adding a 3-season room to R.V.

[jackcsr87]

Hey guys, I'm building a 3-season room next to my r.v. The dimensions are 11' out and 30' across. The height at the trailer is 8'6" and 7'6" at the parallel wall. I got 50 14' 4x4's for free , so can I use them for the roof ? I will put them 12" o/c and sheet with 1/2 " plywood. Will that hold for that span, and what would you reccomend for roofing material and insulation ? Thanks, Jack

[tooltroll]

That's my kind of overkill! Hell, if I had 'em, I'd double them into 4x8s and put 'em on 24" centers- If it's only a 3 season room, why bother insulating? It's just a glorified gazebo with big screen windows, right? Leave them big'ol 4x8s exposed as decoration.
1/2" might be a little light for the plywood, and for a roof pitch that shallow, you can't use shingles- you have to use a flat roof product. (Anything under a 2- or 3- in 12 pitch roof is like that, I believe... not sure where the change is...)

[Tykster]

What i would use is as usual some tar paper first and then some Ice/water shield.. It comes in 50' rolls.. I use it at my job all the time for temporary walls... It works excellent and last about 10 yrs.. Well thats what it says on the box..If you do decide to use that, I would by some SHIPLAP wet/dry roofing cement to cover your nail heads... its very fast,simple and effective...

[jackcsr87]

Thanks guys, Actually Tooltroll, it's going to be a little more than a screen room. I'm putting 12- 30"x65" doublehung windows in that I got for a good deal too. So I'll be insulating the walls with r-13 . I wish I would have done some insulating with the floor but I think it's too late. I'll have a wood burning stove in there also. The walls are 2x4's with 1/2"plywood then vinyl siding (mostly windows anyway) do you think I should bother with housewrap (tyvek) ? I do have a roll of 6 mil. visqueen but would that be a good thing to wrap the walls with either on the interior or exterior ? I'll be hanging out there during hunting season, so the warmer the better. Momma thinks I'll be roughing it in the woods...Ha..Ha !!!

[Sweep]

Am I correct in assuming that you will not be getting a permit?

[tooltroll]

OK, gotcha. I'd still double up the 4x4s to give a thick insulation cavity. Don't know if I'd bother with tyvek with so many double-hungs (I'm assuming they're older, non EE, since you're getting them on the cheap.) Visqueen is a damp proofing, not an air infiltration barrier- I suppose you could use it as a vapor barrier, but as a wrap (on the exterior) it'll cause moisture problems. Do the tar paper and ice shield, like Tykster suggested, and cover it with a roll roofing product to protect the ice shield from physical damage (hail, tree branches, etc.)

[Sweep]

For a roof slope of only 1" per foot roll roofing must use the concealed nail method. An alternative is 19 inch-selvage double coverage roll roofing. These methods involve the use of a great deal of asphalt cement.
It would be easier to raise the high point of the roof until it has a minimum slope of 2.5 inches per foot and install self-sealing asphalt shingles with ice & water shield underlayment (no roofing felt).

[jackcsr87]

Thanks Tooltroll and Sweep, So you say 2.5 inches per foot. That would put the high end 27.5 inches above the low end. That also puts me at 9'-9". The trailer is 8'...my question would be how do I flash that 1'-9" from the trailer to the top of the high point ? or do I just make a little wall there and side it and flash under the siding and onto the trailer roof ? I was trying to keep that end low so I could flash a few inches on the roof ... down the gap and onto the trailer roof with one piece of flashing. But if you got an idea....I'm all ears. thanks, Jack

[Sweep]

There is a flashing tape that is just like ice & water shield but it has a thin aluminim face. If the surface of the trailer is clean/smooth and you use a small heavy roller to apply it, it might work at the base of the wall you describe.

[Tykster]

HD sells Ice/water shield that is self adhesive...It hase a film backing that will overlap your next piece of 6"... You can lay your first piece, and before you adhere your first piece to your second, tack a few nails 4" back of where your first piece will overlap your second...On a hot day it will self bond pretty darn good within minutes...if not you can pick up a little propane bunzomatic torche maybe 15 bucks, and just run it along each joint to seal it immediatly..

[Sweep]

The only advantage of the aluminum surfaced tape is that it can be left exposed to the weather & sun but Ice & Water Shield cannot.