My wife and I are in the middle of re-claiming our 3 season front porch and we are interested in suggestions or best approach for insulating it so that it can be turned into a year-round room.
Here are the details — The porch is a one story structure attached to the house and set on concrete footers. The dimensions are 9ft deep by 30ft wide. The floor joists are 2 x 6. The original wood floor is solid. There is a 3ft crawl space underneith that has a plain dirt floor. The outside and inside wall material is stucco. Lattice covers the opening between the bottom of the floor and the ground so the crawl space is exposed.
To date we have removed the old windows (broken) and repaired the two corner posts (rotted), installed two additional posts, and re-enforced the floor joists. While we were renovating, we were able to put bats of insulation in the outside walls. We plan on installing new double pane windows and a hard wood floor.
We figure that we have to insulate the floor and the ceiling. For the floor I am concerned that it will be difficult to keep the insulation dry due to the exposed crawl space. For the roof, I am looking for suggestions. We need to re-shingle anyway so taking some shingles off to get access is not an issue.
Let me know if I left out any details. Thanks in advance for your help.
Replies
I've lived and worked over various crawl spaces for years and think I've come up with some "best methods" to combat the three problems: moisture, critters, and cold feet. There seems to be a preponderance of evidence that points to SEALING crawl spaces. Do a search on this BB or internet to find lots of recommendations.
Probably will lead you to replacing the lattice with pressure treated plates, studs, and plywood (stucco over the plywood?) putting down at least 6 mil plastic continuous over the dirt and up the new inside crawl space walls, and perhaps using rigid on the inside crawl space walls and extended into the perimeter ground as far as you can economically get. Then of course there's always fiberglass bats in the joist spaces with 7/16 OSB nailed from underneath. Or if you're going to pull the subfloor, you could rip the OSB to fit and fasten on 2X2 ledgers from the top, then insulate and floor.
But then you said you wanted to "reclaim" the porch...
Where is this located? in town or out in the country? What climate?
Edited 4/14/2003 2:32:02 PM ET by johnnyd
We live in an urban neighborhood in Minneapolis. For the most part the space is fairly dry outside of the obvious -- rainy/snowy days.
Do you necessarily have to seal the whole space with plywood, poly, etc or can you seal off the insulation between the joists much like making a horizontal wall and leave the space open? Are we dreaming that we could have an insulated porch with an open space beneith (only covered by lattice)?
I also didn't understand you comment about ripping up the sub floor. I can get at the joists from underneith w/o ripping out anything. Maybe I misunderstood.
No, I've actually got a cabin with a floor deck, suspended on posts and beams over a sloping site. It's made of 2X8s, 3/4 " plywood on top and 7/16 OSB on the bottom with fiberglass batts in the joist spaces. It's tolerable for occasional winter use, but the floor IS cold, and when I add on to the cabin this summer, I will be using wood stem walls for the addition, sealing that crawl space, and eventually create a sealed crawl space under the cabin too, as we plan to live there year-around.
This is out in the woods of SE Minnesota, so I have a potential of critters getting in, which you probably don't have to worry about.
Wouldn't hurt to try just insulating in the joists and see how you tolerate the floor. You'll have do do that part anyway, and if it's not acceptable, you can always go the next step and seal off the space.
Thanks for the advice. We will probably try an insulate the joists first and see how it goes. The three outside walls are already windows that run 2/3 the height of the wall so I don't think the room will be very warm on some Jan days no matter what we do. On the plus side it does have a SW exposure so it can get pretty warm from the sun.
One question -- Do I need to use any kind of a vapor barrier or just the OSB on the bottom of the joists?
Mike
I just used OSB right on the joists...in two cases, one an addition over a very tight crawl space with no venting but not "sealed", and one on the cabin discussed above. The addition has one room with 3/4" maple over felt (tarpaper) and 3/4" subfloor and an entry and bathroom with vinyl over the subfloor. That bathroom floor is COLD, the hardwood not so bad. I think you should definately apply felt under your finished floor. Good luck.
Interesting technique on the cabin...since the floor deck is on post and beams (20X24 with three beams on ~8' centers) we nailed the joists together in 4 ' sections, applied the OSB underneath while the platform was cantalivered out over the low side of the slope, and then slid the whole assembly onto the beams, ready for the next section. The last slide into final position was a grunt, but three of us with some help from a sledge just managed. Then we filled in with fiberglass on the top and laid the subfloor over.
We've done a few of these. We used 2" rigid insulation in between the joists then seal it up with 1/2" sheething held in place with 2"x 2" works well and not to hard to install.
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