one logical order inwhich to do things.
p
I just did one like that a couple months ago
I ripped some scrap into 1x2s and tacked it at the bottom insides of the joist spaces. Then I ( this was small 10' x 12' space and I always have short ends and window cutouts of sheathing around) used shorts of ply or osb sheathing and const adhesive to fit them in the bottoms. The 1/8" gaps between sheets would allow water out if any got in.
Then I ripped foam ins, laid it in on the ply nice and snug, then filled her uyp with unfaced batts, and sheathed over with T&G Advantech, glued and nailed. I used PL Premium adhesive for the glue and hit the seams and joints too for a fairly weather tight floor deck.
I had it framed in a week later and had two heavy rains meantime.
I have done the same once before with no trouble. These were within a foot of the ground.
I also did one more the way you describe about 2-1/2 feet off the ground several years ago with a constant sheathing across the bottom of the joists. I driled a few holes in that to let water escape during construction, then filled them over when the roof was on.
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Suggestion #2
After you frame the floor, roll on elastomeric roofing & proceed at whatever pace you want. Come back and squeegee out the door openings if it rains.
HD carries the Henry line at $56 or so for 5 gals - 2 coats should do it - lots less work!
I've also seen this done with rolled roofing. there is a local contractor that specializes in adding second floors to ranch style houses. He installs a rolled roof over the new floor, then just leaves it there, and installs his UL right over it.
The only difference is that he does not have to worry about vapor barriers. You would need to make sure you do not trap moisture if you do this.
I would think that'd be a disaster trying to get a flat finished floor, given the extra 1/8" at laps in rolled roofing
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Good point. I do not know how he handles the overlap. I thought it was a good idea when he explained it, but I never experimented with it. This guy said he's done it a number of times, and just leaves it there under the UL.
I've done similar once with ice and water shield
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we do additions all the time. Often we lay the subfloor and glue and nail as normal but leave 1-3 sheets only attached with a few screws, this gives us the ability to pull them up and have large openings to the crawl after things are dried in. Just cut the bottom of the groove off and lay the piece down like normal. this way the tongue will still slide in and the top groove is left to cover the tongue on the next piece.
that size addition one man can insulate in about 4 good hours so you pop up the pieces jump in and bang out the insulation and then when all the crawl work is done including hvac and mechanical you glue and nail the t&g down for good.
Edited 12/31/2006 12:32 am ET by dinodad
sub out the insulation. They can probably do the job, l & m for what you can buy the insulation for anyway.
What about a tempered crawlspace?
You would be surprised at how well construction adhesive seals osb edges, especially pl. Once the sheets are down, apply enough adhesive so it will fill any voids when smoothed out with a 4" putty knife. Work the adhesive into the wood and try to leave a thin film over the osb.
Do the same with any stray nail holes.
Sounds crazy, but we've had seams hold up under weeks of constant rain and it only takes an hour and a case of const. adhesive to do a good job on a job your size.
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